cWEB/cweb.c

#include "cweb.h"
#define WL_NOINCLUDE
#define HTTP_NOINCLUDE
#define CRYPT_BLOWFISH_NOINCLUDE
////////////////////////////////////////////////////////////////////////////////////////
// 3p/chttp.h
////////////////////////////////////////////////////////////////////////////////////////

#ifndef HTTP_AMALGAMATION
#define HTTP_AMALGAMATION

// This file was generated automatically. Do not modify directly!

////////////////////////////////////////////////////////////////////////////////////////
// src/basic.h
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/basic.h"
#ifndef CHTTP_BASIC_INCLUDED
#define CHTTP_BASIC_INCLUDED

#include <stdbool.h>

// String type used throughout cHTTP.
typedef struct {
	char *ptr;
	int   len;
} HTTP_String;

// Compare two strings and return true iff they have
// the same contents.
bool http_streq(HTTP_String s1, HTTP_String s2);

// Compre two strings case-insensitively (uppercase and
// lowercase versions of a letter are considered the same)
// and return true iff they have the same contents.
bool http_streqcase(HTTP_String s1, HTTP_String s2);

// Remove spaces and tabs from the start and the end of
// a string. This doesn't change the original string and
// the new one references the contents of the original one.
HTTP_String http_trim(HTTP_String s);

// TODO: comment
void print_bytes(HTTP_String prefix, HTTP_String src);

// Macro to simplify converting string literals to
// HTTP_String.
//
// Instead of doing this:
//
//   char *s = "some string";
//
// You do this:
//
//   HTTP_String s = HTTP_STR("some string")
//
// This is a bit cumbersome, but better than null-terminated
// strings, having a pointer and length variable pairs whenever
// a function operates on a string. If this wasn't a library
// I would have done for
//
//   #define S(X) ...
//
// But I don't want to cause collisions with user code.
#define HTTP_STR(X) ((HTTP_String) {(X), sizeof(X)-1})

// Returns the number of items of a static array.
#define HTTP_COUNT(X) (sizeof(X) / sizeof((X)[0]))

// TODO: comment
#define HTTP_UNPACK(X) (X).len, (X).ptr

// Macro used to make invariants of the code more explicit.
//
// Say you have some function that operates on two integers
// and that by design their sum is always 100. This macro is
// useful to make that explicit:
//
//   void func(int a, int b)
//   {
//     HTTP_ASSERT(a + b == 100);
//     ...
//   }
//
// Assertions are about documentation, *not* error management.
//
// In non-release builds (where NDEBUG is not defined) asserted
// expressions are evaluated and if not true, the program is halted.
// This is quite nice as they offer a way to document code in
// a way that can be checked at runtime, unlike regular comments
// like this one.
#ifdef NDEBUG
#define HTTP_ASSERT(X) ((void) 0)
#else
#define HTTP_ASSERT(X) {if (!(X)) { __builtin_trap(); }}
#endif

#endif // CHTTP_BASIC_INCLUDED

////////////////////////////////////////////////////////////////////////////////////////
// src/parse.h
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/parse.h"
#ifndef PARSE_INCLUDED
#define PARSE_INCLUDED

#ifndef HTTP_AMALGAMATION
#include "basic.h"
#endif

#define HTTP_MAX_HEADERS 32

typedef struct {
	unsigned int data;
} HTTP_IPv4;

typedef struct {
	unsigned short data[8];
} HTTP_IPv6;

typedef enum {
	HTTP_HOST_MODE_VOID = 0,
	HTTP_HOST_MODE_NAME,
	HTTP_HOST_MODE_IPV4,
	HTTP_HOST_MODE_IPV6,
} HTTP_HostMode;

typedef struct {
	HTTP_HostMode mode;
	HTTP_String   text;
	union {
		HTTP_String name;
		HTTP_IPv4   ipv4;
		HTTP_IPv6   ipv6;
	};
} HTTP_Host;

typedef struct {
	HTTP_String userinfo;
	HTTP_Host   host;
	int         port;
} HTTP_Authority;

// ZII
typedef struct {
	HTTP_String    scheme;
	HTTP_Authority authority;
	HTTP_String    path;
	HTTP_String    query;
	HTTP_String    fragment;
} HTTP_URL;

typedef enum {
	HTTP_METHOD_GET,
	HTTP_METHOD_HEAD,
	HTTP_METHOD_POST,
	HTTP_METHOD_PUT,
	HTTP_METHOD_DELETE,
	HTTP_METHOD_CONNECT,
	HTTP_METHOD_OPTIONS,
	HTTP_METHOD_TRACE,
	HTTP_METHOD_PATCH,
} HTTP_Method;

typedef struct {
	HTTP_String name;
	HTTP_String value;
} HTTP_Header;

typedef struct {
    bool        secure;
	HTTP_Method method;
	HTTP_URL    url;
	int         minor;
	int         num_headers;
	HTTP_Header headers[HTTP_MAX_HEADERS];
	HTTP_String body;
} HTTP_Request;

typedef struct {
    void*       context;
	int         minor;
	int         status;
	HTTP_String reason;
	int         num_headers;
	HTTP_Header headers[HTTP_MAX_HEADERS];
	HTTP_String body;
} HTTP_Response;

int         http_parse_ipv4     (char *src, int len, HTTP_IPv4     *ipv4);
int         http_parse_ipv6     (char *src, int len, HTTP_IPv6     *ipv6);
int         http_parse_url      (char *src, int len, HTTP_URL      *url);
int         http_parse_request  (char *src, int len, HTTP_Request  *req);
int         http_parse_response (char *src, int len, HTTP_Response *res);

int         http_find_header    (HTTP_Header *headers, int num_headers, HTTP_String name);

HTTP_String http_get_cookie     (HTTP_Request *req, HTTP_String name);
HTTP_String http_get_param      (HTTP_String body, HTTP_String str, char *mem, int cap);
int         http_get_param_i    (HTTP_String body, HTTP_String str);


#endif // PARSE_INCLUDED

////////////////////////////////////////////////////////////////////////////////////////
// src/engine.h
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/engine.h"
#ifndef HTTP_ENGINE_INCLUDED
#define HTTP_ENGINE_INCLUDED

#ifndef HTTP_AMALGAMATION
#include "parse.h"
#endif

typedef enum {
	HTTP_MEMFUNC_MALLOC,
	HTTP_MEMFUNC_FREE,
} HTTP_MemoryFuncTag;

typedef void*(*HTTP_MemoryFunc)(HTTP_MemoryFuncTag tag,
	void *ptr, int len, void *data);

typedef struct {

	HTTP_MemoryFunc memfunc;
	void *memfuncdata;

	unsigned long long curs;

	char*        data;
	unsigned int head;
	unsigned int size;
	unsigned int used;
	unsigned int limit;

	char*        read_target;
	unsigned int read_target_size;

	int flags;
} HTTP_ByteQueue;

typedef unsigned long long HTTP_ByteQueueOffset;

#define HTTP_ENGINE_STATEBIT_CLIENT        (1 << 0)
#define HTTP_ENGINE_STATEBIT_CLOSED        (1 << 1)
#define HTTP_ENGINE_STATEBIT_RECV_BUF      (1 << 2)
#define HTTP_ENGINE_STATEBIT_RECV_ACK      (1 << 3)
#define HTTP_ENGINE_STATEBIT_SEND_BUF      (1 << 4)
#define HTTP_ENGINE_STATEBIT_SEND_ACK      (1 << 5)
#define HTTP_ENGINE_STATEBIT_REQUEST       (1 << 6)
#define HTTP_ENGINE_STATEBIT_RESPONSE      (1 << 7)
#define HTTP_ENGINE_STATEBIT_PREP          (1 << 8)
#define HTTP_ENGINE_STATEBIT_PREP_HEADER   (1 << 9)
#define HTTP_ENGINE_STATEBIT_PREP_BODY_BUF (1 << 10)
#define HTTP_ENGINE_STATEBIT_PREP_BODY_ACK (1 << 11)
#define HTTP_ENGINE_STATEBIT_PREP_ERROR    (1 << 12)
#define HTTP_ENGINE_STATEBIT_PREP_URL      (1 << 13)
#define HTTP_ENGINE_STATEBIT_PREP_STATUS   (1 << 14)
#define HTTP_ENGINE_STATEBIT_CLOSING       (1 << 15)

typedef enum {
	HTTP_ENGINE_STATE_NONE = 0,
	HTTP_ENGINE_STATE_CLIENT_PREP_URL      = HTTP_ENGINE_STATEBIT_CLIENT | HTTP_ENGINE_STATEBIT_PREP | HTTP_ENGINE_STATEBIT_PREP_URL,
	HTTP_ENGINE_STATE_CLIENT_PREP_HEADER   = HTTP_ENGINE_STATEBIT_CLIENT | HTTP_ENGINE_STATEBIT_PREP | HTTP_ENGINE_STATEBIT_PREP_HEADER,
	HTTP_ENGINE_STATE_CLIENT_PREP_BODY_BUF = HTTP_ENGINE_STATEBIT_CLIENT | HTTP_ENGINE_STATEBIT_PREP | HTTP_ENGINE_STATEBIT_PREP_BODY_BUF,
	HTTP_ENGINE_STATE_CLIENT_PREP_BODY_ACK = HTTP_ENGINE_STATEBIT_CLIENT | HTTP_ENGINE_STATEBIT_PREP | HTTP_ENGINE_STATEBIT_PREP_BODY_ACK,
	HTTP_ENGINE_STATE_CLIENT_PREP_ERROR    = HTTP_ENGINE_STATEBIT_CLIENT | HTTP_ENGINE_STATEBIT_PREP | HTTP_ENGINE_STATEBIT_PREP_ERROR,
	HTTP_ENGINE_STATE_CLIENT_SEND_BUF      = HTTP_ENGINE_STATEBIT_CLIENT | HTTP_ENGINE_STATEBIT_SEND_BUF,
	HTTP_ENGINE_STATE_CLIENT_SEND_ACK      = HTTP_ENGINE_STATEBIT_CLIENT | HTTP_ENGINE_STATEBIT_SEND_ACK,
	HTTP_ENGINE_STATE_CLIENT_RECV_BUF      = HTTP_ENGINE_STATEBIT_CLIENT | HTTP_ENGINE_STATEBIT_RECV_BUF,
	HTTP_ENGINE_STATE_CLIENT_RECV_ACK      = HTTP_ENGINE_STATEBIT_CLIENT | HTTP_ENGINE_STATEBIT_RECV_ACK,
	HTTP_ENGINE_STATE_CLIENT_READY         = HTTP_ENGINE_STATEBIT_CLIENT | HTTP_ENGINE_STATEBIT_RESPONSE,
	HTTP_ENGINE_STATE_CLIENT_CLOSED        = HTTP_ENGINE_STATEBIT_CLIENT | HTTP_ENGINE_STATEBIT_CLOSED,
	HTTP_ENGINE_STATE_SERVER_RECV_BUF      = HTTP_ENGINE_STATEBIT_RECV_BUF,
	HTTP_ENGINE_STATE_SERVER_RECV_ACK      = HTTP_ENGINE_STATEBIT_RECV_ACK,
	HTTP_ENGINE_STATE_SERVER_PREP_STATUS   = HTTP_ENGINE_STATEBIT_REQUEST | HTTP_ENGINE_STATEBIT_PREP | HTTP_ENGINE_STATEBIT_PREP_STATUS,
	HTTP_ENGINE_STATE_SERVER_PREP_HEADER   = HTTP_ENGINE_STATEBIT_REQUEST | HTTP_ENGINE_STATEBIT_PREP | HTTP_ENGINE_STATEBIT_PREP_HEADER,
	HTTP_ENGINE_STATE_SERVER_PREP_BODY_BUF = HTTP_ENGINE_STATEBIT_REQUEST | HTTP_ENGINE_STATEBIT_PREP | HTTP_ENGINE_STATEBIT_PREP_BODY_BUF,
	HTTP_ENGINE_STATE_SERVER_PREP_BODY_ACK = HTTP_ENGINE_STATEBIT_REQUEST | HTTP_ENGINE_STATEBIT_PREP | HTTP_ENGINE_STATEBIT_PREP_BODY_ACK,
	HTTP_ENGINE_STATE_SERVER_PREP_ERROR    = HTTP_ENGINE_STATEBIT_REQUEST | HTTP_ENGINE_STATEBIT_PREP | HTTP_ENGINE_STATEBIT_PREP_ERROR,
	HTTP_ENGINE_STATE_SERVER_SEND_BUF      = HTTP_ENGINE_STATEBIT_SEND_BUF,
	HTTP_ENGINE_STATE_SERVER_SEND_ACK      = HTTP_ENGINE_STATEBIT_SEND_ACK,
	HTTP_ENGINE_STATE_SERVER_CLOSED        = HTTP_ENGINE_STATEBIT_CLIENT,
} HTTP_EngineState;

typedef struct {
	HTTP_EngineState state;
	HTTP_ByteQueue   input;
	HTTP_ByteQueue   output;
	int numexch;
	int reqsize;
	int closing;
	int keepalive;
	HTTP_ByteQueueOffset response_offset;
	HTTP_ByteQueueOffset content_length_offset;
	HTTP_ByteQueueOffset content_length_value_offset;
	union {
		HTTP_Request  req;
		HTTP_Response res;
	} result;
} HTTP_Engine;

void             http_engine_init    (HTTP_Engine *eng, int client, HTTP_MemoryFunc memfunc, void *memfuncdata);
void             http_engine_free    (HTTP_Engine *eng);

void             http_engine_close   (HTTP_Engine *eng);
HTTP_EngineState http_engine_state   (HTTP_Engine *eng);

const char*      http_engine_statestr(HTTP_EngineState state); // TODO: remove

char*            http_engine_recvbuf (HTTP_Engine *eng, int *cap);
void             http_engine_recvack (HTTP_Engine *eng, int num);
char*            http_engine_sendbuf (HTTP_Engine *eng, int *len);
void             http_engine_sendack (HTTP_Engine *eng, int num);

HTTP_Request*    http_engine_getreq  (HTTP_Engine *eng);
HTTP_Response*   http_engine_getres  (HTTP_Engine *eng);

void             http_engine_url     (HTTP_Engine *eng, HTTP_Method method, HTTP_String url, int minor);
void             http_engine_status  (HTTP_Engine *eng, int status);
void             http_engine_header  (HTTP_Engine *eng, HTTP_String str);
void             http_engine_body    (HTTP_Engine *eng, HTTP_String str); 
void             http_engine_bodycap (HTTP_Engine *eng, int mincap);
char*            http_engine_bodybuf (HTTP_Engine *eng, int *cap);
void             http_engine_bodyack (HTTP_Engine *eng, int num);
void             http_engine_done    (HTTP_Engine *eng);
void             http_engine_undo    (HTTP_Engine *eng);

#endif // HTTP_ENGINE_INCLUDED

////////////////////////////////////////////////////////////////////////////////////////
// src/cert.h
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/cert.h"
#ifndef CERT_INCLUDED
#define CERT_INCLUDED

#ifndef HTTP_AMALGAMATION
#include "basic.h"
#endif

// This is an utility to create self-signed certificates
// useful when testing HTTPS servers locally. This is only
// meant to be used by people starting out with a library
// and simplifying the zero to one phase.
//
// The C, O, and CN are respectively country name, organization name,
// and common name of the certificate. For instance:
//
//   C="IT"
//   O="My Organization"
//   CN="my_website.com"
//
// The output is a certificate file in PEM format and a private
// key file with the key used to sign the certificate.
int http_create_test_certificate(HTTP_String C, HTTP_String O, HTTP_String CN,
    HTTP_String cert_file, HTTP_String key_file);

#endif // CERT_INCLUDED

////////////////////////////////////////////////////////////////////////////////////////
// src/client.h
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/client.h"
#ifndef CLIENT_INCLUDED
#define CLIENT_INCLUDED

#include <stdbool.h>

#ifndef HTTP_AMALGAMATION
#include "parse.h"
#endif

// Initialize the global state of cHTTP.
//
// cHTTP tries to avoid global state. What this function
// does is call the global initialization functions of
// its dependencies (OpenSSL and Winsock)
int http_global_init(void);

// Free the global state of cHTTP.
void http_global_free(void);

// Opaque type describing an "HTTP client". Any request
// that is started must always be associated to an HTTP
// client object.
typedef struct HTTP_Client HTTP_Client;

// Handle for a pending request. This should be considered
// opaque. Don't read or modify its fields!
typedef struct {
    void *data0;
    int   data1;
    int   data2;
} HTTP_RequestBuilder;

// Initialize a client object. If something goes wrong,
// NULL is returned.
HTTP_Client *http_client_init(void);

// Deinitialize a client object
void http_client_free(HTTP_Client *client);

// Create a request object associated to the given client.
// On success, 0 is returned and the handle is initialized.
// On error, -1 is returned.
int http_client_get_builder(HTTP_Client *client, HTTP_RequestBuilder *builder);

void http_request_builder_user_data(HTTP_RequestBuilder builder, void *user_data);

// Enable/disable I/O tracing for the specified request.
// This must be done when the request is in the initialization
// phase.
void http_request_builder_trace(HTTP_RequestBuilder builder, bool trace);

// Set the method and URL of the specified request object.
// This must be the first thing you do after http_client_request
// is called (you may http_request_trace before, but nothing
// else!)
void http_request_builder_line(HTTP_RequestBuilder builder, HTTP_Method method, HTTP_String url);

// Append a header to the specified request. You must call
// this after http_request_line and may do so multiple times.
void http_request_builder_header(HTTP_RequestBuilder builder, HTTP_String str);

// Append some data to the request's body. You must call
// this after either http_request_line or http_request_header.
void http_request_builder_body(HTTP_RequestBuilder builder, HTTP_String str);

// Mark the initialization of the request as completed and
// perform the request.
void http_request_builder_submit(HTTP_RequestBuilder builder);

// Free resources associated to a request. This must be called
// after the request has completed.
//
// TODO: allow aborting pending requests
void http_response_free(HTTP_Response *res);

// Wait for the completion of one request associated to
// the client. The handle of the resolved request is returned
// through the handle output parameter. If you're not
// interested in which request completed (like when you
// have only one pending request), you can pass NULL.
//
// On error -1 is retutned, else 0 is returned and the
// handle is initialized.
//
// Note that calling this function when no requests are
// pending is considered an error. 
int http_client_wait(HTTP_Client *client, HTTP_Response **res, void **user_data);

// TODO: comment
HTTP_Response *http_get(HTTP_String url,
    HTTP_String *headers, int num_headers);

// TODO: comment
HTTP_Response *http_post(HTTP_String url,
    HTTP_String *headers, int num_headers,
    HTTP_String body);

#endif // CLIENT_INCLUDED

////////////////////////////////////////////////////////////////////////////////////////
// src/server.h
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/server.h"
#ifndef HTTP_SERVER_INCLUDED
#define HTTP_SERVER_INCLUDED

#include <stdint.h>

#ifndef HTTP_AMALGAMATION
#include "parse.h"
#endif

typedef struct {
    void *data0;
    int   data1;
    int   data2;
} HTTP_ResponseBuilder;

typedef struct HTTP_Server HTTP_Server;

HTTP_Server *http_server_init(HTTP_String addr, uint16_t port);

HTTP_Server *http_server_init_ex(HTTP_String addr, uint16_t port,
    uint16_t secure_port, HTTP_String cert_key, HTTP_String private_key);

void         http_server_free              (HTTP_Server *server);
int          http_server_wait              (HTTP_Server *server, HTTP_Request **req, HTTP_ResponseBuilder *handle);
int          http_server_add_website       (HTTP_Server *server, HTTP_String domain, HTTP_String cert_file, HTTP_String key_file);
void         http_response_builder_status  (HTTP_ResponseBuilder res, int status);
void         http_response_builder_header  (HTTP_ResponseBuilder res, HTTP_String str);
void         http_response_builder_body    (HTTP_ResponseBuilder res, HTTP_String str);
void         http_response_builder_bodycap (HTTP_ResponseBuilder res, int mincap);
char*        http_response_builder_bodybuf (HTTP_ResponseBuilder res, int *cap);
void         http_response_builder_bodyack (HTTP_ResponseBuilder res, int num);
void         http_response_builder_undo    (HTTP_ResponseBuilder res);
void         http_response_builder_done    (HTTP_ResponseBuilder res);

#endif // HTTP_SERVER_INCLUDED

////////////////////////////////////////////////////////////////////////////////////////
// src/router.h
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/router.h"
#ifndef HTTP_ROUTER_INCLUDED
#define HTTP_ROUTER_INCLUDED

#ifndef HTTP_AMALGAMATION
#include "server.h"
#endif

typedef struct HTTP_Router HTTP_Router;
typedef void (*HTTP_RouterFunc)(HTTP_Request*, HTTP_ResponseBuilder, void*);;

HTTP_Router* http_router_init    (void);
void         http_router_free    (HTTP_Router *router);
void         http_router_resolve (HTTP_Router *router, HTTP_Request *req, HTTP_ResponseBuilder res);
void         http_router_dir     (HTTP_Router *router, HTTP_String endpoint, HTTP_String path);
void         http_router_func    (HTTP_Router *router, HTTP_Method method, HTTP_String endpoint, HTTP_RouterFunc func, void*);
int          http_serve          (char *addr, int port, HTTP_Router *router);

#endif // HTTP_ROUTER_INCLUDED
#endif // HTTP_AMALGAMATION

////////////////////////////////////////////////////////////////////////////////////////
// 3p/chttp.c
////////////////////////////////////////////////////////////////////////////////////////

#ifndef HTTP_NOINCLUDE
#include "chttp.h"
#endif

////////////////////////////////////////////////////////////////////////////////////////
// src/sec.h
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/sec.h"
#ifndef SEC_INCLUDED
#define SEC_INCLUDED


#ifndef HTTP_AMALGAMATION
#include "basic.h"
#endif

#ifndef HTTPS_ENABLED

typedef struct {
} SecureContext;

#else

#define MAX_CERTS 10

#include <stdbool.h>

#include <openssl/ssl.h>

typedef struct {
    char domain[128];
    SSL_CTX *ctx;
} CertData;

typedef struct {

    bool is_server;

    SSL_CTX *ctx;

    // Only used when server
    int num_certs;
    CertData certs[MAX_CERTS];

} SecureContext;

#endif

void secure_context_global_init(void);
void secure_context_global_free(void);

int secure_context_init_as_client(SecureContext *sec);

int secure_context_init_as_server(SecureContext *sec,
    HTTP_String cert_file, HTTP_String key_file);

int secure_context_add_cert(SecureContext *sec,
    HTTP_String domain, HTTP_String cert_file,
    HTTP_String key_file);

void secure_context_free(SecureContext *sec);

#endif // SEC_INCLUDED

////////////////////////////////////////////////////////////////////////////////////////
// src/socket_raw.h
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/socket_raw.h"
#ifndef SOCKET_RAW_INCLUDED
#define SOCKET_RAW_INCLUDED

#include <stdint.h>
#include <stdbool.h>

#ifdef _WIN32
#include <winsock2.h>
#define RAW_SOCKET SOCKET
#define BAD_SOCKET INVALID_SOCKET
#define POLL WSAPoll
#define CLOSE_SOCKET closesocket
#endif

#ifdef __linux__
#include <poll.h>
#include <unistd.h>
#define RAW_SOCKET int
#define BAD_SOCKET -1
#define POLL poll
#define CLOSE_SOCKET close
#endif

#ifndef HTTP_AMALGAMATION
#include "basic.h"
#endif

int  socket_raw_global_init(void);
void socket_raw_global_free(void);

int set_socket_blocking(RAW_SOCKET sock, bool value);

RAW_SOCKET listen_socket(HTTP_String addr, uint16_t port, bool reuse_addr, int backlog);

#endif // SOCKET_RAW_INCLUDED

////////////////////////////////////////////////////////////////////////////////////////
// src/socket.h
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/socket.h"
#ifndef SOCKET_INCLUDED
#define SOCKET_INCLUDED

// This module implements the socket state machine to encapsulate
// the complexity of non-blocking TCP and TLS sockets.
//
// A socket is represented by the "Socket" structure, which may
// be in a number of states. As far as an user of the interface
// is concerned, the socket may be DIED, READY, or in an internal
// state that requires waiting for an event. Therefore, if the
// socket is not DIED or READY, the user needs to wait for the
// events specified in the [socket->events] field, then call the
// socket_update function. At some point the socket will become
// either READY or DIED.
//
// When the socket reaches the DIED state, the user must call
// socket_free.
//
// If the socket is ESTABLISHED_READY, the user may call socket_read,
// socket_write, or socket_close on it.

#ifndef HTTP_AMALGAMATION
#include "sec.h"
#include "parse.h"
#include "socket_raw.h"
#endif

typedef struct PendingConnect PendingConnect;

// These should only be relevant to socket.c
typedef enum {
    SOCKET_STATE_FREE,
    SOCKET_STATE_DIED,
    SOCKET_STATE_ESTABLISHED_WAIT,
    SOCKET_STATE_ESTABLISHED_READY,
    SOCKET_STATE_PENDING,
    SOCKET_STATE_ACCEPTED,
    SOCKET_STATE_CONNECTED,
    SOCKET_STATE_CONNECTING,
    SOCKET_STATE_SHUTDOWN,
} SocketState;

typedef struct {
    SocketState state;

    RAW_SOCKET raw;
    int events;

    void *user_data;
    PendingConnect *pending_connect;

#ifdef HTTPS_ENABLED
    SSL *ssl;
#endif

    SecureContext *sec;

} Socket;

void  socket_connect(Socket *sock, SecureContext *sec, HTTP_String hostname, uint16_t port, void *user_data);
void  socket_connect_ipv4(Socket *sock, SecureContext *sec, HTTP_IPv4 addr, uint16_t port, void *user_data);
void  socket_connect_ipv6(Socket *sock, SecureContext *sec, HTTP_IPv6 addr, uint16_t port, void *user_data);
void  socket_accept(Socket *sock, SecureContext *sec, RAW_SOCKET raw);
void  socket_update(Socket *sock);
void  socket_close(Socket *sock);
bool  socket_ready(Socket *sock);
bool  socket_died(Socket *sock);
int   socket_read(Socket *sock, char *dst, int max);
int   socket_write(Socket *sock, char *src, int len);
void  socket_free(Socket *sock);
bool  socket_secure(Socket *sock);
void  socket_set_user_data(Socket *sock, void *user_data);
void* socket_get_user_data(Socket *sock);

#endif // SOCKET_INCLUDED

////////////////////////////////////////////////////////////////////////////////////////
// src/socket_pool.h
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/socket_pool.h"
#ifndef SOCKET_POOL_INCLUDED
#define SOCKET_POOL_INCLUDED

#ifndef HTTP_AMALGAMATION
#include "basic.h"
#include "socket.h"
#include "socket_raw.h"
#endif

typedef struct SocketPool SocketPool;

typedef int SocketHandle;

typedef enum {
    SOCKET_EVENT_DIED,
    SOCKET_EVENT_READY,
    SOCKET_EVENT_ERROR,
    SOCKET_EVENT_SIGNAL,
} SocketEventType;

typedef struct {
    SocketEventType type;
    SocketHandle handle;
    void *user_data;
} SocketEvent;

int  socket_pool_global_init(void);
void socket_pool_global_free(void);

SocketPool *socket_pool_init(HTTP_String addr,
    uint16_t port, uint16_t secure_port, int max_socks,
    bool reuse_addr, int backlog, HTTP_String cert_file,
    HTTP_String key_file);

void socket_pool_free(SocketPool *pool);

int socket_pool_add_cert(SocketPool *pool, HTTP_String domain, HTTP_String cert_file, HTTP_String key_file);

SocketEvent socket_pool_wait(SocketPool *pool);

void socket_pool_set_user_data(SocketPool *pool, SocketHandle handle, void *user_data);

void socket_pool_close(SocketPool *pool, SocketHandle handle);

int socket_pool_connect(SocketPool *pool, bool secure,
    HTTP_String addr, uint16_t port, void *user_data);

int socket_pool_connect_ipv4(SocketPool *pool, bool secure,
    HTTP_IPv4 addr, uint16_t port, void *user_data);

int socket_pool_connect_ipv6(SocketPool *pool, bool secure,
    HTTP_IPv6 addr, uint16_t port, void *user_data);

int socket_pool_read(SocketPool *pool, SocketHandle handle, char *dst, int len);

int socket_pool_write(SocketPool *pool, SocketHandle handle, char *src, int len);

bool socket_pool_secure(SocketPool *pool, SocketHandle handle);

#endif // SOCKET_POOL_INCLUDED

////////////////////////////////////////////////////////////////////////////////////////
// src/basic.c
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/basic.c"
#include <stddef.h>
#include <string.h>

#ifndef HTTP_AMALGAMATION
#include "basic.h"
#endif

bool http_streq(HTTP_String s1, HTTP_String s2)
{
	if (s1.len != s2.len)
		return false;

    for (int i = 0; i < s1.len; i++)
		if (s1.ptr[i] != s2.ptr[i])
			return false;

	return true;
}

static char to_lower(char c)
{
	if (c >= 'A' && c <= 'Z')
		return c - 'A' + 'a';
	return c;
}

bool http_streqcase(HTTP_String s1, HTTP_String s2)
{
	if (s1.len != s2.len)
		return false;

	for (int i = 0; i < s1.len; i++)
		if (to_lower(s1.ptr[i]) != to_lower(s2.ptr[i]))
			return false;

	return true;
}

HTTP_String http_trim(HTTP_String s)
{
	int i = 0;
	while (i < s.len && (s.ptr[i] == ' ' || s.ptr[i] == '\t'))
		i++;

	if (i == s.len) {
		s.ptr = NULL;
		s.len = 0;
	} else {
		s.ptr += i;
		s.len -= i;
		while (s.ptr[s.len-1] == ' ' || s.ptr[s.len-1] == '\t')
			s.len--;
	}

	return s;
}

static bool is_printable(char c)
{
    return c >= ' ' && c <= '~';
}

#include <stdio.h>
void print_bytes(HTTP_String prefix, HTTP_String src)
{
    if (src.len == 0)
        return;

    FILE *stream = stdout;

    bool new_line = true;
    int cur = 0;
    for (;;) {
        int start = cur;

        while (cur < src.len && is_printable(src.ptr[cur]))
            cur++;

        if (new_line) {
            fwrite(prefix.ptr, 1, prefix.len, stream);
            new_line = false;
        }

        fwrite(src.ptr + start, 1, cur - start, stream);

        if (cur == src.len)
            break;

        if (src.ptr[cur] == '\n') {
            putc('\\', stream);
            putc('n',  stream);
            putc('\n', stream);
            new_line = true;
        } else if (src.ptr[cur] == '\r') {
            putc('\\', stream);
            putc('r',  stream);
        } else {
            putc('.', stream);
        }
        cur++;
    }
    putc('\n', stream);
}

////////////////////////////////////////////////////////////////////////////////////////
// src/parse.c
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/parse.c"
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <assert.h>
#include <stdlib.h>
#include <limits.h>

#ifndef HTTP_AMALGAMATION
#include "parse.h"
#include "basic.h"
#endif

// From RFC 9112
//   request-target = origin-form
//                  / absolute-form
//                  / authority-form
//                  / asterisk-form
//   origin-form    = absolute-path [ "?" query ]
//   absolute-form  = absolute-URI
//   authority-form = uri-host ":" port
//   asterisk-form  = "*"
//
// From RFC 9110
//   URI-reference = <URI-reference, see [URI], Section 4.1>
//   absolute-URI  = <absolute-URI, see [URI], Section 4.3>
//   relative-part = <relative-part, see [URI], Section 4.2>
//   authority     = <authority, see [URI], Section 3.2>
//   uri-host      = <host, see [URI], Section 3.2.2>
//   port          = <port, see [URI], Section 3.2.3>
//   path-abempty  = <path-abempty, see [URI], Section 3.3>
//   segment       = <segment, see [URI], Section 3.3>
//   query         = <query, see [URI], Section 3.4>
//
//   absolute-path = 1*( "/" segment )
//   partial-URI   = relative-part [ "?" query ]
//
// From RFC 3986:
//   segment       = *pchar
//   pchar         = unreserved / pct-encoded / sub-delims / ":" / "@"
//   pct-encoded   = "%" HEXDIG HEXDIG
//   sub-delims    = "!" / "$" / "&" / "'" / "(" / ")"
//                 / "*" / "+" / "," / ";" / "="
//   unreserved    = ALPHA / DIGIT / "-" / "." / "_" / "~"
//   query         = *( pchar / "/" / "?" )
//   absolute-URI  = scheme ":" hier-part [ "?" query ]
//   hier-part     = "//" authority path-abempty
//                 / path-absolute
//                 / path-rootless
//                 / path-empty
//   scheme      = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )

typedef struct {
	char *src;
	int len;
	int cur;
} Scanner;

static int is_digit(char c)
{
	return c >= '0' && c <= '9';
}

static int is_alpha(char c)
{
	return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
}

static int is_hex_digit(char c)
{
	return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F');
}

// From RFC 3986:
//   sub-delims = "!" / "$" / "&" / "'" / "(" / ")"
//              / "*" / "+" / "," / ";" / "="
static int is_sub_delim(char c)
{
	return c == '!' || c == '$' || c == '&' || c == '\''
		|| c == '(' || c == ')' || c == '*' || c == '+'
		|| c == ',' || c == ';' || c == '=';
}

// From RFC 3986:
//   unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"
static int is_unreserved(char c)
{
	return is_alpha(c) || is_digit(c)
		|| c == '-' || c == '.'
		|| c == '_' || c == '~';
}

// From RFC 3986:
//   pchar = unreserved / pct-encoded / sub-delims / ":" / "@"
static int is_pchar(char c)
{
	return is_unreserved(c) || is_sub_delim(c) || c == ':' || c == '@';
}

static int is_tchar(char c)
{
	return is_digit(c) || is_alpha(c)
		|| c == '!' || c == '#' || c == '$'
		|| c == '%' || c == '&' || c == '\''
		|| c == '*' || c == '+' || c == '-'
		|| c == '.' || c == '^' || c == '_'
		|| c == '~';
}

static int is_vchar(char c)
{
	return c >= ' ' && c <= '~';
}

#define CONSUME_OPTIONAL_SEQUENCE(scanner, func)                                        \
    while ((scanner)->cur < (scanner)->len && (func)((scanner)->src[(scanner)->cur]))   \
        (scanner)->cur++;

static int
consume_absolute_path(Scanner *s)
{
	if (s->cur == s->len || s->src[s->cur] != '/')
		return -1; // ERROR
	s->cur++;

	for (;;) {

        CONSUME_OPTIONAL_SEQUENCE(s, is_pchar);

		if (s->cur == s->len || s->src[s->cur] != '/')
			break;
		s->cur++;
	}

	return 0;
}

// If abempty=1:
//   path-abempty  = *( "/" segment )
// else:
//   path-absolute = "/" [ segment-nz *( "/" segment ) ]
//   path-rootless = segment-nz *( "/" segment )
//   path-empty    = 0<pchar>
static int parse_path(Scanner *s, HTTP_String *path, int abempty)
{
	int start = s->cur;

	if (abempty) {

		// path-abempty
		while (s->cur < s->len && s->src[s->cur] == '/') {
			do
				s->cur++;
			while (s->cur < s->len && is_pchar(s->src[s->cur]));
		}

	} else if (s->cur < s->len && (s->src[s->cur] == '/')) {

		// path-absolute
		s->cur++;
		if (s->cur < s->len && is_pchar(s->src[s->cur])) {
			s->cur++;
			for (;;) {

                CONSUME_OPTIONAL_SEQUENCE(s, is_pchar);

				if (s->cur == s->len || s->src[s->cur] != '/')
					break;
				s->cur++;
			}
		}

	} else if (s->cur < s->len && is_pchar(s->src[s->cur])) {

		// path-rootless
		s->cur++;
		for (;;) {

            CONSUME_OPTIONAL_SEQUENCE(s, is_pchar)

			if (s->cur == s->len || s->src[s->cur] != '/')
				break;
			s->cur++;
		}

	} else {
		// path->empty
		// (do nothing)
	}

	*path = (HTTP_String) {
		s->src + start,
		s->cur - start,
	};
	if (path->len == 0)
		path->ptr = NULL;

	return 0;
}

// RFC 3986:
//   query = *( pchar / "/" / "?" )
static int is_query(char c)
{
	return is_pchar(c) || c == '/' || c == '?';
}

// RFC 3986:
//   fragment = *( pchar / "/" / "?" )
static int is_fragment(char c)
{
	return is_pchar(c) || c == '/' || c == '?';
}

static int little_endian(void)
{
    uint16_t x = 1;
    return *((uint8_t*) &x);
}

static void invert_bytes(void *p, int len)
{
	char *c = p;
	for (int i = 0; i < len/2; i++) {
		char tmp = c[i];
		c[i] = c[len-i-1];
		c[len-i-1] = tmp;
	}
}

static int parse_ipv4(Scanner *s, HTTP_IPv4 *ipv4)
{
	unsigned int out = 0;
	int i = 0;
	for (;;) {

		if (s->cur == s->len || !is_digit(s->src[s->cur]))
			return -1;

		int b = 0;
		do {
			int x = s->src[s->cur++] - '0';
			if (b > (UINT8_MAX - x) / 10)
				return -1;
			b = b * 10 + x;
		} while (s->cur < s->len && is_digit(s->src[s->cur]));

		out <<= 8;
		out |= (unsigned char) b;

		i++;
		if (i == 4)
			break;

		if (s->cur == s->len || s->src[s->cur] != '.')
			return -1;
		s->cur++;
	}

	if (little_endian())
		invert_bytes(&out, 4);

	ipv4->data = out;
	return 0;
}

static int hex_digit_to_int(char c)
{
	if (c >= 'a' && c <= 'f') return c - 'a' + 10;
	if (c >= 'A' && c <= 'F') return c - 'A' + 10;
	if (c >= '0' && c <= '9') return c - '0';
	return -1;
}

static int parse_ipv6_comp(Scanner *s)
{
	unsigned short buf;

	if (s->cur == s->len || !is_hex_digit(s->src[s->cur]))
		return -1;
	buf = hex_digit_to_int(s->src[s->cur]);
	s->cur++;

	if (s->cur == s->len || !is_hex_digit(s->src[s->cur]))
		return buf;
	buf <<= 4;
	buf |= hex_digit_to_int(s->src[s->cur]);
	s->cur++;

	if (s->cur == s->len || !is_hex_digit(s->src[s->cur]))
		return buf;
	buf <<= 4;
	buf |= hex_digit_to_int(s->src[s->cur]);
	s->cur++;

	if (s->cur == s->len || !is_hex_digit(s->src[s->cur]))
		return buf;
	buf <<= 4;
	buf |= hex_digit_to_int(s->src[s->cur]);
	s->cur++;

	return (int) buf;
}

static int parse_ipv6(Scanner *s, HTTP_IPv6 *ipv6)
{
	unsigned short head[8];
	unsigned short tail[8];
	int head_len = 0;
	int tail_len = 0;

	if (s->len - s->cur > 1
		&& s->src[s->cur+0] == ':'
		&& s->src[s->cur+1] == ':')
		s->cur += 2;
	else {

		for (;;) {

			int ret = parse_ipv6_comp(s);
			if (ret < 0) return ret;

			head[head_len++] = (unsigned short) ret;
			if (head_len == 8) break;

			if (s->cur == s->len || s->src[s->cur] != ':')
				return -1;
			s->cur++;

			if (s->cur < s->len && s->src[s->cur] == ':') {
				s->cur++;
				break;
			}
		}
	}

	if (head_len < 8) {
		while (s->cur < s->len && is_hex_digit(s->src[s->cur])) {

			int ret = parse_ipv6_comp(s);
			if (ret < 0) return ret;

			tail[tail_len++] = (unsigned short) ret;
			if (head_len + tail_len == 8) break;

			if (s->cur == s->len || s->src[s->cur] != ':')
				break;
			s->cur++;
		}
	}

	for (int i = 0; i < head_len; i++)
		ipv6->data[i] = head[i];

	for (int i = 0; i < 8 - head_len - tail_len; i++)
		ipv6->data[head_len + i] = 0;

	for (int i = 0; i < tail_len; i++)
		ipv6->data[8 - tail_len + i] = tail[i];

	if (little_endian())
		for (int i = 0; i < 8; i++)
			invert_bytes(&ipv6->data[i], 2);

	return 0;
}

// From RFC 3986:
//   reg-name = *( unreserved / pct-encoded / sub-delims )
static int is_regname(char c)
{
	return is_unreserved(c) || is_sub_delim(c);
}

static int parse_regname(Scanner *s, HTTP_String *regname)
{
	if (s->cur == s->len || !is_regname(s->src[s->cur]))
		return -1;
	int start = s->cur;
	do
		s->cur++;
	while (s->cur < s->len && is_regname(s->src[s->cur]));
	regname->ptr = s->src + start;
	regname->len = s->cur - start;
	return 0;
}

static int parse_host(Scanner *s, HTTP_Host *host)
{
	int ret;
	if (s->cur < s->len && s->src[s->cur] == '[') {

		s->cur++;

		int start = s->cur;
		HTTP_IPv6 ipv6;
		ret = parse_ipv6(s, &ipv6);
		if (ret < 0) return ret;

		host->mode = HTTP_HOST_MODE_IPV6;
		host->ipv6 = ipv6;
		host->text = (HTTP_String) { s->src + start, s->cur - start };

		if (s->cur == s->len || s->src[s->cur] != ']')
			return -1;
		s->cur++;

	} else {

		int start = s->cur;
		HTTP_IPv4 ipv4;
		ret = parse_ipv4(s, &ipv4);
		if (ret >= 0) {
			host->mode = HTTP_HOST_MODE_IPV4;
			host->ipv4 = ipv4;
		} else {
			s->cur = start;

			HTTP_String regname;
			ret = parse_regname(s, &regname);
			if (ret < 0) return ret;

			host->mode = HTTP_HOST_MODE_NAME;
			host->name = regname;
		}
		host->text = (HTTP_String) { s->src + start, s->cur - start };
	}

	return 0;
}

// scheme = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
static int is_scheme_head(char c)
{
	return is_alpha(c);
}

static int is_scheme_body(char c)
{
	return is_alpha(c)
		|| is_digit(c)
		|| c == '+'
		|| c == '-'
		|| c == '.';
}

// userinfo = *( unreserved / pct-encoded / sub-delims / ":" )
static int is_userinfo(char c)
{
	return is_unreserved(c) || is_sub_delim(c) || c == ':'; // TODO: PCT encoded
}

// authority = [ userinfo "@" ] host [ ":" port ]
static int parse_authority(Scanner *s, HTTP_Authority *authority)
{
	HTTP_String userinfo;
	{
		int start = s->cur;

        CONSUME_OPTIONAL_SEQUENCE(s, is_userinfo);

		if (s->cur < s->len && s->src[s->cur] == '@') {
			userinfo = (HTTP_String) {
				s->src + start,
				s->cur - start
			};
			s->cur++;
		} else {
			// Rollback
			s->cur = start;
			userinfo = (HTTP_String) {NULL, 0};
		}
	}

	HTTP_Host host;
	{
		int ret = parse_host(s, &host);
		if (ret < 0)
			return ret;
	}

	int port = 0;
	if (s->cur < s->len && s->src[s->cur] == ':') {
		s->cur++;
		if (s->cur < s->len && is_digit(s->src[s->cur])) {
			port = s->src[s->cur++] - '0';
			while (s->cur < s->len && is_digit(s->src[s->cur])) {
				int x = s->src[s->cur++] - '0';
				if (port > (UINT16_MAX - x) / 10)
					return -1; // ERROR: Port too big
				port = port * 10 + x;
			}
		}
	}

	authority->userinfo = userinfo;
	authority->host = host;
	authority->port = port;
	return 0;
}

static int parse_uri(Scanner *s, HTTP_URL *url, int allow_fragment)
{
	HTTP_String scheme = {0};
	{
		int start = s->cur;
		if (s->cur == s->len || !is_scheme_head(s->src[s->cur]))
			return -1; // ERROR: Missing scheme
		do
			s->cur++;
		while (s->cur < s->len && is_scheme_body(s->src[s->cur]));
		scheme = (HTTP_String) {
			s->src + start,
			s->cur - start,
		};

		if (s->cur == s->len || s->src[s->cur] != ':') 
			return -1; // ERROR: Missing ':' after scheme
		s->cur++;
	}

	int abempty = 0;
	HTTP_Authority authority = {0};
	if (s->len - s->cur > 1
		&& s->src[s->cur+0] == '/'
		&& s->src[s->cur+1] == '/') {

		s->cur += 2;

		int ret = parse_authority(s, &authority);
		if (ret < 0) return ret;

		abempty = 1;
	}

	HTTP_String path;
	int ret = parse_path(s, &path, abempty);
	if (ret < 0) return ret;

	HTTP_String query = {0};
	if (s->cur < s->len && s->src[s->cur] == '?') {
		int start = s->cur;
		do
			s->cur++;
		while (s->cur < s->len && is_query(s->src[s->cur]));
		query = (HTTP_String) {
			s->src + start,
			s->cur - start,
		};
	}

	HTTP_String fragment = {0};
	if (allow_fragment && s->cur < s->len && s->src[s->cur] == '#') {
		int start = s->cur;
		do
			s->cur++;
		while (s->cur < s->len && is_fragment(s->src[s->cur]));
		fragment = (HTTP_String) {
			s->src + start,
			s->cur - start,
		};
	}

	url->scheme    = scheme;
	url->authority = authority;
	url->path      = path;
	url->query     = query;
	url->fragment  = fragment;

	return 1;
}

// authority-form = host ":" port
// host           = IP-literal / IPv4address / reg-name
// IP-literal    = "[" ( IPv6address / IPvFuture  ) "]"
// reg-name      = *( unreserved / pct-encoded / sub-delims )
static int parse_authority_form(Scanner *s, HTTP_Host *host, int *port)
{
	int ret;
	
	ret = parse_host(s, host);
	if (ret < 0) return ret;

	// Default port value
	*port = 0;

	if (s->cur == s->len || s->src[s->cur] != ':')
		return 0; // No port
	s->cur++;

	if (s->cur == s->len || !is_digit(s->src[s->cur]))
		return 0; // No port

	int buf = 0;
	do {
		int x = s->src[s->cur++] - '0';
		if (buf > (UINT16_MAX - x) / 10)
			return -1; // ERROR
		buf = buf * 10 + x;
	} while (s->cur < s->len && is_digit(s->src[s->cur]));

	*port = buf;
	return 0;
}

static int parse_origin_form(Scanner *s, HTTP_String *path, HTTP_String *query)
{
	int ret, start;

	start = s->cur;
	ret = consume_absolute_path(s);
	if (ret < 0) return ret;
	*path = (HTTP_String) { s->src + start, s->cur - start };

	if (s->cur < s->len && s->src[s->cur] == '?') {
		start = s->cur;
		do
			s->cur++;
		while (s->cur < s->len && is_query(s->src[s->cur]));
		*query = (HTTP_String) { s->src + start, s->cur - start };
	} else
		*query = (HTTP_String) { NULL, 0 };

	return 0;
}

static int parse_asterisk_form(Scanner *s)
{
	if (s->len - s->cur < 2
		|| s->src[s->cur+0] != '*'
		|| s->src[s->cur+1] != ' ')
		return -1;
	s->cur++;
	return 0;
}

static int parse_request_target(Scanner *s, HTTP_URL *url)
{
	int ret;

	memset(url, 0, sizeof(HTTP_URL));

	// asterisk-form
	ret = parse_asterisk_form(s);
	if (ret >= 0) return ret;

	ret = parse_uri(s, url, 0);
	if (ret >= 0) return ret;

	ret = parse_authority_form(s, &url->authority.host, &url->authority.port);
	if (ret >= 0) return ret;

	ret = parse_origin_form(s, &url->path, &url->query);
	if (ret >= 0) return ret;

	return -1;
}

bool consume_str(Scanner *scan, HTTP_String token)
{
    HTTP_ASSERT(token.len > 0);

    if (token.len > scan->len - scan->cur)
        return false;

    for (int i = 0; i < token.len; i++)
        if (scan->src[scan->cur + i] != token.ptr[i])
            return false;

    scan->cur += token.len;
    return true;
}

static int is_header_body(char c)
{
	return is_vchar(c) || c == ' ' || c == '\t';
}

static int parse_headers(Scanner *s, HTTP_Header *headers, int max_headers)
{
	int num_headers = 0;
    while (!consume_str(s, HTTP_STR("\r\n"))) {

        // RFC 9112:
		//   field-line = field-name ":" OWS field-value OWS
		//
		// RFC 9110:
		//   field-value    = *field-content
		//   field-content  = field-vchar
		//                    [ 1*( SP / HTAB / field-vchar ) field-vchar ]
		//   field-vchar    = VCHAR / obs-text
		//   obs-text       = %x80-FF

		int start;
		
		if (s->cur == s->len || !is_tchar(s->src[s->cur]))
			return -1; // ERROR
		start = s->cur;
		do
			s->cur++;
		while (s->cur < s->len && is_tchar(s->src[s->cur]));
		HTTP_String name = { s->src + start, s->cur - start };

		if (s->cur == s->len || s->src[s->cur] != ':')
			return -1; // ERROR
		s->cur++;

        start = s->cur;
        CONSUME_OPTIONAL_SEQUENCE(s, is_header_body);
		HTTP_String body = { s->src + start, s->cur - start };
		body = http_trim(body);

        if (num_headers < max_headers)
            headers[num_headers++] = (HTTP_Header) { name, body };

        if (!consume_str(s, HTTP_STR("\r\n"))) {
            return -1;
        }
    }

    return num_headers;
}

typedef enum {
    TRANSFER_ENCODING_OPTION_CHUNKED,
    TRANSFER_ENCODING_OPTION_COMPRESS,
    TRANSFER_ENCODING_OPTION_DEFLATE,
    TRANSFER_ENCODING_OPTION_GZIP,
} TransferEncodingOption;

static bool is_space(char c)
{
    return c == ' ' || c == '\t';
}

static int
parse_transfer_encoding(HTTP_String src, TransferEncodingOption *dst, int max)
{
    Scanner s = { src.ptr, src.len, 0 };

    int num = 0;
    for (;;) {
        
        CONSUME_OPTIONAL_SEQUENCE(&s, is_space);

        TransferEncodingOption opt;
        if (0) {}
        else if (consume_str(&s, HTTP_STR("chunked")))  opt = TRANSFER_ENCODING_OPTION_CHUNKED;
        else if (consume_str(&s, HTTP_STR("compress"))) opt = TRANSFER_ENCODING_OPTION_COMPRESS;
        else if (consume_str(&s, HTTP_STR("deflate")))  opt = TRANSFER_ENCODING_OPTION_DEFLATE;
        else if (consume_str(&s, HTTP_STR("gzip")))     opt = TRANSFER_ENCODING_OPTION_GZIP;
        else return -1; // Invalid option

        if (num == max)
            return -1; // Too many options
        dst[num++] = opt;

        CONSUME_OPTIONAL_SEQUENCE(&s, is_space);

        if (s.cur == s.len)
            break;

        if (s.src[s.cur] != ',')
            return -1; // Missing comma separator
    }

    return num;
}

static int
parse_content_length(const char *src, int len, uint64_t *out)
{
    int cur = 0;
    while (cur < len && (src[cur] == ' ' || src[cur] == '\t'))
        cur++;

    if (cur == len || !is_digit(src[cur]))
        return -1;

    uint64_t buf = 0;
    do {
        int d = src[cur++] - '0';
        if (buf > (UINT64_MAX - d) / 10)
            return -1;
        buf = buf * 10 + d;
    } while (cur < len && is_digit(src[cur]));

    *out = buf;
    return 0;
}

static int parse_body(Scanner *s,
    HTTP_Header *headers, int num_headers,
    HTTP_String *body, bool body_expected)
{

    // RFC 9112 section 6:
    //   The presence of a message body in a request is signaled by a Content-Length or
    //   Transfer-Encoding header field. Request message framing is independent of method
    //   semantics.

    int header_index = http_find_header(headers, num_headers, HTTP_STR("Transfer-Encoding"));
    if (header_index != -1) {

        // RFC 9112 section 6.1:
        //   A server MAY reject a request that contains both Content-Length and Transfer-Encoding
        //   or process such a request in accordance with the Transfer-Encoding alone. Regardless,
        //   the server MUST close the connection after responding to such a request to avoid the
        //   potential attacks.
        if (http_find_header(headers, num_headers, HTTP_STR("Content-Length")) != -1)
            return -1;

        HTTP_String value = headers[header_index].value;

        // RFC 9112 section 6.1:
        //   If any transfer coding other than chunked is applied to a request's content, the
        //   sender MUST apply chunked as the final transfer coding to ensure that the message
        //   is properly framed. If any transfer coding other than chunked is applied to a
        //   response's content, the sender MUST either apply chunked as the final transfer
        //   coding or terminate the message by closing the connection.

        TransferEncodingOption opts[8];
        int num = parse_transfer_encoding(value, opts, HTTP_COUNT(opts));
        if (num != 1 || opts[0] != TRANSFER_ENCODING_OPTION_CHUNKED)
            return -1;

        HTTP_String chunks_maybe[128];
        HTTP_String *chunks = chunks_maybe;
        int num_chunks = 0;
        int max_chunks = HTTP_COUNT(chunks_maybe);

        #define FREE_CHUNK_LIST         \
            if (chunks != chunks_maybe) \
                free(chunks);

        char *content_start = s->src + s->cur;

        for (;;) {

            // RFC 9112 section 7.1:
            //   The chunked transfer coding wraps content in order to transfer it as a series of chunks,
            //   each with its own size indicator, followed by an OPTIONAL trailer section containing
            //   trailer fields.

            if (s->cur == s->len) {
                FREE_CHUNK_LIST
                return 0; // Incomplete request
            }

            if (!is_hex_digit(s->src[s->cur])) {
                FREE_CHUNK_LIST
                return -1;
            }

            int chunk_len = 0;

            do {
                char c = s->src[s->cur++];
                int  n = hex_digit_to_int(c);
                if (chunk_len > (INT_MAX - n) / 16) {
                    FREE_CHUNK_LIST
                    return -1; // overflow
                }
                chunk_len = chunk_len * 16 + n;
            } while (s->cur < s->len && is_hex_digit(s->src[s->cur]));

            if (s->cur == s->len) {
                FREE_CHUNK_LIST
                return 0; // Incomplete request
            }
            if (s->src[s->cur] != '\r') {
                FREE_CHUNK_LIST
                return -1;
            }
            s->cur++;

            if (s->cur == s->len) {
                FREE_CHUNK_LIST
                return 0;
            }
            if (s->src[s->cur] != '\n') {
                FREE_CHUNK_LIST
                return -1;
            }
            s->cur++;

            char *chunk_ptr = s->src + s->cur;

            if (chunk_len > s->len - s->cur) {
                FREE_CHUNK_LIST
                return 0; // Incomplete request
            }
            s->cur += chunk_len;

            if (s->cur == s->len)
                return 0; // Incomplete request
            if (s->src[s->cur] != '\r') {
                FREE_CHUNK_LIST
                return -1;
            }
            s->cur++;

            if (s->cur == s->len) {
                FREE_CHUNK_LIST
                return 0; // Incomplete request
            }
            if (s->src[s->cur] != '\n') {
                FREE_CHUNK_LIST
                return -1;
            }
            s->cur++;

            if (chunk_len == 0)
                break;

            if (num_chunks == max_chunks) {

                max_chunks *= 2;

                HTTP_String *new_chunks = malloc(max_chunks * sizeof(HTTP_String));
                if (new_chunks == NULL) {
                    if (chunks != chunks_maybe)
                        free(chunks);
                    return -1;
                }

                for (int i = 0; i < num_chunks; i++)
                    new_chunks[i] = chunks[i];

                if (chunks != chunks_maybe)
                    free(chunks);

                chunks = new_chunks;
            }
            chunks[num_chunks++] = (HTTP_String) { chunk_ptr, chunk_len };
        }

        char *content_ptr = content_start;
        for (int i = 0; i < num_chunks; i++) {
            memmove(content_ptr, chunks[i].ptr, chunks[i].len);
            content_ptr += chunks[i].len;
        }

        *body = (HTTP_String) {
            content_start,
            content_ptr - content_start
        };

        if (chunks != chunks_maybe)
            free(chunks);

        return 1;
    }

    // RFC 9112 section 6.3:
    //   If a valid Content-Length header field is present without Transfer-Encoding,
    //   its decimal value defines the expected message body length in octets.

    header_index = http_find_header(headers, num_headers, HTTP_STR("Content-Length"));
    if (header_index != -1) {

        // Have Content-Length
        HTTP_String value = headers[header_index].value;

        uint64_t tmp;
        if (parse_content_length(value.ptr, value.len, &tmp) < 0)
            return -1;
        if (tmp > INT_MAX)
            return -1;
        int len = (int) tmp;

        if (len > s->len - s->cur)
            return 0; // Incomplete request

        *body = (HTTP_String) { s->src + s->cur, len };

        s->cur += len;
        return 1;
    }

    // No Content-Length or Transfer-Encoding
    if (body_expected) return -1;

    *body = (HTTP_String) { NULL, 0 };
    return 1;
}

static int contains_head(char *src, int len)
{
    int cur = 0;
    while (len - cur > 3) {
        if (src[cur+0] == '\r' &&
            src[cur+1] == '\n' &&
            src[cur+2] == '\r' &&
            src[cur+3] == '\n')
            return 1;
        cur++;
    }
    return 0;
}

static int parse_request(Scanner *s, HTTP_Request *req)
{
    if (!contains_head(s->src + s->cur, s->len - s->cur))
        return 0;

    req->secure = false;

    if (0) {}
    else if (consume_str(s, HTTP_STR("GET ")))     req->method = HTTP_METHOD_GET;
    else if (consume_str(s, HTTP_STR("POST ")))    req->method = HTTP_METHOD_POST;
    else if (consume_str(s, HTTP_STR("PUT ")))     req->method = HTTP_METHOD_PUT;
    else if (consume_str(s, HTTP_STR("HEAD ")))    req->method = HTTP_METHOD_HEAD;
    else if (consume_str(s, HTTP_STR("DELETE ")))  req->method = HTTP_METHOD_DELETE;
    else if (consume_str(s, HTTP_STR("CONNECT "))) req->method = HTTP_METHOD_CONNECT;
    else if (consume_str(s, HTTP_STR("OPTIONS "))) req->method = HTTP_METHOD_OPTIONS;
    else if (consume_str(s, HTTP_STR("TRACE ")))   req->method = HTTP_METHOD_TRACE;
    else if (consume_str(s, HTTP_STR("PATCH ")))   req->method = HTTP_METHOD_PATCH;
    else return -1;

    {
        Scanner s2 = *s;
        int peek = s->cur;
        while (peek < s->len && s->src[peek] != ' ')
            peek++;
        if (peek == s->len)
            return -1;
        s2.len = peek;

        int ret = parse_request_target(&s2, &req->url);
        if (ret < 0) return ret;

        s->cur = s2.cur;
    }

    if (consume_str(s, HTTP_STR(" HTTP/1.1\r\n"))) {
        req->minor = 1;
    } else if (consume_str(s, HTTP_STR(" HTTP/1.0\r\n")) || consume_str(s, HTTP_STR(" HTTP/1\r\n"))) {
        req->minor = 0;
    } else {
        return -1;
    }

    int num_headers = parse_headers(s, req->headers, HTTP_MAX_HEADERS);
    if (num_headers < 0)
        return num_headers;
    req->num_headers = num_headers;

    bool body_expected = true;
    if (req->method == HTTP_METHOD_GET || req->method == HTTP_METHOD_DELETE) // TODO: maybe other methods?
        body_expected = false;

    return parse_body(s, req->headers, req->num_headers, &req->body, body_expected);
}

int http_find_header(HTTP_Header *headers, int num_headers, HTTP_String name)
{
	for (int i = 0; i < num_headers; i++)
		if (http_streqcase(name, headers[i].name))
			return i;
	return -1;
}

static int parse_response(Scanner *s, HTTP_Response *res)
{
	if (!contains_head(s->src + s->cur, s->len - s->cur))
		return 0;

    if (consume_str(s, HTTP_STR("HTTP/1.1 "))) {
        res->minor = 1;
    } else if (consume_str(s, HTTP_STR("HTTP/1.0 ")) || consume_str(s, HTTP_STR("HTTP/1 "))) {
        res->minor = 0;
    } else {
        return -1;
    }

    if (s->len - s->cur < 5
        || s->src[s->cur+0] != ' '
        || !is_digit(s->src[s->cur+1])
        || !is_digit(s->src[s->cur+2])
        || !is_digit(s->src[s->cur+3])
        || s->src[s->cur+4] != ' ')
        return -1;
    s->cur += 5;

    res->status =
        (s->src[s->cur-2] - '0') * 1 +
        (s->src[s->cur-3] - '0') * 10 +
        (s->src[s->cur-4] - '0') * 100;

    while (s->cur < s->len && (
        s->src[s->cur] == '\t' ||
        s->src[s->cur] == ' ' ||
        is_vchar(s->src[s->cur]))) // TODO: obs-text
        s->cur++;

    if (s->len - s->cur < 2
        || s->src[s->cur+0] != '\r'
        || s->src[s->cur+1] != '\n')
        return -1;
    s->cur += 2;

    int num_headers = parse_headers(s, res->headers, HTTP_MAX_HEADERS);
    if (num_headers < 0)
        return num_headers;
    res->num_headers = num_headers;

    bool body_expected = true; // TODO

    return parse_body(s, res->headers, res->num_headers, &res->body, body_expected);
}

int http_parse_ipv4(char *src, int len, HTTP_IPv4 *ipv4)
{
    Scanner s = {src, len, 0};
    int ret = parse_ipv4(&s, ipv4);
    if (ret < 0) return ret;
    return s.cur;
}

int http_parse_ipv6(char *src, int len, HTTP_IPv6 *ipv6)
{
    Scanner s = {src, len, 0};
    int ret = parse_ipv6(&s, ipv6);
    if (ret < 0) return ret;
    return s.cur;
}

int http_parse_url(char *src, int len, HTTP_URL *url)
{
    Scanner s = {src, len, 0};
    int ret = parse_uri(&s, url, 1);
    if (ret == 1)
        return s.cur;
    return ret;
}

int http_parse_request(char *src, int len, HTTP_Request *req)
{
    Scanner s = {src, len, 0};
    int ret = parse_request(&s, req);
    if (ret == 1)
        return s.cur;
    return ret;
}

int http_parse_response(char *src, int len, HTTP_Response *res)
{
    Scanner s = {src, len, 0};
    int ret = parse_response(&s, res);
    if (ret == 1)
        return s.cur;
    return ret;
}

HTTP_String http_get_cookie(HTTP_Request *req, HTTP_String name)
{
    // TODO: best-effort implementation

    for (int i = 0; i < req->num_headers; i++) {

        if (!http_streqcase(req->headers[i].name, HTTP_STR("Cookie")))
            continue;

        char *src = req->headers[i].value.ptr;
        int   len = req->headers[i].value.len;
        int   cur = 0;

        // Cookie: name1=value1; name2=value2; name3=value3

        for (;;) {

            while (cur < len && src[cur] == ' ')
                cur++;

            int off = cur;
            while (cur < len && src[cur] != '=')
                cur++;

            HTTP_String cookie_name = { src + off, cur - off };

            if (cur == len)
                break;
            cur++;

            off = cur;
            while (cur < len && src[cur] != ';')
                cur++;

            HTTP_String cookie_value = { src + off, cur - off };

            if (http_streq(name, cookie_name))
                return cookie_value;

            if (cur == len)
                break;
            cur++;
        }
    }

    return HTTP_STR("");
}

HTTP_String http_get_param(HTTP_String body, HTTP_String str, char *mem, int cap)
{
    // This is just a best-effort implementation

    char *src = body.ptr;
    int   len = body.len;
    int   cur = 0;

    if (cur < len && src[cur] == '?')
        cur++;

    while (cur < len) {

        HTTP_String name;
        {
            int off = cur;
            while (cur < len && src[cur] != '=' && src[cur] != '&')
                cur++;
            name = (HTTP_String) { src + off, cur - off };
        }

        HTTP_String body = HTTP_STR("");
        if (cur < len) {
            cur++;
            if (src[cur-1] == '=') {
                int off = cur;
                while (cur < len && src[cur] != '&')
                    cur++;
                body = (HTTP_String) { src + off, cur - off };

                if (cur < len)
                    cur++;
            }
        }

        if (http_streq(str, name)) {

            bool percent_encoded = false;
            for (int i = 0; i < body.len; i++)
                if (body.ptr[i] == '+' || body.ptr[i] == '%') {
                    percent_encoded = true;
                    break;
                }

            if (!percent_encoded)
                return body;

            if (body.len > cap)
                return (HTTP_String) { NULL, 0 };

            HTTP_String decoded = { mem, 0 };
            for (int i = 0; i < body.len; i++) {

                char c = body.ptr[i];
                if (c == '+')
                    c = ' ';
                else {
                    if (body.ptr[i] == '%') {
                        if (body.len - i < 3
                            || !is_hex_digit(body.ptr[i+1])
                            || !is_hex_digit(body.ptr[i+2]))
                            return (HTTP_String) { NULL, 0 };

                        int h = hex_digit_to_int(body.ptr[i+1]);
                        int l = hex_digit_to_int(body.ptr[i+2]);
                        c = (h << 4) | l;

                        i += 2;
                    }
                }

                decoded.ptr[decoded.len++] = c;
            }

            return decoded;
        }
    }

    return HTTP_STR("");
}

static bool is_digit(char c)
{
    return c >= '0' && c <= '9';
}

int http_get_param_i(HTTP_String body, HTTP_String str)
{
    char buf[128];
    HTTP_String out = http_get_param(body, str, buf, SIZEOF(buf));
    if (out.len == 0 || !is_digit(out.ptr[0]))
        return -1;

    int cur = 0;
    int res = 0;
    do {
        int d = out.ptr[cur++] - '0';
        if (res > (INT_MAX - d) / 10)
            return -1;
        res = res * 10 + d;
    } while (cur < out.len && is_digit(out.ptr[cur]));

    return res;
}

////////////////////////////////////////////////////////////////////////////////////////
// src/engine.c
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/engine.c"
#include <stdio.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <stdarg.h>
#include <assert.h> // TODO: remove some of these headers
#include <stddef.h>
#include <limits.h>
#include <stdint.h>
#include <string.h>

#ifndef HTTP_AMALGAMATION
#include "basic.h"
#include "engine.h"
#endif

// This is the implementation of a byte queue useful
// for systems that need to process engs of bytes.
//
// It features sticky errors, a zero-copy interface,
// and a safe mechanism to patch previously written
// bytes.
//
// Only up to 4GB of data can be stored at once.

enum {
	BYTE_QUEUE_ERROR = 1 << 0,
	BYTE_QUEUE_READ  = 1 << 1,
	BYTE_QUEUE_WRITE = 1 << 2,
};

static void*
callback_malloc(HTTP_ByteQueue *queue, int len)
{
	return queue->memfunc(HTTP_MEMFUNC_MALLOC, NULL, len, queue->memfuncdata);
}

static void
callback_free(HTTP_ByteQueue *queue, void *ptr, int len)
{
	queue->memfunc(HTTP_MEMFUNC_FREE, ptr, len, queue->memfuncdata);
}

// Initialize the queue
static void
byte_queue_init(HTTP_ByteQueue *queue, unsigned int limit, HTTP_MemoryFunc memfunc, void *memfuncdata)
{
	queue->flags = 0;
	queue->head = 0;
	queue->size = 0;
	queue->used = 0;
	queue->curs = 0;
	queue->limit = limit;
	queue->data = NULL;
	queue->read_target = NULL;
	queue->memfunc = memfunc;
	queue->memfuncdata = memfuncdata;
}

// Deinitialize the queue
static void
byte_queue_free(HTTP_ByteQueue *queue)
{
	if (queue->read_target) {
		if (queue->read_target != queue->data)
			callback_free(queue, queue->read_target, queue->read_target_size);
		queue->read_target = NULL;
		queue->read_target_size = 0;
	}

	callback_free(queue, queue->data, queue->size);
	queue->data = NULL;
}

static int
byte_queue_error(HTTP_ByteQueue *queue)
{
	return queue->flags & BYTE_QUEUE_ERROR;
}

static int
byte_queue_empty(HTTP_ByteQueue *queue)
{
	return queue->used == 0;
}

// Start a read operation on the queue.
//
// This function returnes the pointer to the memory region containing the bytes
// to read. Callers can't read more than [*len] bytes from it. To complete the
// read, the [byte_queue_read_ack] function must be called with the number of
// bytes that were acknowledged by the caller.
//
// Note:
//   - You can't have more than one pending read.
static char*
byte_queue_read_buf(HTTP_ByteQueue *queue, int *len)
{
	if (queue->flags & BYTE_QUEUE_ERROR) {
		*len = 0;
		return NULL;
	}

	HTTP_ASSERT((queue->flags & BYTE_QUEUE_READ) == 0);
	queue->flags |= BYTE_QUEUE_READ;
	queue->read_target      = queue->data;
	queue->read_target_size = queue->size;

	*len = queue->used;
	if (queue->data == NULL)
		return NULL;
	return queue->data + queue->head;
}

// Complete a previously started operation on the queue.
static void
byte_queue_read_ack(HTTP_ByteQueue *queue, int num)
{
	HTTP_ASSERT(num >= 0);

	if (queue->flags & BYTE_QUEUE_ERROR)
		return;

	if ((queue->flags & BYTE_QUEUE_READ) == 0)
		return;

	queue->flags &= ~BYTE_QUEUE_READ;

	HTTP_ASSERT((unsigned int) num <= queue->used);
	queue->head += (unsigned int) num;
	queue->used -= (unsigned int) num;
	queue->curs += (unsigned int) num;

	if (queue->read_target) {
		if (queue->read_target != queue->data)
			callback_free(queue, queue->read_target, queue->read_target_size);
		queue->read_target = NULL;
		queue->read_target_size = 0;
	}
}

static char*
byte_queue_write_buf(HTTP_ByteQueue *queue, int *cap)
{
	if ((queue->flags & BYTE_QUEUE_ERROR) || queue->data == NULL) {
		*cap = 0;
		return NULL;
	}

	HTTP_ASSERT((queue->flags & BYTE_QUEUE_WRITE) == 0);
	queue->flags |= BYTE_QUEUE_WRITE;

	unsigned int ucap = queue->size - (queue->head + queue->used);
	if (ucap > INT_MAX) ucap = INT_MAX;

	*cap = (int) ucap;
	return queue->data + (queue->head + queue->used);
}

static void
byte_queue_write_ack(HTTP_ByteQueue *queue, int num)
{
	HTTP_ASSERT(num >= 0);

	if (queue->flags & BYTE_QUEUE_ERROR)
		return;

	if ((queue->flags & BYTE_QUEUE_WRITE) == 0)
		return;

	queue->flags &= ~BYTE_QUEUE_WRITE;
	queue->used += (unsigned int) num;
}

// Sets the minimum capacity for the next write operation
// and returns 1 if the content of the queue was moved, else
// 0 is returned.
//
// You must not call this function while a write is pending.
// In other words, you must do this:
//
//   byte_queue_write_setmincap(queue, mincap);
//   dst = byte_queue_write_buf(queue, &cap);
//   ...
//   byte_queue_write_ack(num);
//
// And NOT this:
//
//   dst = byte_queue_write_buf(queue, &cap);
//   byte_queue_write_setmincap(queue, mincap); <-- BAD
//   ...
//   byte_queue_write_ack(num);
//
static int
byte_queue_write_setmincap(HTTP_ByteQueue *queue, int mincap)
{
	HTTP_ASSERT(mincap >= 0);
	unsigned int umincap = (unsigned int) mincap;

	// Sticky error
	if (queue->flags & BYTE_QUEUE_ERROR)
		return 0;

	// In general, the queue's contents look like this:
	//
	//                           size
	//                           v
	//   [___xxxxxxxxxxxx________]
	//   ^   ^           ^
	//   0   head        head + used
	//
	// This function needs to make sure that at least [mincap]
	// bytes are available on the right side of the content.
	//
	// We have 3 cases:
	//
	//   1) If there is enough memory already, this function doesn't
	//      need to do anything.
	//
	//   2) If there isn't enough memory on the right but there is
	//      enough free memory if we cound the left unused region,
	//      then the content is moved back to the
	//      start of the buffer.
	//
	//   3) If there isn't enough memory considering both sides, this
	//      function needs to allocate a new buffer.
	//
	// If there are pending read or write operations, the application
	// is holding pointers to the buffer, so we need to make sure
	// to not invalidate them. The only real problem is pending reads
	// since this function can only be called before starting a write
	// opearation.
	//
	// To avoid invalidating the read pointer when we allocate a new
	// buffer, we don't free the old buffer. Instead, we store the
	// pointer in the "old" field so that the read ack function can
	// free it.
	//
	// To avoid invalidating the pointer when we are moving back the
	// content since there is enough memory at the start of the buffer,
	// we just avoid that. Even if there is enough memory considering
	// left and right free regions, we allocate a new buffer.

	HTTP_ASSERT((queue->flags & BYTE_QUEUE_WRITE) == 0);

	unsigned int total_free_space = queue->size - queue->used;
	unsigned int free_space_after_data = queue->size - queue->used - queue->head;

	int moved = 0;
	if (free_space_after_data < umincap) {

		if (total_free_space < umincap || (queue->read_target == queue->data)) {
			// Resize required

			if (queue->used + umincap > queue->limit) {
				queue->flags |= BYTE_QUEUE_ERROR;
				return 0;
			}

			unsigned int size;
			if (queue->size > UINT32_MAX / 2)
				size = UINT32_MAX;
			else
				size = 2 * queue->size;

			if (size < queue->used + umincap)
				size = queue->used + umincap;

			if (size > queue->limit)
				size = queue->limit;

			char *data = callback_malloc(queue, size);
			if (!data) {
				queue->flags |= BYTE_QUEUE_ERROR;
				return 0;
			}

			if (queue->used > 0)
				memcpy(data, queue->data + queue->head, queue->used);

			if (queue->read_target != queue->data)
				callback_free(queue, queue->data, queue->size);

			queue->data = data;
			queue->head = 0;
			queue->size = size;

		} else {
			// Move required
			memmove(queue->data, queue->data + queue->head, queue->used);
			queue->head = 0;
		}

		moved = 1;
	}

	return moved;
}

static HTTP_ByteQueueOffset
byte_queue_offset(HTTP_ByteQueue *queue)
{
	if (queue->flags & BYTE_QUEUE_ERROR)
		return (HTTP_ByteQueueOffset) { 0 };
	return (HTTP_ByteQueueOffset) { queue->curs + queue->used };
}

static unsigned int
byte_queue_size_from_offset(HTTP_ByteQueue *queue, HTTP_ByteQueueOffset off)
{
	return queue->curs + queue->used - off;
}

static void
byte_queue_patch(HTTP_ByteQueue *queue, HTTP_ByteQueueOffset off,
	char *src, unsigned int len)
{
	if (queue->flags & BYTE_QUEUE_ERROR)
		return;

	// Check that the offset is in range
	HTTP_ASSERT(off >= queue->curs && off - queue->curs < queue->used);

	// Check that the length is in range
	HTTP_ASSERT(len <= queue->used - (off - queue->curs));

	// Perform the patch
	char *dst = queue->data + queue->head + (off - queue->curs);
	memcpy(dst, src, len);
}

static void
byte_queue_remove_from_offset(HTTP_ByteQueue *queue, HTTP_ByteQueueOffset offset)
{
	if (queue->flags & BYTE_QUEUE_ERROR)
		return;

	unsigned long long num = (queue->curs + queue->used) - offset;
	HTTP_ASSERT(num <= queue->used);

	queue->used -= num;
}

static void
byte_queue_write(HTTP_ByteQueue *queue, const char *str, int len)
{
    if (str == NULL) str = "";
	if (len < 0) len = strlen(str);

	int cap;
	byte_queue_write_setmincap(queue, len);
	char *dst = byte_queue_write_buf(queue, &cap);
	if (dst) memcpy(dst, str, len);
	byte_queue_write_ack(queue, len);
}

static void
byte_queue_write_fmt2(HTTP_ByteQueue *queue, const char *fmt, va_list args)
{
	if (queue->flags & BYTE_QUEUE_ERROR)
		return;

	va_list args2;
	va_copy(args2, args);

	int cap;
	byte_queue_write_setmincap(queue, 128);
	char *dst = byte_queue_write_buf(queue, &cap);

	int len = vsnprintf(dst, cap, fmt, args);
	if (len < 0) {
		queue->flags |= BYTE_QUEUE_ERROR;
		va_end(args2);
		return;
	}

	if (len > cap) {
		byte_queue_write_ack(queue, 0);
		byte_queue_write_setmincap(queue, len+1);
		dst = byte_queue_write_buf(queue, &cap);
		vsnprintf(dst, cap, fmt, args2);
	}

	byte_queue_write_ack(queue, len);

	va_end(args2);
}

static void
byte_queue_write_fmt(HTTP_ByteQueue *queue, const char *fmt, ...)
{
	va_list args;
	va_start(args, fmt);
	byte_queue_write_fmt2(queue, fmt, args);
	va_end(args);
}

#define TEN_SPACES "          "

void http_engine_init(HTTP_Engine *eng, int client, HTTP_MemoryFunc memfunc, void *memfuncdata)
{
	if (client)
		eng->state = HTTP_ENGINE_STATE_CLIENT_PREP_URL;
	else
		eng->state = HTTP_ENGINE_STATE_SERVER_RECV_BUF;

	eng->closing = 0;
	eng->numexch = 0;

	byte_queue_init(&eng->input,  1<<20, memfunc, memfuncdata);
	byte_queue_init(&eng->output, 1<<20, memfunc, memfuncdata);
}

void http_engine_free(HTTP_Engine *eng)
{
	byte_queue_free(&eng->input);
	byte_queue_free(&eng->output);
	eng->state = HTTP_ENGINE_STATE_NONE;
}

void http_engine_close(HTTP_Engine *eng)
{
	if (eng->state & HTTP_ENGINE_STATEBIT_CLIENT)
		eng->state = HTTP_ENGINE_STATE_CLIENT_CLOSED;
	else
		eng->state = HTTP_ENGINE_STATE_SERVER_CLOSED;
}

HTTP_EngineState http_engine_state(HTTP_Engine *eng)
{
	return eng->state;
}

const char* http_engine_statestr(HTTP_EngineState state) { // TODO: remove
    switch (state) {
        case HTTP_ENGINE_STATE_NONE: return "NONE";
        case HTTP_ENGINE_STATE_CLIENT_PREP_URL: return "CLIENT_PREP_URL";
        case HTTP_ENGINE_STATE_CLIENT_PREP_HEADER: return "CLIENT_PREP_HEADER";
        case HTTP_ENGINE_STATE_CLIENT_PREP_BODY_BUF: return "CLIENT_PREP_BODY_BUF";
        case HTTP_ENGINE_STATE_CLIENT_PREP_BODY_ACK: return "CLIENT_PREP_BODY_ACK";
        case HTTP_ENGINE_STATE_CLIENT_PREP_ERROR: return "CLIENT_PREP_ERROR";
        case HTTP_ENGINE_STATE_CLIENT_SEND_BUF: return "CLIENT_SEND_BUF";
        case HTTP_ENGINE_STATE_CLIENT_SEND_ACK: return "CLIENT_SEND_ACK";
        case HTTP_ENGINE_STATE_CLIENT_RECV_BUF: return "CLIENT_RECV_BUF";
        case HTTP_ENGINE_STATE_CLIENT_RECV_ACK: return "CLIENT_RECV_ACK";
        case HTTP_ENGINE_STATE_CLIENT_READY: return "CLIENT_READY";
        case HTTP_ENGINE_STATE_CLIENT_CLOSED: return "CLIENT_CLOSED";
        case HTTP_ENGINE_STATE_SERVER_RECV_BUF: return "SERVER_RECV_BUF";
        case HTTP_ENGINE_STATE_SERVER_RECV_ACK: return "SERVER_RECV_ACK";
        case HTTP_ENGINE_STATE_SERVER_PREP_STATUS: return "SERVER_PREP_STATUS";
        case HTTP_ENGINE_STATE_SERVER_PREP_HEADER: return "SERVER_PREP_HEADER";
        case HTTP_ENGINE_STATE_SERVER_PREP_BODY_BUF: return "SERVER_PREP_BODY_BUF";
        case HTTP_ENGINE_STATE_SERVER_PREP_BODY_ACK: return "SERVER_PREP_BODY_ACK";
        case HTTP_ENGINE_STATE_SERVER_PREP_ERROR: return "SERVER_PREP_ERROR";
        case HTTP_ENGINE_STATE_SERVER_SEND_BUF: return "SERVER_SEND_BUF";
        case HTTP_ENGINE_STATE_SERVER_SEND_ACK: return "SERVER_SEND_ACK";
        case HTTP_ENGINE_STATE_SERVER_CLOSED: return "SERVER_CLOSED";
        default: return "UNKNOWN";
    }
}

char *http_engine_recvbuf(HTTP_Engine *eng, int *cap)
{
	if ((eng->state & HTTP_ENGINE_STATEBIT_RECV_BUF) == 0) {
		*cap = 0;
		return NULL;
	}

	eng->state &= ~HTTP_ENGINE_STATEBIT_RECV_BUF;
	eng->state |=  HTTP_ENGINE_STATEBIT_RECV_ACK;

	byte_queue_write_setmincap(&eng->input, 1<<9);
	if (byte_queue_error(&eng->input)) {
		*cap = 0;
		if (eng->state & HTTP_ENGINE_STATEBIT_CLIENT)
			eng->state = HTTP_ENGINE_STATE_CLIENT_CLOSED;
		else
			eng->state = HTTP_ENGINE_STATE_SERVER_CLOSED;
		return NULL;
	}

	return byte_queue_write_buf(&eng->input, cap);
}

static int
should_keep_alive(HTTP_Engine *eng)
{
	HTTP_ASSERT(eng->state & HTTP_ENGINE_STATEBIT_PREP);

#if 0
	// If the parent system doesn't want us to reuse
	// the connection, we certainly can't keep alive.
	if ((eng->state & TINYHTTP_STREAM_REUSE) == 0)
		return 0;
#endif

	if (eng->numexch >= 100) // TODO: Make this a parameter
		return 0;

	HTTP_Request *req = &eng->result.req;

	// If the client is using HTTP/1.0, we can't
	// keep alive.
	if (req->minor == 0)
		return 0;

	// TODO: This assumes "Connection" can only hold a single token,
	//       but this is not true.
	int i = http_find_header(req->headers, req->num_headers, HTTP_STR("Connection"));
	if (i >= 0 && http_streqcase(req->headers[i].value, HTTP_STR("Close")))
		return 0;

	return 1;
}

static void process_incoming_request(HTTP_Engine *eng)
{
	HTTP_ASSERT(eng->state == HTTP_ENGINE_STATE_SERVER_RECV_ACK
		|| eng->state == HTTP_ENGINE_STATE_SERVER_SEND_ACK
		|| eng->state == HTTP_ENGINE_STATE_SERVER_PREP_BODY_BUF
		|| eng->state == HTTP_ENGINE_STATE_SERVER_PREP_ERROR);

	char *src;
	int len;
	src = byte_queue_read_buf(&eng->input, &len);

	int ret = http_parse_request(src, len, &eng->result.req);

	if (ret == 0) {
		byte_queue_read_ack(&eng->input, 0);
		eng->state = HTTP_ENGINE_STATE_SERVER_RECV_BUF;
		return;
	}

	if (ret < 0) {
		byte_queue_read_ack(&eng->input, 0);
		byte_queue_write(&eng->output,
			"HTTP/1.1 400 Bad Request\r\n"
			"Connection: Close\r\n"
			"Content-Length: 0\r\n"
			"\r\n", -1
		);
		if (byte_queue_error(&eng->output))
			eng->state = HTTP_ENGINE_STATE_SERVER_CLOSED;
		else {
			eng->closing = 1;
			eng->state = HTTP_ENGINE_STATE_SERVER_SEND_BUF;
		}
		return;
	}

	HTTP_ASSERT(ret > 0);

	eng->state = HTTP_ENGINE_STATE_SERVER_PREP_STATUS;
	eng->reqsize = ret;
	eng->keepalive = should_keep_alive(eng);
	eng->response_offset = byte_queue_offset(&eng->output);
}

void http_engine_recvack(HTTP_Engine *eng, int num)
{
	if ((eng->state & HTTP_ENGINE_STATEBIT_RECV_ACK) == 0)
		return;

	byte_queue_write_ack(&eng->input, num);

	if (eng->state & HTTP_ENGINE_STATEBIT_CLIENT) {
		
		char *src;
		int len;
		src = byte_queue_read_buf(&eng->input, &len);

		int ret = http_parse_response(src, len, &eng->result.res);

		if (ret == 0) {
			byte_queue_read_ack(&eng->input, 0);
			eng->state = HTTP_ENGINE_STATE_CLIENT_RECV_BUF;
			return;
		}

		if (ret < 0) {
			eng->state = HTTP_ENGINE_STATE_CLIENT_CLOSED;
			return;
		}

		HTTP_ASSERT(ret > 0);

		eng->state = HTTP_ENGINE_STATE_CLIENT_READY;

	} else {
		process_incoming_request(eng);
	}
}

char *http_engine_sendbuf(HTTP_Engine *eng, int *len)
{
	if ((eng->state & HTTP_ENGINE_STATEBIT_SEND_BUF) == 0) {
		*len = 0;
		return NULL;
	}

	eng->state &= ~HTTP_ENGINE_STATEBIT_SEND_BUF;
	eng->state |=  HTTP_ENGINE_STATEBIT_SEND_ACK;

	return byte_queue_read_buf(&eng->output, len);
}

void http_engine_sendack(HTTP_Engine *eng, int num)
{
	if (eng->state != HTTP_ENGINE_STATE_SERVER_SEND_ACK &&
		eng->state != HTTP_ENGINE_STATE_CLIENT_SEND_ACK)
		return;

	byte_queue_read_ack(&eng->output, num);

	if (eng->state & HTTP_ENGINE_STATEBIT_CLIENT) {
		if (byte_queue_empty(&eng->output))
			eng->state = HTTP_ENGINE_STATE_CLIENT_RECV_BUF;
		else
			eng->state = HTTP_ENGINE_STATE_CLIENT_SEND_BUF;
	} else {
		if (byte_queue_empty(&eng->output)) {
			if (!eng->closing && eng->keepalive)
				process_incoming_request(eng);
			else
				eng->state = HTTP_ENGINE_STATE_SERVER_CLOSED;
		} else
			eng->state = HTTP_ENGINE_STATE_SERVER_SEND_BUF;
	}
}

HTTP_Request *http_engine_getreq(HTTP_Engine *eng)
{
	if ((eng->state & HTTP_ENGINE_STATEBIT_REQUEST) == 0)
		return NULL;
	return &eng->result.req;
}

HTTP_Response *http_engine_getres(HTTP_Engine *eng)
{
	if ((eng->state & HTTP_ENGINE_STATEBIT_RESPONSE) == 0)
		return NULL;
	return &eng->result.res;
}

void http_engine_url(HTTP_Engine *eng, HTTP_Method method, HTTP_String url, int minor)
{
	if (eng->state != HTTP_ENGINE_STATE_CLIENT_PREP_URL)
		return;

	eng->response_offset = byte_queue_offset(&eng->output); // TODO: rename response_offset to something that makes sense for clients

	HTTP_URL parsed_url;
	int ret = http_parse_url(url.ptr, url.len, &parsed_url);
	if (ret != url.len) {
		eng->state = HTTP_ENGINE_STATE_CLIENT_PREP_ERROR;
		return;
	}

	HTTP_String method_and_space = HTTP_STR("???");
	switch (method) {
		case HTTP_METHOD_GET    : method_and_space = HTTP_STR("GET ");     break;
		case HTTP_METHOD_HEAD   : method_and_space = HTTP_STR("HEAD ");    break;
		case HTTP_METHOD_POST   : method_and_space = HTTP_STR("POST ");    break;
		case HTTP_METHOD_PUT    : method_and_space = HTTP_STR("PUT ");     break;
		case HTTP_METHOD_DELETE : method_and_space = HTTP_STR("DELETE ");  break;
		case HTTP_METHOD_CONNECT: method_and_space = HTTP_STR("CONNECT "); break;
		case HTTP_METHOD_OPTIONS: method_and_space = HTTP_STR("OPTIONS "); break;
		case HTTP_METHOD_TRACE  : method_and_space = HTTP_STR("TRACE ");   break;
		case HTTP_METHOD_PATCH  : method_and_space = HTTP_STR("PATCH ");   break;
	}

	HTTP_String path = parsed_url.path;
	if (path.len == 0)
		path = HTTP_STR("/");

	byte_queue_write(&eng->output, method_and_space.ptr, method_and_space.len);
	byte_queue_write(&eng->output, path.ptr, path.len);
	byte_queue_write(&eng->output, parsed_url.query.ptr, parsed_url.query.len);
	byte_queue_write(&eng->output, minor ? " HTTP/1.1\r\nHost: " : " HTTP/1.0\r\nHost: ", -1);
	byte_queue_write(&eng->output, parsed_url.authority.host.text.ptr, parsed_url.authority.host.text.len);
	if (parsed_url.authority.port > 0)
		byte_queue_write_fmt(&eng->output, "%d", parsed_url.authority.port);
	byte_queue_write(&eng->output, "\r\n", 2);

	eng->keepalive = 1; // TODO

	eng->state = HTTP_ENGINE_STATE_CLIENT_PREP_HEADER;
}


static const char*
get_status_text(int code)
{
	switch(code) {

		case 100: return "Continue";
		case 101: return "Switching Protocols";
		case 102: return "Processing";

		case 200: return "OK";
		case 201: return "Created";
		case 202: return "Accepted";
		case 203: return "Non-Authoritative Information";
		case 204: return "No Content";
		case 205: return "Reset Content";
		case 206: return "Partial Content";
		case 207: return "Multi-Status";
		case 208: return "Already Reported";

		case 300: return "Multiple Choices";
		case 301: return "Moved Permanently";
		case 302: return "Found";
		case 303: return "See Other";
		case 304: return "Not Modified";
		case 305: return "Use Proxy";
		case 306: return "Switch Proxy";
		case 307: return "Temporary Redirect";
		case 308: return "Permanent Redirect";

		case 400: return "Bad Request";
		case 401: return "Unauthorized";
		case 402: return "Payment Required";
		case 403: return "Forbidden";
		case 404: return "Not Found";
		case 405: return "Method Not Allowed";
		case 406: return "Not Acceptable";
		case 407: return "Proxy Authentication Required";
		case 408: return "Request Timeout";
		case 409: return "Conflict";
		case 410: return "Gone";
		case 411: return "Length Required";
		case 412: return "Precondition Failed";
		case 413: return "Request Entity Too Large";
		case 414: return "Request-URI Too Long";
		case 415: return "Unsupported Media Type";
		case 416: return "Requested Range Not Satisfiable";
		case 417: return "Expectation Failed";
		case 418: return "I'm a teapot";
		case 420: return "Enhance your calm";
		case 422: return "Unprocessable Entity";
		case 426: return "Upgrade Required";
		case 429: return "Too many requests";
		case 431: return "Request Header Fields Too Large";
		case 449: return "Retry With";
		case 451: return "Unavailable For Legal Reasons";

		case 500: return "Internal Server Error";
		case 501: return "Not Implemented";
		case 502: return "Bad Gateway";
		case 503: return "Service Unavailable";
		case 504: return "Gateway Timeout";
		case 505: return "HTTP Version Not Supported";
		case 509: return "Bandwidth Limit Exceeded";
	}
	return "???";
}

void http_engine_status(HTTP_Engine *eng, int status)
{
	if (eng->state != HTTP_ENGINE_STATE_SERVER_PREP_STATUS)
		return;

	byte_queue_write_fmt(&eng->output,
		"HTTP/1.1 %d %s\r\n",
		status, get_status_text(status));

	eng->state = HTTP_ENGINE_STATE_SERVER_PREP_HEADER;
}

void http_engine_header(HTTP_Engine *eng, HTTP_String str)
{
	if ((eng->state & HTTP_ENGINE_STATEBIT_PREP_HEADER) == 0)
		return;

	// TODO: Check that the header is valid

	byte_queue_write(&eng->output, str.ptr, str.len);
	byte_queue_write(&eng->output, "\r\n", 2);
}

void http_engine_header_fmt2(HTTP_Engine *eng, const char *fmt, va_list args)
{
	if ((eng->state & HTTP_ENGINE_STATEBIT_PREP_HEADER) == 0)
		return;

	// TODO: Check that the header is valid

	byte_queue_write_fmt2(&eng->output, fmt, args);
	byte_queue_write(&eng->output, "\r\n", 2);
}

void http_engine_header_fmt(HTTP_Engine *eng, const char *fmt, ...)
{
	va_list args;
	va_start(args, fmt);
	http_engine_header_fmt2(eng, fmt, args);
	va_end(args);
}

static void
complete_message_head(HTTP_Engine *eng)
{
	if (eng->keepalive) byte_queue_write(&eng->output, "Connection: Keep-Alive\r\n", -1);
	else                byte_queue_write(&eng->output, "Connection: Close\r\n", -1);

	byte_queue_write(&eng->output, "Content-Length: ", -1);
	eng->content_length_value_offset = byte_queue_offset(&eng->output);
	byte_queue_write(&eng->output, TEN_SPACES "\r\n", -1);

	byte_queue_write(&eng->output, "\r\n", -1);
	eng->content_length_offset = byte_queue_offset(&eng->output);
}

static void complete_message_body(HTTP_Engine *eng)
{
	unsigned int content_length = byte_queue_size_from_offset(&eng->output, eng->content_length_offset);

	if (content_length > UINT32_MAX) {
		// TODO
	}

	char tmp[10];

	tmp[0] = '0' + content_length / 1000000000; content_length %= 1000000000;
	tmp[1] = '0' + content_length / 100000000;  content_length %= 100000000;
	tmp[2] = '0' + content_length / 10000000;   content_length %= 10000000;
	tmp[3] = '0' + content_length / 1000000;    content_length %= 1000000;
	tmp[4] = '0' + content_length / 100000;     content_length %= 100000;
	tmp[5] = '0' + content_length / 10000;      content_length %= 10000;
	tmp[6] = '0' + content_length / 1000;       content_length %= 1000;
	tmp[7] = '0' + content_length / 100;        content_length %= 100;
	tmp[8] = '0' + content_length / 10;         content_length %= 10;
	tmp[9] = '0' + content_length;

	int i = 0;
	while (i < 9 && tmp[i] == '0')
		i++;

	byte_queue_patch(&eng->output, eng->content_length_value_offset, tmp + i, 10 - i);
}

void http_engine_body(HTTP_Engine *eng, HTTP_String str)
{
	http_engine_bodycap(eng, str.len);
	int cap;
	char *buf = http_engine_bodybuf(eng, &cap);
	if (buf) {
		memcpy(buf, str.ptr, str.len);
		http_engine_bodyack(eng, str.len);
	}
}

static void ensure_body_entered(HTTP_Engine *eng)
{
	if (eng->state & HTTP_ENGINE_STATEBIT_CLIENT) {

		if (eng->state == HTTP_ENGINE_STATE_CLIENT_PREP_HEADER) {
			complete_message_head(eng);
			eng->state = HTTP_ENGINE_STATE_CLIENT_PREP_BODY_BUF;
		}

	} else {

		if (eng->state == HTTP_ENGINE_STATE_SERVER_PREP_HEADER) {
			complete_message_head(eng);
			eng->state = HTTP_ENGINE_STATE_SERVER_PREP_BODY_BUF;
		}
	}
}

void http_engine_bodycap(HTTP_Engine *eng, int mincap)
{
	ensure_body_entered(eng);
	if (eng->state != HTTP_ENGINE_STATE_CLIENT_PREP_BODY_BUF &&
		eng->state != HTTP_ENGINE_STATE_SERVER_PREP_BODY_BUF)
		return;

	byte_queue_write_setmincap(&eng->output, mincap);
}

char *http_engine_bodybuf(HTTP_Engine *eng, int *cap)
{
	ensure_body_entered(eng);
	if (eng->state != HTTP_ENGINE_STATE_CLIENT_PREP_BODY_BUF &&
		eng->state != HTTP_ENGINE_STATE_SERVER_PREP_BODY_BUF) {
		*cap = 0;
		return NULL;
	}

	if (eng->state & HTTP_ENGINE_STATEBIT_CLIENT)
		eng->state = HTTP_ENGINE_STATE_CLIENT_PREP_BODY_ACK;
	else
		eng->state = HTTP_ENGINE_STATE_SERVER_PREP_BODY_ACK;

	return byte_queue_write_buf(&eng->output, cap);
}

void http_engine_bodyack(HTTP_Engine *eng, int num)
{
	if (eng->state != HTTP_ENGINE_STATE_CLIENT_PREP_BODY_ACK &&
		eng->state != HTTP_ENGINE_STATE_SERVER_PREP_BODY_ACK)
		return;

	byte_queue_write_ack(&eng->output, num);

	if (eng->state & HTTP_ENGINE_STATEBIT_CLIENT)
		eng->state = HTTP_ENGINE_STATE_CLIENT_PREP_BODY_BUF;
	else
		eng->state = HTTP_ENGINE_STATE_SERVER_PREP_BODY_BUF;
}

void http_engine_done(HTTP_Engine *eng)
{
	if ((eng->state & HTTP_ENGINE_STATEBIT_PREP) == 0)
		return;

	if (eng->state & HTTP_ENGINE_STATEBIT_CLIENT) {

		if (eng->state == HTTP_ENGINE_STATE_CLIENT_PREP_URL) {
			eng->state = HTTP_ENGINE_STATE_CLIENT_CLOSED;
			return;
		}

		if (eng->state == HTTP_ENGINE_STATE_CLIENT_PREP_HEADER) {
			complete_message_head(eng);
			eng->state = HTTP_ENGINE_STATE_CLIENT_PREP_BODY_BUF;
		}

		if (eng->state == HTTP_ENGINE_STATE_CLIENT_PREP_BODY_BUF)
			complete_message_body(eng);

		if (eng->state == HTTP_ENGINE_STATE_CLIENT_PREP_ERROR) {
			eng->state = HTTP_ENGINE_STATE_CLIENT_CLOSED;
			return;
		}

		if (byte_queue_error(&eng->output)) {
			eng->state = HTTP_ENGINE_STATE_CLIENT_CLOSED;
			return;
		}

		eng->state = HTTP_ENGINE_STATE_CLIENT_SEND_BUF;

	} else {

		if (eng->state == HTTP_ENGINE_STATE_SERVER_PREP_HEADER) {
			complete_message_head(eng);
			eng->state = HTTP_ENGINE_STATE_SERVER_PREP_BODY_BUF;
		}

		if (eng->state == HTTP_ENGINE_STATE_SERVER_PREP_BODY_BUF)
			complete_message_body(eng);

		if (eng->state == HTTP_ENGINE_STATE_SERVER_PREP_ERROR) {
			byte_queue_remove_from_offset(&eng->output, eng->response_offset);
			byte_queue_write(&eng->output,
				"HTTP/1.1 500 Internal Server Error\r\n"
				"Content-Length: 0\r\n"
				"Connection: Close\r\n"
				"\r\n",
				-1
			);
		}

		if (byte_queue_error(&eng->output)) {
			eng->state = HTTP_ENGINE_STATE_SERVER_CLOSED;
			return;
		}

		byte_queue_read_ack(&eng->input, eng->reqsize);
		eng->state = HTTP_ENGINE_STATE_SERVER_SEND_BUF;
	}
}

void http_engine_undo(HTTP_Engine *eng)
{
	if ((eng->state & HTTP_ENGINE_STATEBIT_PREP) == 0)
		return;

	byte_queue_write_ack(&eng->output, 0);
	byte_queue_remove_from_offset(&eng->output, eng->response_offset);

	if (eng->state & HTTP_ENGINE_STATEBIT_CLIENT)
		eng->state = HTTP_ENGINE_STATE_CLIENT_PREP_URL;
	else
		eng->state = HTTP_ENGINE_STATE_SERVER_PREP_STATUS;
}

////////////////////////////////////////////////////////////////////////////////////////
// src/cert.c
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/cert.c"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#ifdef HTTPS_ENABLED
#include <openssl/pem.h>
#include <openssl/conf.h>
#include <openssl/x509v3.h>
#include <openssl/rsa.h>
#include <openssl/evp.h>
#include <openssl/bn.h>
#endif

#ifndef HTTP_AMALGAMATION
#include "cert.h"
#endif

#ifdef HTTPS_ENABLED

static EVP_PKEY *generate_rsa_key_pair(int key_bits)
{
    EVP_PKEY_CTX *ctx = EVP_PKEY_CTX_new_id(EVP_PKEY_RSA, NULL);
    if (!ctx)
        return NULL;

    if (EVP_PKEY_keygen_init(ctx) <= 0) {
        EVP_PKEY_CTX_free(ctx);
        return NULL;
    }

    if (EVP_PKEY_CTX_set_rsa_keygen_bits(ctx, key_bits) <= 0) {
        EVP_PKEY_CTX_free(ctx);
        return NULL;
    }

    EVP_PKEY *pkey = NULL;
    if (EVP_PKEY_keygen(ctx, &pkey) <= 0) {
        EVP_PKEY_CTX_free(ctx);
        return NULL;
    }

    EVP_PKEY_CTX_free(ctx);
    return pkey;
}

static X509 *create_certificate(EVP_PKEY *pkey, HTTP_String C, HTTP_String O, HTTP_String CN, int days)
{
    X509 *x509 = X509_new();
    if (!x509)
        return NULL;

    // Set version (version 3)
    X509_set_version(x509, 2);
    
    // Set serial number
    ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
    
    // Set validity period
    X509_gmtime_adj(X509_get_notBefore(x509), 0);
    X509_gmtime_adj(X509_get_notAfter(x509), 31536000L * days); // days * seconds_per_year

    // Set public key
    X509_set_pubkey(x509, pkey);

    // Set subject name
    X509_NAME *name = X509_get_subject_name(x509);
    X509_NAME_add_entry_by_txt(name, "C",  MBSTRING_ASC, (unsigned char*) C.ptr,  C.len,  -1, 0);
    X509_NAME_add_entry_by_txt(name, "O",  MBSTRING_ASC, (unsigned char*) O.ptr,  O.len,  -1, 0);
    X509_NAME_add_entry_by_txt(name, "CN", MBSTRING_ASC, (unsigned char*) CN.ptr, CN.len, -1, 0);

    // Set issuer name (same as subject for self-signed)
    X509_set_issuer_name(x509, name);

    if (!X509_sign(x509, pkey, EVP_sha256())) {
        X509_free(x509);
        return NULL;
    }

    return x509;
}

static int save_private_key(EVP_PKEY *pkey, HTTP_String file)
{
    char copy[1<<10];
    if (file.len >= (int) sizeof(copy))
        return -1;
    memcpy(copy, file.ptr, file.len);
    copy[file.len] = '\0';

    FILE *fp = fopen(copy, "wb");
    if (!fp)
        return -1;

    // Write private key in PEM format
    if (!PEM_write_PrivateKey(fp, pkey, NULL, NULL, 0, NULL, NULL)) {
        fclose(fp);
        return -1;
    }

    fclose(fp);
    return 0;
}

static int save_certificate(X509 *x509, HTTP_String file)
{
    char copy[1<<10];
    if (file.len >= (int) sizeof(copy))
        return -1;
    memcpy(copy, file.ptr, file.len);
    copy[file.len] = '\0';

    FILE *fp = fopen(copy, "wb");
    if (!fp)
        return -1;

    // Write certificate in PEM format
    if (!PEM_write_X509(fp, x509)) {
        fclose(fp);
        return -1;
    }

    fclose(fp);
    return 0;
}

int http_create_test_certificate(HTTP_String C, HTTP_String O, HTTP_String CN,
    HTTP_String cert_file, HTTP_String key_file)
{
    EVP_PKEY *pkey = generate_rsa_key_pair(2048);
    if (pkey == NULL)
        return -1;

    X509 *x509 = create_certificate(pkey, C, O, CN, 1);
    if (x509 == NULL) {
        EVP_PKEY_free(pkey);
        return -1;
    }

    if (save_private_key(pkey, key_file) < 0) {
        X509_free(x509);
        EVP_PKEY_free(pkey);
        return -1;
    }

    if (save_certificate(x509, cert_file) < 0) {
        X509_free(x509);
        EVP_PKEY_free(pkey);
        return -1;
    }

    X509_free(x509);
    EVP_PKEY_free(pkey);
    return 0;
}

#else

int http_create_test_certificate(HTTP_String C, HTTP_String O, HTTP_String CN,
    HTTP_String cert_file, HTTP_String key_file)
{
    (void) C;
    (void) O;
    (void) CN;
    (void) cert_file;
    (void) key_file;
    return -1;
}

#endif

////////////////////////////////////////////////////////////////////////////////////////
// src/sec.c
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/sec.c"
#ifndef HTTP_AMALGAMATION
#include "sec.h"
#endif

#ifndef HTTPS_ENABLED

void secure_context_global_init(void)
{
}

void secure_context_global_free(void)
{
}

int secure_context_init_as_client(SecureContext *sec)
{
    (void) sec;
    return 0;
}

int secure_context_init_as_server(SecureContext *sec,
    HTTP_String cert_file, HTTP_String key_file)
{
    (void) sec;
    (void) cert_file;
    (void) key_file;
    return 0;
}

int secure_context_add_cert(SecureContext *sec,
    HTTP_String domain, HTTP_String cert_file,
    HTTP_String key_file)
{
    (void) sec;
    (void) domain;
    (void) cert_file;
    (void) key_file;
    return -1;
}

void secure_context_free(SecureContext *sec)
{
    (void) sec;
}

#else

void secure_context_global_init(void)
{
    SSL_library_init();
    SSL_load_error_strings();
    OpenSSL_add_all_algorithms();
}

void secure_context_global_free(void)
{
    EVP_cleanup();
}

int secure_context_init_as_client(SecureContext *sec)
{
    SSL_CTX *ctx = SSL_CTX_new(TLS_client_method());
    if (!ctx)
        return -1;

    SSL_CTX_set_min_proto_version(ctx, TLS1_2_VERSION);
    
    SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, NULL);
    
    if (SSL_CTX_set_default_verify_paths(ctx) != 1) {
        SSL_CTX_free(ctx);
        return -1;
    }

    sec->is_server = false;
    sec->ctx = ctx;
    sec->num_certs = 0;
    return 0;
}

static int servername_callback(SSL *ssl, int *ad, void *arg)
{
    SecureContext *sec = arg;

    (void) ad; // TODO: use this?

    const char *servername = SSL_get_servername(ssl, TLSEXT_NAMETYPE_host_name);
    if (servername == NULL)
        return SSL_TLSEXT_ERR_NOACK;
    
    for (int i = 0; i < sec->num_certs; i++) {
        CertData *cert = &sec->certs[i];
        if (!strcmp(cert->domain, servername)) {
            SSL_set_SSL_CTX(ssl, cert->ctx);
            return SSL_TLSEXT_ERR_OK;
        }
    }

    return SSL_TLSEXT_ERR_NOACK;
}

int secure_context_init_as_server(SecureContext *sec,
    HTTP_String cert_file, HTTP_String key_file)
{
    SSL_CTX *ctx = SSL_CTX_new(TLS_server_method());
    if (!ctx)
        return -1;

    SSL_CTX_set_min_proto_version(ctx, TLS1_2_VERSION);
    
    char cert_buffer[1024];
    if (cert_file.len >= (int) sizeof(cert_buffer)) {
        SSL_CTX_free(ctx);
        return -1;
    }
    memcpy(cert_buffer, cert_file.ptr, cert_file.len);
    cert_buffer[cert_file.len] = '\0';
    
    // Copy private key file path to static buffer
    char key_buffer[1024];
    if (key_file.len >= (int) sizeof(key_buffer)) {
        SSL_CTX_free(ctx);
        return -1;
    }
    memcpy(key_buffer, key_file.ptr, key_file.len);
    key_buffer[key_file.len] = '\0';
    
    // Load certificate and private key
    if (SSL_CTX_use_certificate_file(ctx, cert_buffer, SSL_FILETYPE_PEM) != 1) {
        SSL_CTX_free(ctx);
        return -1;
    }
    
    if (SSL_CTX_use_PrivateKey_file(ctx, key_buffer, SSL_FILETYPE_PEM) != 1) {
        SSL_CTX_free(ctx);
        return -1;
    }
    
    // Verify that the private key matches the certificate
    if (SSL_CTX_check_private_key(ctx) != 1) {
        SSL_CTX_free(ctx);
        return -1;
    }

    SSL_CTX_set_tlsext_servername_callback(ctx, servername_callback);
    SSL_CTX_set_tlsext_servername_arg(ctx, sec);

    sec->is_server = true;
    sec->ctx = ctx;
    sec->num_certs = 0;
    return 0;
}

void secure_context_free(SecureContext *sec)
{
    SSL_CTX_free(sec->ctx);
    for (int i = 0; i < sec->num_certs; i++)
        SSL_CTX_free(sec->certs[i].ctx);
}

int secure_context_add_cert(SecureContext *sec,
    HTTP_String domain, HTTP_String cert_file,
    HTTP_String key_file)
{
    if (!sec->is_server)
        return -1;

    if (sec->num_certs == MAX_CERTS)
        return -1;

    SSL_CTX *ctx = SSL_CTX_new(TLS_server_method());
    if (!ctx)
        return -1;

    SSL_CTX_set_min_proto_version(ctx, TLS1_2_VERSION);
    
    char cert_buffer[1024];
    if (cert_file.len >= (int) sizeof(cert_buffer)) {
        SSL_CTX_free(ctx);
        return -1;
    }
    memcpy(cert_buffer, cert_file.ptr, cert_file.len);
    cert_buffer[cert_file.len] = '\0';
    
    char key_buffer[1024];
    if (key_file.len >= (int) sizeof(key_buffer)) {
        SSL_CTX_free(ctx);
        return -1;
    }
    memcpy(key_buffer, key_file.ptr, key_file.len);
    key_buffer[key_file.len] = '\0';
    
    if (SSL_CTX_use_certificate_file(ctx, cert_buffer, SSL_FILETYPE_PEM) != 1) {
        SSL_CTX_free(ctx);
        return -1;
    }
    
    if (SSL_CTX_use_PrivateKey_file(ctx, key_buffer, SSL_FILETYPE_PEM) != 1) {
        SSL_CTX_free(ctx);
        return -1;
    }
    
    if (SSL_CTX_check_private_key(ctx) != 1) {
        SSL_CTX_free(ctx);
        return -1;
    }

    CertData *cert = &sec->certs[sec->num_certs];
    if (domain.len >= (int) sizeof(cert->domain)) {
        SSL_CTX_free(ctx);
        return -1;
    }
    memcpy(cert->domain, domain.ptr, domain.len);
    cert->domain[domain.len] = '\0';
    cert->ctx = ctx;
    sec->num_certs++;
    return 0;
}

#endif

////////////////////////////////////////////////////////////////////////////////////////
// src/socket_raw.c
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/socket_raw.c"
#include <string.h>

#ifdef _WIN32
#include <ws2tcpip.h>
#endif

#ifdef __linux__
#include <fcntl.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#endif

#ifndef HTTP_AMALGAMATION
#include "socket_raw.h"
#endif

int socket_raw_global_init(void)
{
#ifdef _WIN32
    WSADATA wsaData;
    int result = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (result != 0)
        return 1;
#endif
    return 0;
}

void socket_raw_global_free(void)
{
#ifdef _WIN32
    WSACleanup();
#endif
}

int set_socket_blocking(RAW_SOCKET sock, bool value)
{
#ifdef _WIN32
    u_long mode = !value;
    if (ioctlsocket(sock, FIONBIO, &mode) == SOCKET_ERROR)
        return -1;
#endif

#ifdef __linux__
    int flags = fcntl(sock, F_GETFL, 0);
    if (flags < 0)
        return -1;
    if (value) flags &= ~O_NONBLOCK;
    else       flags |= O_NONBLOCK;
    if (fcntl(sock, F_SETFL, flags) < 0)
        return -1;
#endif
    
    return 0;
}

RAW_SOCKET listen_socket(HTTP_String addr, uint16_t port, bool reuse_addr, int backlog)
{
    RAW_SOCKET sock = socket(AF_INET, SOCK_STREAM, 0);
    if (sock == BAD_SOCKET)
        return BAD_SOCKET;

    if (set_socket_blocking(sock, false) < 0) {
        CLOSE_SOCKET(sock);
        return BAD_SOCKET;
    }

    if (reuse_addr) {
        int one = 1;
        setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void*) &one, sizeof(one));
    }

    struct in_addr addr_buf;
    if (addr.len == 0)
        addr_buf.s_addr = htonl(INADDR_ANY);
    else {

        char copy[100];
        if (addr.len >= (int) sizeof(copy)) {
            CLOSE_SOCKET(sock);
            return BAD_SOCKET;
        }
        memcpy(copy, addr.ptr, addr.len);
        copy[addr.len] = '\0';

        if (inet_pton(AF_INET, copy, &addr_buf) < 0) {
            CLOSE_SOCKET(sock);
            return BAD_SOCKET;
        }
    }

    struct sockaddr_in bind_buf;
    bind_buf.sin_family = AF_INET;
    bind_buf.sin_addr   = addr_buf;
    bind_buf.sin_port   = htons(port);
    if (bind(sock, (struct sockaddr*) &bind_buf, sizeof(bind_buf)) < 0) { // TODO: how does bind fail on windows?
        CLOSE_SOCKET(sock);
        return BAD_SOCKET;
    }

    if (listen(sock, backlog) < 0) { // TODO: how does listen fail on windows?
        CLOSE_SOCKET(sock);
        return BAD_SOCKET;
    }

    return sock;
}

////////////////////////////////////////////////////////////////////////////////////////
// src/socket.c
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/socket.c"
#include <stdio.h> // snprintf
#include <assert.h>
#include <string.h>
#include <stdlib.h>

#ifdef _WIN32
#include <ws2tcpip.h>
#endif

#ifdef __linux__
#include <netdb.h>
#include <errno.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#endif

#ifdef HTTPS_ENABLED
#include <openssl/ssl.h>
#include <openssl/err.h>
#endif

#ifndef HTTP_AMALGAMATION
#include "basic.h"
#include "socket.h"
#endif

typedef struct {
    bool is_ipv4;
    union {
        HTTP_IPv4 ipv4;
        HTTP_IPv6 ipv6;
    };
} PendingConnectAddr;

struct PendingConnect {
    uint16_t port;
    int      cursor;
    int      num_addrs;
    int      max_addrs;
    PendingConnectAddr *addrs;
    char*    hostname; // null-terminated
    int      hostname_len;
};

static PendingConnect*
pending_connect_init(HTTP_String hostname, uint16_t port, int max_addrs)
{
    PendingConnect *pending_connect = malloc(sizeof(PendingConnect) + max_addrs * sizeof(PendingConnectAddr) + hostname.len + 1);
    if (pending_connect == NULL)
        return NULL;
    pending_connect->port = port;
    pending_connect->cursor = 0;
    pending_connect->num_addrs = 0;
    pending_connect->max_addrs = max_addrs;
    pending_connect->addrs = (PendingConnectAddr*) (pending_connect + 1);
    pending_connect->hostname = (char*) (pending_connect->addrs + max_addrs);
    memcpy(pending_connect->hostname, hostname.ptr, hostname.len);
    pending_connect->hostname[hostname.len] = '\0';
    pending_connect->hostname_len = hostname.len;
    return pending_connect;
}

static void
pending_connect_free(PendingConnect *pending_connect)
{
    free(pending_connect);
}

static void
pending_connect_add_ipv4(PendingConnect *pending_connect, HTTP_IPv4 ipv4)
{
    if (pending_connect->num_addrs == pending_connect->max_addrs)
        return;
    pending_connect->addrs[pending_connect->num_addrs++] = (PendingConnectAddr) { .is_ipv4=true, .ipv4=ipv4 };
}

static void
pending_connect_add_ipv6(PendingConnect *pending_connect, HTTP_IPv6 ipv6)
{
    if (pending_connect->num_addrs == pending_connect->max_addrs)
        return;
    pending_connect->addrs[pending_connect->num_addrs++] = (PendingConnectAddr) { .is_ipv4=false, .ipv6=ipv6 };
}

static int
next_connect_addr(PendingConnect *pending_connect, PendingConnectAddr *addr)
{
    if (pending_connect->cursor == pending_connect->num_addrs)
        return -1;
    *addr = pending_connect->addrs[pending_connect->cursor++];
    return 0;
}

// Initializes a FREE socket with the information required to
// connect to specified host name. The resulting socket state
// is DIED if an error occurred or PENDING.
void socket_connect(Socket *sock, SecureContext *sec,
    HTTP_String hostname, uint16_t port, void *user_data)
{
    PendingConnect *pending_connect;

    int max_addrs = 30;
    pending_connect = pending_connect_init(hostname, port, max_addrs);
    if (pending_connect == NULL) {
        sock->state = SOCKET_STATE_DIED;
        sock->events = 0;
        return;
    }

    char portstr[16];
    int len = snprintf(portstr, sizeof(portstr), "%u", port);
    if (len < 0 || len >= (int) sizeof(portstr)) {
        pending_connect_free(pending_connect);
        sock->state = SOCKET_STATE_DIED;
        sock->events = 0;
        return;
    }

    // DNS query
    struct addrinfo hints = {0};
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;

    struct addrinfo *res = NULL;
    int ret = getaddrinfo(pending_connect->hostname, portstr, &hints, &res);
    if (ret != 0) {
        pending_connect_free(pending_connect);
        sock->state = SOCKET_STATE_DIED;
        sock->events = 0;
        return;
    }

    for (struct addrinfo *rp = res; rp; rp = rp->ai_next) {
        if (rp->ai_family == AF_INET) {
            HTTP_IPv4 *ipv4 = (void*) &((struct sockaddr_in*)rp->ai_addr)->sin_addr;
            pending_connect_add_ipv4(pending_connect, *ipv4);
        } else if (rp->ai_family == AF_INET6) {
            HTTP_IPv6 *ipv6 = (void*) &((struct sockaddr_in6*)rp->ai_addr)->sin6_addr;
            pending_connect_add_ipv6(pending_connect, *ipv6);
        }
    }

    freeaddrinfo(res);

    sock->state = SOCKET_STATE_PENDING;
    sock->events = 0;

    sock->raw = BAD_SOCKET;
    sock->user_data = user_data;
    sock->pending_connect = pending_connect;
    sock->sec = sec;

#ifdef HTTPS_ENABLED
    sock->ssl = NULL;
#endif

    socket_update(sock);
}

// Just like socket_connect, but the raw IPv4 address is specified
void socket_connect_ipv4(Socket *sock, SecureContext *sec,
    HTTP_IPv4 addr, uint16_t port, void *user_data)
{
    PendingConnect *pending_connect;
    
    pending_connect = pending_connect_init(HTTP_STR(""), port, 1);
    if (pending_connect == NULL) {
        sock->state = SOCKET_STATE_DIED;
        sock->events = 0;
        return;
    }

    pending_connect_add_ipv4(pending_connect, addr);

    sock->state = SOCKET_STATE_PENDING;
    sock->events = 0;

    sock->raw = BAD_SOCKET;
    sock->user_data = user_data;
    sock->pending_connect = pending_connect;
    sock->sec = sec;

#ifdef HTTPS_ENABLED
    sock->ssl = NULL;
#endif

    socket_update(sock);
}

// Just like socket_connect, but the raw IPv6 address is specified
void socket_connect_ipv6(Socket *sock, SecureContext *sec,
    HTTP_IPv6 addr, uint16_t port, void *user_data)
{
    PendingConnect *pending_connect;
    
    pending_connect = pending_connect_init(HTTP_STR(""), port, 1);
    if (pending_connect == NULL) {
        sock->state = SOCKET_STATE_DIED;
        sock->events = 0;
        return;
    }

    pending_connect_add_ipv6(pending_connect, addr);

    sock->state = SOCKET_STATE_PENDING;
    sock->events = 0;

    sock->raw = BAD_SOCKET;
    sock->user_data = user_data;
    sock->pending_connect = pending_connect;
    sock->sec = sec;

#ifdef HTTPS_ENABLED
    sock->ssl = NULL;
#endif

    socket_update(sock);
}

void socket_accept(Socket *sock, SecureContext *sec, RAW_SOCKET raw)
{
    sock->state = SOCKET_STATE_ACCEPTED;
    sock->raw = raw;
    sock->events = 0;
    sock->user_data = NULL;
    sock->pending_connect = NULL;
    sock->sec = sec;

#ifdef HTTPS_ENABLED
    sock->ssl = NULL;
#endif

    if (set_socket_blocking(raw, false) < 0) {
        sock->state  = SOCKET_STATE_DIED;
        sock->events = 0;
        return;
    }

    socket_update(sock);
}

void socket_close(Socket *sock)
{
    // TODO: maybe we don't want to always set to SHUTDOWN. What if the socket is DIED for instance?
    sock->state  = SOCKET_STATE_SHUTDOWN;
    sock->events = 0;
    socket_update(sock);
}

bool socket_ready(Socket *sock)
{
    return sock->state == SOCKET_STATE_ESTABLISHED_READY;
}

bool socket_died(Socket *sock)
{
    return sock->state == SOCKET_STATE_DIED;
}

// TODO: when is the pending_connect data freed?

static bool connect_pending(void)
{
#ifdef _WIN32
    return WSAGetLastError() == WSAEWOULDBLOCK;
#else
    return errno == EINPROGRESS;
#endif
}

static bool
connect_failed_because_or_peer_2(int err)
{
#ifdef _WIN32
    return err == WSAECONNREFUSED
        || err == WSAETIMEDOUT
        || err == WSAENETUNREACH
        || err == WSAEHOSTUNREACH;
#else
    return err == ECONNREFUSED
        || err == ETIMEDOUT
        || err == ENETUNREACH
        || err == EHOSTUNREACH;
#endif
}

static bool
connect_failed_because_or_peer(void)
{
#ifdef _WIN32
    int err = WSAGetLastError();
#else
    int err = errno;
#endif
    return connect_failed_because_or_peer_2(err);
}

// Processes the socket until it's either ready, died, or would block
void socket_update(Socket *sock)
{
    sock->events = 0;

    bool again;
    do {

        again = false;

        switch (sock->state) {
        case SOCKET_STATE_PENDING:
        {
            // In this state we need to pop an address from the pending connect
            // data and try connect to it. This state is reached when a socket
            // is initialized using one of the socket_connect functions or by
            // failing to connect before the established state is reached.

            // If this isn't the first connection attempt we may have old
            // descriptors that need freeing before trying again.
            {
#ifdef HTTPS_ENABLED
                if (sock->ssl) {
                    SSL_free(sock->ssl);
                    sock->ssl = NULL;
                }
#endif
                if (sock->raw != BAD_SOCKET)
                    CLOSE_SOCKET(sock->raw);
            }

            // Pop the next address from the pending connect data
            PendingConnectAddr addr;
            if (next_connect_addr(sock->pending_connect, &addr) < 0) {
                sock->state  = SOCKET_STATE_DIED;
                sock->events = 0;
                break;
            }
            uint16_t port = sock->pending_connect->port;

            // Create a kernel socket object
            int family = addr.is_ipv4 ? AF_INET : AF_INET6;
            RAW_SOCKET raw = socket(family, SOCK_STREAM, 0);
            if (raw == BAD_SOCKET) {
                sock->state  = SOCKET_STATE_PENDING;
                sock->events = 0;
                again = true;
                break;
            }

            // Configure it
            if (set_socket_blocking(raw, false) < 0) {
                CLOSE_SOCKET(raw);
                sock->state  = SOCKET_STATE_DIED;
                sock->events = 0;
                break;
            }

            // Now perform the connect

            struct sockaddr_in  connect_buf_4;
            struct sockaddr_in6 connect_buf_6;
            struct sockaddr*    connect_buf;
            int    connect_buf_len;

            if (addr.is_ipv4) {

                connect_buf = (struct sockaddr*) &connect_buf_4;
                connect_buf_len = sizeof(connect_buf_4);

                connect_buf_4.sin_family = AF_INET;
                connect_buf_4.sin_port = htons(port);
                memcpy(&connect_buf_4.sin_addr, &addr.ipv4, sizeof(HTTP_IPv4));

            } else {

                connect_buf = (struct sockaddr*) &connect_buf_6;
                connect_buf_len = sizeof(connect_buf_6);

                connect_buf_6.sin6_family = AF_INET6;
                connect_buf_6.sin6_port = htons(port);
                memcpy(&connect_buf_6.sin6_addr, &addr.ipv6, sizeof(HTTP_IPv6));
            }

            int ret = connect(raw, connect_buf, connect_buf_len);

            // We divide the connect() results in four categories:
            //
            //   1) The connect resolved immediately. I'm not sure how this can happen,
            //      but we may as well handle it. This allows us to skip a step.
            //
            //   2) The connect operation is pending. This is what we expect most of the time.
            //
            //   3) The connect operation failed because the target address wasn't good
            //      for some reason. It make sense to try connecting to a different address
            //
            //   4) The connect operation failed for unknown reasons. There isn't much we
            //      can do at this point.

            if (ret == 0) {
                // Connected immediately
                sock->raw    = raw;
                sock->state  = SOCKET_STATE_CONNECTED;
                sock->events = 0;
                again = true;
                break;
            }

            if (connect_pending()) { // TODO: I'm pretty sure all the error numbers need to be changed for windows
                // Connection pending
                sock->raw = raw;
                sock->state = SOCKET_STATE_CONNECTING;
                sock->events = POLLOUT;
                break;
            }

            // Connect failed

            // If remote peer not working, try next address
            if (connect_failed_because_or_peer()) {
                sock->state = SOCKET_STATE_PENDING;
                sock->events = 0;
                again = true;
            } else {
                sock->state = SOCKET_STATE_DIED;
                sock->events = 0;
            }
        }
        break;

        case SOCKET_STATE_CONNECTING:
        {
            // We reach this point when a connect() operation on the
            // socket started and then the descriptor was marked as
            // ready for output. This means the operation is complete.

            int err = 0;
            socklen_t len = sizeof(err);

            if (getsockopt(sock->raw, SOL_SOCKET, SO_ERROR, (void*) &err, &len) < 0 || err != 0) {

                // If remote peer not working, try next address
                if (connect_failed_because_or_peer_2(err)) {
                    sock->state = SOCKET_STATE_PENDING;
                    sock->events = 0;
                    again = true;
                    break;
                }

                sock->state = SOCKET_STATE_DIED;
                sock->events = 0;
                break;
            }

            // Connect succeeded
            sock->state = SOCKET_STATE_CONNECTED;
            sock->events = 0;
            again = true;
        }
        break;

        case SOCKET_STATE_CONNECTED:
        {
            if (!socket_secure(sock)) {

                pending_connect_free(sock->pending_connect);
                sock->pending_connect = NULL;

                sock->events = 0;
                sock->state = SOCKET_STATE_ESTABLISHED_READY;

            } else {
#ifdef HTTPS_ENABLED
                // Start SSL handshake

                if (sock->ssl == NULL) {
                    sock->ssl = SSL_new(sock->sec->ctx);
                    if (sock->ssl == NULL) {
                        ERR_print_errors_fp(stderr); // TODO: remove
                        sock->state  = SOCKET_STATE_DIED;
                        sock->events = 0;
                        break;
                    }

                    if (SSL_set_fd(sock->ssl, sock->raw) != 1) {
                        sock->state  = SOCKET_STATE_DIED;
                        sock->events = 0;
                        break;
                    }

                    char *hostname = NULL;
                    if (sock->pending_connect->hostname[0])
                        hostname = sock->pending_connect->hostname;

                    if (hostname)
                        SSL_set_tlsext_host_name(sock->ssl, hostname);
                }

                int ret = SSL_connect(sock->ssl);
                if (ret == 1) {
                    // Handshake done

                    pending_connect_free(sock->pending_connect);
                    sock->pending_connect = NULL;

                    sock->state  = SOCKET_STATE_ESTABLISHED_READY;
                    sock->events = 0;
                    break;
                }

                int err = SSL_get_error(sock->ssl, ret);
                if (err == SSL_ERROR_WANT_READ) {
                    sock->events = POLLIN;
                    break;
                }

                if (err == SSL_ERROR_WANT_WRITE) {
                    sock->events = POLLOUT;
                    break;
                }

                sock->state  = SOCKET_STATE_PENDING;
                sock->events = 0;
                again = true;
#else
                assert(0);
#endif
            }
        }
        break;

        case SOCKET_STATE_ACCEPTED:
        {
            if (!socket_secure(sock)) {
                sock->state  = SOCKET_STATE_ESTABLISHED_READY;
                sock->events = 0;
            } else {
#ifdef HTTPS_ENABLED
                // Start server-side SSL handshake
                if (!sock->ssl) {

                    sock->ssl = SSL_new(sock->sec->ctx);
                    if (sock->ssl == NULL) {
                        sock->state  = SOCKET_STATE_DIED;
                        sock->events = 0;
                        break;
                    }

                    if (SSL_set_fd(sock->ssl, sock->raw) != 1) {
                        sock->state  = SOCKET_STATE_DIED;
                        sock->events = 0;
                        break;
                    }
                }

                int ret = SSL_accept(sock->ssl);
                if (ret == 1) {
                    // Handshake done
                    sock->state = SOCKET_STATE_ESTABLISHED_READY;
                    sock->events = 0;
                    break;
                }

                int err = SSL_get_error(sock->ssl, ret);
                if (err == SSL_ERROR_WANT_READ) {
                    sock->events = POLLIN;
                    break;
                }

                if (err == SSL_ERROR_WANT_WRITE) {
                    sock->events = POLLOUT;
                    break;
                }

                // Server socket error - close the connection
                sock->state  = SOCKET_STATE_DIED;
                sock->events = 0;
#else
               assert(0);
#endif
            }
        }
        break;

        case SOCKET_STATE_ESTABLISHED_WAIT:
        {
            sock->state = SOCKET_STATE_ESTABLISHED_READY;
            sock->events = 0;
        }
        break;

        case SOCKET_STATE_SHUTDOWN:
        {
            if (!socket_secure(sock)) {
                sock->state = SOCKET_STATE_DIED;
                sock->events = 0;
            } else {
#ifdef HTTPS_ENABLED
                int ret = SSL_shutdown(sock->ssl);
                if (ret == 1) {
                    sock->state  = SOCKET_STATE_DIED;
                    sock->events = 0;
                    break;
                }

                int err = SSL_get_error(sock->ssl, ret);
                if (err == SSL_ERROR_WANT_READ) {
                    sock->events = POLLIN;
                    break;
                }
                
                if (err == SSL_ERROR_WANT_WRITE) {
                    sock->events = POLLOUT;
                    break;
                }

                sock->state  = SOCKET_STATE_DIED;
                sock->events = 0;
#else
                assert(0);
#endif
            }
        }
        break;

        default:
            // Do nothing
            break;
        }

    } while (again);
}

static bool would_block(void)
{
#ifdef _WIN32
    int err = WSAGetLastError();
    return err == WSAEWOULDBLOCK;
#else
    return errno == EAGAIN || errno == EWOULDBLOCK;
#endif
}

static bool interrupted(void)
{
#ifdef _WIN32
    return false;
#else
    return errno == EINTR;
#endif
}

int socket_read(Socket *sock, char *dst, int max)
{
    // If not ESTABLISHED, set state to DIED and return
    if (sock->state != SOCKET_STATE_ESTABLISHED_READY) {
        sock->state = SOCKET_STATE_DIED;
        sock->events = 0;
        return 0;
    }

    if (!socket_secure(sock)) {
        int ret = recv(sock->raw, dst, max, 0);
        if (ret == 0) {
            sock->state  = SOCKET_STATE_DIED;
            sock->events = 0;
        } else {
            if (ret < 0) {
                if (would_block()) {
                    sock->state  = SOCKET_STATE_ESTABLISHED_WAIT;
                    sock->events = POLLIN;
                } else {
                    if (!interrupted()) {
                        sock->state  = SOCKET_STATE_DIED;
                        sock->events = 0;
                    }
                }
                ret = 0;
            }
        }
        return ret;
    } else {
#ifdef HTTPS_ENABLED
        int ret = SSL_read(sock->ssl, dst, max);
        if (ret <= 0) {
            int err = SSL_get_error(sock->ssl, ret);
            if (err == SSL_ERROR_WANT_READ) {
                sock->state  = SOCKET_STATE_ESTABLISHED_WAIT;
                sock->events = POLLIN;
            } else if (err == SSL_ERROR_WANT_WRITE) {
                sock->state = SOCKET_STATE_ESTABLISHED_WAIT;
                sock->events = POLLOUT;
            } else {
                fprintf(stderr, "OpenSSL error in socket_read: ");
                ERR_print_errors_fp(stderr);
                sock->state  = SOCKET_STATE_DIED;
                sock->events = 0;
            }
            ret = 0;
        }
        return ret;
#else
        assert(0);
        return -1;
#endif
    }
}

int socket_write(Socket *sock, char *src, int len)
{
    // If not ESTABLISHED, set state to DIED and return
    if (sock->state != SOCKET_STATE_ESTABLISHED_READY) {
        sock->state  = SOCKET_STATE_DIED;
        sock->events = 0;
        return 0;
    }

    if (!socket_secure(sock)) {
        int ret = send(sock->raw, src, len, 0);
        if (ret < 0) {
            if (would_block()) {
                sock->state  = SOCKET_STATE_ESTABLISHED_WAIT;
                sock->events = POLLOUT;
            } else {
                if (!interrupted()) {
                    sock->state = SOCKET_STATE_DIED;
                    sock->events = 0;
                }
            }
            ret = 0;
        }
        return ret;
    } else {
#ifdef HTTPS_ENABLED
        int ret = SSL_write(sock->ssl, src, len);
        if (ret <= 0) {
            int err = SSL_get_error(sock->ssl, ret);
            if (err == SSL_ERROR_WANT_READ) {
                sock->state  = SOCKET_STATE_ESTABLISHED_WAIT;
                sock->events = POLLIN;
            } else if (err == SSL_ERROR_WANT_WRITE) {
                sock->state  = SOCKET_STATE_ESTABLISHED_WAIT;
                sock->events = POLLOUT;
            } else {
                fprintf(stderr, "OpenSSL error in socket_write: ");
                ERR_print_errors_fp(stderr);
                sock->state  = SOCKET_STATE_DIED;
                sock->events = 0;
            }
            ret = 0;
        }
        return ret;
#else
        assert(0);
#endif
    }
}

bool socket_secure(Socket *sock)
{
#ifdef HTTPS_ENABLED
    return sock->sec != NULL;
#else
    (void) sock;
    return false;
#endif
}

void socket_free(Socket *sock)
{
    if (sock->pending_connect != NULL)
        pending_connect_free(sock->pending_connect);

    if (sock->raw != BAD_SOCKET)
        CLOSE_SOCKET(sock->raw);

#ifdef HTTPS_ENABLED
    if (sock->ssl)
        SSL_free(sock->ssl);
#endif

    sock->state = SOCKET_STATE_FREE;
}

void socket_set_user_data(Socket *sock, void *user_data)
{
    sock->user_data = user_data;
}

void *socket_get_user_data(Socket *sock)
{
    return sock->user_data;
}

////////////////////////////////////////////////////////////////////////////////////////
// src/socket_pool.c
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/socket_pool.c"
#include <assert.h>
#include <stdlib.h>

#ifdef __linux__
#include <errno.h>
#include <sys/socket.h>
#endif

#ifndef HTTP_AMALGAMATION
#include "socket_pool.h"
#endif

#define SOCKET_HARD_LIMIT (1<<10)
#define MAX_CERTS 10

struct SocketPool {

    SecureContext sec;

    RAW_SOCKET listen_sock;
    RAW_SOCKET secure_sock;

    int num_socks;
    int max_socks;
    Socket socks[];
};

int socket_pool_global_init(void)
{
    int ret = socket_raw_global_init();
    if (ret < 0)
        return -1;

    secure_context_global_init();
    return 0;
}

void socket_pool_global_free(void)
{
    secure_context_global_free();
    socket_raw_global_free();
}

SocketPool *socket_pool_init(HTTP_String addr,
    uint16_t port, uint16_t secure_port, int max_socks,
    bool reuse_addr, int backlog, HTTP_String cert_file,
    HTTP_String key_file)
{
    if (max_socks > SOCKET_HARD_LIMIT)
        return NULL;

    SocketPool *pool = malloc(sizeof(SocketPool) + max_socks * sizeof(Socket));
    if (pool == NULL)
        return NULL;

    pool->num_socks = 0;
    pool->max_socks = max_socks;

    for (int i = 0; i < pool->max_socks; i++)
        pool->socks[i].state = SOCKET_STATE_FREE;

    if (port == 0)
        pool->listen_sock = BAD_SOCKET;
    else {
        pool->listen_sock = listen_socket(addr, port, reuse_addr, backlog);
        if (pool->listen_sock == BAD_SOCKET) {
            free(pool);
            return NULL;
        }
    }

    if (secure_port == 0)
        pool->secure_sock = BAD_SOCKET;
    else {
#ifndef HTTPS_ENABLED
        (void) cert_file;
        (void) key_file;
        if (pool->listen_sock != BAD_SOCKET)
            CLOSE_SOCKET(pool->listen_sock);
        free(pool);
        return NULL;
#else
        if (secure_context_init_as_server(&pool->sec, cert_file, key_file) < 0) {
            if (pool->listen_sock != BAD_SOCKET)
                CLOSE_SOCKET(pool->listen_sock);
            free(pool);
            return NULL;
        }

        pool->secure_sock = listen_socket(addr, secure_port, reuse_addr, backlog);
        if (pool->secure_sock == BAD_SOCKET) {
            if (pool->listen_sock != BAD_SOCKET) CLOSE_SOCKET(pool->listen_sock);
            free(pool);
            return NULL;
        }
#endif
    }

#ifdef HTTPS_ENABLED
    if (port == 0 && secure_port == 0) {
        if (secure_context_init_as_client(&pool->sec) < 0) {
            if (pool->listen_sock != BAD_SOCKET) CLOSE_SOCKET(pool->listen_sock);
            if (pool->secure_sock != BAD_SOCKET) CLOSE_SOCKET(pool->secure_sock);
            free(pool);
            return NULL;
        }
    }
#endif

    for (int i = 0; i < max_socks; i++)
        pool->socks[i].state = SOCKET_STATE_FREE;

    return pool;
}

void socket_pool_free(SocketPool *pool)
{
    for (int i = 0, j = 0; j < pool->num_socks; i++) {

        Socket *sock = &pool->socks[i];

        if (sock->state == SOCKET_STATE_FREE)
            continue;
        j++;

        socket_free(sock);
    }

    secure_context_free(&pool->sec);

    if (pool->secure_sock != BAD_SOCKET) CLOSE_SOCKET(pool->secure_sock);
    if (pool->listen_sock != BAD_SOCKET) CLOSE_SOCKET(pool->listen_sock);
}

int socket_pool_add_cert(SocketPool *pool, HTTP_String domain, HTTP_String cert_file, HTTP_String key_file)
{
    return secure_context_add_cert(&pool->sec, domain, cert_file, key_file);
}

void socket_pool_set_user_data(SocketPool *pool, SocketHandle handle, void *user_data)
{
    Socket *sock = &pool->socks[handle];
    socket_set_user_data(sock, user_data);
}

void socket_pool_close(SocketPool *pool, SocketHandle handle)
{
    Socket *sock = &pool->socks[handle];
    socket_close(sock);
}

static Socket *find_free_socket(SocketPool *pool)
{
    if (pool->num_socks == pool->max_socks)
        return NULL;

    int i = 0;
    while (pool->socks[i].state != SOCKET_STATE_FREE)
        i++;

    return &pool->socks[i];
}

int socket_pool_connect(SocketPool *pool, bool secure,
    HTTP_String addr, uint16_t port, void *user_data)
{
    Socket *sock = find_free_socket(pool);
    if (sock == NULL)
        return -1;

    socket_connect(sock, secure ? &pool->sec : NULL, addr, port, user_data);

    if (socket_died(sock)) {
        socket_free(sock);
        return -1;
    }

    pool->num_socks++;
    return 0;
}

int socket_pool_connect_ipv4(SocketPool *pool, bool secure,
    HTTP_IPv4 addr, uint16_t port, void *user_data)
{
    Socket *sock = find_free_socket(pool);
    if (sock == NULL)
        return -1;

    socket_connect_ipv4(sock, secure ? &pool->sec : NULL, addr, port, user_data);

    if (socket_died(sock)) {
        socket_free(sock);
        return -1;
    }

    pool->num_socks++;
    return 0;
}

int socket_pool_connect_ipv6(SocketPool *pool, bool secure,
    HTTP_IPv6 addr, uint16_t port, void *user_data)
{
    Socket *sock = find_free_socket(pool);
    if (sock == NULL)
        return -1;

    socket_connect_ipv6(sock, secure ? &pool->sec : NULL, addr, port, user_data);

    if (socket_died(sock)) {
        socket_free(sock);
        return -1;
    }

    pool->num_socks++;
    return 0;
}

#include <stdio.h> // TODO: remove

SocketEvent socket_pool_wait(SocketPool *pool)
{
    for (;;) {

        // First, iterate over all sockets to find one that
        // died or is ready.

        for (int i = 0, j = 0; j < pool->num_socks; i++) {

            Socket *sock = &pool->socks[i];

            if (sock->state == SOCKET_STATE_FREE)
                continue;
            j++;

            if (socket_died(sock)) {
                void *user_data = socket_get_user_data(sock);
                socket_free(sock);
                pool->num_socks--;
                return (SocketEvent) { SOCKET_EVENT_DIED, -1, user_data };
            }

            if (socket_ready(sock))
                return (SocketEvent) { SOCKET_EVENT_READY, i, socket_get_user_data(sock) };

            assert(sock->events);
        }

        // If we reached this point, we either have no sockets
        // or all sockets need to wait for some event. Waiting
        // when no sockets are available is only allowed when
        // the pool is in server mode.

        int indices[SOCKET_HARD_LIMIT+2];
        struct pollfd polled[SOCKET_HARD_LIMIT+2];
        int num_polled = 0;

        if (pool->num_socks < pool->max_socks) {

            if (pool->listen_sock != BAD_SOCKET) {
                indices[num_polled] = -1;
                polled[num_polled].fd = pool->listen_sock;
                polled[num_polled].events = POLLIN;
                polled[num_polled].revents = 0;
                num_polled++;
            }

            if (pool->secure_sock != BAD_SOCKET) {
                indices[num_polled] = -1;
                polled[num_polled].fd = pool->secure_sock;
                polled[num_polled].events = POLLIN;
                polled[num_polled].revents = 0;
                num_polled++;
            }
        }

        for (int i = 0, j = 0; j < pool->num_socks; i++) {

            Socket *sock = &pool->socks[i];

            if (sock->state == SOCKET_STATE_FREE)
                continue;
            j++;

            indices[num_polled] = i;
            polled[num_polled].fd = sock->raw;
            polled[num_polled].events = sock->events;
            polled[num_polled].revents = 0;
            num_polled++;
        }

        if (num_polled == 0)
            return (SocketEvent) { SOCKET_EVENT_ERROR, -1, NULL };

        int ret = POLL(polled, num_polled, -1);
        if (ret < 0) {

            if (errno == EINTR)
                return (SocketEvent) { SOCKET_EVENT_SIGNAL, -1, NULL };

            return (SocketEvent) { SOCKET_EVENT_ERROR, -1, NULL };
        }

        for (int i = 0; i < num_polled; i++) {

            Socket *sock;
            
            if (polled[i].fd == pool->listen_sock || polled[i].fd == pool->secure_sock) {

                bool secure = false;
                if (polled[i].fd == pool->secure_sock)
                    secure = true;

                Socket *sock = find_free_socket(pool);
                if (sock == NULL)
                    continue;

                RAW_SOCKET raw = accept(polled[i].fd, NULL, NULL);
                if (raw == BAD_SOCKET)
                    continue;

                socket_accept(sock, secure ? &pool->sec : NULL, raw);

                if (socket_died(sock)) {
                    socket_free(sock);
                    continue;
                }

                pool->num_socks++;

            } else {
                int j = indices[i];
                sock = &pool->socks[j];

                if (polled[i].revents)
                    socket_update(sock);
            }
        }
    }

    // This branch is unreachable
    return (SocketEvent) { SOCKET_EVENT_ERROR, -1, NULL };
}

int socket_pool_read(SocketPool *pool, SocketHandle handle, char *dst, int len)
{
    return socket_read(&pool->socks[handle], dst, len);
}

int socket_pool_write(SocketPool *pool, SocketHandle handle, char *src, int len)
{
    return socket_write(&pool->socks[handle], src, len);
}

bool socket_pool_secure(SocketPool *pool, SocketHandle handle)
{
    return socket_secure(&pool->socks[handle]);
}

////////////////////////////////////////////////////////////////////////////////////////
// src/client.c
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/client.c"
#include <stdint.h>
#include <assert.h>
#include <stdlib.h>
#include <stdbool.h>

#ifdef _WIN32
#define WIN32_LEAN_AND_MEAN
#include <winsock2.h>
#define POLL WSAPoll
#endif

#ifdef __linux__
#include <poll.h>
#define POLL poll
#endif

#ifndef HTTP_AMALGAMATION
#include "client.h"
#include "engine.h"
#include "socket_pool.h"
#endif

#define CLIENT_MAX_CONNS 256

typedef enum {
    CLIENT_CONNECTION_FREE,
    CLIENT_CONNECTION_INIT,
    CLIENT_CONNECTION_INIT_ERROR,
    CLIENT_CONNECTION_WAIT,
    CLIENT_CONNECTION_DONE,
} ClientConnectionState;

typedef struct {
    ClientConnectionState state;
    uint16_t     gen;
    SocketHandle sock;
    HTTP_Engine  eng;
    bool         trace;
    void*        user_data;
} ClientConnection;

struct HTTP_Client {

    SocketPool *socket_pool;

    int num_conns;
    ClientConnection conns[CLIENT_MAX_CONNS];

    int ready_head;
    int ready_count;
    int ready[CLIENT_MAX_CONNS];
};

int http_global_init(void)
{
    int ret = socket_pool_global_init();
    if (ret < 0)
        return -1;
    return 0;
}

void http_global_free(void)
{
    socket_pool_global_free();
}

// Rename the memory function
static void* client_memfunc(HTTP_MemoryFuncTag tag, void *ptr, int len, void *data) {
    (void)data;
    switch (tag) {
        case HTTP_MEMFUNC_MALLOC:
            return malloc(len);
        case HTTP_MEMFUNC_FREE:
            free(ptr);
            return NULL;
    }
    return NULL;
}

HTTP_Client *http_client_init(void)
{
    HTTP_Client *client = malloc(sizeof(HTTP_Client));
    if (client == NULL)
        return NULL;

    int max_socks = 100;
    SocketPool *socket_pool = socket_pool_init(HTTP_STR(""), 0, 0, max_socks, false, 0, HTTP_STR(""), HTTP_STR(""));
    if (socket_pool == NULL) {
        free(client);
        return NULL;
    }
    client->socket_pool = socket_pool;

    for (int i = 0; i < CLIENT_MAX_CONNS; i++) {
        client->conns[i].state = CLIENT_CONNECTION_FREE;
        client->conns[i].gen  = 1;
    }

    client->num_conns = 0;
    client->ready_head = 0;
    client->ready_count = 0;

    return client;
}

void http_client_free(HTTP_Client *client)
{
    for (int i = 0, j = 0; j < client->num_conns; i++) {

        if (client->conns[i].state == CLIENT_CONNECTION_FREE)
            continue;
        j++;

        // TODO
    }

    socket_pool_free(client->socket_pool);
    free(client);
}

int http_client_get_builder(HTTP_Client *client, HTTP_RequestBuilder *builder)
{
    if (client->num_conns == CLIENT_MAX_CONNS)
        return -1;

    int i = 0;
    while (client->conns[i].state != CLIENT_CONNECTION_FREE)
        i++;

    client->conns[i].sock = -1;
    client->conns[i].user_data = NULL;
    client->conns[i].trace = false;
    client->conns[i].state = CLIENT_CONNECTION_INIT;
    http_engine_init(&client->conns[i].eng, 1, client_memfunc, NULL);

    client->num_conns++;

    *builder = (HTTP_RequestBuilder) { client, i, client->conns[i].gen };
    return 0;
}

int http_client_wait(HTTP_Client *client, HTTP_Response **result, void **user_data)
{
    while (client->ready_count == 0) {

        SocketEvent event = socket_pool_wait(client->socket_pool);
        switch (event.type) {

            case SOCKET_EVENT_DIED:
            {
                ClientConnection *conn = event.user_data;
                conn->state = CLIENT_CONNECTION_DONE;

                int tail = (client->ready_head + client->ready_count) % CLIENT_MAX_CONNS;
                client->ready[tail] = conn - client->conns;
                client->ready_count++;
            }
            break;

            case SOCKET_EVENT_READY:
            {
                ClientConnection *conn = event.user_data;

                if (conn->sock == -1)
                    conn->sock = event.handle;

                HTTP_EngineState engine_state;
                engine_state = http_engine_state(&conn->eng);

                if (engine_state == HTTP_ENGINE_STATE_CLIENT_RECV_BUF) {
                    int len;
                    char *buf;
                    buf = http_engine_recvbuf(&conn->eng, &len);
                    if (buf) {
                        int ret = socket_pool_read(client->socket_pool, conn->sock, buf, len);
                        if (conn->trace)
                            print_bytes(HTTP_STR(">> "), (HTTP_String) { buf, ret });
                        http_engine_recvack(&conn->eng, ret);
                    }
                } else if (engine_state == HTTP_ENGINE_STATE_CLIENT_SEND_BUF) {
                    int len;
                    char *buf;
                    buf = http_engine_sendbuf(&conn->eng, &len);
                    if (buf) {
                        int ret = socket_pool_write(client->socket_pool, conn->sock, buf, len);
                        if (conn->trace)
                            print_bytes(HTTP_STR("<< "), (HTTP_String) { buf, ret });
                        http_engine_sendack(&conn->eng, ret);
                    }
                }

                engine_state = http_engine_state(&conn->eng);

                if (engine_state == HTTP_ENGINE_STATE_CLIENT_CLOSED ||
                    engine_state == HTTP_ENGINE_STATE_CLIENT_READY)
                    socket_pool_close(client->socket_pool, conn->sock);
            }
            break;

            case SOCKET_EVENT_ERROR:
            return -1;

            case SOCKET_EVENT_SIGNAL:
            return 1;
        }
    }

    int index = client->ready[client->ready_head];
    client->ready_head = (client->ready_head + 1) % CLIENT_MAX_CONNS;
    client->ready_count--;

    ClientConnection *conn = &client->conns[index];

    HTTP_Response *result2 = http_engine_getres(&conn->eng);

    if (result)
        *result = result2;

    if (user_data)
        *user_data = conn->user_data;

    if (result2 == NULL) {
        http_engine_free(&conn->eng);
        conn->state = CLIENT_CONNECTION_FREE;
        client->num_conns--;
    } else {
        result2->context = client;
    }

    return 0;
}

static ClientConnection *client_builder_to_conn(HTTP_RequestBuilder handle)
{
    if (handle.data0 == NULL)
        return NULL;

    HTTP_Client *client = handle.data0;

    if (handle.data1 >= CLIENT_MAX_CONNS)
        return NULL;

    ClientConnection *conn = &client->conns[handle.data1];

    if (handle.data2 != conn->gen)
        return NULL;

    return conn;
}

void http_request_builder_user_data(HTTP_RequestBuilder builder, void *user_data)
{
    ClientConnection *conn = client_builder_to_conn(builder);
    if (conn == NULL)
        return;
    if (conn->state != CLIENT_CONNECTION_INIT)
        return;

    conn->user_data = user_data;
}

void http_request_builder_trace(HTTP_RequestBuilder builder, bool trace)
{
    ClientConnection *conn = client_builder_to_conn(builder);
    if (conn == NULL)
        return;
    if (conn->state != CLIENT_CONNECTION_INIT)
        return;

    conn->trace = trace;
}

void http_request_builder_line(HTTP_RequestBuilder builder, HTTP_Method method, HTTP_String url)
{
    ClientConnection *conn = client_builder_to_conn(builder);
    if (conn == NULL)
        return;
    if (conn->state != CLIENT_CONNECTION_INIT)
        return;

    HTTP_Client *client = builder.data0;

    HTTP_URL parsed_url;
    int ret = http_parse_url(url.ptr, url.len, &parsed_url);
    if (ret != url.len) {
        conn->state = CLIENT_CONNECTION_INIT_ERROR;
        return;
    }

    bool secure = false;
    if (http_streq(parsed_url.scheme, HTTP_STR("https"))) {
        secure = true;
    } else if (!http_streq(parsed_url.scheme, HTTP_STR("http"))) {
        conn->state = CLIENT_CONNECTION_INIT_ERROR;
        return;
    }

    int port = parsed_url.authority.port;
    if (port == 0) {
        if (secure)
            port = 443;
        else
            port = 80;
    }

    switch (parsed_url.authority.host.mode) {
        case HTTP_HOST_MODE_IPV4: ret = socket_pool_connect_ipv4(client->socket_pool, secure, parsed_url.authority.host.ipv4, port, conn); break;
        case HTTP_HOST_MODE_IPV6: ret = socket_pool_connect_ipv6(client->socket_pool, secure, parsed_url.authority.host.ipv6, port, conn); break;
        case HTTP_HOST_MODE_NAME: ret = socket_pool_connect     (client->socket_pool, secure, parsed_url.authority.host.name, port, conn); break;
        case HTTP_HOST_MODE_VOID: ret = -1; return;
    }

    if (ret < 0) {
        conn->state = CLIENT_CONNECTION_INIT_ERROR;
        return;
    }

    http_engine_url(&conn->eng, method, url, 1);
}

void http_request_builder_header(HTTP_RequestBuilder handle, HTTP_String str)
{
    ClientConnection *conn = client_builder_to_conn(handle);
    if (conn == NULL)
        return;
    if (conn->state != CLIENT_CONNECTION_INIT)
        return;

    http_engine_header(&conn->eng, str);
}

void http_request_builder_body(HTTP_RequestBuilder handle, HTTP_String str)
{
    ClientConnection *conn = client_builder_to_conn(handle);
    if (conn == NULL)
        return;
    if (conn->state != CLIENT_CONNECTION_INIT)
        return;

    http_engine_body(&conn->eng, str);
}

void http_request_builder_submit(HTTP_RequestBuilder handle)
{
    HTTP_Client *client = handle.data0;
    ClientConnection *conn = client_builder_to_conn(handle);
    if (conn == NULL)
        return;
    if (conn->state != CLIENT_CONNECTION_INIT &&
        conn->state != CLIENT_CONNECTION_INIT_ERROR)
        return;

    // TODO: invalidate the handle

    if (conn->state == CLIENT_CONNECTION_INIT_ERROR) {

        conn->state = CLIENT_CONNECTION_DONE;

        int tail = (client->ready_head + client->ready_count) % CLIENT_MAX_CONNS;
        client->ready[tail] = conn - client->conns;
        client->ready_count++;

    } else {
        http_engine_done(&conn->eng);
        conn->state = CLIENT_CONNECTION_WAIT;
    }
}

void http_response_free(HTTP_Response *res)
{
    if (res == NULL)
        return;

    HTTP_Client *client = res->context;

    ClientConnection *conn = NULL;
    for (int i = 0, j = 0; j < client->num_conns; i++) {

        if (client->conns[i].state == CLIENT_CONNECTION_FREE)
            continue;
        j++;

        if (client->conns[i].state != CLIENT_CONNECTION_DONE)
            continue;

        if (http_engine_getres(&client->conns[i].eng) == res) {
            conn = &client->conns[i];
            break;
        }
    }

    HTTP_ASSERT(conn);

    http_engine_free(&conn->eng);
    conn->state = CLIENT_CONNECTION_FREE;
    client->num_conns--;
}

static HTTP_Client *default_client___; // TODO: deinitialize the default client when http_global_free is called

static HTTP_Client *get_default_client(void)
{
    if (default_client___ == NULL)
        default_client___ = http_client_init();
    return default_client___;
}

HTTP_Response *http_get(HTTP_String url, HTTP_String *headers, int num_headers)
{
    HTTP_Client *client = get_default_client();
    if (client == NULL)
        return NULL;

    HTTP_RequestBuilder builder;
    int ret = http_client_get_builder(client, &builder);
    if (ret < 0)
        return NULL;
    http_request_builder_line(builder, HTTP_METHOD_GET, url);
    for (int i = 0; i < num_headers; i++)
        http_request_builder_header(builder, headers[i]);
    http_request_builder_submit(builder);

    HTTP_Response *res;
    ret = http_client_wait(client, &res, NULL); // TODO: it's assumed there is only one request pending
    if (ret < 0)
        return NULL;

    return res;
}

HTTP_Response *http_post(HTTP_String url, HTTP_String *headers, int num_headers, HTTP_String body)
{
    HTTP_Client *client = get_default_client();
    if (client == NULL)
        return NULL;

    HTTP_RequestBuilder builder;
    int ret = http_client_get_builder(client, &builder);
    if (ret < 0)
        return NULL;
    http_request_builder_line(builder, HTTP_METHOD_POST, url);
    for (int i = 0; i < num_headers; i++)
        http_request_builder_header(builder, headers[i]);
    http_request_builder_body(builder, body);
    http_request_builder_submit(builder);

    HTTP_Response *res;
    ret = http_client_wait(client, &res, NULL); // TODO: it's assumed there is only one request pending
    if (ret < 0)
        return NULL;

    return res;
}

////////////////////////////////////////////////////////////////////////////////////////
// src/server.c
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/server.c"
#include <stdint.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdbool.h>

#ifndef HTTP_AMALGAMATION
#include "engine.h"
#include "server.h"
#include "socket_pool.h"
#endif

#define MAX_CONNS (1<<10)

typedef struct {
    bool         used;
    uint16_t     gen;
    HTTP_Engine  engine;
    SocketHandle sock;
} Connection;

struct HTTP_Server {

    SocketPool *socket_pool;

    int num_conns;
    Connection conns[MAX_CONNS];

    int ready_head;
    int ready_count;
    int ready[MAX_CONNS];
};

HTTP_Server *http_server_init(HTTP_String addr, uint16_t port)
{
    return http_server_init_ex(addr, port, 0, HTTP_STR(""), HTTP_STR(""));
}

HTTP_Server *http_server_init_ex(HTTP_String addr, uint16_t port,
    uint16_t secure_port, HTTP_String cert_file, HTTP_String key_file)
{
    HTTP_Server *server = malloc(sizeof(HTTP_Server));
    if (server == NULL)
        return NULL;

    int backlog = 32;
    bool reuse_addr = true;
    SocketPool *socket_pool = socket_pool_init(addr, port, secure_port, MAX_CONNS, reuse_addr, backlog, cert_file, key_file);
    if (socket_pool == NULL) {
        free(server);
        return NULL;
    }

    server->socket_pool = socket_pool;
    server->num_conns = 0;
    server->ready_head = 0;
    server->ready_count = 0;

    for (int i = 0; i < MAX_CONNS; i++) {
        server->conns[i].used = false;
        server->conns[i].gen = 1;
    }

    return server;
}

void http_server_free(HTTP_Server *server)
{
    for (int i = 0, j = 0; j < server->num_conns; i++) {

        if (!server->conns[i].used)
            continue;
        j++;

        // TODO
    }

    socket_pool_free(server->socket_pool);
    free(server);
}

int http_server_add_website(HTTP_Server *server, HTTP_String domain, HTTP_String cert_file, HTTP_String key_file)
{
    return socket_pool_add_cert(server->socket_pool, domain, cert_file, key_file);
}

static void* server_memfunc(HTTP_MemoryFuncTag tag, void *ptr, int len, void *data) {
    (void)data;
    switch (tag) {
        case HTTP_MEMFUNC_MALLOC:
            return malloc(len);
        case HTTP_MEMFUNC_FREE:
            free(ptr);
            return NULL;
    }
    return NULL;
}

int http_server_wait(HTTP_Server *server, HTTP_Request **req, HTTP_ResponseBuilder *builder)
{
    while (server->ready_count == 0) {

        SocketEvent event = socket_pool_wait(server->socket_pool);
        switch (event.type) {

            case SOCKET_EVENT_DIED:
            {
                Connection *conn = event.user_data;
                HTTP_ASSERT(conn);

                http_engine_free(&conn->engine);
                conn->used = false;
                conn->gen++;
                server->num_conns--;
            }
            break;

            case SOCKET_EVENT_READY:
            {
                Connection *conn = event.user_data;
                if (conn == NULL) {

                    // Connection was just accepted

                    if (server->num_conns == MAX_CONNS) {
                        socket_pool_close(server->socket_pool, event.handle);
                        break;
                    }

                    int i = 0;
                    while (server->conns[i].used)
                        i++;

                    conn = &server->conns[i];
                    conn->used = true;
                    conn->sock = event.handle;
                    http_engine_init(&conn->engine, 0, server_memfunc, NULL);
                    socket_pool_set_user_data(server->socket_pool, event.handle, conn);
                    server->num_conns++;
                }

                switch (http_engine_state(&conn->engine)) {

                    int len;
                    char *buf;

                    case HTTP_ENGINE_STATE_SERVER_RECV_BUF:
                    buf = http_engine_recvbuf(&conn->engine, &len);
                    if (buf) {
                        int ret = socket_pool_read(server->socket_pool, conn->sock, buf, len);
                        http_engine_recvack(&conn->engine, ret);
                    }
                    break;

                    case HTTP_ENGINE_STATE_SERVER_SEND_BUF:
                    buf = http_engine_sendbuf(&conn->engine, &len);
                    if (buf) {
                        int ret = socket_pool_write(server->socket_pool, conn->sock, buf, len);
                        http_engine_sendack(&conn->engine, ret);
                    }
                    break;

                    default:
                    break;
                }

                switch (http_engine_state(&conn->engine)) {

                    int tail;

                    case HTTP_ENGINE_STATE_SERVER_PREP_STATUS:
                    tail = (server->ready_head + server->ready_count) % MAX_CONNS;
                    server->ready[tail] = conn - server->conns;
                    server->ready_count++;
                    break;

                    case HTTP_ENGINE_STATE_SERVER_CLOSED:
                    socket_pool_close(server->socket_pool, conn->sock);
                    break;

                    default:
                    break;
                }
            }
            break;

            case SOCKET_EVENT_ERROR:
            return -1;

            case SOCKET_EVENT_SIGNAL:
            return 1;
        }
    }

    int index = server->ready[server->ready_head];
    server->ready_head = (server->ready_head + 1) % MAX_CONNS;
    server->ready_count--;

    *req = http_engine_getreq(&server->conns[index].engine);
    (*req)->secure = socket_pool_secure(server->socket_pool, server->conns[index].sock);

    *builder = (HTTP_ResponseBuilder) { server, index, server->conns[index].gen };
    return 0;
}

static Connection*
server_builder_to_conn(HTTP_ResponseBuilder builder)
{
	HTTP_Server *server = builder.data0;
	if (builder.data1 >= MAX_CONNS)
		return NULL;

	Connection *conn = &server->conns[builder.data1];
	if (conn->gen != builder.data2)
		return NULL;

	return conn;
}

void http_response_builder_status(HTTP_ResponseBuilder res, int status)
{
	Connection *conn = server_builder_to_conn(res);
	if (conn == NULL)
		return;

	http_engine_status(&conn->engine, status);
}

void http_response_builder_header(HTTP_ResponseBuilder res, HTTP_String str)
{
	Connection *conn = server_builder_to_conn(res);
	if (conn == NULL)
		return;

	http_engine_header(&conn->engine, str);
}

void http_response_builder_body(HTTP_ResponseBuilder res, HTTP_String str)
{
	Connection *conn = server_builder_to_conn(res);
	if (conn == NULL)
		return;

	http_engine_body(&conn->engine, str);
}

void http_response_builder_bodycap(HTTP_ResponseBuilder res, int mincap)
{
	Connection *conn = server_builder_to_conn(res);
	if (conn == NULL)
		return;

	http_engine_bodycap(&conn->engine, mincap);
}

char *http_response_builder_bodybuf(HTTP_ResponseBuilder res, int *cap)
{
	Connection *conn = server_builder_to_conn(res);
	if (conn == NULL) {
		*cap = 0;
		return NULL;
	}

	return http_engine_bodybuf(&conn->engine, cap);
}

void http_response_builder_bodyack(HTTP_ResponseBuilder res, int num)
{
	Connection *conn = server_builder_to_conn(res);
	if (conn == NULL)
		return;

	http_engine_bodyack(&conn->engine, num);
}

void http_response_builder_undo(HTTP_ResponseBuilder res)
{
	Connection *conn = server_builder_to_conn(res);
	if (conn == NULL)
		return;

	http_engine_undo(&conn->engine);
}

void http_response_builder_done(HTTP_ResponseBuilder res)
{
    HTTP_Server *server = res.data0;
    Connection *conn = server_builder_to_conn(res);
    if (conn == NULL)
        return;

    http_engine_done(&conn->engine);

    conn->gen++;
    if (conn->gen == 0 || conn->gen == UINT16_MAX)
        conn->gen = 1;

    HTTP_EngineState state = http_engine_state(&conn->engine);

    if (state == HTTP_ENGINE_STATE_SERVER_PREP_STATUS) {
        int tail = (server->ready_head + server->ready_count) % MAX_CONNS;
        server->ready[tail] = res.data1;
        server->ready_count++;
    }

    if (state == HTTP_ENGINE_STATE_SERVER_CLOSED)
        socket_pool_close(server->socket_pool, conn->sock);
}

////////////////////////////////////////////////////////////////////////////////////////
// src/router.c
////////////////////////////////////////////////////////////////////////////////////////

#line 1 "src/router.c"
#include <string.h>
#include <stdlib.h>
#include <limits.h>

#ifdef _WIN32
#include <windows.h>
#endif

#ifdef __linux__
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
#endif

#ifndef HTTP_AMALGAMATION
#include "router.h"
#endif

#ifndef HTTP_AMALGAMATION
bool is_alpha(char c)
{
	return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
}
bool is_digit(char c)
{
	return c >= '0' && c <= '9';
}
#endif // HTTP_AMALGAMATION

typedef enum {
	ROUTE_STATIC_DIR,
	ROUTE_DYNAMIC,
} RouteType;

typedef struct {
	RouteType type;
	HTTP_String endpoint;
	HTTP_String path;
	HTTP_RouterFunc func;
	void *ptr;
} Route;

struct HTTP_Router {
	int num_routes;
	int max_routes;
	Route routes[];
};

HTTP_Router *http_router_init(void)
{
	int max_routes = 32;
	HTTP_Router *router = malloc(sizeof(HTTP_Router) + max_routes * sizeof(Route));
	if (router == NULL)
		return NULL;
	router->max_routes = max_routes;
	router->num_routes = 0;
	return router;
}

void http_router_free(HTTP_Router *router)
{
	free(router);
}

void http_router_dir(HTTP_Router *router, HTTP_String endpoint, HTTP_String path)
{
	if (router->num_routes == router->max_routes)
		abort();
	Route *route = &router->routes[router->num_routes++];
	route->type = ROUTE_STATIC_DIR;
	route->endpoint = endpoint;
	route->path = path;
}

void http_router_func(HTTP_Router *router, HTTP_Method method,
	HTTP_String endpoint, HTTP_RouterFunc func, void *ptr)
{
	if (router->num_routes == router->max_routes)
		abort();
	Route *route = &router->routes[router->num_routes++];
	(void) method; // TODO: Don't ignore the method
	route->type = ROUTE_DYNAMIC;
	route->endpoint = endpoint;
	route->func = func;
	route->ptr  = ptr;
}

static int valid_component_char(char c)
{
	return is_alpha(c) || is_digit(c) || c == '-' || c == '_' || c == '.'; // TODO
}

static int parse_and_sanitize_path(HTTP_String path, HTTP_String *comps, int max_comps)
{
	// We treat relative and absolute paths the same
	if (path.len > 0 && path.ptr[0] == '/') {
		path.ptr++;
		path.len--;
		if (path.len == 0)
			return 0;
	}

	int num = 0;
	int cur = 0;
	for (;;) {
		if (cur == path.len || !valid_component_char(path.ptr[cur]))
			return -1; // Empty component
		int start = cur;
		do
			cur++;
		while (cur < path.len && valid_component_char(path.ptr[cur]));
		HTTP_String comp = { path.ptr + start, cur - start };

		if (http_streq(comp, HTTP_STR(".."))) {
			if (num == 0)
				return -1;
			num--;
		} else if (!http_streq(comp, HTTP_STR("."))) {
			if (num == max_comps)
				return -1;
			comps[num++] = comp;
		}

		if (cur < path.len) {
			if (path.ptr[cur] != '/')
				return -1;
			cur++;
		}

		if (cur == path.len)
			break;
	}

	return num;
}

static int
serialize_parsed_path(HTTP_String *comps, int num_comps, char *dst, int max)
{
	int len = 0;
	for (int i = 0; i < num_comps; i++)
		len += comps[i].len + 1;

	if (len >= max)
		return -1;

	int copied = 0;
	for (int i = 0; i < num_comps; i++) {

		if (i > 0)
			dst[copied++] = '/';

		memcpy(dst + copied,
			comps[i].ptr,
			comps[i].len);

		copied += comps[i].len;
	}

	dst[copied] = '\0';
	return copied;
}

#define MAX_COMPS 32

static int sanitize_path(HTTP_String path, char *dst, int max)
{
	HTTP_String comps[MAX_COMPS];
	int num_comps = parse_and_sanitize_path(path, comps, MAX_COMPS);
	if (num_comps < 0) return -1;

	return serialize_parsed_path(comps, num_comps, dst, max);
}

static int swap_parents(HTTP_String original_parent_path, HTTP_String new_parent_path, HTTP_String path, char *mem, int max)
{
	int num_original_parent_path_comps;
	HTTP_String  original_parent_path_comps[MAX_COMPS];

	int num_new_parent_path_comps;
	HTTP_String  new_parent_path_comps[MAX_COMPS];

	int num_path_comps;
	HTTP_String  path_comps[MAX_COMPS];

	num_original_parent_path_comps = parse_and_sanitize_path(original_parent_path, original_parent_path_comps, MAX_COMPS);
	num_new_parent_path_comps      = parse_and_sanitize_path(new_parent_path,      new_parent_path_comps,      MAX_COMPS);
	num_path_comps                 = parse_and_sanitize_path(path,                 path_comps,                 MAX_COMPS);
	if (num_original_parent_path_comps < 0 || num_new_parent_path_comps < 0 || num_path_comps < 0)
		return -1;

	int match = 1;
	if (num_path_comps < num_original_parent_path_comps)
		match = 0;
	else {
		for (int i = 0; i < num_original_parent_path_comps; i++)
			if (!http_streq(original_parent_path_comps[i], path_comps[i])) {
				match = 0;
				break;
			}
	}
	if (!match)
		return 0;

	int num_result_comps = num_new_parent_path_comps + num_path_comps - num_original_parent_path_comps;
	if (num_result_comps < 0 || num_result_comps > MAX_COMPS)
		return -1;
	
	HTTP_String result_comps[MAX_COMPS];
	for (int i = 0; i < num_new_parent_path_comps; i++)
		result_comps[i] = new_parent_path_comps[i];
	
	for (int i = 0; i < num_path_comps; i++)
		result_comps[num_new_parent_path_comps + i] = path_comps[num_original_parent_path_comps + i];

	return serialize_parsed_path(result_comps, num_result_comps, mem, max);
}

#if _WIN32
typedef HANDLE File;
#else
typedef int File;
#endif

static int file_open(const char *path, File *handle, int *size)
{
#ifdef _WIN32
	*handle = CreateFileA(
		path,
		GENERIC_READ,
		FILE_SHARE_READ,
		NULL,
		OPEN_EXISTING,
		FILE_ATTRIBUTE_NORMAL,
		NULL
	);
	if (*handle == INVALID_HANDLE_VALUE) {
		DWORD error = GetLastError();
		if (error == ERROR_FILE_NOT_FOUND)
			return 1;
		if (error == ERROR_ACCESS_DENIED)
			return 1;
		return -1;
	}
	LARGE_INTEGER fileSize;
	if (!GetFileSizeEx(*handle, &fileSize)) {
		CloseHandle(*handle);
		return -1;
	}
	if (fileSize.QuadPart > INT_MAX) {
		CloseHandle(*handle);
		return -1;
	}
	*size = (int) fileSize.QuadPart;
	return 0;
#else
	*handle = open(path, O_RDONLY);
	if (*handle < 0) {
		if (errno == ENOENT)
			return 1;
		return -1;
	}
	struct stat info;
	if (fstat(*handle, &info) < 0) {
		close(*handle);
		return -1;
	}
	if (S_ISDIR(info.st_mode)) {
		close(*handle);
		return 1;
	}
	if (info.st_size > INT_MAX) {
		close(*handle);
		return -1;
	}
	*size = (int) info.st_size;
	return 0;
#endif
}

static void file_close(File file)
{
#ifdef _WIN32
	CloseHandle(file);
#else
	close(file);
#endif
}

static int file_read(File file, char *dst, int max)
{
#ifdef _WIN32
	DWORD num;
	BOOL ok = ReadFile(file, dst, max, &num, NULL);
	if (!ok)
		return -1;
	return (int) num;
#else
	return read(file, dst, max);
#endif
}

static int serve_file_or_index(HTTP_ResponseBuilder res, HTTP_String base_endpoint, HTTP_String base_path, HTTP_String endpoint)
{
	char mem[1<<12];
	int ret = swap_parents(base_endpoint, base_path, endpoint, mem, sizeof(mem));
	if (ret <= 0)
		return ret;
	HTTP_String path = {mem, ret}; // Note that this is zero terminated

	int size;
	File file;
	ret = file_open(path.ptr, &file, &size);
	if (ret == -1) {
		http_response_builder_status(res, 500);
		http_response_builder_done(res);
		return 1;
	}
	if (ret == 1) {

		// File missing

		char index[] = "index.html";
		if (path.len + sizeof(index) + 1 > sizeof(mem)) {
			http_response_builder_status(res, 500);
			http_response_builder_done(res);
			return 1;
		}
		path.ptr[path.len++] = '/';
		memcpy(path.ptr + path.len, index, sizeof(index));
		path.len += sizeof(index)-1;

		ret = file_open(path.ptr, &file, &size);
		if (ret == -1) {
			http_response_builder_status(res, 500);
			http_response_builder_done(res);
			return 1;
		}
		if (ret == 1)
			return 0; // File missing
	}
	HTTP_ASSERT(ret == 0);

	int cap;
	char *dst;
	http_response_builder_status(res, 200);
	http_response_builder_bodycap(res, size);
	dst = http_response_builder_bodybuf(res, &cap);
	if (dst) {
		int copied = 0;
		while (copied < size) {
			int ret = file_read(file, dst + copied, size - copied);
			if (ret < 0) goto err;
			if (ret == 0) break;
			copied += ret;
		}
		if (copied < size) goto err;
		http_response_builder_bodyack(res, size);
	}
	http_response_builder_done(res);
	file_close(file);
	return 1;
err:
	http_response_builder_bodyack(res, 0);
	http_response_builder_undo(res);
	http_response_builder_status(res, 500);
	http_response_builder_done(res);
	file_close(file);
	return 1;
}

static int serve_dynamic_route(Route *route, HTTP_Request *req, HTTP_ResponseBuilder res)
{
	char path_mem[1<<12];
	int path_len = sanitize_path(req->url.path, path_mem, (int) sizeof(path_mem));
	if (path_len < 0) {
		http_response_builder_status(res, 400);
		http_response_builder_body(res, HTTP_STR("Invalid path"));
		http_response_builder_done(res);
		return 1;
	}
	HTTP_String path = {path_mem, path_len};

	if (!http_streq(path, route->endpoint))
		return 0;

	route->func(req, res, route->ptr);
	return 1;
}

void http_router_resolve(HTTP_Router *router, HTTP_Request *req, HTTP_ResponseBuilder res)
{
	for (int i = 0; i < router->num_routes; i++) {
		Route *route = &router->routes[i];
		switch (route->type) {
		case ROUTE_STATIC_DIR:
			if (serve_file_or_index(res,
				route->endpoint,
				route->path,
				req->url.path))
				return;
			break;

		case ROUTE_DYNAMIC:
			if (serve_dynamic_route(route, req, res))
				return;
			break;

		default:
			http_response_builder_status(res, 500);
			http_response_builder_done(res);
			return;
		}
	}
	http_response_builder_status(res, 404);
	http_response_builder_done(res);
}

int http_serve(char *addr, int port, HTTP_Router *router)
{
	int ret;

	HTTP_Server *server = http_server_init_ex((HTTP_String) { addr, strlen(addr) }, port, 0, (HTTP_String) {}, (HTTP_String) {});
	if (server == NULL) {
		http_router_free(router);
		return -1;
	}

	for (;;) {
		HTTP_Request *req;
		HTTP_ResponseBuilder res;
		ret = http_server_wait(server, &req, &res);
		if (ret < 0) {
			http_server_free(server);
			http_router_free(router);
			return -1;
		}
		if (ret == 0)
			continue;
		http_router_resolve(router, req, res);
	}

	http_server_free(server);
	http_router_free(router);
	return 0;
}

////////////////////////////////////////////////////////////////////////////////////////
// 3p/crypt_blowfish.h
////////////////////////////////////////////////////////////////////////////////////////

/*
 * Written by Solar Designer <solar at openwall.com> in 2000-2011.
 * No copyright is claimed, and the software is hereby placed in the public
 * domain.  In case this attempt to disclaim copyright and place the software
 * in the public domain is deemed null and void, then the software is
 * Copyright (c) 2000-2011 Solar Designer and it is hereby released to the
 * general public under the following terms:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted.
 *
 * There's ABSOLUTELY NO WARRANTY, express or implied.
 *
 * See crypt_blowfish.c for more information.
 */

#ifndef _CRYPT_BLOWFISH_H
#define _CRYPT_BLOWFISH_H

extern int _crypt_output_magic(const char *setting, char *output, int size);
extern char *_crypt_blowfish_rn(const char *key, const char *setting,
	char *output, int size);
extern char *_crypt_gensalt_blowfish_rn(const char *prefix,
	unsigned long count,
	const char *input, int size, char *output, int output_size);

#endif

////////////////////////////////////////////////////////////////////////////////////////
// 3p/crypt_blowfish.c
////////////////////////////////////////////////////////////////////////////////////////

/*
 * The crypt_blowfish homepage is:
 *
 *	http://www.openwall.com/crypt/
 *
 * This code comes from John the Ripper password cracker, with reentrant
 * and crypt(3) interfaces added, but optimizations specific to password
 * cracking removed.
 *
 * Written by Solar Designer <solar at openwall.com> in 1998-2014.
 * No copyright is claimed, and the software is hereby placed in the public
 * domain.  In case this attempt to disclaim copyright and place the software
 * in the public domain is deemed null and void, then the software is
 * Copyright (c) 1998-2014 Solar Designer and it is hereby released to the
 * general public under the following terms:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted.
 *
 * There's ABSOLUTELY NO WARRANTY, express or implied.
 *
 * It is my intent that you should be able to use this on your system,
 * as part of a software package, or anywhere else to improve security,
 * ensure compatibility, or for any other purpose.  I would appreciate
 * it if you give credit where it is due and keep your modifications in
 * the public domain as well, but I don't require that in order to let
 * you place this code and any modifications you make under a license
 * of your choice.
 *
 * This implementation is fully compatible with OpenBSD's bcrypt.c for prefix
 * "$2b$", originally by Niels Provos <provos at citi.umich.edu>, and it uses
 * some of his ideas.  The password hashing algorithm was designed by David
 * Mazieres <dm at lcs.mit.edu>.  For information on the level of
 * compatibility for bcrypt hash prefixes other than "$2b$", please refer to
 * the comments in BF_set_key() below and to the included crypt(3) man page.
 *
 * There's a paper on the algorithm that explains its design decisions:
 *
 *	http://www.usenix.org/events/usenix99/provos.html
 *
 * Some of the tricks in BF_ROUND might be inspired by Eric Young's
 * Blowfish library (I can't be sure if I would think of something if I
 * hadn't seen his code).
 */

#include <string.h>

#include <errno.h>
#ifndef __set_errno
#define __set_errno(val) errno = (val)
#endif

#ifndef CRYPT_BLOWFISH_NOINCLUDE
/* Just to make sure the prototypes match the actual definitions */
#include "crypt_blowfish.h"
#endif // CRYPT_BLOWFISH_NOINCLUDE

#ifdef __i386__
#define BF_ASM				1
#define BF_SCALE			1
#elif defined(__x86_64__) || defined(__alpha__) || defined(__hppa__)
#define BF_ASM				0
#define BF_SCALE			1
#else
#define BF_ASM				0
#define BF_SCALE			0
#endif

typedef unsigned int BF_word;
typedef signed int BF_word_signed;

/* Number of Blowfish rounds, this is also hardcoded into a few places */
#define BF_N				16

typedef BF_word BF_key[BF_N + 2];

typedef struct {
	BF_word S[4][0x100];
	BF_key P;
} BF_ctx;

/*
 * Magic IV for 64 Blowfish encryptions that we do at the end.
 * The string is "OrpheanBeholderScryDoubt" on big-endian.
 */
static BF_word BF_magic_w[6] = {
	0x4F727068, 0x65616E42, 0x65686F6C,
	0x64657253, 0x63727944, 0x6F756274
};

/*
 * P-box and S-box tables initialized with digits of Pi.
 */
static BF_ctx BF_init_state = {
	{
		{
			0xd1310ba6, 0x98dfb5ac, 0x2ffd72db, 0xd01adfb7,
			0xb8e1afed, 0x6a267e96, 0xba7c9045, 0xf12c7f99,
			0x24a19947, 0xb3916cf7, 0x0801f2e2, 0x858efc16,
			0x636920d8, 0x71574e69, 0xa458fea3, 0xf4933d7e,
			0x0d95748f, 0x728eb658, 0x718bcd58, 0x82154aee,
			0x7b54a41d, 0xc25a59b5, 0x9c30d539, 0x2af26013,
			0xc5d1b023, 0x286085f0, 0xca417918, 0xb8db38ef,
			0x8e79dcb0, 0x603a180e, 0x6c9e0e8b, 0xb01e8a3e,
			0xd71577c1, 0xbd314b27, 0x78af2fda, 0x55605c60,
			0xe65525f3, 0xaa55ab94, 0x57489862, 0x63e81440,
			0x55ca396a, 0x2aab10b6, 0xb4cc5c34, 0x1141e8ce,
			0xa15486af, 0x7c72e993, 0xb3ee1411, 0x636fbc2a,
			0x2ba9c55d, 0x741831f6, 0xce5c3e16, 0x9b87931e,
			0xafd6ba33, 0x6c24cf5c, 0x7a325381, 0x28958677,
			0x3b8f4898, 0x6b4bb9af, 0xc4bfe81b, 0x66282193,
			0x61d809cc, 0xfb21a991, 0x487cac60, 0x5dec8032,
			0xef845d5d, 0xe98575b1, 0xdc262302, 0xeb651b88,
			0x23893e81, 0xd396acc5, 0x0f6d6ff3, 0x83f44239,
			0x2e0b4482, 0xa4842004, 0x69c8f04a, 0x9e1f9b5e,
			0x21c66842, 0xf6e96c9a, 0x670c9c61, 0xabd388f0,
			0x6a51a0d2, 0xd8542f68, 0x960fa728, 0xab5133a3,
			0x6eef0b6c, 0x137a3be4, 0xba3bf050, 0x7efb2a98,
			0xa1f1651d, 0x39af0176, 0x66ca593e, 0x82430e88,
			0x8cee8619, 0x456f9fb4, 0x7d84a5c3, 0x3b8b5ebe,
			0xe06f75d8, 0x85c12073, 0x401a449f, 0x56c16aa6,
			0x4ed3aa62, 0x363f7706, 0x1bfedf72, 0x429b023d,
			0x37d0d724, 0xd00a1248, 0xdb0fead3, 0x49f1c09b,
			0x075372c9, 0x80991b7b, 0x25d479d8, 0xf6e8def7,
			0xe3fe501a, 0xb6794c3b, 0x976ce0bd, 0x04c006ba,
			0xc1a94fb6, 0x409f60c4, 0x5e5c9ec2, 0x196a2463,
			0x68fb6faf, 0x3e6c53b5, 0x1339b2eb, 0x3b52ec6f,
			0x6dfc511f, 0x9b30952c, 0xcc814544, 0xaf5ebd09,
			0xbee3d004, 0xde334afd, 0x660f2807, 0x192e4bb3,
			0xc0cba857, 0x45c8740f, 0xd20b5f39, 0xb9d3fbdb,
			0x5579c0bd, 0x1a60320a, 0xd6a100c6, 0x402c7279,
			0x679f25fe, 0xfb1fa3cc, 0x8ea5e9f8, 0xdb3222f8,
			0x3c7516df, 0xfd616b15, 0x2f501ec8, 0xad0552ab,
			0x323db5fa, 0xfd238760, 0x53317b48, 0x3e00df82,
			0x9e5c57bb, 0xca6f8ca0, 0x1a87562e, 0xdf1769db,
			0xd542a8f6, 0x287effc3, 0xac6732c6, 0x8c4f5573,
			0x695b27b0, 0xbbca58c8, 0xe1ffa35d, 0xb8f011a0,
			0x10fa3d98, 0xfd2183b8, 0x4afcb56c, 0x2dd1d35b,
			0x9a53e479, 0xb6f84565, 0xd28e49bc, 0x4bfb9790,
			0xe1ddf2da, 0xa4cb7e33, 0x62fb1341, 0xcee4c6e8,
			0xef20cada, 0x36774c01, 0xd07e9efe, 0x2bf11fb4,
			0x95dbda4d, 0xae909198, 0xeaad8e71, 0x6b93d5a0,
			0xd08ed1d0, 0xafc725e0, 0x8e3c5b2f, 0x8e7594b7,
			0x8ff6e2fb, 0xf2122b64, 0x8888b812, 0x900df01c,
			0x4fad5ea0, 0x688fc31c, 0xd1cff191, 0xb3a8c1ad,
			0x2f2f2218, 0xbe0e1777, 0xea752dfe, 0x8b021fa1,
			0xe5a0cc0f, 0xb56f74e8, 0x18acf3d6, 0xce89e299,
			0xb4a84fe0, 0xfd13e0b7, 0x7cc43b81, 0xd2ada8d9,
			0x165fa266, 0x80957705, 0x93cc7314, 0x211a1477,
			0xe6ad2065, 0x77b5fa86, 0xc75442f5, 0xfb9d35cf,
			0xebcdaf0c, 0x7b3e89a0, 0xd6411bd3, 0xae1e7e49,
			0x00250e2d, 0x2071b35e, 0x226800bb, 0x57b8e0af,
			0x2464369b, 0xf009b91e, 0x5563911d, 0x59dfa6aa,
			0x78c14389, 0xd95a537f, 0x207d5ba2, 0x02e5b9c5,
			0x83260376, 0x6295cfa9, 0x11c81968, 0x4e734a41,
			0xb3472dca, 0x7b14a94a, 0x1b510052, 0x9a532915,
			0xd60f573f, 0xbc9bc6e4, 0x2b60a476, 0x81e67400,
			0x08ba6fb5, 0x571be91f, 0xf296ec6b, 0x2a0dd915,
			0xb6636521, 0xe7b9f9b6, 0xff34052e, 0xc5855664,
			0x53b02d5d, 0xa99f8fa1, 0x08ba4799, 0x6e85076a
		}, {
			0x4b7a70e9, 0xb5b32944, 0xdb75092e, 0xc4192623,
			0xad6ea6b0, 0x49a7df7d, 0x9cee60b8, 0x8fedb266,
			0xecaa8c71, 0x699a17ff, 0x5664526c, 0xc2b19ee1,
			0x193602a5, 0x75094c29, 0xa0591340, 0xe4183a3e,
			0x3f54989a, 0x5b429d65, 0x6b8fe4d6, 0x99f73fd6,
			0xa1d29c07, 0xefe830f5, 0x4d2d38e6, 0xf0255dc1,
			0x4cdd2086, 0x8470eb26, 0x6382e9c6, 0x021ecc5e,
			0x09686b3f, 0x3ebaefc9, 0x3c971814, 0x6b6a70a1,
			0x687f3584, 0x52a0e286, 0xb79c5305, 0xaa500737,
			0x3e07841c, 0x7fdeae5c, 0x8e7d44ec, 0x5716f2b8,
			0xb03ada37, 0xf0500c0d, 0xf01c1f04, 0x0200b3ff,
			0xae0cf51a, 0x3cb574b2, 0x25837a58, 0xdc0921bd,
			0xd19113f9, 0x7ca92ff6, 0x94324773, 0x22f54701,
			0x3ae5e581, 0x37c2dadc, 0xc8b57634, 0x9af3dda7,
			0xa9446146, 0x0fd0030e, 0xecc8c73e, 0xa4751e41,
			0xe238cd99, 0x3bea0e2f, 0x3280bba1, 0x183eb331,
			0x4e548b38, 0x4f6db908, 0x6f420d03, 0xf60a04bf,
			0x2cb81290, 0x24977c79, 0x5679b072, 0xbcaf89af,
			0xde9a771f, 0xd9930810, 0xb38bae12, 0xdccf3f2e,
			0x5512721f, 0x2e6b7124, 0x501adde6, 0x9f84cd87,
			0x7a584718, 0x7408da17, 0xbc9f9abc, 0xe94b7d8c,
			0xec7aec3a, 0xdb851dfa, 0x63094366, 0xc464c3d2,
			0xef1c1847, 0x3215d908, 0xdd433b37, 0x24c2ba16,
			0x12a14d43, 0x2a65c451, 0x50940002, 0x133ae4dd,
			0x71dff89e, 0x10314e55, 0x81ac77d6, 0x5f11199b,
			0x043556f1, 0xd7a3c76b, 0x3c11183b, 0x5924a509,
			0xf28fe6ed, 0x97f1fbfa, 0x9ebabf2c, 0x1e153c6e,
			0x86e34570, 0xeae96fb1, 0x860e5e0a, 0x5a3e2ab3,
			0x771fe71c, 0x4e3d06fa, 0x2965dcb9, 0x99e71d0f,
			0x803e89d6, 0x5266c825, 0x2e4cc978, 0x9c10b36a,
			0xc6150eba, 0x94e2ea78, 0xa5fc3c53, 0x1e0a2df4,
			0xf2f74ea7, 0x361d2b3d, 0x1939260f, 0x19c27960,
			0x5223a708, 0xf71312b6, 0xebadfe6e, 0xeac31f66,
			0xe3bc4595, 0xa67bc883, 0xb17f37d1, 0x018cff28,
			0xc332ddef, 0xbe6c5aa5, 0x65582185, 0x68ab9802,
			0xeecea50f, 0xdb2f953b, 0x2aef7dad, 0x5b6e2f84,
			0x1521b628, 0x29076170, 0xecdd4775, 0x619f1510,
			0x13cca830, 0xeb61bd96, 0x0334fe1e, 0xaa0363cf,
			0xb5735c90, 0x4c70a239, 0xd59e9e0b, 0xcbaade14,
			0xeecc86bc, 0x60622ca7, 0x9cab5cab, 0xb2f3846e,
			0x648b1eaf, 0x19bdf0ca, 0xa02369b9, 0x655abb50,
			0x40685a32, 0x3c2ab4b3, 0x319ee9d5, 0xc021b8f7,
			0x9b540b19, 0x875fa099, 0x95f7997e, 0x623d7da8,
			0xf837889a, 0x97e32d77, 0x11ed935f, 0x16681281,
			0x0e358829, 0xc7e61fd6, 0x96dedfa1, 0x7858ba99,
			0x57f584a5, 0x1b227263, 0x9b83c3ff, 0x1ac24696,
			0xcdb30aeb, 0x532e3054, 0x8fd948e4, 0x6dbc3128,
			0x58ebf2ef, 0x34c6ffea, 0xfe28ed61, 0xee7c3c73,
			0x5d4a14d9, 0xe864b7e3, 0x42105d14, 0x203e13e0,
			0x45eee2b6, 0xa3aaabea, 0xdb6c4f15, 0xfacb4fd0,
			0xc742f442, 0xef6abbb5, 0x654f3b1d, 0x41cd2105,
			0xd81e799e, 0x86854dc7, 0xe44b476a, 0x3d816250,
			0xcf62a1f2, 0x5b8d2646, 0xfc8883a0, 0xc1c7b6a3,
			0x7f1524c3, 0x69cb7492, 0x47848a0b, 0x5692b285,
			0x095bbf00, 0xad19489d, 0x1462b174, 0x23820e00,
			0x58428d2a, 0x0c55f5ea, 0x1dadf43e, 0x233f7061,
			0x3372f092, 0x8d937e41, 0xd65fecf1, 0x6c223bdb,
			0x7cde3759, 0xcbee7460, 0x4085f2a7, 0xce77326e,
			0xa6078084, 0x19f8509e, 0xe8efd855, 0x61d99735,
			0xa969a7aa, 0xc50c06c2, 0x5a04abfc, 0x800bcadc,
			0x9e447a2e, 0xc3453484, 0xfdd56705, 0x0e1e9ec9,
			0xdb73dbd3, 0x105588cd, 0x675fda79, 0xe3674340,
			0xc5c43465, 0x713e38d8, 0x3d28f89e, 0xf16dff20,
			0x153e21e7, 0x8fb03d4a, 0xe6e39f2b, 0xdb83adf7
		}, {
			0xe93d5a68, 0x948140f7, 0xf64c261c, 0x94692934,
			0x411520f7, 0x7602d4f7, 0xbcf46b2e, 0xd4a20068,
			0xd4082471, 0x3320f46a, 0x43b7d4b7, 0x500061af,
			0x1e39f62e, 0x97244546, 0x14214f74, 0xbf8b8840,
			0x4d95fc1d, 0x96b591af, 0x70f4ddd3, 0x66a02f45,
			0xbfbc09ec, 0x03bd9785, 0x7fac6dd0, 0x31cb8504,
			0x96eb27b3, 0x55fd3941, 0xda2547e6, 0xabca0a9a,
			0x28507825, 0x530429f4, 0x0a2c86da, 0xe9b66dfb,
			0x68dc1462, 0xd7486900, 0x680ec0a4, 0x27a18dee,
			0x4f3ffea2, 0xe887ad8c, 0xb58ce006, 0x7af4d6b6,
			0xaace1e7c, 0xd3375fec, 0xce78a399, 0x406b2a42,
			0x20fe9e35, 0xd9f385b9, 0xee39d7ab, 0x3b124e8b,
			0x1dc9faf7, 0x4b6d1856, 0x26a36631, 0xeae397b2,
			0x3a6efa74, 0xdd5b4332, 0x6841e7f7, 0xca7820fb,
			0xfb0af54e, 0xd8feb397, 0x454056ac, 0xba489527,
			0x55533a3a, 0x20838d87, 0xfe6ba9b7, 0xd096954b,
			0x55a867bc, 0xa1159a58, 0xcca92963, 0x99e1db33,
			0xa62a4a56, 0x3f3125f9, 0x5ef47e1c, 0x9029317c,
			0xfdf8e802, 0x04272f70, 0x80bb155c, 0x05282ce3,
			0x95c11548, 0xe4c66d22, 0x48c1133f, 0xc70f86dc,
			0x07f9c9ee, 0x41041f0f, 0x404779a4, 0x5d886e17,
			0x325f51eb, 0xd59bc0d1, 0xf2bcc18f, 0x41113564,
			0x257b7834, 0x602a9c60, 0xdff8e8a3, 0x1f636c1b,
			0x0e12b4c2, 0x02e1329e, 0xaf664fd1, 0xcad18115,
			0x6b2395e0, 0x333e92e1, 0x3b240b62, 0xeebeb922,
			0x85b2a20e, 0xe6ba0d99, 0xde720c8c, 0x2da2f728,
			0xd0127845, 0x95b794fd, 0x647d0862, 0xe7ccf5f0,
			0x5449a36f, 0x877d48fa, 0xc39dfd27, 0xf33e8d1e,
			0x0a476341, 0x992eff74, 0x3a6f6eab, 0xf4f8fd37,
			0xa812dc60, 0xa1ebddf8, 0x991be14c, 0xdb6e6b0d,
			0xc67b5510, 0x6d672c37, 0x2765d43b, 0xdcd0e804,
			0xf1290dc7, 0xcc00ffa3, 0xb5390f92, 0x690fed0b,
			0x667b9ffb, 0xcedb7d9c, 0xa091cf0b, 0xd9155ea3,
			0xbb132f88, 0x515bad24, 0x7b9479bf, 0x763bd6eb,
			0x37392eb3, 0xcc115979, 0x8026e297, 0xf42e312d,
			0x6842ada7, 0xc66a2b3b, 0x12754ccc, 0x782ef11c,
			0x6a124237, 0xb79251e7, 0x06a1bbe6, 0x4bfb6350,
			0x1a6b1018, 0x11caedfa, 0x3d25bdd8, 0xe2e1c3c9,
			0x44421659, 0x0a121386, 0xd90cec6e, 0xd5abea2a,
			0x64af674e, 0xda86a85f, 0xbebfe988, 0x64e4c3fe,
			0x9dbc8057, 0xf0f7c086, 0x60787bf8, 0x6003604d,
			0xd1fd8346, 0xf6381fb0, 0x7745ae04, 0xd736fccc,
			0x83426b33, 0xf01eab71, 0xb0804187, 0x3c005e5f,
			0x77a057be, 0xbde8ae24, 0x55464299, 0xbf582e61,
			0x4e58f48f, 0xf2ddfda2, 0xf474ef38, 0x8789bdc2,
			0x5366f9c3, 0xc8b38e74, 0xb475f255, 0x46fcd9b9,
			0x7aeb2661, 0x8b1ddf84, 0x846a0e79, 0x915f95e2,
			0x466e598e, 0x20b45770, 0x8cd55591, 0xc902de4c,
			0xb90bace1, 0xbb8205d0, 0x11a86248, 0x7574a99e,
			0xb77f19b6, 0xe0a9dc09, 0x662d09a1, 0xc4324633,
			0xe85a1f02, 0x09f0be8c, 0x4a99a025, 0x1d6efe10,
			0x1ab93d1d, 0x0ba5a4df, 0xa186f20f, 0x2868f169,
			0xdcb7da83, 0x573906fe, 0xa1e2ce9b, 0x4fcd7f52,
			0x50115e01, 0xa70683fa, 0xa002b5c4, 0x0de6d027,
			0x9af88c27, 0x773f8641, 0xc3604c06, 0x61a806b5,
			0xf0177a28, 0xc0f586e0, 0x006058aa, 0x30dc7d62,
			0x11e69ed7, 0x2338ea63, 0x53c2dd94, 0xc2c21634,
			0xbbcbee56, 0x90bcb6de, 0xebfc7da1, 0xce591d76,
			0x6f05e409, 0x4b7c0188, 0x39720a3d, 0x7c927c24,
			0x86e3725f, 0x724d9db9, 0x1ac15bb4, 0xd39eb8fc,
			0xed545578, 0x08fca5b5, 0xd83d7cd3, 0x4dad0fc4,
			0x1e50ef5e, 0xb161e6f8, 0xa28514d9, 0x6c51133c,
			0x6fd5c7e7, 0x56e14ec4, 0x362abfce, 0xddc6c837,
			0xd79a3234, 0x92638212, 0x670efa8e, 0x406000e0
		}, {
			0x3a39ce37, 0xd3faf5cf, 0xabc27737, 0x5ac52d1b,
			0x5cb0679e, 0x4fa33742, 0xd3822740, 0x99bc9bbe,
			0xd5118e9d, 0xbf0f7315, 0xd62d1c7e, 0xc700c47b,
			0xb78c1b6b, 0x21a19045, 0xb26eb1be, 0x6a366eb4,
			0x5748ab2f, 0xbc946e79, 0xc6a376d2, 0x6549c2c8,
			0x530ff8ee, 0x468dde7d, 0xd5730a1d, 0x4cd04dc6,
			0x2939bbdb, 0xa9ba4650, 0xac9526e8, 0xbe5ee304,
			0xa1fad5f0, 0x6a2d519a, 0x63ef8ce2, 0x9a86ee22,
			0xc089c2b8, 0x43242ef6, 0xa51e03aa, 0x9cf2d0a4,
			0x83c061ba, 0x9be96a4d, 0x8fe51550, 0xba645bd6,
			0x2826a2f9, 0xa73a3ae1, 0x4ba99586, 0xef5562e9,
			0xc72fefd3, 0xf752f7da, 0x3f046f69, 0x77fa0a59,
			0x80e4a915, 0x87b08601, 0x9b09e6ad, 0x3b3ee593,
			0xe990fd5a, 0x9e34d797, 0x2cf0b7d9, 0x022b8b51,
			0x96d5ac3a, 0x017da67d, 0xd1cf3ed6, 0x7c7d2d28,
			0x1f9f25cf, 0xadf2b89b, 0x5ad6b472, 0x5a88f54c,
			0xe029ac71, 0xe019a5e6, 0x47b0acfd, 0xed93fa9b,
			0xe8d3c48d, 0x283b57cc, 0xf8d56629, 0x79132e28,
			0x785f0191, 0xed756055, 0xf7960e44, 0xe3d35e8c,
			0x15056dd4, 0x88f46dba, 0x03a16125, 0x0564f0bd,
			0xc3eb9e15, 0x3c9057a2, 0x97271aec, 0xa93a072a,
			0x1b3f6d9b, 0x1e6321f5, 0xf59c66fb, 0x26dcf319,
			0x7533d928, 0xb155fdf5, 0x03563482, 0x8aba3cbb,
			0x28517711, 0xc20ad9f8, 0xabcc5167, 0xccad925f,
			0x4de81751, 0x3830dc8e, 0x379d5862, 0x9320f991,
			0xea7a90c2, 0xfb3e7bce, 0x5121ce64, 0x774fbe32,
			0xa8b6e37e, 0xc3293d46, 0x48de5369, 0x6413e680,
			0xa2ae0810, 0xdd6db224, 0x69852dfd, 0x09072166,
			0xb39a460a, 0x6445c0dd, 0x586cdecf, 0x1c20c8ae,
			0x5bbef7dd, 0x1b588d40, 0xccd2017f, 0x6bb4e3bb,
			0xdda26a7e, 0x3a59ff45, 0x3e350a44, 0xbcb4cdd5,
			0x72eacea8, 0xfa6484bb, 0x8d6612ae, 0xbf3c6f47,
			0xd29be463, 0x542f5d9e, 0xaec2771b, 0xf64e6370,
			0x740e0d8d, 0xe75b1357, 0xf8721671, 0xaf537d5d,
			0x4040cb08, 0x4eb4e2cc, 0x34d2466a, 0x0115af84,
			0xe1b00428, 0x95983a1d, 0x06b89fb4, 0xce6ea048,
			0x6f3f3b82, 0x3520ab82, 0x011a1d4b, 0x277227f8,
			0x611560b1, 0xe7933fdc, 0xbb3a792b, 0x344525bd,
			0xa08839e1, 0x51ce794b, 0x2f32c9b7, 0xa01fbac9,
			0xe01cc87e, 0xbcc7d1f6, 0xcf0111c3, 0xa1e8aac7,
			0x1a908749, 0xd44fbd9a, 0xd0dadecb, 0xd50ada38,
			0x0339c32a, 0xc6913667, 0x8df9317c, 0xe0b12b4f,
			0xf79e59b7, 0x43f5bb3a, 0xf2d519ff, 0x27d9459c,
			0xbf97222c, 0x15e6fc2a, 0x0f91fc71, 0x9b941525,
			0xfae59361, 0xceb69ceb, 0xc2a86459, 0x12baa8d1,
			0xb6c1075e, 0xe3056a0c, 0x10d25065, 0xcb03a442,
			0xe0ec6e0e, 0x1698db3b, 0x4c98a0be, 0x3278e964,
			0x9f1f9532, 0xe0d392df, 0xd3a0342b, 0x8971f21e,
			0x1b0a7441, 0x4ba3348c, 0xc5be7120, 0xc37632d8,
			0xdf359f8d, 0x9b992f2e, 0xe60b6f47, 0x0fe3f11d,
			0xe54cda54, 0x1edad891, 0xce6279cf, 0xcd3e7e6f,
			0x1618b166, 0xfd2c1d05, 0x848fd2c5, 0xf6fb2299,
			0xf523f357, 0xa6327623, 0x93a83531, 0x56cccd02,
			0xacf08162, 0x5a75ebb5, 0x6e163697, 0x88d273cc,
			0xde966292, 0x81b949d0, 0x4c50901b, 0x71c65614,
			0xe6c6c7bd, 0x327a140a, 0x45e1d006, 0xc3f27b9a,
			0xc9aa53fd, 0x62a80f00, 0xbb25bfe2, 0x35bdd2f6,
			0x71126905, 0xb2040222, 0xb6cbcf7c, 0xcd769c2b,
			0x53113ec0, 0x1640e3d3, 0x38abbd60, 0x2547adf0,
			0xba38209c, 0xf746ce76, 0x77afa1c5, 0x20756060,
			0x85cbfe4e, 0x8ae88dd8, 0x7aaaf9b0, 0x4cf9aa7e,
			0x1948c25c, 0x02fb8a8c, 0x01c36ae4, 0xd6ebe1f9,
			0x90d4f869, 0xa65cdea0, 0x3f09252d, 0xc208e69f,
			0xb74e6132, 0xce77e25b, 0x578fdfe3, 0x3ac372e6
		}
	}, {
		0x243f6a88, 0x85a308d3, 0x13198a2e, 0x03707344,
		0xa4093822, 0x299f31d0, 0x082efa98, 0xec4e6c89,
		0x452821e6, 0x38d01377, 0xbe5466cf, 0x34e90c6c,
		0xc0ac29b7, 0xc97c50dd, 0x3f84d5b5, 0xb5470917,
		0x9216d5d9, 0x8979fb1b
	}
};

static unsigned char BF_itoa64[64 + 1] =
	"./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

static unsigned char BF_atoi64[0x60] = {
	64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 0, 1,
	54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 64, 64, 64, 64, 64,
	64, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
	17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 64, 64, 64, 64, 64,
	64, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42,
	43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 64, 64, 64, 64, 64
};

#define BF_safe_atoi64(dst, src) \
{ \
	tmp = (unsigned char)(src); \
	if ((unsigned int)(tmp -= 0x20) >= 0x60) return -1; \
	tmp = BF_atoi64[tmp]; \
	if (tmp > 63) return -1; \
	(dst) = tmp; \
}

static int BF_decode(BF_word *dst, const char *src, int size)
{
	unsigned char *dptr = (unsigned char *)dst;
	unsigned char *end = dptr + size;
	const unsigned char *sptr = (const unsigned char *)src;
	unsigned int tmp, c1, c2, c3, c4;

	do {
		BF_safe_atoi64(c1, *sptr++);
		BF_safe_atoi64(c2, *sptr++);
		*dptr++ = (c1 << 2) | ((c2 & 0x30) >> 4);
		if (dptr >= end) break;

		BF_safe_atoi64(c3, *sptr++);
		*dptr++ = ((c2 & 0x0F) << 4) | ((c3 & 0x3C) >> 2);
		if (dptr >= end) break;

		BF_safe_atoi64(c4, *sptr++);
		*dptr++ = ((c3 & 0x03) << 6) | c4;
	} while (dptr < end);

	return 0;
}

static void BF_encode(char *dst, const BF_word *src, int size)
{
	const unsigned char *sptr = (const unsigned char *)src;
	const unsigned char *end = sptr + size;
	unsigned char *dptr = (unsigned char *)dst;
	unsigned int c1, c2;

	do {
		c1 = *sptr++;
		*dptr++ = BF_itoa64[c1 >> 2];
		c1 = (c1 & 0x03) << 4;
		if (sptr >= end) {
			*dptr++ = BF_itoa64[c1];
			break;
		}

		c2 = *sptr++;
		c1 |= c2 >> 4;
		*dptr++ = BF_itoa64[c1];
		c1 = (c2 & 0x0f) << 2;
		if (sptr >= end) {
			*dptr++ = BF_itoa64[c1];
			break;
		}

		c2 = *sptr++;
		c1 |= c2 >> 6;
		*dptr++ = BF_itoa64[c1];
		*dptr++ = BF_itoa64[c2 & 0x3f];
	} while (sptr < end);
}

static void BF_swap(BF_word *x, int count)
{
	static int endianness_check = 1;
	char *is_little_endian = (char *)&endianness_check;
	BF_word tmp;

	if (*is_little_endian)
	do {
		tmp = *x;
		tmp = (tmp << 16) | (tmp >> 16);
		*x++ = ((tmp & 0x00FF00FF) << 8) | ((tmp >> 8) & 0x00FF00FF);
	} while (--count);
}

#if BF_SCALE
/* Architectures which can shift addresses left by 2 bits with no extra cost */
#define BF_ROUND(L, R, N) \
	tmp1 = L & 0xFF; \
	tmp2 = L >> 8; \
	tmp2 &= 0xFF; \
	tmp3 = L >> 16; \
	tmp3 &= 0xFF; \
	tmp4 = L >> 24; \
	tmp1 = data.ctx.S[3][tmp1]; \
	tmp2 = data.ctx.S[2][tmp2]; \
	tmp3 = data.ctx.S[1][tmp3]; \
	tmp3 += data.ctx.S[0][tmp4]; \
	tmp3 ^= tmp2; \
	R ^= data.ctx.P[N + 1]; \
	tmp3 += tmp1; \
	R ^= tmp3;
#else
/* Architectures with no complicated addressing modes supported */
#define BF_INDEX(S, i) \
	(*((BF_word *)(((unsigned char *)S) + (i))))
#define BF_ROUND(L, R, N) \
	tmp1 = L & 0xFF; \
	tmp1 <<= 2; \
	tmp2 = L >> 6; \
	tmp2 &= 0x3FC; \
	tmp3 = L >> 14; \
	tmp3 &= 0x3FC; \
	tmp4 = L >> 22; \
	tmp4 &= 0x3FC; \
	tmp1 = BF_INDEX(data.ctx.S[3], tmp1); \
	tmp2 = BF_INDEX(data.ctx.S[2], tmp2); \
	tmp3 = BF_INDEX(data.ctx.S[1], tmp3); \
	tmp3 += BF_INDEX(data.ctx.S[0], tmp4); \
	tmp3 ^= tmp2; \
	R ^= data.ctx.P[N + 1]; \
	tmp3 += tmp1; \
	R ^= tmp3;
#endif

/*
 * Encrypt one block, BF_N is hardcoded here.
 */
#define BF_ENCRYPT \
	L ^= data.ctx.P[0]; \
	BF_ROUND(L, R, 0); \
	BF_ROUND(R, L, 1); \
	BF_ROUND(L, R, 2); \
	BF_ROUND(R, L, 3); \
	BF_ROUND(L, R, 4); \
	BF_ROUND(R, L, 5); \
	BF_ROUND(L, R, 6); \
	BF_ROUND(R, L, 7); \
	BF_ROUND(L, R, 8); \
	BF_ROUND(R, L, 9); \
	BF_ROUND(L, R, 10); \
	BF_ROUND(R, L, 11); \
	BF_ROUND(L, R, 12); \
	BF_ROUND(R, L, 13); \
	BF_ROUND(L, R, 14); \
	BF_ROUND(R, L, 15); \
	tmp4 = R; \
	R = L; \
	L = tmp4 ^ data.ctx.P[BF_N + 1];

#if BF_ASM
#define BF_body() \
	_BF_body_r(&data.ctx);
#else
#define BF_body() \
	L = R = 0; \
	ptr = data.ctx.P; \
	do { \
		ptr += 2; \
		BF_ENCRYPT; \
		*(ptr - 2) = L; \
		*(ptr - 1) = R; \
	} while (ptr < &data.ctx.P[BF_N + 2]); \
\
	ptr = data.ctx.S[0]; \
	do { \
		ptr += 2; \
		BF_ENCRYPT; \
		*(ptr - 2) = L; \
		*(ptr - 1) = R; \
	} while (ptr < &data.ctx.S[3][0xFF]);
#endif

static void BF_set_key(const char *key, BF_key expanded, BF_key initial,
    unsigned char flags)
{
	const char *ptr = key;
	unsigned int bug, i, j;
	BF_word safety, sign, diff, tmp[2];

/*
 * There was a sign extension bug in older revisions of this function.  While
 * we would have liked to simply fix the bug and move on, we have to provide
 * a backwards compatibility feature (essentially the bug) for some systems and
 * a safety measure for some others.  The latter is needed because for certain
 * multiple inputs to the buggy algorithm there exist easily found inputs to
 * the correct algorithm that produce the same hash.  Thus, we optionally
 * deviate from the correct algorithm just enough to avoid such collisions.
 * While the bug itself affected the majority of passwords containing
 * characters with the 8th bit set (although only a percentage of those in a
 * collision-producing way), the anti-collision safety measure affects
 * only a subset of passwords containing the '\xff' character (not even all of
 * those passwords, just some of them).  This character is not found in valid
 * UTF-8 sequences and is rarely used in popular 8-bit character encodings.
 * Thus, the safety measure is unlikely to cause much annoyance, and is a
 * reasonable tradeoff to use when authenticating against existing hashes that
 * are not reliably known to have been computed with the correct algorithm.
 *
 * We use an approach that tries to minimize side-channel leaks of password
 * information - that is, we mostly use fixed-cost bitwise operations instead
 * of branches or table lookups.  (One conditional branch based on password
 * length remains.  It is not part of the bug aftermath, though, and is
 * difficult and possibly unreasonable to avoid given the use of C strings by
 * the caller, which results in similar timing leaks anyway.)
 *
 * For actual implementation, we set an array index in the variable "bug"
 * (0 means no bug, 1 means sign extension bug emulation) and a flag in the
 * variable "safety" (bit 16 is set when the safety measure is requested).
 * Valid combinations of settings are:
 *
 * Prefix "$2a$": bug = 0, safety = 0x10000
 * Prefix "$2b$": bug = 0, safety = 0
 * Prefix "$2x$": bug = 1, safety = 0
 * Prefix "$2y$": bug = 0, safety = 0
 */
	bug = (unsigned int)flags & 1;
	safety = ((BF_word)flags & 2) << 15;

	sign = diff = 0;

	for (i = 0; i < BF_N + 2; i++) {
		tmp[0] = tmp[1] = 0;
		for (j = 0; j < 4; j++) {
			tmp[0] <<= 8;
			tmp[0] |= (unsigned char)*ptr; /* correct */
			tmp[1] <<= 8;
			tmp[1] |= (BF_word_signed)(signed char)*ptr; /* bug */
/*
 * Sign extension in the first char has no effect - nothing to overwrite yet,
 * and those extra 24 bits will be fully shifted out of the 32-bit word.  For
 * chars 2, 3, 4 in each four-char block, we set bit 7 of "sign" if sign
 * extension in tmp[1] occurs.  Once this flag is set, it remains set.
 */
			if (j)
				sign |= tmp[1] & 0x80;
			if (!*ptr)
				ptr = key;
			else
				ptr++;
		}
		diff |= tmp[0] ^ tmp[1]; /* Non-zero on any differences */

		expanded[i] = tmp[bug];
		initial[i] = BF_init_state.P[i] ^ tmp[bug];
	}

/*
 * At this point, "diff" is zero iff the correct and buggy algorithms produced
 * exactly the same result.  If so and if "sign" is non-zero, which indicates
 * that there was a non-benign sign extension, this means that we have a
 * collision between the correctly computed hash for this password and a set of
 * passwords that could be supplied to the buggy algorithm.  Our safety measure
 * is meant to protect from such many-buggy to one-correct collisions, by
 * deviating from the correct algorithm in such cases.  Let's check for this.
 */
	diff |= diff >> 16; /* still zero iff exact match */
	diff &= 0xffff; /* ditto */
	diff += 0xffff; /* bit 16 set iff "diff" was non-zero (on non-match) */
	sign <<= 9; /* move the non-benign sign extension flag to bit 16 */
	sign &= ~diff & safety; /* action needed? */

/*
 * If we have determined that we need to deviate from the correct algorithm,
 * flip bit 16 in initial expanded key.  (The choice of 16 is arbitrary, but
 * let's stick to it now.  It came out of the approach we used above, and it's
 * not any worse than any other choice we could make.)
 *
 * It is crucial that we don't do the same to the expanded key used in the main
 * Eksblowfish loop.  By doing it to only one of these two, we deviate from a
 * state that could be directly specified by a password to the buggy algorithm
 * (and to the fully correct one as well, but that's a side-effect).
 */
	initial[0] ^= sign;
}

static const unsigned char flags_by_subtype[26] =
	{2, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 4, 0};

static char *BF_crypt(const char *key, const char *setting,
	char *output, int size,
	BF_word min)
{
#if BF_ASM
	extern void _BF_body_r(BF_ctx *ctx);
#endif
	struct {
		BF_ctx ctx;
		BF_key expanded_key;
		union {
			BF_word salt[4];
			BF_word output[6];
		} binary;
	} data;
	BF_word L, R;
	BF_word tmp1, tmp2, tmp3, tmp4;
	BF_word *ptr;
	BF_word count;
	int i;

	if (size < 7 + 22 + 31 + 1) {
		__set_errno(ERANGE);
		return NULL;
	}

	if (setting[0] != '$' ||
	    setting[1] != '2' ||
	    setting[2] < 'a' || setting[2] > 'z' ||
	    !flags_by_subtype[(unsigned int)(unsigned char)setting[2] - 'a'] ||
	    setting[3] != '$' ||
	    setting[4] < '0' || setting[4] > '3' ||
	    setting[5] < '0' || setting[5] > '9' ||
	    (setting[4] == '3' && setting[5] > '1') ||
	    setting[6] != '$') {
		__set_errno(EINVAL);
		return NULL;
	}

	count = (BF_word)1 << ((setting[4] - '0') * 10 + (setting[5] - '0'));
	if (count < min || BF_decode(data.binary.salt, &setting[7], 16)) {
		__set_errno(EINVAL);
		return NULL;
	}
	BF_swap(data.binary.salt, 4);

	BF_set_key(key, data.expanded_key, data.ctx.P,
	    flags_by_subtype[(unsigned int)(unsigned char)setting[2] - 'a']);

	memcpy(data.ctx.S, BF_init_state.S, sizeof(data.ctx.S));

	L = R = 0;
	for (i = 0; i < BF_N + 2; i += 2) {
		L ^= data.binary.salt[i & 2];
		R ^= data.binary.salt[(i & 2) + 1];
		BF_ENCRYPT;
		data.ctx.P[i] = L;
		data.ctx.P[i + 1] = R;
	}

	ptr = data.ctx.S[0];
	do {
		ptr += 4;
		L ^= data.binary.salt[(BF_N + 2) & 3];
		R ^= data.binary.salt[(BF_N + 3) & 3];
		BF_ENCRYPT;
		*(ptr - 4) = L;
		*(ptr - 3) = R;

		L ^= data.binary.salt[(BF_N + 4) & 3];
		R ^= data.binary.salt[(BF_N + 5) & 3];
		BF_ENCRYPT;
		*(ptr - 2) = L;
		*(ptr - 1) = R;
	} while (ptr < &data.ctx.S[3][0xFF]);

	do {
		int done;

		for (i = 0; i < BF_N + 2; i += 2) {
			data.ctx.P[i] ^= data.expanded_key[i];
			data.ctx.P[i + 1] ^= data.expanded_key[i + 1];
		}

		done = 0;
		do {
			BF_body();
			if (done)
				break;
			done = 1;

			tmp1 = data.binary.salt[0];
			tmp2 = data.binary.salt[1];
			tmp3 = data.binary.salt[2];
			tmp4 = data.binary.salt[3];
			for (i = 0; i < BF_N; i += 4) {
				data.ctx.P[i] ^= tmp1;
				data.ctx.P[i + 1] ^= tmp2;
				data.ctx.P[i + 2] ^= tmp3;
				data.ctx.P[i + 3] ^= tmp4;
			}
			data.ctx.P[16] ^= tmp1;
			data.ctx.P[17] ^= tmp2;
		} while (1);
	} while (--count);

	for (i = 0; i < 6; i += 2) {
		L = BF_magic_w[i];
		R = BF_magic_w[i + 1];

		count = 64;
		do {
			BF_ENCRYPT;
		} while (--count);

		data.binary.output[i] = L;
		data.binary.output[i + 1] = R;
	}

	memcpy(output, setting, 7 + 22 - 1);
	output[7 + 22 - 1] = BF_itoa64[(int)
		BF_atoi64[(int)setting[7 + 22 - 1] - 0x20] & 0x30];

/* This has to be bug-compatible with the original implementation, so
 * only encode 23 of the 24 bytes. :-) */
	BF_swap(data.binary.output, 6);
	BF_encode(&output[7 + 22], data.binary.output, 23);
	output[7 + 22 + 31] = '\0';

	return output;
}

int _crypt_output_magic(const char *setting, char *output, int size)
{
	if (size < 3)
		return -1;

	output[0] = '*';
	output[1] = '0';
	output[2] = '\0';

	if (setting[0] == '*' && setting[1] == '0')
		output[1] = '1';

	return 0;
}

/*
 * Please preserve the runtime self-test.  It serves two purposes at once:
 *
 * 1. We really can't afford the risk of producing incompatible hashes e.g.
 * when there's something like gcc bug 26587 again, whereas an application or
 * library integrating this code might not also integrate our external tests or
 * it might not run them after every build.  Even if it does, the miscompile
 * might only occur on the production build, but not on a testing build (such
 * as because of different optimization settings).  It is painful to recover
 * from incorrectly-computed hashes - merely fixing whatever broke is not
 * enough.  Thus, a proactive measure like this self-test is needed.
 *
 * 2. We don't want to leave sensitive data from our actual password hash
 * computation on the stack or in registers.  Previous revisions of the code
 * would do explicit cleanups, but simply running the self-test after hash
 * computation is more reliable.
 *
 * The performance cost of this quick self-test is around 0.6% at the "$2a$08"
 * setting.
 */
char *_crypt_blowfish_rn(const char *key, const char *setting,
	char *output, int size)
{
	const char *test_key = "8b \xd0\xc1\xd2\xcf\xcc\xd8";
	const char *test_setting = "$2a$00$abcdefghijklmnopqrstuu";
	static const char * const test_hashes[2] =
		{"i1D709vfamulimlGcq0qq3UvuUasvEa\0\x55", /* 'a', 'b', 'y' */
		"VUrPmXD6q/nVSSp7pNDhCR9071IfIRe\0\x55"}; /* 'x' */
	const char *test_hash = test_hashes[0];
	char *retval;
	const char *p;
	int save_errno, ok;
	struct {
		char s[7 + 22 + 1];
		char o[7 + 22 + 31 + 1 + 1 + 1];
	} buf;

/* Hash the supplied password */
	_crypt_output_magic(setting, output, size);
	retval = BF_crypt(key, setting, output, size, 16);
	save_errno = errno;

/*
 * Do a quick self-test.  It is important that we make both calls to BF_crypt()
 * from the same scope such that they likely use the same stack locations,
 * which makes the second call overwrite the first call's sensitive data on the
 * stack and makes it more likely that any alignment related issues would be
 * detected by the self-test.
 */
	memcpy(buf.s, test_setting, sizeof(buf.s));
	if (retval) {
		unsigned int flags = flags_by_subtype[
		    (unsigned int)(unsigned char)setting[2] - 'a'];
		test_hash = test_hashes[flags & 1];
		buf.s[2] = setting[2];
	}
	memset(buf.o, 0x55, sizeof(buf.o));
	buf.o[sizeof(buf.o) - 1] = 0;
	p = BF_crypt(test_key, buf.s, buf.o, sizeof(buf.o) - (1 + 1), 1);

	ok = (p == buf.o &&
	    !memcmp(p, buf.s, 7 + 22) &&
	    !memcmp(p + (7 + 22), test_hash, 31 + 1 + 1 + 1));

	{
		const char *k = "\xff\xa3" "34" "\xff\xff\xff\xa3" "345";
		BF_key ae, ai, ye, yi;
		BF_set_key(k, ae, ai, 2); /* $2a$ */
		BF_set_key(k, ye, yi, 4); /* $2y$ */
		ai[0] ^= 0x10000; /* undo the safety (for comparison) */
		ok = ok && ai[0] == 0xdb9c59bc && ye[17] == 0x33343500 &&
		    !memcmp(ae, ye, sizeof(ae)) &&
		    !memcmp(ai, yi, sizeof(ai));
	}

	__set_errno(save_errno);
	if (ok)
		return retval;

/* Should not happen */
	_crypt_output_magic(setting, output, size);
	__set_errno(EINVAL); /* pretend we don't support this hash type */
	return NULL;
}

char *_crypt_gensalt_blowfish_rn(const char *prefix, unsigned long count,
	const char *input, int size, char *output, int output_size)
{
	if (size < 16 || output_size < 7 + 22 + 1 ||
	    (count && (count < 4 || count > 31)) ||
	    prefix[0] != '$' || prefix[1] != '2' ||
	    (prefix[2] != 'a' && prefix[2] != 'b' && prefix[2] != 'y')) {
		if (output_size > 0) output[0] = '\0';
		__set_errno((output_size < 7 + 22 + 1) ? ERANGE : EINVAL);
		return NULL;
	}

	if (!count) count = 5;

	output[0] = '$';
	output[1] = '2';
	output[2] = prefix[2];
	output[3] = '$';
	output[4] = '0' + count / 10;
	output[5] = '0' + count % 10;
	output[6] = '$';

	BF_encode(&output[7], (const BF_word *)input, 16);
	output[7 + 22] = '\0';

	return output;
}

////////////////////////////////////////////////////////////////////////////////////////
// 3p/wl.h
////////////////////////////////////////////////////////////////////////////////////////

#include <stdint.h>
#include <stdbool.h>

typedef struct WL_Runtime  WL_Runtime;
typedef struct WL_Compiler WL_Compiler;

typedef struct {
    char *ptr;
    int   len;
} WL_String;

typedef struct {
    char *ptr;
    int   len;
    int   cur;
} WL_Arena;

typedef struct {
    char *ptr;
    int   len;
} WL_Program;

typedef enum {
    WL_ADD_ERROR,
    WL_ADD_AGAIN,
    WL_ADD_LINK,
} WL_AddResultType;

typedef struct {
    WL_AddResultType type;
    WL_String        path;
} WL_AddResult;

typedef enum {
    WL_EVAL_NONE,
    WL_EVAL_DONE,
    WL_EVAL_ERROR,
    WL_EVAL_OUTPUT,
    WL_EVAL_SYSVAR,
    WL_EVAL_SYSCALL,
} WL_EvalResultType;

typedef struct {
    WL_EvalResultType type;
    WL_String str;
} WL_EvalResult;

WL_Compiler*  wl_compiler_init  (WL_Arena *arena);
WL_AddResult  wl_compiler_add   (WL_Compiler *compiler, WL_String content);
int           wl_compiler_link  (WL_Compiler *compiler, WL_Program *program);
WL_String     wl_compiler_error (WL_Compiler *compiler);
int           wl_dump_ast       (WL_Compiler *compiler, char *dst, int cap);
void          wl_dump_program   (WL_Program program);

WL_Runtime*   wl_runtime_init   (WL_Arena *arena, WL_Program program);
WL_EvalResult wl_runtime_eval   (WL_Runtime *rt);
WL_String     wl_runtime_error  (WL_Runtime *rt);
void          wl_runtime_dump   (WL_Runtime *rt);

bool wl_streq      (WL_String a, char *b, int blen);
int  wl_arg_count  (WL_Runtime *rt);
bool wl_arg_none   (WL_Runtime *rt, int idx);
bool wl_arg_bool   (WL_Runtime *rt, int idx, bool *x);
bool wl_arg_s64    (WL_Runtime *rt, int idx, int64_t *x);
bool wl_arg_f64    (WL_Runtime *rt, int idx, double *x);
bool wl_arg_str    (WL_Runtime *rt, int idx, WL_String *x);
bool wl_arg_array  (WL_Runtime *rt, int idx);
bool wl_arg_map    (WL_Runtime *rt, int idx);
bool wl_peek_none  (WL_Runtime *rt, int off);
bool wl_peek_bool  (WL_Runtime *rt, int off, bool *x);
bool wl_peek_s64   (WL_Runtime *rt, int off, int64_t *x);
bool wl_peek_f64   (WL_Runtime *rt, int off, double *x);
bool wl_peek_str   (WL_Runtime *rt, int off, WL_String *x);
bool wl_pop_any    (WL_Runtime *rt);
bool wl_pop_none   (WL_Runtime *rt);
bool wl_pop_bool   (WL_Runtime *rt, bool *x);
bool wl_pop_s64    (WL_Runtime *rt, int64_t *x);
bool wl_pop_f64    (WL_Runtime *rt, double *x);
bool wl_pop_str    (WL_Runtime *rt, WL_String *x);
void wl_push_none  (WL_Runtime *rt);
void wl_push_true  (WL_Runtime *rt);
void wl_push_false (WL_Runtime *rt);
void wl_push_s64   (WL_Runtime *rt, int64_t x);
void wl_push_f64   (WL_Runtime *rt, double x);
void wl_push_str   (WL_Runtime *rt, WL_String x);
void wl_push_array (WL_Runtime *rt, int cap);
void wl_push_map   (WL_Runtime *rt, int cap);
void wl_push_arg   (WL_Runtime *rt, int idx);
void wl_insert     (WL_Runtime *rt);
void wl_append     (WL_Runtime *rt);

////////////////////////////////////////////////////////////////////////////////////////
// 3p/wl.c
////////////////////////////////////////////////////////////////////////////////////////

#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>

#ifndef WL_NOINCLUDE
#include "wl.h"
#endif // WL_NOINCLUDE

/////////////////////////////////////////////////////////////////////////
// BASIC
/////////////////////////////////////////////////////////////////////////

typedef struct {
    char *ptr;
    int   len;
} String;

typedef struct {
    char *buf;
    int   cap;
    bool  yes;
} Error;

#define S(X) (String) { (X), SIZEOF(X)-1 }

#ifdef _WIN32
#define LLD "lld"
#define LLU "llu"
#else
#define LLD "ld"
#define LLU "lu"
#endif

#define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
#define MAX(X, Y) ((X) > (Y) ? (X) : (Y))
#define SIZEOF(X) (int) sizeof(X)
#define ALIGNOF(X) (int) _Alignof(X)
#define COUNT(X) (int) (sizeof(X)/sizeof((X)[0]))

#ifndef NDEBUG
#define UNREACHABLE __builtin_trap()
#define ASSERT(X) if (!(X)) __builtin_trap();
#else
#define UNREACHABLE {}
#define ASSERT(X) {}
#endif

static bool is_space(char c)
{
    return c == ' ' || c == '\t' || c == '\r' || c == '\n';
}

static bool is_digit(char c)
{
    return c >= '0' && c <= '9';
}

static bool is_alpha(char c)
{
    return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
}

static bool is_printable(char c)
{
    return c >= ' ' && c <= '~';
}

static bool is_hex_digit(char c)
{
    return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F');
}

#if 0
static char to_lower(char c)
{
    if (c >= 'A' && c <= 'Z')
        return c - 'A' + 'a';
    return c;
}
#endif

static int hex_digit_to_int(char c)
{
    if (c >= 'a' && c <= 'f')
        return c - 'a' + 10;

    if (c >= 'A' && c <= 'F')
        return c - 'A' + 10;

    return c - '0';
}

static bool streq(String a, String b)
{
    if (a.len != b.len)
        return false;
    for (int i = 0; i < a.len; i++)
        if (a.ptr[i] != b.ptr[i])
            return false;
    return true;
}

#if 0
static bool streqcase(String a, String b)
{
    if (a.len != b.len)
        return false;
    for (int i = 0; i < a.len; i++)
        if (to_lower(a.ptr[i]) != to_lower(b.ptr[i]))
            return false;
    return true;
}
#endif

#define REPORT(err, fmt, ...) report((err), __FILE__, __LINE__, fmt, ## __VA_ARGS__)
static void report(Error *err, char *file, int line, char *fmt, ...)
{
    if (err->yes) return;

    if (err->cap > 0) {

        va_list args;
        va_start(args, fmt);
        int len = vsnprintf(err->buf, err->cap, fmt, args);
        va_end(args);
        ASSERT(len >= 0);

        if (err->cap > len) {
            int ret = snprintf(err->buf + len, err->cap - len,
                " (reported at %s:%d)", file, line);
            ASSERT(ret >= 0);
            len += ret;
        }

        if (len > err->cap)
            len = err->cap-1;
        err->buf[len] = '\0';
    }

    err->yes = true;
}

/////////////////////////////////////////////////////////////////////////
// ARENA
/////////////////////////////////////////////////////////////////////////

static void *alloc(WL_Arena *a, int len, int align)
{
    int pad = -(intptr_t) (a->ptr + a->cur) & (align-1);
    if (a->len - a->cur < len + pad)
        return NULL;
    void *ret = a->ptr + a->cur + pad;
    a->cur += pad + len;
    return ret;
}

static bool grow_alloc(WL_Arena *a, char *p, int new_len)
{
    int new_cur = (p - a->ptr) + new_len;
    if (new_cur > a->len)
        return false;
    a->cur = new_cur;
    return true;
}

#if 0
static String copystr(String s, WL_Arena *a)
{
    char *p = alloc(a, s.len, 1);
    if (p == NULL)
        return (String) { NULL, 0 };
    memcpy(p, s.ptr, s.len);
    return (String) { p, s.len };
}
#endif

/////////////////////////////////////////////////////////////////////////
// WRITER
/////////////////////////////////////////////////////////////////////////

typedef struct {
    char *dst;
    int   cap;
    int   len;
} Writer;

static void write_raw_mem(Writer *w, void *ptr, int len)
{
    if (w->cap > w->len) {
        int cpy = MIN(w->cap - w->len, len);
        if (ptr && w->dst)
            memcpy(w->dst + w->len, ptr, cpy);
    }
    w->len += len;
}

static void write_raw_u8 (Writer *w, uint8_t  x) { write_raw_mem(w, &x, SIZEOF(x)); }
//static void write_raw_u16(Writer *w, uint16_t x) { write_raw_mem(w, &x, SIZEOF(x)); }
static void write_raw_u32(Writer *w, uint32_t x) { write_raw_mem(w, &x, SIZEOF(x)); }
//static void write_raw_u64(Writer *w, uint64_t x) { write_raw_mem(w, &x, SIZEOF(x)); }
//static void write_raw_s8 (Writer *w, int8_t   x) { write_raw_mem(w, &x, SIZEOF(x)); }
//static void write_raw_s16(Writer *w, int16_t  x) { write_raw_mem(w, &x, SIZEOF(x)); }
//static void write_raw_s32(Writer *w, int32_t  x) { write_raw_mem(w, &x, SIZEOF(x)); }
static void write_raw_s64(Writer *w, int64_t  x) { write_raw_mem(w, &x, SIZEOF(x)); }
//static void write_raw_f32(Writer *w, float    x) { write_raw_mem(w, &x, SIZEOF(x)); }
static void write_raw_f64(Writer *w, double   x) { write_raw_mem(w, &x, SIZEOF(x)); }

static void write_text(Writer *w, String str)
{
    write_raw_mem(w, str.ptr, str.len);
}

static void write_text_s64(Writer *w, int64_t n)
{
    int len;
    if (w->len < w->cap)
        len = snprintf(w->dst + w->len, w->cap - w->len, "%" LLD, n);
    else
        len = snprintf(NULL, 0, "%" LLD, n);
    ASSERT(len >= 0);
    w->len += len;
}

static void write_text_f64(Writer *w, double n)
{
    int len;
    if (w->len < w->cap)
        len = snprintf(w->dst + w->len, w->cap - w->len, "%2.2f", n);
    else
        len = snprintf(NULL, 0, "%2.2f", n);
    ASSERT(len >= 0);
    w->len += len;
}

static void patch_mem(Writer *w, void *src, int off, int len)
{
    ASSERT(off + len <= w->len);
    if (off < w->cap) {
        int cpy = MIN(w->cap - off, len);
        memcpy(w->dst + off, src, cpy);
    }
}

/////////////////////////////////////////////////////////////////////////
// PARSER
/////////////////////////////////////////////////////////////////////////

typedef struct {
    char *src;
    int   len;
    int   cur;
} Scanner;

typedef enum {
    TOKEN_END,
    TOKEN_ERROR,
    TOKEN_IDENT,
    TOKEN_KWORD_IF,
    TOKEN_KWORD_ELSE,
    TOKEN_KWORD_WHILE,
    TOKEN_KWORD_FOR,
    TOKEN_KWORD_IN,
    TOKEN_KWORD_PROCEDURE,
    TOKEN_KWORD_LET,
    TOKEN_KWORD_NONE,
    TOKEN_KWORD_TRUE,
    TOKEN_KWORD_FALSE,
    TOKEN_KWORD_INCLUDE,
    TOKEN_KWORD_LEN,
    TOKEN_KWORD_ESCAPE,
    TOKEN_VALUE_FLOAT,
    TOKEN_VALUE_INT,
    TOKEN_VALUE_STR,
    TOKEN_OPER_EQL,
    TOKEN_OPER_NQL,
    TOKEN_OPER_LSS,
    TOKEN_OPER_GRT,
    TOKEN_OPER_ADD,
    TOKEN_OPER_SUB,
    TOKEN_OPER_MUL,
    TOKEN_OPER_DIV,
    TOKEN_OPER_MOD,
    TOKEN_OPER_ASS,
    TOKEN_OPER_SHOVEL,
    TOKEN_PAREN_OPEN,
    TOKEN_PAREN_CLOSE,
    TOKEN_BRACKET_OPEN,
    TOKEN_BRACKET_CLOSE,
    TOKEN_CURLY_OPEN,
    TOKEN_CURLY_CLOSE,
    TOKEN_DOT,
    TOKEN_COMMA,
    TOKEN_COLON,
    TOKEN_DOLLAR,
    TOKEN_NEWLINE,
} TokType;

typedef struct {
    TokType type;
    int64_t ival;
    double  fval;
    String  sval;
} Token;

typedef enum {
    NODE_PROCEDURE_DECL,
    NODE_PROCEDURE_ARG,
    NODE_PROCEDURE_CALL,
    NODE_VAR_DECL,
    NODE_COMPOUND,
    NODE_GLOBAL,
    NODE_IFELSE,
    NODE_FOR,
    NODE_WHILE,
    NODE_INCLUDE,
    NODE_SELECT,
    NODE_NESTED,
    NODE_OPER_ESCAPE,
    NODE_OPER_LEN,
    NODE_OPER_POS,
    NODE_OPER_NEG,
    NODE_OPER_ASS,
    NODE_OPER_EQL,
    NODE_OPER_NQL,
    NODE_OPER_LSS,
    NODE_OPER_GRT,
    NODE_OPER_ADD,
    NODE_OPER_SUB,
    NODE_OPER_MUL,
    NODE_OPER_DIV,
    NODE_OPER_MOD,
    NODE_OPER_SHOVEL,
    NODE_VALUE_INT,
    NODE_VALUE_FLOAT,
    NODE_VALUE_STR,
    NODE_VALUE_NONE,
    NODE_VALUE_TRUE,
    NODE_VALUE_FALSE,
    NODE_VALUE_VAR,
    NODE_VALUE_SYSVAR,
    NODE_VALUE_HTML,
    NODE_VALUE_ARRAY,
    NODE_VALUE_MAP,
} NodeType;

typedef struct Node Node;
struct Node {
    NodeType type;
    Node *next;

    Node *key;

    Node *left;
    Node *right;

    Node *child;

    uint64_t ival;
    double   fval;
    String   sval;

    String html_tag;
    Node*  html_attr;
    Node*  html_child;
    bool   html_body;

    Node *if_cond;
    Node *if_branch1;
    Node *if_branch2;

    Node *while_cond;
    Node *while_body;

    String for_var1;
    String for_var2;
    Node*  for_set;

    String proc_name;
    Node*  proc_args;
    Node*  proc_body;

    String var_name;
    Node*  var_value;

    String include_path;
    Node*  include_next;
    Node*  include_root;
};

typedef struct {
    Node *node;
    Node *includes;
    int   errlen;
} ParseResult;

typedef struct {
    Scanner   s;
    WL_Arena*    arena;
    char*     errbuf;
    int       errmax;
    int       errlen;
    Node*     include_head;
    Node**    include_tail;
} Parser;

static bool consume_str(Scanner *s, String x)
{
    if (x.len == 0)
        return false;

    if (x.len > s->len - s->cur)
        return false;

    for (int i = 0; i < x.len; i++)
        if (s->src[s->cur+i] != x.ptr[i])
            return false;

    s->cur += x.len;
    return true;
}

#if 0
static void write_token(Writer *w, Token token)
{
    switch (token.type) {

        default                 : write_text(w, S("???"));       break;
        case TOKEN_END          : write_text(w, S("<EOF>"));     break;
        case TOKEN_ERROR        : write_text(w, S("<ERROR>"));   break;
        case TOKEN_IDENT        : write_text(w, token.sval);     break;
        case TOKEN_KWORD_IF     : write_text(w, S("if"));        break;
        case TOKEN_KWORD_ELSE   : write_text(w, S("else"));      break;
        case TOKEN_KWORD_WHILE  : write_text(w, S("while"));     break;
        case TOKEN_KWORD_FOR    : write_text(w, S("for"));       break;
        case TOKEN_KWORD_IN     : write_text(w, S("in"));        break;
        case TOKEN_KWORD_PROCEDURE: write_text(w, S("procedure")); break;
        case TOKEN_KWORD_LET    : write_text(w, S("let"));       break;
        case TOKEN_KWORD_NONE   : write_text(w, S("none"));      break;
        case TOKEN_KWORD_TRUE   : write_text(w, S("true"));      break;
        case TOKEN_KWORD_FALSE  : write_text(w, S("false"));     break;
        case TOKEN_KWORD_INCLUDE: write_text(w, S("include"));   break;
        case TOKEN_KWORD_LEN    : write_text(w, S("len"));       break;
        case TOKEN_KWORD_ESCAPE: write_text(w, S("escape")); break;
        case TOKEN_VALUE_FLOAT  : write_text_f64(w, token.fval); break;
        case TOKEN_VALUE_INT    : write_text_s64(w, token.ival); break;
        case TOKEN_OPER_ASS     : write_text(w, S("="));         break;
        case TOKEN_OPER_EQL     : write_text(w, S("=="));        break;
        case TOKEN_OPER_NQL     : write_text(w, S("!="));        break;
        case TOKEN_OPER_LSS     : write_text(w, S("<"));         break;
        case TOKEN_OPER_GRT     : write_text(w, S(">"));         break;
        case TOKEN_OPER_ADD     : write_text(w, S("+"));         break;
        case TOKEN_OPER_SUB     : write_text(w, S("-"));         break;
        case TOKEN_OPER_MUL     : write_text(w, S("*"));         break;
        case TOKEN_OPER_DIV     : write_text(w, S("/"));         break;
        case TOKEN_OPER_MOD     : write_text(w, S("%"));         break;
        case TOKEN_OPER_SHOVEL  : write_text(w, S("<<"));        break;
        case TOKEN_PAREN_OPEN   : write_text(w, S("("));         break;
        case TOKEN_PAREN_CLOSE  : write_text(w, S(")"));         break;
        case TOKEN_BRACKET_OPEN : write_text(w, S("["));         break;
        case TOKEN_BRACKET_CLOSE: write_text(w, S("]"));         break;
        case TOKEN_CURLY_OPEN   : write_text(w, S("{"));         break;
        case TOKEN_CURLY_CLOSE  : write_text(w, S("}"));         break;
        case TOKEN_DOT          : write_text(w, S("."));         break;
        case TOKEN_COMMA        : write_text(w, S(","));         break;
        case TOKEN_COLON        : write_text(w, S(":"));         break;
        case TOKEN_DOLLAR       : write_text(w, S("$"));         break;
        case TOKEN_NEWLINE      : write_text(w, S("\\n"));       break;

        case TOKEN_VALUE_STR:
        write_text(w, S("\""));
        write_text(w, token.sval); // TODO: Escape
        write_text(w, S("\""));
        break;

    }
}
#endif

static void parser_report(Parser *p, char *fmt, ...)
{
    if (p->errmax == 0 || p->errlen > 0)
        return;

    int line = 1;
    int cur = 0;
    while (cur < p->s.cur) {
        if (p->s.src[cur] == '\n')
            line++;
        cur++;
    }

    int len = snprintf(p->errbuf, p->errmax, "Error (line %d): ", line);
    ASSERT(len >= 0);

    va_list args;
    va_start(args, fmt);
    int ret = vsnprintf(p->errbuf + len, p->errmax - len, fmt, args);
    va_end(args);
    ASSERT(ret >= 0);
    len += ret;

    p->errlen = len;
}

static Node *alloc_node(Parser *p)
{
    Node *n = alloc(p->arena, sizeof(Node), _Alignof(Node));
    if (n == NULL) {
        parser_report(p, "Out of memory");
        return NULL;
    }

    return n;
}

static Token next_token(Parser *p)
{
    for (;;) {
        while (p->s.cur < p->s.len && is_space(p->s.src[p->s.cur]))
            p->s.cur++;

        if (!consume_str(&p->s, S("<!--")))
            break;

        while (p->s.cur < p->s.len) {
            if (consume_str(&p->s, S("-->")))
                break;
            p->s.cur++;
        }
    }

    if (p->s.cur == p->s.len)
        return (Token) { .type=TOKEN_END };
    char c = p->s.src[p->s.cur];

    if (is_alpha(c) || c == '_') {

        int start = p->s.cur;
        do
            p->s.cur++;
        while (p->s.cur < p->s.len && (is_alpha(p->s.src[p->s.cur]) || is_digit(p->s.src[p->s.cur]) || p->s.src[p->s.cur] == '_'));

        String kword = {
            p->s.src + start,
            p->s.cur - start
        };

        if (streq(kword, S("if")))      return (Token) { .type=TOKEN_KWORD_IF      };
        if (streq(kword, S("else")))    return (Token) { .type=TOKEN_KWORD_ELSE    };
        if (streq(kword, S("while")))   return (Token) { .type=TOKEN_KWORD_WHILE   };
        if (streq(kword, S("for")))     return (Token) { .type=TOKEN_KWORD_FOR     };
        if (streq(kword, S("in")))      return (Token) { .type=TOKEN_KWORD_IN      };
        if (streq(kword, S("procedure"))) return (Token) { .type=TOKEN_KWORD_PROCEDURE };
        if (streq(kword, S("let")))     return (Token) { .type=TOKEN_KWORD_LET     };
        if (streq(kword, S("none")))    return (Token) { .type=TOKEN_KWORD_NONE    };
        if (streq(kword, S("true")))    return (Token) { .type=TOKEN_KWORD_TRUE    };
        if (streq(kword, S("false")))   return (Token) { .type=TOKEN_KWORD_FALSE   };
        if (streq(kword, S("include"))) return (Token) { .type=TOKEN_KWORD_INCLUDE };
        if (streq(kword, S("len")))     return (Token) { .type=TOKEN_KWORD_LEN     };
        if (streq(kword, S("escape"))) return (Token) { .type=TOKEN_KWORD_ESCAPE };

        return (Token) { .type=TOKEN_IDENT, .sval=kword };
    }

    if (is_digit(c)) {

        int peek = p->s.cur;
        do
            peek++;
        while (peek < p->s.len && is_digit(p->s.src[peek]));

        if (p->s.len - peek > 1 && p->s.src[peek] == '.' && is_digit(p->s.src[peek+1])) {

            double buf = 0;
            do {
                int d = p->s.src[p->s.cur++] - '0';
                buf = buf * 10 + d;
            } while (p->s.cur < p->s.len && p->s.src[p->s.cur] != '.');

            p->s.cur++;

            double q = 1;
            do {
                int d = p->s.src[p->s.cur++] - '0';
                q /= 10;
                buf += q * d;
            } while (p->s.cur < p->s.len && is_digit(p->s.src[p->s.cur]));

            return (Token) { .type=TOKEN_VALUE_FLOAT, .fval=buf };

        } else {

            uint64_t buf = 0;
            do {
                int d = p->s.src[p->s.cur++] - '0';
                if (buf > (UINT64_MAX - d) / 10) {
                    parser_report(p, "Integer literal overflow");
                    return (Token) { .type=TOKEN_ERROR };
                }
                buf = buf * 10 + d;
            } while (p->s.cur < p->s.len && is_digit(p->s.src[p->s.cur]));

            return (Token) { .type=TOKEN_VALUE_INT, .ival=buf };
        }
    }

    if (c == '\'' || c == '"') {

        char f = c;
        p->s.cur++;

        char *buf = NULL;
        int   len = 0;

        for (;;) {

            int substr_off = p->s.cur;

            while (p->s.cur < p->s.len && is_printable(p->s.src[p->s.cur]) && p->s.src[p->s.cur] != f && p->s.src[p->s.cur] != '\\')
                p->s.cur++;

            int substr_len = p->s.cur - substr_off;

            if (buf == NULL)
                buf = alloc(p->arena, substr_len+1, 1);
            else
                if (!grow_alloc(p->arena, buf, len + substr_len+1))
                    buf = NULL;

            if (buf == NULL) {
                parser_report(p, "Out of memory");
                return (Token) { .type=TOKEN_ERROR };
            }

            if (substr_len > 0) {
                memcpy(
                    buf + len,
                    p->s.src + substr_off,
                    p->s.cur - substr_off
                );
                len += substr_len;
            }

            if (p->s.cur == p->s.len) {
                parser_report(p, "String literal wasn't closed");
                return (Token) { .type=TOKEN_ERROR };
            }

            if (!is_printable(p->s.src[p->s.cur])) {
                parser_report(p, "Invalid byte in string literal");
                return (Token) { .type=TOKEN_ERROR };
            }

            if (p->s.src[p->s.cur] == f)
                break;

            p->s.cur++;
            if (p->s.cur == p->s.len) {
                parser_report(p, "Missing special character after escape character \\");
                return (Token) { .type=TOKEN_ERROR };
            }

            switch (p->s.src[p->s.cur]) {
                case 'n':  buf[len++] = '\n'; break;
                case 't':  buf[len++] = '\t'; break;
                case 'r':  buf[len++] = '\r'; break;
                case '"':  buf[len++] = '"';  break;
                case '\'': buf[len++] = '\''; break;
                case '\\': buf[len++] = '\\'; break;

                case 'x':
                {
                    if (p->s.len - p->s.cur < 3
                        || !is_hex_digit(p->s.src[p->s.cur+1])
                        || !is_hex_digit(p->s.src[p->s.cur+2]))
                        return (Token) { .type=TOKEN_ERROR };
                    buf[len++]
                        = (hex_digit_to_int(p->s.src[p->s.cur+1]) << 4)
                        | (hex_digit_to_int(p->s.src[p->s.cur+2]) << 0);
                    p->s.cur += 2;
                }
                break;

                default:
                parser_report(p, "Invalid character after escape character \\");
                return (Token) { .type=TOKEN_ERROR };
            }

            p->s.cur++;
        }

        p->s.cur++;
        return (Token) { .type=TOKEN_VALUE_STR, .sval=(String) { .ptr=buf, .len=len } };
    }

    if (consume_str(&p->s, S("<<"))) return (Token) { .type=TOKEN_OPER_SHOVEL };
    if (consume_str(&p->s, S("=="))) return (Token) { .type=TOKEN_OPER_EQL };
    if (consume_str(&p->s, S("!="))) return (Token) { .type=TOKEN_OPER_NQL };
    if (consume_str(&p->s, S("<")))  return (Token) { .type=TOKEN_OPER_LSS };
    if (consume_str(&p->s, S(">")))  return (Token) { .type=TOKEN_OPER_GRT };
    if (consume_str(&p->s, S("+")))  return (Token) { .type=TOKEN_OPER_ADD };
    if (consume_str(&p->s, S("-")))  return (Token) { .type=TOKEN_OPER_SUB };
    if (consume_str(&p->s, S("*")))  return (Token) { .type=TOKEN_OPER_MUL };
    if (consume_str(&p->s, S("/")))  return (Token) { .type=TOKEN_OPER_DIV };
    if (consume_str(&p->s, S("%")))  return (Token) { .type=TOKEN_OPER_MOD };
    if (consume_str(&p->s, S("=")))  return (Token) { .type=TOKEN_OPER_ASS };

    if (consume_str(&p->s, S("(")))  return (Token) { .type=TOKEN_PAREN_OPEN };
    if (consume_str(&p->s, S(")")))  return (Token) { .type=TOKEN_PAREN_CLOSE };
    if (consume_str(&p->s, S("[")))  return (Token) { .type=TOKEN_BRACKET_OPEN };
    if (consume_str(&p->s, S("]")))  return (Token) { .type=TOKEN_BRACKET_CLOSE };
    if (consume_str(&p->s, S("{")))  return (Token) { .type=TOKEN_CURLY_OPEN };
    if (consume_str(&p->s, S("}")))  return (Token) { .type=TOKEN_CURLY_CLOSE };
    if (consume_str(&p->s, S(".")))  return (Token) { .type=TOKEN_DOT };
    if (consume_str(&p->s, S(",")))  return (Token) { .type=TOKEN_COMMA };
    if (consume_str(&p->s, S(":")))  return (Token) { .type=TOKEN_COLON };
    if (consume_str(&p->s, S("$")))  return (Token) { .type=TOKEN_DOLLAR };

    parser_report(p, "Invalid character '%c'", c);
    return (Token) { .type=TOKEN_ERROR };
}

static Token next_token_or_newline(Parser *p)
{
    int peek = p->s.cur;
    while (peek < p->s.len && is_space(p->s.src[peek]) && p->s.src[peek] != '\n')
        peek++;

    if (peek < p->s.len && p->s.src[peek] == '\n') {
        p->s.cur = peek+1;
        return (Token) { .type=TOKEN_NEWLINE };
    }

    return next_token(p);
}

enum {
    IGNORE_GRT = 1 << 0,
    IGNORE_LSS = 1 << 1,
    IGNORE_DIV = 1 << 2,
};

static Node *parse_stmt(Parser *p, int opflags);
static Node *parse_expr(Parser *p, int opflags);

static Node *parse_html(Parser *p)
{
    // NOTE: The first < was already consumed

    Token t = next_token(p);
    if (t.type != TOKEN_IDENT) {
        parser_report(p, "HTML tag doesn't start with a name");
        return NULL;
    }
    String tagname = t.sval;

    Node *attr_head;
    Node **attr_tail = &attr_head;

    bool no_body = false;
    Scanner *s = &p->s;
    for (;;) {

        int off = s->cur;

        bool quotes = false;
        while (s->cur < s->len && s->src[s->cur] != '\\' && (quotes || (s->src[s->cur] != '/' && s->src[s->cur] != '>'))) {
            if (s->src[s->cur] == '"')
                quotes = !quotes;
            s->cur++;
        }

        if (s->cur > off) {

            Node *child = alloc_node(p);
            if (child == NULL)
                return NULL;

            child->type = NODE_VALUE_STR;
            child->sval = (String) { p->s.src + off, p->s.cur - off };

            *attr_tail = child;
            attr_tail = &child->next;
        }

        if (s->cur == s->len) {
            ASSERT(0); // TODO
        }
        s->cur++;

        if (s->src[s->cur-1] == '>')
            break;

        if (s->src[s->cur-1] == '/') {
            while (s->cur < s->len && is_space(s->src[s->cur]))
                s->cur++;
            if (s->cur == s->len || s->src[s->cur] != '>') {
                ASSERT(0); // TODO
            }
            s->cur++;
            no_body = true;
            break;
        }

        ASSERT(s->src[s->cur-1] == '\\');

        Node *child = parse_stmt(p, IGNORE_GRT | IGNORE_DIV);
        if (child == NULL)
            return NULL;

        *attr_tail = child;
        attr_tail = &child->next;
    }

    *attr_tail = NULL;

    Node *child_head;
    Node **child_tail = &child_head;

    if (no_body == false)
        for (;;) {

            int off = s->cur;

            while (s->cur < s->len && s->src[s->cur] != '\\' && s->src[s->cur] != '<')
                s->cur++;

            if (s->cur > off) {

                Node *child = alloc_node(p);
                if (child == NULL)
                    return NULL;

                child->type = NODE_VALUE_STR;
                child->sval = (String) { p->s.src + off, p->s.cur - off };

                *child_tail = child;
                child_tail = &child->next;
            }

            if (s->cur == s->len) {
                ASSERT(0); // TODO
            }
            s->cur++;

            if (s->src[s->cur-1] == '<') {

                Scanner saved = *s;
                t = next_token(p);
                if (t.type == TOKEN_OPER_DIV) {

                    t = next_token(p);
                    if (t.type != TOKEN_IDENT) {
                        ASSERT(0); // TODO
                    }
                    String closing_tagname = t.sval;

                    if (!streq(closing_tagname, tagname)) {
                        ASSERT(0); // TODO
                    }

                    t = next_token(p);
                    if (t.type != TOKEN_OPER_GRT) {
                        ASSERT(0);
                    }

                    break;
                }

                *s = saved;

                Node *child = parse_html(p);
                if (child == NULL)
                    return NULL;

                *child_tail = child;
                child_tail = &child->next;

            } else {

                Node *child = parse_stmt(p, IGNORE_LSS);
                if (child == NULL)
                    return NULL;

                *child_tail = child;
                child_tail = &child->next;
            }
        }

    *child_tail = NULL;

    Node *parent = alloc_node(p);
    if (parent == NULL)
        return NULL;

    parent->type = NODE_VALUE_HTML;
    parent->html_tag   = tagname;
    parent->html_attr  = attr_head;
    parent->html_child = child_head;
    parent->html_body  = !no_body;

    return parent;
}

static Node *parse_array(Parser *p)
{
    // Left bracket already consumed

    Node *head;
    Node **tail = &head;

    Scanner saved = p->s;
    Token t = next_token(p);
    if (t.type != TOKEN_BRACKET_CLOSE) {

        p->s = saved;

        for (;;) {

            Node *child = parse_expr(p, 0);
            if (child == NULL)
                return NULL;

            *tail = child;
            tail = &child->next;

            saved = p->s;
            t = next_token(p);
            if (t.type == TOKEN_COMMA) {
                saved = p->s;
                t = next_token(p);
            }

            if (t.type == TOKEN_BRACKET_CLOSE)
                break;

            p->s = saved;
        }
    }

    *tail = NULL;

    Node *parent = alloc_node(p);
    if (parent == NULL)
        return NULL;

    parent->type = NODE_VALUE_ARRAY;
    parent->child  = head;

    return parent;
}

static Node *parse_map(Parser *p)
{
    // Left bracket already consumed

    Node *head;
    Node **tail = &head;

    Scanner saved = p->s;
    Token t = next_token(p);
    if (t.type != TOKEN_CURLY_CLOSE) {

        p->s = saved;

        for (;;) {

            Node *key;

            saved = p->s;
            t = next_token(p);
            if (t.type == TOKEN_IDENT) {
   
                key = alloc_node(p);
                if (key == NULL)
                    return NULL;

                key->type = NODE_VALUE_STR;
                key->sval = t.sval;

            } else {

                p->s = saved;
                key = parse_expr(p, 0);
                if (key == NULL)
                    return NULL;
            }

            t = next_token(p);
            if (t.type != TOKEN_COLON) {
                parser_report(p, "Missing ':' after key inside map literal");
                return NULL;
            }

            Node *child = parse_expr(p, 0);
            if (child == NULL)
                return NULL;
            child->key = key;

            *tail = child;
            tail = &child->next;

            saved = p->s;
            t = next_token(p);
            if (t.type == TOKEN_COMMA) {
                saved = p->s;
                t = next_token(p);
            }

            if (t.type == TOKEN_CURLY_CLOSE)
                break;

            p->s = saved;
        }
    }

    *tail = NULL;

    Node *parent = alloc_node(p);
    if (parent == NULL)
        return NULL;

    parent->type = NODE_VALUE_MAP;
    parent->child  = head;

    return parent;
}

static int precedence(Token t, int flags)
{
    switch (t.type) {

        case TOKEN_OPER_ASS:
        return 1;

        case TOKEN_OPER_SHOVEL:
        if (flags & IGNORE_LSS)
            return -1;
        return 1;

        case TOKEN_OPER_EQL:
        case TOKEN_OPER_NQL:
        return 2;

        case TOKEN_OPER_LSS:
        if (flags & IGNORE_LSS)
            return -1;
        return 2;

        case TOKEN_OPER_GRT:
        if (flags & IGNORE_GRT)
            return -1;
        return 2;

        case TOKEN_OPER_ADD:
        case TOKEN_OPER_SUB:
        return 3;

        case TOKEN_OPER_MUL:
        case TOKEN_OPER_MOD:
        return 4;

        case TOKEN_OPER_DIV:
        if (flags & IGNORE_DIV)
            return -1;
        return 4;

        default:
        break;
    }

    return -1;
}

static bool right_associative(Token t)
{
    return t.type == TOKEN_OPER_ASS;
}

static Node *parse_atom(Parser *p)
{
    Token t = next_token(p);

    Node *ret;
    switch (t.type) {
        case TOKEN_OPER_ADD:
        {
            Node *child = parse_atom(p);
            if (child == NULL)
                return NULL;

            Node *parent = alloc_node(p);
            if (parent == NULL)
                return NULL;

            parent->type = NODE_OPER_POS;
            parent->left = child;

            ret = parent;
        }
        break;

        case TOKEN_OPER_SUB:
        {
            Node *child = parse_atom(p);
            if (child == NULL)
                return NULL;

            Node *parent = alloc_node(p);
            if (parent == NULL)
                return NULL;

            parent->type = NODE_OPER_NEG;
            parent->left = child;

            ret = parent;
        }
        break;

        case TOKEN_KWORD_LEN:
        {
            Node *child = parse_atom(p);
            if (child == NULL)
                return NULL;

            Node *parent = alloc_node(p);
            if (parent == NULL)
                return NULL;

            parent->type = NODE_OPER_LEN;
            parent->left = child;

            ret = parent;
        }
        break;

        case TOKEN_KWORD_ESCAPE:
        {
            Node *child = parse_atom(p);
            if (child == NULL)
                return NULL;

            Node *parent = alloc_node(p);
            if (parent == NULL)
                return NULL;

            parent->type = NODE_OPER_ESCAPE;
            parent->left = child;

            ret = parent;
        }
        break;

        case TOKEN_IDENT:
        {
            Node *node = alloc_node(p);
            if (node == NULL)
                return NULL;

            node->type = NODE_VALUE_VAR;
            node->sval = t.sval;

            ret = node;
        }
        break;

        case TOKEN_VALUE_INT:
        {
            Node *node = alloc_node(p);
            if (node == NULL)
                return NULL;

            node->type = NODE_VALUE_INT;
            node->ival = t.ival;

            ret = node;
        }
        break;

        case TOKEN_VALUE_FLOAT:
        {
            Node *node = alloc_node(p);
            if (node == NULL)
                return NULL;

            node->type = NODE_VALUE_FLOAT;
            node->fval = t.fval;

            ret = node;
        }
        break;

        case TOKEN_VALUE_STR:
        {
            Node *node = alloc_node(p);
            if (node == NULL)
                return NULL;

            node->type = NODE_VALUE_STR;
            node->sval = t.sval;

            ret = node;
        }
        break;

        case TOKEN_KWORD_NONE:
        {
            Node *node = alloc_node(p);
            if (node == NULL)
                return NULL;

            node->type = NODE_VALUE_NONE;
            node->sval = t.sval;

            ret = node;
        }
        break;

        case TOKEN_KWORD_TRUE:
        {
            Node *node = alloc_node(p);
            if (node == NULL)
                return NULL;

            node->type = NODE_VALUE_TRUE;
            node->sval = t.sval;

            ret = node;
        }
        break;
        case TOKEN_KWORD_FALSE:
        {
            Node *node = alloc_node(p);
            if (node == NULL)
                return NULL;

            node->type = NODE_VALUE_FALSE;
            node->sval = t.sval;

            ret = node;
        }
        break;

        case TOKEN_OPER_LSS:
        {
            Node *node = parse_html(p);
            if (node == NULL)
                return NULL;

            ret = node;
        }
        break;

        case TOKEN_PAREN_OPEN:
        {
            Node *node = parse_expr(p, 0);
            if (node == NULL)
                return NULL;

            Token t = next_token(p);
            if (t.type != TOKEN_PAREN_CLOSE) {
                parser_report(p, "Missing ')' after expression");
                return NULL;
            }

            Node *parent = alloc_node(p);
            if (parent == NULL)
                return NULL;

            parent->type = NODE_NESTED;
            parent->left = node;

            ret = parent;
        }
        break;

        case TOKEN_BRACKET_OPEN:
        {
            Node *node = parse_array(p);
            if (node == NULL)
                return NULL;

            ret = node;
        }
        break;

        case TOKEN_CURLY_OPEN:
        {
            Node *node = parse_map(p);
            if (node == NULL)
                return NULL;

            ret = node;
        }
        break;

        case TOKEN_DOLLAR:
        {
            t = next_token(p);
            if (t.type != TOKEN_IDENT) {
                parser_report(p, "Missing identifier after '$'");
                return NULL;
            }

            Node *node = alloc_node(p);
            if (node == NULL)
                return NULL;

            node->type = NODE_VALUE_SYSVAR;
            node->sval = t.sval;

            ret = node;
        }
        break;

        default:
        {
            parser_report(p, "Invalid token inside expression");
        }
        return NULL;
    }

    for (;;) {
        Scanner saved = p->s;
        t = next_token(p);
        if (t.type == TOKEN_DOT) {

            t = next_token(p);
            if (t.type != TOKEN_IDENT) {
                parser_report(p, "Invalid token after '.' where an identifier was expected");
                return NULL;
            }

            Node *child = alloc_node(p);
            if (child == NULL)
                return NULL;

            child->type = NODE_VALUE_STR;
            child->sval = t.sval;

            Node *parent = alloc_node(p);
            if (parent == NULL)
                return NULL;

            parent->type = NODE_SELECT;
            parent->left = ret;
            parent->right = child;

            ret = parent;

        } else if (t.type == TOKEN_BRACKET_OPEN) {

            Node *child = parse_expr(p, 0);
            if (child == NULL)
                return NULL;

            t = next_token(p);
            if (t.type != TOKEN_BRACKET_CLOSE) {
                parser_report(p, "Missing token ']'");
                return NULL;
            }

            Node *parent = alloc_node(p);
            if (parent == NULL)
                return NULL;

            parent->type = NODE_SELECT;
            parent->left = ret;
            parent->right = child;

            ret = parent;

        } else if (t.type == TOKEN_PAREN_OPEN && (ret->type == NODE_VALUE_VAR || ret->type == NODE_VALUE_SYSVAR)) {

            Node *arg_head;
            Node **arg_tail = &arg_head;

            Scanner saved = p->s;
            t = next_token(p);
            if (t.type != TOKEN_PAREN_CLOSE) {

                p->s = saved;

                for (;;) {

                    Node *argval = parse_expr(p, 0);
                    if (argval == NULL)
                        return NULL;

                    *arg_tail = argval;
                    arg_tail = &argval->next;

                    t = next_token(p);
                    if (t.type == TOKEN_PAREN_CLOSE)
                        break;

                    if (t.type != TOKEN_COMMA) {
                        parser_report(p, "Expected ',' after argument in procedure call");
                        return NULL;
                    }
                }
            }

            *arg_tail = NULL;

            Node *parent = alloc_node(p);
            if (parent == NULL)
                return NULL;

            parent->type = NODE_PROCEDURE_CALL;
            parent->left = ret;
            parent->right = arg_head;

            ret = parent;

        } else {
            p->s = saved;
            break;
        }
    }

    return ret;
}

static Node *parse_expr_inner(Parser *p, Node *left, int min_prec, int flags)
{
    for (;;) {

        Scanner saved = p->s;
        Token t1 = next_token_or_newline(p);
        if (precedence(t1, flags) < min_prec) {
            p->s = saved;
           break;
        }

        Node *right = parse_atom(p);
        if (right == NULL)
            return NULL;

        for (;;) {

            saved = p->s;
            Token t2 = next_token_or_newline(p);
            int p1 = precedence(t1, flags);
            int p2 = precedence(t2, flags);
            p->s = saved;

            if (p2 < 0)
                break;

            if (p2 <= p1 && (p1 != p2 || !right_associative(t2)))
                break;

            right = parse_expr_inner(p, right, p1 + (p2 > p1), flags);
            if (right == NULL)
                return NULL;
        }

        Node *parent = alloc_node(p);
        if (parent == NULL)
            return NULL;

        parent->left = left;
        parent->right = right;

        switch (t1.type) {
            case TOKEN_OPER_ASS: parent->type = NODE_OPER_ASS; break;
            case TOKEN_OPER_EQL: parent->type = NODE_OPER_EQL; break;
            case TOKEN_OPER_NQL: parent->type = NODE_OPER_NQL; break;
            case TOKEN_OPER_LSS: parent->type = NODE_OPER_LSS; break;
            case TOKEN_OPER_GRT: parent->type = NODE_OPER_GRT; break;
            case TOKEN_OPER_ADD: parent->type = NODE_OPER_ADD; break;
            case TOKEN_OPER_SUB: parent->type = NODE_OPER_SUB; break;
            case TOKEN_OPER_MUL: parent->type = NODE_OPER_MUL; break;
            case TOKEN_OPER_DIV: parent->type = NODE_OPER_DIV; break;
            case TOKEN_OPER_MOD: parent->type = NODE_OPER_MOD; break;
            case TOKEN_OPER_SHOVEL: parent->type = NODE_OPER_SHOVEL; break;
            default:
            parser_report(p, "Operator not implemented");
            return NULL;
        }

        left = parent;
    }

    return left;
}

static Node *parse_expr(Parser *p, int flags)
{
    Node *left = parse_atom(p);
    if (left == NULL)
        return NULL;

    return parse_expr_inner(p, left, 0, flags);
}

static Node *parse_expr_stmt(Parser *p, int opflags)
{
    Node *e = parse_expr(p, opflags);
    if (e == NULL)
        return NULL;

    return e;
}

static Node *parse_ifelse_stmt(Parser *p, int opflags)
{
    Token t = next_token(p);
    if (t.type != TOKEN_KWORD_IF) {
        parser_report(p, "Missing 'if' keyword before if statement");
        return NULL;
    }

    Node *cond = parse_expr(p, 0);
    if (cond == NULL)
        return NULL;

    t = next_token(p);
    if (t.type != TOKEN_COLON) {
        parser_report(p, "Missing ':' after if condition");
        return NULL;
    }

    Node *if_stmt = parse_stmt(p, opflags);
    if (if_stmt == NULL)
        return NULL;

    Scanner saved = p->s;
    t = next_token(p);

    Node *else_stmt = NULL;
    if (t.type == TOKEN_KWORD_ELSE) {

        else_stmt = parse_stmt(p, opflags);
        if (else_stmt == NULL)
            return NULL;

    } else {
        p->s = saved;
    }

    Node *parent = alloc_node(p);
    if (parent == NULL)
        return NULL;

    parent->type = NODE_IFELSE;
    parent->if_cond = cond;
    parent->if_branch1 = if_stmt;
    parent->if_branch2 = else_stmt;

    return parent;
}

static Node *parse_for_stmt(Parser *p, int opflags)
{
    Token t = next_token(p);
    if (t.type != TOKEN_KWORD_FOR) {
        parser_report(p, "Missing 'for' keyword at the start of a for statement");
        return NULL;
    }

    t = next_token(p);
    if (t.type != TOKEN_IDENT) {
        parser_report(p, "Missing iteraion variable name in for statement");
        return NULL;
    }
    String var1 = t.sval;

    t = next_token(p);

    String var2 = S("");
    if (t.type == TOKEN_COMMA) {

        t = next_token(p);
        if (t.type != TOKEN_IDENT) {
            parser_report(p, "Missing iteration variable name after ',' in for statement");
            return NULL;
        }
        var2 = t.sval;

        t = next_token(p);
    }

    if (t.type != TOKEN_KWORD_IN) {
        parser_report(p, "Missing 'in' keyword after iteration variable name in for statement");
        return NULL;
    }

    Node *set = parse_expr(p, 0);
    if (set == NULL)
        return NULL;

    t = next_token(p);
    if (t.type != TOKEN_COLON) {
        parser_report(p, "Missing ':' after for statement set expression");
        return NULL;
    }

    Node *body = parse_stmt(p, opflags);
    if (body == NULL)
        return NULL;

    Node *parent = alloc_node(p);
    if (parent == NULL)
        return NULL;

    parent->type = NODE_FOR;
    parent->left = body;
    parent->for_var1 = var1;
    parent->for_var2 = var2;
    parent->for_set  = set;

    return parent;
}

static Node *parse_while_stmt(Parser *p, int opflags)
{
    Token t = next_token(p);
    if (t.type != TOKEN_KWORD_WHILE) {
        parser_report(p, "Missing keyword 'while' at the start of a while statement");
        return NULL;
    }

    Node *cond = parse_expr(p, 0);
    if (cond == NULL)
        return NULL;

    t = next_token(p);
    if (t.type != TOKEN_COLON) {
        parser_report(p, "Missing token ':' after while statement condition");
        return NULL;
    }

    Node *stmt = parse_stmt(p, opflags);
    if (stmt == NULL)
        return NULL;

    Node *parent = alloc_node(p);
    if (parent == NULL)
        return NULL;

    parent->type = NODE_WHILE;
    parent->left = stmt;
    parent->while_cond = cond;
    parent->while_body = stmt;

    return parent;
}

static Node *parse_compound_stmt(Parser *p, bool global)
{
    if (!global) {
        Token t = next_token(p);
        if (t.type != TOKEN_CURLY_OPEN) {
            parser_report(p, "Missing '{' at the start of a compound statement");
            return NULL;
        }
    }

    Node *head;
    Node **tail = &head;

    for (;;) {

        Scanner saved = p->s;
        Token t = next_token(p);
        if (!global) {
            if (t.type == TOKEN_CURLY_CLOSE)
                break;
        } else {
            if (t.type == TOKEN_END)
                break;
        }
        p->s = saved;

        Node *node = parse_stmt(p, 0);
        if (node == NULL)
            return NULL;

        *tail = node;
        tail = &node->next;
    }

    *tail = NULL;

    Node *parent = alloc_node(p);
    if (parent == NULL)
        return NULL;

    parent->type = global ? NODE_GLOBAL : NODE_COMPOUND;
    parent->left = head;

    return parent;
}

static Node *parse_proc_decl(Parser *p, int opflags)
{
    Token t = next_token(p);
    if (t.type != TOKEN_KWORD_PROCEDURE) {
        parser_report(p, "Missing keyword 'procedure' at the start of a procedure declaration");
        return NULL;
    }

    t = next_token(p);
    if (t.type != TOKEN_IDENT) {
        parser_report(p, "Missing procedure name after 'procedure' keyword");
        return NULL;
    }
    String name = t.sval;

    t = next_token(p);
    if (t.type != TOKEN_PAREN_OPEN) {
        parser_report(p, "Missing '(' after procedure name in declaration");
        return NULL;
    }

    Node *arg_head;
    Node **arg_tail = &arg_head;

    Scanner saved = p->s;
    t = next_token(p);
    if (t.type != TOKEN_PAREN_CLOSE) {
        p->s = saved;

        for (;;) {

            t = next_token(p);
            if (t.type != TOKEN_IDENT) {
                parser_report(p, "Missing argument name in procedure declaration");
                return NULL;
            }
            String argname = t.sval;

            Node *node = alloc_node(p);
            if (node == NULL)
                return NULL;

            node->type = NODE_PROCEDURE_ARG;
            node->sval = argname;

            *arg_tail = node;
            arg_tail = &node->next;

            Scanner saved = p->s;
            t = next_token(p);
            if (t.type == TOKEN_COMMA) {
                saved = p->s;
                t = next_token(p);
            }

            if (t.type == TOKEN_PAREN_CLOSE)
                break;
            p->s = saved;
        }
    }

    *arg_tail = NULL;

    Node *body = parse_stmt(p, opflags);
    if (body == NULL)
        return NULL;

    Node *parent = alloc_node(p);
    if (parent == NULL)
        return NULL;

    parent->type = NODE_PROCEDURE_DECL;
    parent->proc_name = name;
    parent->proc_args = arg_head;
    parent->proc_body = body;

    return parent;
}

static Node *parse_var_decl(Parser *p, int opflags)
{
    Token t = next_token(p);
    if (t.type != TOKEN_KWORD_LET) {
        parser_report(p, "Missing keyword 'let' at the start of a variable declaration");
        return NULL;
    }

    t = next_token(p);
    if (t.type != TOKEN_IDENT) {
        parser_report(p, "Missing variable name after 'let' keyword");
        return NULL;
    }
    String name = t.sval;

    Scanner saved = p->s;
    t = next_token(p);

    Node *value;
    if (t.type == TOKEN_OPER_ASS) {

        value = parse_expr(p, opflags);
        if (value == NULL)
            return NULL;

    } else {
        p->s = saved;
        value = NULL;
    }

    Node *parent = alloc_node(p);
    if (parent == NULL)
        return NULL;

    parent->type = NODE_VAR_DECL;
    parent->var_name = name;
    parent->var_value = value;

    return parent;
}

static Node *parse_include_stmt(Parser *p)
{
    Token t = next_token(p);
    if (t.type != TOKEN_KWORD_INCLUDE) {
        parser_report(p, "Missing keyword 'include' at the start of an include statement");
        return NULL;
    }

    t = next_token(p);
    if (t.type != TOKEN_VALUE_STR) {
        parser_report(p, "Missing file path string after 'include' keyword");
        return NULL;
    }
    String path = t.sval;

    Node *parent = alloc_node(p);
    if (parent == NULL)
        return NULL;

    parent->type = NODE_INCLUDE;
    parent->include_path = path;
    parent->include_root = NULL;

    *p->include_tail = parent;
    p->include_tail = &parent->include_next;

    return parent;
}

static Node *parse_stmt(Parser *p, int opflags)
{
    Scanner saved = p->s;
    Token t = next_token(p);
    p->s = saved;

    switch (t.type) {

        case TOKEN_KWORD_INCLUDE:
        return parse_include_stmt(p);

        case TOKEN_KWORD_PROCEDURE:
        return parse_proc_decl(p, opflags);

        case TOKEN_KWORD_LET:
        return parse_var_decl(p, opflags);

        case TOKEN_KWORD_IF:
        return parse_ifelse_stmt(p, opflags);

        case TOKEN_KWORD_WHILE:
        return parse_while_stmt(p, opflags);

        case TOKEN_KWORD_FOR:
        return parse_for_stmt(p, opflags);

        case TOKEN_CURLY_OPEN:
        return parse_compound_stmt(p, false);

        default:
        break;
    }

    return parse_expr_stmt(p, opflags);
}

static void write_node(Writer *w, Node *node)
{
    switch (node->type) {

        case NODE_VALUE_NONE : write_text(w, S("none")); break;
        case NODE_VALUE_TRUE : write_text(w, S("true")); break;
        case NODE_VALUE_FALSE: write_text(w, S("false")); break;

        case NODE_NESTED:
        write_text(w, S("(nested "));
        write_node(w, node->left);
        write_text(w, S(")"));
        break;

        case NODE_COMPOUND:
        {
            write_text(w, S("(compound "));
            Node *cur = node->left;
            while (cur) {
                write_node(w, cur);
                cur = cur->next;
                if (cur)
                    write_text(w, S(" "));
            }
            write_text(w, S(")"));
        }
        break;

        case NODE_GLOBAL:
        {
            write_text(w, S("(global "));
            Node *cur = node->left;
            while (cur) {
                write_node(w, cur);
                cur = cur->next;
                if (cur)
                    write_text(w, S(" "));
            }
            write_text(w, S(")"));
        }
        break;

        case NODE_OPER_LEN:
        write_text(w, S("(len "));
        write_node(w, node->left);
        write_text(w, S(")"));
        break;

        case NODE_OPER_ESCAPE:
        write_text(w, S("(escape "));
        write_node(w, node->left);
        write_text(w, S(")"));
        break;

        case NODE_OPER_POS:
        write_text(w, S("(+"));
        write_node(w, node->left);
        write_text(w, S(")"));
        break;

        case NODE_OPER_NEG:
        write_text(w, S("("));
        write_text(w, S("-"));
        write_node(w, node->left);
        write_text(w, S(")"));
        break;

        case NODE_OPER_ASS:
        write_text(w, S("("));
        write_node(w, node->left);
        write_text(w, S("="));
        write_node(w, node->right);
        write_text(w, S(")"));
        break;

        case NODE_OPER_EQL:
        write_text(w, S("("));
        write_node(w, node->left);
        write_text(w, S("=="));
        write_node(w, node->right);
        write_text(w, S(")"));
        break;

        case NODE_OPER_NQL:
        write_text(w, S("("));
        write_node(w, node->left);
        write_text(w, S("!="));
        write_node(w, node->right);
        write_text(w, S(")"));
        break;

        case NODE_OPER_LSS:
        write_text(w, S("("));
        write_node(w, node->left);
        write_text(w, S("<"));
        write_node(w, node->right);
        write_text(w, S(")"));
        break;

        case NODE_OPER_GRT:
        write_text(w, S("("));
        write_node(w, node->left);
        write_text(w, S(">"));
        write_node(w, node->right);
        write_text(w, S(")"));
        break;

        case NODE_OPER_ADD:
        write_text(w, S("("));
        write_node(w, node->left);
        write_text(w, S("+"));
        write_node(w, node->right);
        write_text(w, S(")"));
        break;

        case NODE_OPER_SUB:
        write_text(w, S("("));
        write_node(w, node->left);
        write_text(w, S("-"));
        write_node(w, node->right);
        write_text(w, S(")"));
        break;

        case NODE_OPER_MUL:
        write_text(w, S("("));
        write_node(w, node->left);
        write_text(w, S("*"));
        write_node(w, node->right);
        write_text(w, S(")"));
        break;

        case NODE_OPER_DIV:
        write_text(w, S("("));
        write_node(w, node->left);
        write_text(w, S("/"));
        write_node(w, node->right);
        write_text(w, S(")"));
        break;

        case NODE_OPER_MOD:
        write_text(w, S("("));
        write_node(w, node->left);
        write_text(w, S("%%"));
        write_node(w, node->right);
        write_text(w, S(")"));
        break;

        case NODE_OPER_SHOVEL:
        write_text(w, S("("));
        write_node(w, node->left);
        write_text(w, S("<<"));
        write_node(w, node->right);
        write_text(w, S(")"));
        break;

        case NODE_VALUE_INT:
        write_text_s64(w, node->ival);
        break;

        case NODE_VALUE_FLOAT:
        write_text_f64(w, node->fval);
        break;

        case NODE_VALUE_STR:
        write_text(w, S("\""));
        write_text(w, node->sval);
        write_text(w, S("\""));
        break;

        case NODE_VALUE_VAR:
        write_text(w, node->sval);
        break;

        case NODE_VALUE_SYSVAR:
        write_text(w, S("$"));
        write_text(w, node->sval);
        break;

        case NODE_IFELSE:
        write_text(w, S("(if "));
        write_node(w, node->if_cond);
        write_text(w, S(" "));
        write_node(w, node->if_branch1);
        if (node->if_branch2) {
            write_text(w, S(" else "));
            write_node(w, node->if_branch2);
        }
        write_text(w, S(")"));
        break;

        case NODE_WHILE:
        write_text(w, S("(while "));
        write_node(w, node->while_cond);
        write_text(w, S(" "));
        write_node(w, node->while_body);
        write_text(w, S(")"));
        break;

        case NODE_VALUE_HTML:
        {
            write_text(w, S("(html "));
            write_text(w, node->html_tag);

            Node *child = node->html_child;
            while (child) {
                write_text(w, S(" "));
                write_node(w, child);
                child = child->next;
            }

            write_text(w, S(")"));
        }
        break;

        case NODE_FOR:
        write_text(w, S("(for "));
        write_text(w, node->for_var1);
        if (node->for_var2.len > 0) {
            write_text(w, S(", "));
            write_text(w, node->for_var2);
        }
        write_text(w, S(" in "));
        write_node(w, node->for_set);
        write_text(w, S(": "));
        write_node(w, node->left);
        break;

        case NODE_SELECT:
        write_node(w, node->left);
        write_text(w, S("["));
        write_node(w, node->right);
        write_text(w, S("]"));
        break;

        case NODE_VALUE_ARRAY:
        {
            write_text(w, S("["));
            Node *child = node->child;
            while (child) {
                write_node(w, child);
                write_text(w, S(", "));
                child = child->next;
            }
            write_text(w, S("]"));
        }
        break;

        case NODE_VALUE_MAP:
        {
            write_text(w, S("{"));
            Node *child = node->child;
            while (child) {
                write_node(w, child->key);
                write_text(w, S(": "));
                write_node(w, child);
                write_text(w, S(", "));
                child = child->next;
            }
            write_text(w, S("}"));
        }
        break;

        case NODE_PROCEDURE_DECL:
        {
            write_text(w, S("(proc "));
            write_text(w, node->proc_name);
            write_text(w, S("("));
            Node *arg = node->proc_args;
            while (arg) {
                write_node(w, arg);
                arg = arg->next;
                if (arg)
                    write_text(w, S(", "));
            }
            write_text(w, S(")"));
            write_node(w, node->proc_body);
        }
        break;

        case NODE_PROCEDURE_ARG:
        write_text(w, node->sval);
        break;

        case NODE_PROCEDURE_CALL:
        {
            write_node(w, node->left);
            write_text(w, S("("));
            Node *arg = node->right;
            while (arg) {
                write_node(w, arg);
                arg = arg->next;
                if (arg)
                    write_text(w, S(", "));
            }
            write_text(w, S(")"));
        }
        break;

        case NODE_VAR_DECL:
        write_text(w, S("(let "));
        write_text(w, node->var_name);
        if (node->var_value) {
            write_text(w, S(" = "));
            write_node(w, node->var_value);
        }
        write_text(w, S(")"));
        break;

        case NODE_INCLUDE:
        write_text(w, S("include \""));
        write_text(w, node->include_path);
        write_text(w, S("\""));
        break;
    }
}

static ParseResult parse(String src, WL_Arena *arena, char *errbuf, int errmax)
{
    Parser p = {
        .s={ src.ptr, src.len, 0 },
        .arena=arena,
        .errbuf=errbuf,
        .errmax=errmax,
        .errlen=0,
    };

    p.include_tail = &p.include_head;

    Node *node = parse_compound_stmt(&p, true);
    if (node == NULL)
        return (ParseResult) { .node=NULL, .includes=NULL, .errlen=p.errlen };

    *p.include_tail = NULL;
    return (ParseResult) { .node=node, .includes=p.include_head, .errlen=-1 };
}

/////////////////////////////////////////////////////////////////////////
// CODEGEN
/////////////////////////////////////////////////////////////////////////

enum {
    OPCODE_NOPE,
    OPCODE_JUMP,
    OPCODE_JIFP,
    OPCODE_OUTPUT,
    OPCODE_SYSVAR,
    OPCODE_SYSCALL,
    OPCODE_CALL,
    OPCODE_RET,
    OPCODE_GROUP,
    OPCODE_ESCAPE,
    OPCODE_PACK,
    OPCODE_GPOP,
    OPCODE_FOR,
    OPCODE_EXIT,
    OPCODE_VARS,
    OPCODE_POP,
    OPCODE_SETV,
    OPCODE_PUSHV,
    OPCODE_PUSHI,
    OPCODE_PUSHF,
    OPCODE_PUSHS,
    OPCODE_PUSHA,
    OPCODE_PUSHM,
    OPCODE_PUSHN,
    OPCODE_PUSHT,
    OPCODE_PUSHFL,
    OPCODE_LEN,
    OPCODE_NEG,
    OPCODE_EQL,
    OPCODE_NQL,
    OPCODE_LSS,
    OPCODE_GRT,
    OPCODE_ADD,
    OPCODE_SUB,
    OPCODE_MUL,
    OPCODE_DIV,
    OPCODE_MOD,
    OPCODE_APPEND,
    OPCODE_INSERT1,
    OPCODE_INSERT2,
    OPCODE_SELECT,
};

typedef struct UnpatchedCall UnpatchedCall;
struct UnpatchedCall {
    UnpatchedCall *next;
    String         name;
    int            off;
};

typedef enum {
    SYMBOL_VARIABLE,
    SYMBOL_PROCEDURE,
} SymbolType;

typedef struct {
    SymbolType type;
    String     name;
    bool       cnst;
    int        off;
} Symbol;

typedef enum {
    SCOPE_IF,
    SCOPE_ELSE,
    SCOPE_FOR,
    SCOPE_WHILE,
    SCOPE_PROC,
    SCOPE_COMPOUND,
    SCOPE_GLOBAL,
    SCOPE_ASSIGNMENT,
} ScopeType;

typedef struct {
    ScopeType type;
    int idx_syms;
    int max_vars;
    UnpatchedCall *calls;
} Scope;

#define MAX_SYMBOLS 1024
#define MAX_SCOPES 128
#define MAX_UNPATCHED_CALLS 32

typedef struct {

    Writer code;
    Writer data;

    int num_scopes;
    Scope scopes[MAX_SCOPES];

    int num_syms;
    Symbol syms[MAX_SYMBOLS];

    UnpatchedCall *free_list_calls;
    UnpatchedCall calls[MAX_UNPATCHED_CALLS];

    bool  err;
    char *errmsg;
    int   errcap;

    int data_off;

} Codegen;

static void cg_report(Codegen *cg, char *fmt, ...)
{
    if (cg->err) return;

    va_list args;
    va_start(args, fmt);
    int len = vsnprintf(cg->errmsg, cg->errcap, fmt, args);
    va_end(args);

    if (len > cg->errcap)
        len = cg->errcap-1;

    cg->errmsg[len] = '\0';
    cg->err = true;
}

static int cg_write_u8(Codegen *cg, uint8_t x)
{
    if (cg->err) return -1;

    int off = cg->code.len;
    write_raw_u8(&cg->code, x);
    return off;
}

static int cg_write_u32(Codegen *cg, uint32_t x)
{
    if (cg->err) return -1;

    int off = cg->code.len;
    write_raw_u32(&cg->code, x);
    return off;
}

static int cg_write_s64(Codegen *cg, int64_t x)
{
    if (cg->err) return -1;

    int off = cg->code.len;
    write_raw_s64(&cg->code, x);
    return off;
}

static int cg_write_f64(Codegen *cg, double x)
{
    if (cg->err) return -1;

    int off = cg->code.len;
    write_raw_f64(&cg->code, x);
    return off;
}

static void cg_write_str(Codegen *cg, String x)
{
    if (cg->err) return;

    int off = cg->data.len;
    write_text(&cg->data, x);
    write_raw_u32(&cg->code, off);
    write_raw_u32(&cg->code, x.len);
}

static void cg_patch_u8(Codegen *cg, int off, uint8_t x)
{
    if (cg->err) return;

    patch_mem(&cg->code, &x, off, SIZEOF(x));
}

static void cg_patch_u32(Codegen *cg, int off, uint32_t x)
{
    if (cg->err) return;

    patch_mem(&cg->code, &x, off, SIZEOF(x));
}

static uint32_t cg_current_offset(Codegen *cg)
{
    return cg->code.len;
}

int count_nodes(Node *head)
{
    int n = 0;
    Node *node = head;
    while (node) {
        n++;
        node = node->next;
    }
    return n;
}

static Scope *parent_scope(Codegen *cg)
{
    ASSERT(cg->num_scopes > 0);

    int parent = cg->num_scopes-1;
    while (cg->scopes[parent].type != SCOPE_PROC && cg->scopes[parent].type != SCOPE_GLOBAL)
        parent--;

    return &cg->scopes[parent];
}

static bool inside_assignment(Codegen *cg)
{
    ASSERT(cg->num_scopes > 0);

    int parent = cg->num_scopes-1;
    while (cg->scopes[parent].type != SCOPE_PROC
        && cg->scopes[parent].type != SCOPE_GLOBAL
        && cg->scopes[parent].type != SCOPE_ASSIGNMENT)
        parent--;

    return cg->scopes[parent].type == SCOPE_ASSIGNMENT;
}

static int count_function_vars(Codegen *cg)
{
    int n = 0;
    Scope *scope = parent_scope(cg);
    for (int i = scope->idx_syms; i < cg->num_syms; i++)
        if (cg->syms[i].type == SYMBOL_VARIABLE)
            n++;
    return n;
}

static Symbol *cg_find_symbol(Codegen *cg, String name, bool local)
{
    if (cg->err) return NULL;

    if (name.len == 0) return NULL;
    ASSERT(cg->num_scopes > 0);
    Scope *scope = local ? &cg->scopes[cg->num_scopes-1] : parent_scope(cg);
    for (int i = cg->num_syms-1; i >= scope->idx_syms; i--)
        if (streq(cg->syms[i].name, name))
            return &cg->syms[i];
    return NULL;
}

static int cg_declare_variable(Codegen *cg, String name, bool cnst)
{
    if (cg->err) return -1;

    Symbol *sym = cg_find_symbol(cg, name, true);
    if (sym) {
        cg_report(cg, "Variable declared twice");
        return -1;
    }

    if (cg->num_syms == MAX_SYMBOLS) {
        cg_report(cg, "Symbol count limit reached");
        return -1;
    }

    int off = count_function_vars(cg);

    Scope *parent = parent_scope(cg);
    parent->max_vars = MAX(parent->max_vars, off+1);

    cg->syms[cg->num_syms++] = (Symbol) {
        .type = SYMBOL_VARIABLE,
        .name = name,
        .cnst = cnst,
        .off  = off,
    };
    return off;
}

static void cg_declare_procedure(Codegen *cg, String name, int off)
{
    if (cg->err) return;

    Symbol *sym = cg_find_symbol(cg, name, true);
    if (sym) {
        cg_report(cg, "Procedure declared twice");
        return;
    }

    if (cg->num_syms == MAX_SYMBOLS) {
        cg_report(cg, "Symbol count limit reached");
        return;
    }

    cg->syms[cg->num_syms++] = (Symbol) {
        .type = SYMBOL_PROCEDURE,
        .name = name,
        .cnst = true,
        .off  = off,
    };
}

static void cg_push_scope(Codegen *cg, ScopeType type)
{
    if (cg->err) return;

    if (cg->num_scopes == MAX_SCOPES) {
        cg_report(cg, "Scope limit reached");
        return;
    }

    Scope *scope = &cg->scopes[cg->num_scopes++];
    scope->type     = type;
    scope->idx_syms = cg->num_syms;
    scope->max_vars = 0;
    scope->calls    = NULL;
}

static void cg_pop_scope(Codegen *cg)
{
    if (cg->err) return;

    ASSERT(cg->num_scopes > 0);
    Scope *scope = &cg->scopes[cg->num_scopes-1];

    Scope *parent_scope = NULL;
    if (cg->num_scopes > 1)
        parent_scope = &cg->scopes[cg->num_scopes-2];

    while (scope->calls) {

        UnpatchedCall *call = scope->calls;
        scope->calls = call->next;

        ASSERT(call - cg->calls >= 0 && call - cg->calls < MAX_UNPATCHED_CALLS);

        Symbol *sym = cg_find_symbol(cg, call->name, true);

        if (sym == NULL) {
            if (parent_scope == NULL) {
                cg_report(cg, "Undefined function '%.*s'",
                    scope->calls->name.len,
                    scope->calls->name.ptr);
                    return;
                }
            call->next = parent_scope->calls;
            parent_scope->calls = call; 
            continue;
        }

        if (sym->type != SYMBOL_PROCEDURE) {
            cg_report(cg, "Symbol '%.*s' is not a procedure", call->name.len, call->name.ptr);
            return;
        }

        cg_patch_u32(cg, call->off, sym->off);

        call->next = cg->free_list_calls;
        cg->free_list_calls = call;

        // TODO: remove
        ASSERT(cg->scopes[cg->num_scopes-1].calls == NULL || (cg->scopes[cg->num_scopes-1].calls - cg->calls >= 0 && cg->scopes[cg->num_scopes-1].calls - cg->calls < MAX_UNPATCHED_CALLS));
    }

    cg->num_syms = scope->idx_syms;
    cg->num_scopes--;
}

static void cg_append_unpatched_call(Codegen *cg, String name, int p)
{
    if (cg->err) return;

    if (cg->free_list_calls == NULL) {
        cg_report(cg, "Out of memory");
        return;
    }
    UnpatchedCall *call = cg->free_list_calls;
    cg->free_list_calls = call->next;

    ASSERT(call - cg->calls >= 0 && call - cg->calls < MAX_UNPATCHED_CALLS);

    call->name = name;
    call->off  = p;
    call->next = NULL;

    ASSERT(cg->num_scopes > 0);
    Scope *scope = &cg->scopes[cg->num_scopes-1];

    call->next = scope->calls;
    scope->calls = call;
}

static bool cg_global_scope(Codegen *cg)
{
    Scope *scope = parent_scope(cg);
    return scope->type == SCOPE_GLOBAL;
}

static void cg_flush_pushs(Codegen *cg)
{
    if (cg->data_off != -1) {
        if (cg->data_off < cg->data.len) {
            cg_write_u8(cg, OPCODE_PUSHS);
            cg_write_u32(cg, cg->data_off);
            cg_write_u32(cg, cg->data.len - cg->data_off);
        }
        cg->data_off = -1;
    }
}

static int cg_write_opcode(Codegen *cg, uint8_t opcode)
{
    ASSERT(opcode != OPCODE_PUSHS);
    cg_flush_pushs(cg);
    return cg_write_u8(cg, opcode);
}

static void cg_write_pushs(Codegen *cg, String str, bool dont_group)
{
    if (dont_group) {
        cg_flush_pushs(cg);
        cg_write_u8(cg, OPCODE_PUSHS);
        cg_write_str(cg, str);
    } else {
        if (cg->data_off == -1)
            cg->data_off = cg->data.len;
        write_raw_mem(&cg->data, str.ptr, str.len);
    }
}

static void walk_node(Codegen *cg, Node *node, bool inside_html);

static void walk_expr_node(Codegen *cg, Node *node, bool one)
{
    // TODO: remove
    ASSERT(cg->scopes[cg->num_scopes-1].calls == NULL || (cg->scopes[cg->num_scopes-1].calls - cg->calls >= 0 && cg->scopes[cg->num_scopes-1].calls - cg->calls < MAX_UNPATCHED_CALLS));

    switch (node->type) {

        case NODE_NESTED:
        walk_expr_node(cg, node->left, one);
        break;

        case NODE_OPER_LEN:
        walk_expr_node(cg, node->left, true);
        cg_write_opcode(cg, OPCODE_LEN);
        break;

        case NODE_OPER_ESCAPE:
        cg_write_opcode(cg, OPCODE_GROUP);
        walk_expr_node(cg, node->left, false);
        cg_write_opcode(cg, OPCODE_ESCAPE);
        break;

        case NODE_OPER_POS:
        walk_expr_node(cg, node->left, one);
        break;

        case NODE_OPER_NEG:
        walk_expr_node(cg, node->left, true);
        cg_write_opcode(cg, OPCODE_NEG);
        break;

        case NODE_OPER_ASS:
        {
            Node *dst = node->left;
            Node *src = node->right;

            if (dst->type == NODE_VALUE_VAR) {

                String name = dst->sval;
                Symbol *sym = cg_find_symbol(cg, name, false);
                if (sym == NULL) {
                    cg_report(cg, "Write to undeclared variable");
                    return;
                }
                if (sym->type == SYMBOL_PROCEDURE) {
                    cg_report(cg, "Symbol is not a variable");
                    return;
                }
                if (sym->cnst) {
                    cg_report(cg, "Variable is constant");
                    return;
                }

                cg_push_scope(cg, SCOPE_ASSIGNMENT);
                walk_expr_node(cg, src, true);
                cg_pop_scope(cg);

                cg_write_opcode(cg, OPCODE_SETV);
                cg_write_u8(cg, sym->off);

                if (!one)
                    cg_write_opcode(cg, OPCODE_POP);

            } else if (dst->type == NODE_SELECT) {

                cg_push_scope(cg, SCOPE_ASSIGNMENT);
                walk_expr_node(cg, src, true);
                cg_pop_scope(cg);

                walk_expr_node(cg, dst->left,  true);
                walk_expr_node(cg, dst->right, true);
                cg_write_opcode(cg, OPCODE_INSERT2);

                if (!one)
                    cg_write_opcode(cg, OPCODE_POP);

            } else {

                cg_report(cg, "Assignment left side can't be assigned to");
                return;
            }
        }
        break;

        case NODE_OPER_SHOVEL:
        {
            walk_expr_node(cg, node->left, true);

            cg_push_scope(cg, SCOPE_ASSIGNMENT);
            walk_expr_node(cg, node->right, true);
            cg_pop_scope(cg);

            cg_write_opcode(cg, OPCODE_APPEND);
            if (!one)
                cg_write_opcode(cg, OPCODE_POP);
        }
        break;

        case NODE_OPER_EQL:
        walk_expr_node(cg, node->left, true);
        walk_expr_node(cg, node->right, true);
        cg_write_opcode(cg, OPCODE_EQL);
        break;

        case NODE_OPER_NQL:
        walk_expr_node(cg, node->left, true);
        walk_expr_node(cg, node->right, true);
        cg_write_opcode(cg, OPCODE_NQL);
        break;

        case NODE_OPER_LSS:
        walk_expr_node(cg, node->left, true);
        walk_expr_node(cg, node->right, true);
        cg_write_opcode(cg, OPCODE_LSS);
        break;

        case NODE_OPER_GRT:
        walk_expr_node(cg, node->left, true);
        walk_expr_node(cg, node->right, true);
        cg_write_opcode(cg, OPCODE_GRT);
        break;

        case NODE_OPER_ADD:
        walk_expr_node(cg, node->left, true);
        walk_expr_node(cg, node->right, true);
        cg_write_opcode(cg, OPCODE_ADD);
        break;

        case NODE_OPER_SUB:
        walk_expr_node(cg, node->left, true);
        walk_expr_node(cg, node->right, true);
        cg_write_opcode(cg, OPCODE_SUB);
        break;

        case NODE_OPER_MUL:
        walk_expr_node(cg, node->left, true);
        walk_expr_node(cg, node->right, true);
        cg_write_opcode(cg, OPCODE_MUL);
        break;

        case NODE_OPER_DIV:
        walk_expr_node(cg, node->left, true);
        walk_expr_node(cg, node->right, true);
        cg_write_opcode(cg, OPCODE_DIV);
        break;

        case NODE_OPER_MOD:
        walk_expr_node(cg, node->left, true);
        walk_expr_node(cg, node->right, true);
        cg_write_opcode(cg, OPCODE_MOD);
        break;

        case NODE_VALUE_INT:
        cg_write_opcode(cg, OPCODE_PUSHI);
        cg_write_s64(cg, node->ival);
        break;

        case NODE_VALUE_FLOAT:
        cg_write_opcode(cg, OPCODE_PUSHF);
        cg_write_f64(cg, node->fval);
        break;

        case NODE_VALUE_STR:
        cg_write_pushs(cg, node->sval, one);
        break;

        case NODE_VALUE_NONE:
        cg_write_opcode(cg, OPCODE_PUSHN);
        break;

        case NODE_VALUE_TRUE:
        cg_write_opcode(cg, OPCODE_PUSHT);
        break;

        case NODE_VALUE_FALSE:
        cg_write_opcode(cg, OPCODE_PUSHFL);
        break;

        case NODE_VALUE_VAR:
        {
            String name = node->sval;
            Symbol *sym = cg_find_symbol(cg, name, false);
            if (sym == NULL) {
                cg_report(cg, "Access to undeclared variable '%.*s'", name.len, name.ptr);
                return;
            }
            if (sym->type == SYMBOL_PROCEDURE) {
                cg_report(cg, "Symbol is not a variable");
                return;
            }

            cg_write_opcode(cg, OPCODE_PUSHV);
            cg_write_u8(cg, sym->off);
        }
        break;

        case NODE_VALUE_SYSVAR:
        cg_write_opcode(cg, OPCODE_SYSVAR);
        cg_write_str(cg, node->sval);
        break;

        case NODE_VALUE_HTML:
        {
            if (one)
                cg_write_opcode(cg, OPCODE_GROUP);

            cg_write_pushs(cg, S("<"), false);
            cg_write_pushs(cg, node->html_tag, false);

            Node *child = node->html_attr;
            while (child) {
                walk_node(cg, child, true);
                child = child->next;
            }

            if (!node->html_body) {
                cg_write_pushs(cg, S("/>"), false);
            } else {
                cg_write_pushs(cg, S(">"), false);
                Node *child = node->html_child;
                while (child) {
                    walk_node(cg, child, true);
                    child = child->next;
                }
                cg_write_pushs(cg, S("</"), false);
                cg_write_pushs(cg, node->html_tag, false);
                cg_write_pushs(cg, S(">"), false);
            }

            if (one)
                cg_write_opcode(cg, OPCODE_PACK);
        }
        break;

        case NODE_VALUE_ARRAY:
        {
            cg_write_opcode(cg, OPCODE_PUSHA);
            cg_write_u32(cg, count_nodes(node->child));

            Node *child = node->child;
            while (child) {
                walk_expr_node(cg, child, true);
                cg_write_opcode(cg, OPCODE_APPEND);
                child = child->next;
            }
        }
        break;

        case NODE_VALUE_MAP:
        {
            cg_write_opcode(cg, OPCODE_PUSHM);
            cg_write_u32(cg, count_nodes(node->child));

            Node *child = node->child;
            while (child) {
                walk_expr_node(cg, child, true);
                walk_expr_node(cg, child->key, true);
                cg_write_opcode(cg, OPCODE_INSERT1);
                child = child->next;
            }
        }
        break;

        case NODE_SELECT:
        {
            Node *set = node->left;
            Node *key = node->right;
            walk_expr_node(cg, set, true);
            walk_expr_node(cg, key, true);
            cg_write_opcode(cg, OPCODE_SELECT);
        }
        break;

        case NODE_PROCEDURE_CALL:
        {
            if (one)
                cg_write_opcode(cg, OPCODE_GROUP);

            int count = 0;
            Node *arg = node->right;
            while (arg) {
                walk_expr_node(cg, arg, true);
                count++;
                arg = arg->next;
            }

            Node *proc = node->left;
            if (proc->type == NODE_VALUE_VAR) {
                
                cg_write_opcode(cg, OPCODE_CALL);
                cg_write_u8(cg, count);
                int p = cg_write_u32(cg, 0);
                cg_append_unpatched_call(cg, proc->sval, p);

            } else {

                ASSERT(proc->type == NODE_VALUE_SYSVAR);
                cg_write_opcode(cg, OPCODE_SYSCALL);
                cg_write_u8(cg, count);
                cg_write_str(cg, proc->sval);
            }

            if (one)
                cg_write_opcode(cg, OPCODE_PACK);
        }
        break;

        default:
        UNREACHABLE;
    }
}

static void walk_node(Codegen *cg, Node *node, bool inside_html)
{
    // TODO: remove
    ASSERT(cg->scopes[cg->num_scopes-1].calls == NULL || (cg->scopes[cg->num_scopes-1].calls - cg->calls >= 0 && cg->scopes[cg->num_scopes-1].calls - cg->calls < MAX_UNPATCHED_CALLS));

    switch (node->type) {

        case NODE_GLOBAL:
        for (Node *child = node->left;
            child; child = child->next) {
            walk_node(cg, child, false);
        }
        break;

        case NODE_COMPOUND:
        cg_push_scope(cg, SCOPE_COMPOUND);
        for (Node *child = node->left;
            child; child = child->next)
            walk_node(cg, child, inside_html);
        cg_pop_scope(cg);
        break;

        case NODE_PROCEDURE_DECL:
        {
            cg_push_scope(cg, SCOPE_PROC);

            cg_write_opcode(cg, OPCODE_JUMP);
            int off0 = cg_write_u32(cg, 0);

            #define MAX_ARGS 128

            int num_args = 0;
            Node *args[MAX_ARGS];

            Node *arg = node->proc_args;
            while (arg) {
                if (num_args == MAX_ARGS) {
                    cg_report(cg, "Procedure argument limit reached");
                    return;
                }
                args[num_args++] = arg;
                arg = arg->next;
            }

            for (int i = num_args-1; i >= 0; i--)
                cg_declare_variable(cg, args[i]->sval, false);

            int off1 = cg_write_opcode(cg, OPCODE_VARS);
            int off2 = cg_write_u8(cg, 0);

            walk_node(cg, node->proc_body, false);
            cg_write_opcode(cg, OPCODE_RET);

            cg_patch_u8 (cg, off2, count_function_vars(cg));
            cg_patch_u32(cg, off0, cg_current_offset(cg));

            cg_pop_scope(cg);

            cg_declare_procedure(cg, node->proc_name, off1);
        }
        break;

        case NODE_VAR_DECL:
        {
            int off = cg_declare_variable(cg, node->var_name, false);
            if (node->var_value) {
                cg_push_scope(cg, SCOPE_ASSIGNMENT);
                walk_expr_node(cg, node->var_value, true);
                cg_pop_scope(cg);
            } else
                cg_write_opcode(cg, OPCODE_PUSHN);
            cg_write_opcode(cg, OPCODE_SETV);
            cg_write_u8(cg, off);
            cg_write_opcode(cg, OPCODE_POP);
        }
        break;

        case NODE_IFELSE:
        {
            // If there is no else branch:
            //
            //   <cond>
            //   JIFP end
            //   <left>
            // end:
            //   ...
            //
            // If there is:
            //
            //   <cond>
            //   JIFP else
            //   <left>
            //   JUMP end
            // else:
            //   <right>
            // end:
            //   ...

            if (node->if_branch2) {

                walk_expr_node(cg, node->if_cond, true);

                cg_write_opcode(cg, OPCODE_JIFP);
                int p1 = cg_write_u32(cg, 0);

                cg_push_scope(cg, SCOPE_IF);
                walk_node(cg, node->if_branch1, inside_html);
                cg_pop_scope(cg);

                cg_write_opcode(cg, OPCODE_JUMP);
                int p2 = cg_write_u32(cg, 0);

                cg_flush_pushs(cg);
                cg_patch_u32(cg, p1, cg_current_offset(cg));

                cg_push_scope(cg, SCOPE_ELSE);
                walk_node(cg, node->if_branch2, inside_html);
                cg_pop_scope(cg);

                cg_flush_pushs(cg);
                cg_patch_u32(cg, p2, cg_current_offset(cg));

            } else {

                walk_expr_node(cg, node->if_cond, true);

                cg_write_opcode(cg, OPCODE_JIFP);
                int p1 = cg_write_u32(cg, 0);

                cg_push_scope(cg, SCOPE_IF);
                walk_node(cg, node->if_branch1, inside_html);
                cg_pop_scope(cg);

                cg_flush_pushs(cg);
                cg_patch_u32(cg, p1, cg_current_offset(cg));
            }
        }
        break;

        case NODE_FOR:
        {
            cg_push_scope(cg, SCOPE_FOR);

            int var_1 = cg_declare_variable(cg, node->for_var1, false);
            int var_2 = cg_declare_variable(cg, node->for_var2, true);
            int var_3 = cg_declare_variable(cg, (String) { NULL, 0 }, true);

            walk_expr_node(cg, node->for_set, true);
            cg_write_opcode(cg, OPCODE_SETV);
            cg_write_u8(cg, var_3);
            cg_write_opcode(cg, OPCODE_POP);

            cg_write_opcode(cg, OPCODE_PUSHI);
            cg_write_s64(cg, -1);
            cg_write_opcode(cg, OPCODE_SETV);
            cg_write_u8(cg, var_2);
            cg_write_opcode(cg, OPCODE_POP);

            int start = cg_write_opcode(cg, OPCODE_FOR);
            cg_write_u8(cg, var_3);
            cg_write_u8(cg, var_1);
            cg_write_u8(cg, var_2);
            int p = cg_write_u32(cg, 0);

            walk_node(cg, node->left, inside_html);

            cg_write_opcode(cg, OPCODE_JUMP);
            cg_write_u32(cg, start);

            cg_patch_u32(cg, p, cg_current_offset(cg));

            cg_pop_scope(cg);
        }
        break;

        case NODE_WHILE:
        {
            // start:
            //   <cond>
            //   JIFP end
            //   <body>
            //   JUMP start
            // end:
            //   ...

            int start = cg_current_offset(cg);

            walk_expr_node(cg, node->while_cond, true);

            cg_write_opcode(cg, OPCODE_JIFP);
            int p = cg_write_u32(cg, 0);

            cg_push_scope(cg, SCOPE_WHILE);
            walk_node(cg, node->left, inside_html);
            cg_pop_scope(cg);

            cg_write_opcode(cg, OPCODE_JUMP);
            cg_write_u32(cg, start);

            cg_patch_u32(cg, p, cg_current_offset(cg));
        }
        break;

        case NODE_INCLUDE:
        walk_node(cg, node->include_root, false);
        break;

        default:
        walk_expr_node(cg, node, false);
        if (cg_global_scope(cg) && !inside_assignment(cg) && !inside_html)
            cg_write_opcode(cg, OPCODE_OUTPUT);
        break;
    }
}

#define WL_MAGIC 0xFEEDBEEF

static int codegen(Node *node, char *dst, int cap, char *errmsg, int errcap)
{
    char *hdr;
    if (cap < SIZEOF(uint32_t) * 3)
        hdr = NULL;
    else {
        hdr = dst;
        dst += SIZEOF(uint32_t) * 3;
        cap -= SIZEOF(uint32_t) * 3;
    }

    Codegen cg = {
        .code = { dst,         cap/2, 0 },
        .data = { dst + cap/2, cap/2, 0 },
        .num_scopes = 0,
        .err = false,
        .errmsg = errmsg,
        .errcap = errcap,
        .data_off = -1,
    };

    cg.free_list_calls = cg.calls;
    for (int i = 0; i < MAX_UNPATCHED_CALLS-1; i++)
        cg.calls[i].next = &cg.calls[i+1];
    cg.calls[MAX_UNPATCHED_CALLS-1].next = NULL;

    cg_push_scope(&cg, SCOPE_GLOBAL);
    cg_write_opcode(&cg, OPCODE_VARS);
    int off = cg_write_u8(&cg, 0);
    walk_node(&cg, node, false);
    cg_write_opcode(&cg, OPCODE_EXIT);
    cg_patch_u8(&cg, off, cg.scopes[0].max_vars);
    cg_pop_scope(&cg);

    if (cg.err)
        return -1;

    if (hdr) {

        uint32_t magic = WL_MAGIC;
        uint32_t code_len = cg.code.len;
        uint32_t data_len = cg.data.len;
        memcpy(hdr + 0, &magic   , sizeof(uint32_t));
        memcpy(hdr + 4, &code_len, sizeof(uint32_t));
        memcpy(hdr + 8, &data_len, sizeof(uint32_t));

        if (cg.code.len + cg.data.len <= cap)
            memmove(dst + cg.code.len, dst + cap/2, cg.data.len);
    }

    return cg.code.len + cg.data.len + SIZEOF(uint32_t) * 3;
}

static int write_instr(Writer *w, char *src, int len, String data)
{
    if (len == 0)
        return -1;

    switch (src[0]) {

        uint8_t b0;
        uint8_t b1;
        uint8_t b2;
        uint32_t w0;
        uint32_t w1;
        int64_t i;
        double  d;

        case OPCODE_NOPE:
        write_text(w, S("NOPE\n"));
        return 1;

        case OPCODE_JUMP:
        if (len < 5) return -1;
        memcpy(&w0, src + 1, sizeof(uint32_t));
        write_text(w, S("JUMP "));
        write_text_s64(w, w0);
        write_text(w, S("\n"));
        return 5;

        case OPCODE_JIFP:
        if (len < 5) return -1;
        memcpy(&w0, src + 1, sizeof(uint32_t));
        write_text(w, S("JIFP "));
        write_text_s64(w, w0);
        write_text(w, S("\n"));
        return 5;

        case OPCODE_OUTPUT:
        write_text(w, S("OUTPUT\n"));
        return 1;

        case OPCODE_SYSVAR:
        if (len < 9) return -1;
        memcpy(&w0, src + 1, sizeof(uint32_t));
        memcpy(&w1, src + 5, sizeof(uint32_t));
        write_text(w, S("SYSVAR \""));
        write_text(w, (String) { data.ptr + w0, w1 });
        write_text(w, S("\"\n"));
        return 9;

        case OPCODE_SYSCALL:
        if (len < 10) return -1;
        memcpy(&b0, src + 1, sizeof(uint8_t));
        memcpy(&w0, src + 2, sizeof(uint32_t));
        memcpy(&w1, src + 6, sizeof(uint32_t));
        write_text(w, S("SYSCALL "));
        write_text_s64(w, b0);
        write_text(w, S(" \""));
        write_text(w, (String) { data.ptr + w0, w1 });
        write_text(w, S("\"\n"));
        return 10;

        case OPCODE_CALL:
        if (len < 6) return -1;
        memcpy(&b0, src + 1, sizeof(uint8_t));
        memcpy(&w0, src + 2, sizeof(uint32_t));
        write_text(w, S("CALL "));
        write_text_s64(w, b0);
        write_text(w, S(" "));
        write_text_s64(w, w0);
        write_text(w, S("\n"));
        return 6;

        case OPCODE_RET:
        write_text(w, S("RET\n"));
        return 1;

        case OPCODE_GROUP:
        write_text(w, S("GROUP\n"));
        return 1;

        case OPCODE_ESCAPE:
        write_text(w, S("ESCAPE\n"));
        return 1;

        case OPCODE_PACK:
        write_text(w, S("PACK\n"));
        return 1;

        case OPCODE_GPOP:
        write_text(w, S("GPOP\n"));
        return 1;

        case OPCODE_FOR:
        if (len < 8) return -1;
        memcpy(&b0, src + 1, sizeof(b0));
        memcpy(&b1, src + 2, sizeof(b1));
        memcpy(&b2, src + 3, sizeof(b2));
        memcpy(&w0, src + 4, sizeof(w0));
        write_text(w, S("FOR "));
        write_text_s64(w, b0);
        write_text(w, S(" "));
        write_text_s64(w, b1);
        write_text(w, S(" "));
        write_text_s64(w, b2);
        write_text(w, S(" "));
        write_text_s64(w, w0);
        write_text(w, S("\n"));
        return 8;

        case OPCODE_EXIT:
        write_text(w, S("EXIT\n"));
        return 1;

        case OPCODE_VARS:
        if (len < 2) return -1;
        memcpy(&b0, src + 1, sizeof(b0));
        write_text(w, S("VARS "));
        write_text_s64(w, b0);
        write_text(w, S("\n"));
        return 2;

        case OPCODE_POP:
        write_text(w, S("POP\n"));
        return 1;

        case OPCODE_SETV:
        if (len < 2) return -1;
        memcpy(&b0, src + 1, sizeof(uint8_t));
        write_text(w, S("SETV "));
        write_text_s64(w, b0);
        write_text(w, S("\n"));
        return 2;

        case OPCODE_PUSHV:
        if (len < 2) return -1;
        memcpy(&b0, src + 1, sizeof(uint8_t));
        write_text(w, S("PUSHV "));
        write_text_s64(w, b0);
        write_text(w, S("\n"));
        return 2;

        case OPCODE_PUSHI:
        if (len < 9) return -1;
        memcpy(&i, src + 1, sizeof(int64_t));
        write_text(w, S("PUSHI "));
        write_text_s64(w, i);
        write_text(w, S("\n"));
        return 9;

        case OPCODE_PUSHF:
        if (len < 9) return -1;
        memcpy(&d, src + 1, sizeof(double));
        write_text(w, S("PUSHF "));
        write_text_f64(w, d);
        write_text(w, S("\n"));
        return 9;

        case OPCODE_PUSHS:
        if (len < 9) return -1;
        memcpy(&w0, src + 1, sizeof(uint32_t));
        memcpy(&w1, src + 5, sizeof(uint32_t));
        write_text(w, S("PUSHS \""));
        write_text(w, (String) { data.ptr + w0, w1 });
        write_text(w, S("\"\n"));
        return 9;

        case OPCODE_PUSHA:
        if (len < 5) return -1;
        memcpy(&w0, src + 1, sizeof(w0));
        write_text(w, S("PUSHA "));
        write_text_s64(w, w0);
        write_text(w, S("\n"));
        return 5;

        case OPCODE_PUSHM:
        if (len < 5) return -1;
        memcpy(&w0, src + 1, sizeof(w0));
        write_text(w, S("PUSHM "));
        write_text_s64(w, w0);
        write_text(w, S("\n"));
        return 5;

        case OPCODE_PUSHN:
        write_text(w, S("PUSHN\n"));
        return 1;

        case OPCODE_PUSHT:
        write_text(w, S("PUSHT\n"));
        return 1;

        case OPCODE_PUSHFL:
        write_text(w, S("PUSHFL\n"));
        return 1;

        case OPCODE_LEN:
        write_text(w, S("LEN\n"));
        return 1;

        case OPCODE_NEG:
        write_text(w, S("NEG\n"));
        return 1;

        case OPCODE_EQL:
        write_text(w, S("EQL\n"));
        return 1;

        case OPCODE_NQL:
        write_text(w, S("NQL\n"));
        return 1;

        case OPCODE_LSS:
        write_text(w, S("LSS\n"));
        return 1;

        case OPCODE_GRT:
        write_text(w, S("GRT\n"));
        return 1;

        case OPCODE_ADD:
        write_text(w, S("ADD\n"));
        return 1;

        case OPCODE_SUB:
        write_text(w, S("SUB\n"));
        return 1;

        case OPCODE_MUL:
        write_text(w, S("MUL\n"));
        return 1;

        case OPCODE_DIV:
        write_text(w, S("DIV\n"));
        return 1;

        case OPCODE_MOD:
        write_text(w, S("MOD\n"));
        return 1;

        case OPCODE_APPEND:
        write_text(w, S("APPEND\n"));
        return 1;

        case OPCODE_INSERT1:
        write_text(w, S("INSERT1\n"));
        return 1;

        case OPCODE_INSERT2:
        write_text(w, S("INSERT2\n"));
        return 1;

        case OPCODE_SELECT:
        write_text(w, S("SELECT\n"));
        return 1;

        default:
        write_text(w, S("byte "));
        write_text_s64(w, src[0]);
        return 1;
    }

    return -1;
}

static int write_program(WL_Program program, char *dst, int cap)
{
    if (program.len < 3 * sizeof(uint32_t))
        return -1;

    uint32_t magic;
    uint32_t code_len;
    uint32_t data_len;

    memcpy(&magic   , program.ptr + 0, sizeof(uint32_t));
    memcpy(&code_len, program.ptr + 4, sizeof(uint32_t));
    memcpy(&data_len, program.ptr + 8, sizeof(uint32_t));

    if (magic != WL_MAGIC)
        return -1;

    if (code_len + data_len + 3 * sizeof(uint32_t) != program.len)
        return -1;

    String code = { program.ptr + 3 * sizeof(uint32_t)           , code_len };
    String data = { program.ptr + 3 * sizeof(uint32_t) + code_len, data_len };

    Writer w = { dst, cap, 0 };

    int cur = 0;
    while (cur < code.len) {
        write_text_s64(&w, cur);
        write_text(&w, S(": "));
        int ret = write_instr(&w, code.ptr + cur, code.len - cur, data);
        if (ret < 0) return -1;
        cur += ret;
    }

    return w.len;
}

void wl_dump_program(WL_Program program)
{
    char buf[1<<10];
    int len = write_program(program, buf, SIZEOF(buf));

    if (len < 0) {
        printf("Invalid program\n");
        return;
    }

    if (len > SIZEOF(buf)) {
        char *p = malloc(len+1);
        if (p == NULL) {
            printf("Out of memory\n");
            return;
        }
        write_program(program, p, len);
        p[len] = '\0';
        fwrite(p, 1, len, stdout);
    } else {
        fwrite(buf, 1, len, stdout);
    }
}

/////////////////////////////////////////////////////////////////////////
// COMPILER
/////////////////////////////////////////////////////////////////////////

#define FILE_LIMIT 128

typedef struct {
    String file;
    Node*  root;
    Node*  includes;
} CompiledFile;

struct WL_Compiler {

    WL_Arena*    arena;
    CompiledFile files[FILE_LIMIT];
    int          num_files;
    String       waiting_file;

    bool err;
    char msg[1<<8];
};

WL_Compiler *wl_compiler_init(WL_Arena *arena)
{
    WL_Compiler *compiler = alloc(arena, SIZEOF(WL_Compiler), _Alignof(WL_Compiler));
    if (compiler == NULL)
        return NULL;
    compiler->arena = arena;
    compiler->num_files = 0;
    compiler->waiting_file = (String) { NULL, 0 };
    compiler->err = false;
    return compiler;
}

WL_AddResult wl_compiler_add(WL_Compiler *compiler, WL_String content)
{
    if (compiler->err)
        return (WL_AddResult) { .type=WL_ADD_ERROR };

    ParseResult pres = parse((String) { content.ptr, content.len }, compiler->arena, compiler->msg, SIZEOF(compiler->msg));
    if (pres.node == NULL) {
        compiler->err = true;
        return (WL_AddResult) { .type=WL_ADD_ERROR };
    }

    CompiledFile compiled_file = {
        .file = compiler->waiting_file,
        .root = pres.node,
        .includes = pres.includes,
    };
    compiler->files[compiler->num_files++] = compiled_file;
    compiler->waiting_file = (String) { NULL, 0 };

    for (int i = 0; i < compiler->num_files; i++) {

        Node *include = compiler->files[i].includes;
        while (include) {

            ASSERT(include->type == NODE_INCLUDE);

            if (include->include_root == NULL) {
                for (int j = 0; j < compiler->num_files; j++) {
                    if (streq(include->include_path, compiler->files[j].file)) {
                        include->include_root = compiler->files[j].root;
                        break;
                    }
                }
            }

            if (include->include_root == NULL) {

                if (compiler->num_files == FILE_LIMIT) {
                    ASSERT(0); // TODO
                }

                // TODO: Make the path relative to the compiled file

                compiler->waiting_file = include->include_path;
                return (WL_AddResult) { .type=WL_ADD_AGAIN, .path={ include->include_path.ptr, include->include_path.len } };
            }

            include = include->include_next;
        }
    }

    return (WL_AddResult) { .type=WL_ADD_LINK };
}

int wl_compiler_link(WL_Compiler *compiler, WL_Program *program)
{
    if (compiler->err) return -1;

    if (compiler->num_files == 0 || compiler->waiting_file.len > 0) {
        int len = snprintf(compiler->msg, SIZEOF(compiler->msg), "Missing files in compilation unit");
        if (len > SIZEOF(compiler->msg))
            len = SIZEOF(compiler->msg)-1;
        compiler->msg[len] = '\0';
        compiler->err = true;
        return -1;
    }

    char *dst = compiler->arena->ptr + compiler->arena->cur;
    int   cap = compiler->arena->len - compiler->arena->cur;

    int len = codegen(compiler->files[0].root, dst, cap, compiler->msg, SIZEOF(compiler->msg));
    if (len < 0) {
        compiler->err = true;
        return -1;
    }
    if (len > cap) {
        int len = snprintf(compiler->msg, SIZEOF(compiler->msg), "Out of memory");
        if (len > SIZEOF(compiler->msg))
            len = SIZEOF(compiler->msg)-1;
        compiler->msg[len] = '\0';
        compiler->err = true;
        return -1;
    }

    *program = (WL_Program) { dst, len };

    compiler->arena->cur += len;
    return 0;
}

WL_String wl_compiler_error(WL_Compiler *compiler)
{
    return compiler->err
        ? (WL_String) { compiler->msg, strlen(compiler->msg) }
        : (WL_String) { NULL, 0 };
}

int wl_dump_ast(WL_Compiler *compiler, char *dst, int cap)
{
    Writer w = { dst, cap, 0 };
    for (int i = 0; i < compiler->num_files; i++) {
        write_text(&w, S("(file \""));
        write_text(&w, compiler->files[i].file);
        write_text(&w, S("\" "));
        write_node(&w, compiler->files[i].root);
        write_text(&w, S(")"));
    }
    return w.len;
}

/////////////////////////////////////////////////////////////////////////
// OBJECT MODEL
/////////////////////////////////////////////////////////////////////////

typedef enum {
    TYPE_NONE,
    TYPE_BOOL,
    TYPE_INT,
    TYPE_FLOAT,
    TYPE_STRING,
    TYPE_ARRAY,
    TYPE_MAP,
    TYPE_ERROR,
} Type;

#define TAG_ERROR 0
#define TAG_POSITIVE_INT 1
#define TAG_NEGATIVE_INT 2
#define TAG_BOOL 3
#define TAG_NONE 4
#define TAG_PTR  5

#define VALUE_NONE  ((0 << 3) | TAG_NONE)
#define VALUE_TRUE  ((0 << 3) | TAG_BOOL)
#define VALUE_FALSE ((1 << 3) | TAG_BOOL)
#define VALUE_ERROR ((0 << 3) | TAG_ERROR)

typedef uint64_t Value;

typedef struct Extension Extension;
struct Extension {
    Extension *next;
    int count;
    int capacity;
    Value vals[];
};

typedef struct {
    Type  type;
    int   count;
    int   capacity;
    Extension *ext;
    Value vals[];
} AggregateValue;

typedef struct {
    Type   type;
    double raw;
} FloatValue;

typedef struct {
    Type    type;
    int64_t raw;
} IntValue;

typedef struct {
    Type type;
    int  len;
    char data[];
} StringValue;

static int value_convert_to_str(Value v, char *dst, int cap);

static Type value_type(Value v)
{
    switch (v & 7) {
        case TAG_ERROR: return TYPE_ERROR;
        case TAG_POSITIVE_INT: return TYPE_INT;
        case TAG_NEGATIVE_INT: return TYPE_INT;
        case TAG_BOOL : return TYPE_BOOL;
        case TAG_NONE : return TYPE_NONE;
        case TAG_PTR  : return *(Type*) (v & ~(Value) 7); break;
    }
    return TAG_ERROR;
}

static int64_t value_to_s64(Value v)
{
    ASSERT(value_type(v) == TYPE_INT);

    if ((v & 7) == TAG_POSITIVE_INT)
        return (int64_t) (v >> 3);

    if ((v & 7) == TAG_NEGATIVE_INT)
        return (int64_t) ((v >> 3) | ((Value) 7 << 61));

    IntValue *p = (IntValue*) (v & ~(Value) 7);
    return p->raw;
}

static double value_to_f64(Value v)
{
    ASSERT(value_type(v) == TYPE_FLOAT);

    FloatValue *p = (FloatValue*) (v & ~(Value) 7);
    return p->raw;
}

static String value_to_str(Value v)
{
    ASSERT(value_type(v) == TYPE_STRING);

    StringValue *p = (StringValue*) (v & ~(Value) 7);
    return (String) { p->data, p->len };
}

/*

2 bits -> 2^2 = 4

00000   0    .
00001   1    .
00010   2    .
00011   3    .
00100   4    .
00101   5    .
00110   6    .
00111   7    .
01000   8
01001   9
01010   10
01011   11
01100   12
01101   13
01110   14
01111   15
10000  -16
10001  -15
10010  -14
10011  -13
10100  -12
10101  -11
10110  -10
10111  -9
11000  -8    .
11001  -7    .
11010  -6    .
11011  -5    .
11100  -4    .
11101  -3    .
11110  -2    .
11111  -1    .

*/

static Value value_from_s64(int64_t x, WL_Arena *arena, Error *err)
{
    Value v = (Value) x;
    Value upper3bits = v >> 61;

    if (upper3bits == 0)
        return (v << 3) | TAG_POSITIVE_INT;

    if (upper3bits == 7)
        return (v << 3) | TAG_NEGATIVE_INT;

    IntValue *p = alloc(arena, SIZEOF(IntValue), _Alignof(IntValue));
    if (p == NULL) {
        REPORT(err, "Out of memory");
        return VALUE_ERROR;
    }

    p->type = TYPE_INT;
    p->raw  = x;

    ASSERT(((Value) p & 7) == 0);
    return ((Value) p) | TAG_PTR;
}

static Value value_from_f64(double x, WL_Arena *arena, Error *err)
{
    FloatValue *v = alloc(arena, SIZEOF(FloatValue), _Alignof(FloatValue));
    if (v == NULL) {
        REPORT(err, "Out of memory");
        return VALUE_ERROR;
    }

    v->type = TYPE_FLOAT;
    v->raw  = x;

    ASSERT(((uintptr_t) v & 7) == 0);
    return ((Value) v) | TAG_PTR;
}

static Value value_from_str(String x, WL_Arena *arena, Error *err)
{
    StringValue *v = alloc(arena, SIZEOF(StringValue) + x.len, 8);
    if (v == NULL) {
        REPORT(err, "Out of memory");
        return VALUE_ERROR;
    }

    v->type = TYPE_STRING;
    v->len = x.len;
    memcpy(v->data, x.ptr, x.len);

    ASSERT(((uintptr_t) v & 7) == 0);
    return ((Value) v) | TAG_PTR;
}

static Value aggregate_empty(bool map, uint32_t cap, WL_Arena *arena, Error *err)
{
    AggregateValue *v = alloc(arena, SIZEOF(AggregateValue) + 2 * cap * SIZEOF(Value), MAX(_Alignof(AggregateValue), 8));
    if (v == NULL) {
        REPORT(err, "Out of memory");
        return VALUE_ERROR;
    }

    v->type = map ? TYPE_MAP : TYPE_ARRAY;
    v->count = 0;
    v->capacity = cap;
    v->ext = NULL;

    ASSERT(((uintptr_t) v & 7) == 0);
    return ((Value) v) | TAG_PTR;
}

static int64_t aggregate_length(AggregateValue *agg)
{
    int64_t n = agg->count;

    Extension *ext = agg->ext;
    while (ext) {
        n += ext->count;
        ext = ext->next;
    }

    return n;
}

static Value *aggregate_select_by_raw_index(AggregateValue *agg, int64_t idx)
{
    ASSERT(agg->type == TYPE_ARRAY || agg->type == TYPE_MAP);

    if (idx < 0 || idx >= aggregate_length(agg))
        return NULL;

    if (idx < agg->count)
        return &agg->vals[idx];

    idx -= agg->count;
    Extension *ext = agg->ext;
    while (ext) {
        if (idx < ext->count)
            return &ext->vals[idx];
        idx -= ext->count;
        ext = ext->next;
    }

    UNREACHABLE;
    return NULL;
}

static bool value_eql(Value a, Value b);

static Value *aggregate_select(AggregateValue *agg, Value key)
{
    if (agg->type == TYPE_MAP) {

        for (int i = 0; i < agg->count; i += 2)
            if (value_eql(agg->vals[i], key))
                return &agg->vals[i+1];

        Extension *ext = agg->ext;
        while (ext) {
            for (int i = 0; i < ext->count; i += 2)
                if (value_eql(ext->vals[i], key)) {
                    return &ext->vals[i+1];
                }
            ext = ext->next;
        }

        return NULL;
    
    } else {

        ASSERT(agg->type == TYPE_ARRAY);

        if (value_type(key) != TYPE_INT)
            return NULL;
        int64_t idx = value_to_s64(key);

        return aggregate_select_by_raw_index(agg, idx);
    }
}

static bool aggregate_append(AggregateValue *agg, Value v1, Value v2, WL_Arena *arena)
{
    if (agg->count < agg->capacity) {
        agg->vals[agg->count++] = v1;
        if (v2 != VALUE_ERROR)
            agg->vals[agg->count++] = v2;
        return true;
    }

    Extension *tail = agg->ext;
    if (tail)
        while (tail->next)
            tail = tail->next;

    Extension *ext;
    if (tail == NULL || tail->count == tail->capacity) {

        int cap = 8;
        ext = alloc(arena, SIZEOF(Extension) + cap * sizeof(Value), ALIGNOF(Extension));
        if (ext == NULL)
            return false;

        ext->count = 0;
        ext->capacity = cap;
        ext->next = NULL;

        if (tail)
            tail->next = ext;
        else
            agg->ext = ext;

    } else
        ext = tail;

    ext->vals[ext->count++] = v1;
    if (v2 != VALUE_ERROR)
        ext->vals[ext->count++] = v2;
    return true;
}

static Value value_empty_map(uint32_t cap, WL_Arena *arena, Error *err)
{
    return aggregate_empty(true, 2 * cap, arena, err);
}

static Value value_empty_array(uint32_t cap, WL_Arena *arena, Error *err)
{
    return aggregate_empty(false, cap, arena, err);
}

static int64_t value_length(Value set)
{
    ASSERT(value_type(set) == TYPE_MAP || value_type(set) == TYPE_ARRAY);
    AggregateValue *agg = (void*) (set & ~(Value) 7);
    int64_t len = aggregate_length(agg);
    if (agg->type == TYPE_MAP)
        len /= 2;
    return len;
}

static bool value_insert(Value set, Value key, Value val, WL_Arena *arena, Error *err)
{
    Type t = value_type(set);
    if (t != TYPE_MAP && t != TYPE_ARRAY) {
        REPORT(err, "Invalid insertion on non-map and non-array value");
        return false;
    }
    AggregateValue *agg = (void*) (set & ~(Value) 7);

    Value *dst = aggregate_select(agg, key);
    if (dst != NULL) {
        *dst = val;
        return true;
    }

    if (agg->type == TYPE_ARRAY && value_type(key) != TYPE_INT) {
        REPORT(err, "Invalid index used in array access");
        return false;
    }

    if (!aggregate_append(agg, key, val, arena)) {
        REPORT(err, "Out of memory");
        return false;
    }

    return true;
}

static Value value_select(Value set, Value key, Error *err)
{
    Type t = value_type(set);
    if (t != TYPE_MAP && t != TYPE_ARRAY) {
        REPORT(err, "Invalid selection from non-map and non-array value");
        return VALUE_ERROR;
    }
    AggregateValue *agg = (void*) (set & ~(Value) 7);

    Value *dst = aggregate_select(agg, key);
    if (dst) return *dst;

    if (agg->type == TYPE_ARRAY && value_type(key) != TYPE_INT) {
        REPORT(err, "Invalid index used in array access");
        return VALUE_ERROR;
    }

    char key_buf[1<<8];
    int key_len = value_convert_to_str(key, key_buf, SIZEOF(key_buf));
    if (key_len > SIZEOF(key_buf)-1)
        key_len = SIZEOF(key_buf)-1;
    key_buf[key_len] = '\0';

    char set_buf[1<<8];
    int set_len = value_convert_to_str(set, set_buf, SIZEOF(set_buf));
    if (set_len > SIZEOF(set_buf)-1)
        set_len = SIZEOF(set_buf)-1;
    set_buf[set_len] = '\0';

    REPORT(err, "Invalid key '%s' used in access to map '%s'", key_buf, set_buf);
    return VALUE_ERROR;
}

static Value value_select_by_index(Value set, int64_t idx, Error *err)
{
    Type t = value_type(set);
    if (t != TYPE_MAP && t != TYPE_ARRAY) {
        REPORT(err, "Invalid selection from non-map and non-array value");
        return VALUE_ERROR;
    }
    AggregateValue *agg = (void*) (set & ~(Value) 7);

    if (agg->type == TYPE_MAP)
        idx *= 2;

    Value *src = aggregate_select_by_raw_index(agg, idx);
    if (src == NULL) {
        REPORT(err, "Invalid selection from non-map and non-array value");
        return VALUE_ERROR;
    }

    return *src;
}

static bool value_append(Value set, Value val, WL_Arena *arena, Error *err)
{
    Type t = value_type(set);
    if (t != TYPE_ARRAY) {
        REPORT(err, "Invalid append on non-array value");
        return false;
    }
    AggregateValue *agg = (void*) (set & ~(Value) 7);

    if (!aggregate_append(agg, val, VALUE_ERROR, arena)) {
        REPORT(err, "Out of memory");
        return false;
    }

    return true;
}

static bool value_eql(Value a, Value b)
{
    Type t1 = value_type(a);
    Type t2 = value_type(b);

    if (t1 != t2)
        return false;

    switch (t1) {

        case TYPE_NONE:
        return true;

        case TYPE_BOOL:
        return a == b;

        case TYPE_INT:
        return value_to_s64(a) == value_to_s64(b);

        case TYPE_FLOAT:
        return value_to_f64(a) == value_to_f64(b);

        case TYPE_MAP:
        return false; // TODO

        case TYPE_ARRAY:
        return false; // TODO

        case TYPE_STRING:
        return streq(value_to_str(a), value_to_str(b));

        case TYPE_ERROR:
        return true;
    }

    return false;
}

static bool value_nql(Value a, Value b)
{
    return !value_eql(a, b);
}

#define TYPE_PAIR(X, Y) (((uint16_t) (X) << 16) | (uint16_t) (Y))

bool value_greater(Value a, Value b, Error *err)
{
    Type t1 = value_type(a);
    Type t2 = value_type(b);
    switch (TYPE_PAIR(t1, t2)) {
        case TYPE_PAIR(TYPE_INT  , TYPE_INT  ): return value_to_s64(a) > value_to_s64(b);
        case TYPE_PAIR(TYPE_INT  , TYPE_FLOAT): return value_to_s64(a) > value_to_f64(b);
        case TYPE_PAIR(TYPE_FLOAT, TYPE_INT  ): return value_to_f64(a) > value_to_s64(b);
        case TYPE_PAIR(TYPE_FLOAT, TYPE_FLOAT): return value_to_f64(a) > value_to_f64(b);
        default:break;
    }
    REPORT(err, "Invalid '>' operation on non-numeric type");
    return false;
}

bool value_lower(Value a, Value b, Error *err)
{
    Type t1 = value_type(a);
    Type t2 = value_type(b);
    switch (TYPE_PAIR(t1, t2)) {
        case TYPE_PAIR(TYPE_INT  , TYPE_INT  ): return value_to_s64(a) < value_to_s64(b);
        case TYPE_PAIR(TYPE_INT  , TYPE_FLOAT): return value_to_s64(a) < value_to_f64(b);
        case TYPE_PAIR(TYPE_FLOAT, TYPE_INT  ): return value_to_f64(a) < value_to_s64(b);
        case TYPE_PAIR(TYPE_FLOAT, TYPE_FLOAT): return value_to_f64(a) < value_to_f64(b);
        default:break;
    }
    REPORT(err, "Invalid '<' operation on non-numeric type");
    return false;
}

static Value value_neg(Value v, WL_Arena *arena, Error *err)
{
    Type t = value_type(v);
    if (t == TYPE_INT)
        return value_from_s64(-value_to_s64(v), arena, err); // TODO: overflow
    
    if (t == TYPE_FLOAT)
        return value_from_f64(-value_to_f64(v), arena, err);

    REPORT(err, "Invalid '-' operation on non-numeric type");
    return VALUE_ERROR;
}

static Value value_add(Value v1, Value v2, WL_Arena *arena, Error *err)
{
    Type t1 = value_type(v1);
    Type t2 = value_type(v2);

    Value r;
    switch (TYPE_PAIR(t1, t2)) {

        case TYPE_PAIR(TYPE_INT, TYPE_INT):
        {
            int64_t u = value_to_s64(v1);
            int64_t v = value_to_s64(v2);
            // TODO: check overflow and underflow
            r = value_from_s64(u + v, arena, err);
        }
        break;

        case TYPE_PAIR(TYPE_INT, TYPE_FLOAT):
        {
            double u = (double) value_to_s64(v1);
            double v = value_to_f64(v2);
            r = value_from_f64(u + v, arena, err);
        }
        break;

        case TYPE_PAIR(TYPE_FLOAT, TYPE_INT):
        {
            double u = value_to_f64(v1);
            double v = (double) value_to_s64(v2);
            r = value_from_f64(u + v, arena, err);
        }
        break;

        case TYPE_PAIR(TYPE_FLOAT, TYPE_FLOAT):
        {
            double u = value_to_f64(v1);
            double v = value_to_f64(v2);
            // TODO: check overflow and underflow
            r = value_from_f64(u + v, arena, err);
        }
        break;

        default:
        REPORT(err, "Invalid operation '+' on non-numeric value");
        return VALUE_ERROR;
    }

    return r;
}

static Value value_sub(Value v1, Value v2, WL_Arena *arena, Error *err)
{
    Type t1 = value_type(v1);
    Type t2 = value_type(v2);

    Value r;
    switch (TYPE_PAIR(t1, t2)) {

        case TYPE_PAIR(TYPE_INT, TYPE_INT):
        {
            int64_t u = value_to_s64(v1);
            int64_t v = value_to_s64(v2);
            // TODO: check overflow and underflow
            r = value_from_s64(u - v, arena, err);
        }
        break;

        case TYPE_PAIR(TYPE_INT, TYPE_FLOAT):
        {
            double u = (double) value_to_s64(v1);
            double v = value_to_f64(v2);
            r = value_from_f64(u - v, arena, err);
        }
        break;

        case TYPE_PAIR(TYPE_FLOAT, TYPE_INT):
        {
            double u = value_to_f64(v1);
            double v = (double) value_to_s64(v2);
            r = value_from_f64(u - v, arena, err);
        }
        break;

        case TYPE_PAIR(TYPE_FLOAT, TYPE_FLOAT):
        {
            double u = value_to_f64(v1);
            double v = value_to_f64(v2);
            // TODO: check overflow and underflow
            r = value_from_f64(u - v, arena, err);
        }
        break;

        default:
        REPORT(err, "Invalid operation '-' on non-numeric value");
        return VALUE_ERROR;
    }

    return r;
}

static Value value_mul(Value v1, Value v2, WL_Arena *arena, Error *err)
{
    Type t1 = value_type(v1);
    Type t2 = value_type(v2);

    Value r;
    switch (TYPE_PAIR(t1, t2)) {

        case TYPE_PAIR(TYPE_INT, TYPE_INT):
        {
            int64_t u = value_to_s64(v1);
            int64_t v = value_to_s64(v2);
            // TODO: check overflow and underflow
            r = value_from_s64(u * v, arena, err);
        }
        break;

        case TYPE_PAIR(TYPE_INT, TYPE_FLOAT):
        {
            double u = (double) value_to_s64(v1);
            double v = value_to_f64(v2);
            r = value_from_f64(u * v, arena, err);
        }
        break;

        case TYPE_PAIR(TYPE_FLOAT, TYPE_INT):
        {
            double u = value_to_f64(v1);
            double v = (double) value_to_s64(v2);
            r = value_from_f64(u * v, arena, err);
        }
        break;

        case TYPE_PAIR(TYPE_FLOAT, TYPE_FLOAT):
        {
            double u = value_to_f64(v1);
            double v = value_to_f64(v2);
            // TODO: check overflow and underflow
            r = value_from_f64(u * v, arena, err);
        }
        break;

        default:
        REPORT(err, "Invalid operation '*' on non-numeric value");
        return VALUE_ERROR;
    }

    return r;
}

static Value value_div(Value v1, Value v2, WL_Arena *arena, Error *err)
{
    Type t1 = value_type(v1);
    Type t2 = value_type(v2);

    Value r;
    switch (TYPE_PAIR(t1, t2)) {

        case TYPE_PAIR(TYPE_INT, TYPE_INT):
        {
            // TODO: check division by 0

            int64_t u = value_to_s64(v1);
            int64_t v = value_to_s64(v2);
            r = value_from_s64(u / v, arena, err);
        }
        break;

        case TYPE_PAIR(TYPE_INT, TYPE_FLOAT):
        {
            // TODO: check division by 0

            double u = (double) value_to_s64(v1);
            double v = value_to_f64(v2);
            r = value_from_f64(u / v, arena, err);
        }
        break;

        case TYPE_PAIR(TYPE_FLOAT, TYPE_INT):
        {
            // TODO: check division by 0

            double u = value_to_f64(v1);
            double v = (double) value_to_s64(v2);
            r = value_from_f64(u / v, arena, err);
        }
        break;

        case TYPE_PAIR(TYPE_FLOAT, TYPE_FLOAT):
        {
            double u = value_to_f64(v1);
            double v = value_to_f64(v2);
            r = value_from_f64(u / v, arena, err);
        }
        break;

        default:
        REPORT(err, "Invalid operation '/' on non-numeric value");
        return VALUE_ERROR;
    }

    return r;
}

static Value value_mod(Value v1, Value v2, WL_Arena *arena, Error *err)
{
    Type t1 = value_type(v1);
    Type t2 = value_type(v2);

    if (t1 != TYPE_INT || t2 != TYPE_INT) {
        REPORT(err, "Invalid operation '%%' on non-integer value");
        return VALUE_ERROR;
    }

    int64_t u = value_to_s64(v1);
    int64_t v = value_to_s64(v2);
    Value r = value_from_s64(u % v, arena, err);
    return r;
}

static void value_convert_to_str_inner(Writer *w, Value v)
{
    Type t = value_type(v);
    switch (t) {

        case TYPE_NONE:
        break;

        case TYPE_BOOL:
        write_text(w, v == VALUE_TRUE ? S("true") : S("false"));
        break;

        case TYPE_INT:
        write_text_s64(w, value_to_s64(v));
        break;

        case TYPE_FLOAT:
        write_text_f64(w, value_to_f64(v));
        break;

        case TYPE_STRING:
        write_text(w, value_to_str(v));
        break;

        case TYPE_ARRAY:
        {
            AggregateValue *agg = (void*) (v & ~(Value) 7);
            for (int i = 0; i < agg->count; i++)
                value_convert_to_str_inner(w, agg->vals[i]);
            Extension *ext = agg->ext;
            while (ext) {
                for (int i = 0; i < ext->count; i++)
                    value_convert_to_str_inner(w, ext->vals[i]);
                ext = ext->next;
            }
        }
        break;

        case TYPE_MAP:
        write_text(w, S("<map>"));
        break;

        case TYPE_ERROR:
        break;
    }
}

static int value_convert_to_str(Value v, char *dst, int cap)
{
    Writer w = { dst, cap, 0};
    value_convert_to_str_inner(&w, v);
    return w.len;
}

static Value value_escape_packed(Value v, WL_Arena *arena, Error *err);

static int array_escape(Value v, Value *out, int max, WL_Arena *arena, Error *err)
{
    Value v2 = value_empty_array(value_length(v), arena, err);
    if (v2 == VALUE_ERROR) return -1;

    AggregateValue *src = (void*) (v  & ~(Value) 7);

    for (int i = 0; i < src->count; i++) {

        Value child = src->vals[i];

        Value escaped_child = value_escape_packed(child, arena, err);
        if (escaped_child == VALUE_ERROR)
            return -1;

        if (!value_append(v2, escaped_child, arena, err))
            return -1;
    }
    Extension *ext = src->ext;
    while (ext) {
        for (int i = 0; i < ext->count; i++) {

            Value child = src->vals[i];

            Value escaped_child = value_escape_packed(child, arena, err);
            if (escaped_child == VALUE_ERROR)
                return -1;

            if (!value_append(v2, escaped_child, arena, err))
                return -1;
        }
        ext = ext->next;
    }

    if (max == 0)
        return -1;
    out[0] = v2;
    return 1;
}

static int string_escape(Value v, Value *out, int max, WL_Arena *arena, Error *err)
{
    String s = value_to_str(v);

    int i = 0;
    int num = 0;
    for (;;) {

        int off = i;
        while (i < s.len
            && s.ptr[i] != '<'
            && s.ptr[i] != '>'
            && s.ptr[i] != '&'
            && s.ptr[i] != '"'
            && s.ptr[i] != '\'')
            i++;
        String substr = { s.ptr + off, i - off };

        Value escaped_v = value_from_str(substr, arena, err); // TODO: don't copy the string
        if (escaped_v == VALUE_ERROR) return -1;

        if (num == max) {
            REPORT(err, "Escape buffer limit reached");
            return -1;
        }
        out[num++] = escaped_v;

        if (i == s.len) break;

        switch (s.ptr[i++]) {
            case '<' : escaped_v = value_from_str(S("&lt;"),   arena, err); break; // TODO: don't come these strings
            case '>' : escaped_v = value_from_str(S("&gt;"),   arena, err); break;
            case '&' : escaped_v = value_from_str(S("&amp;"),  arena, err); break;
            case '"' : escaped_v = value_from_str(S("&quot;"), arena, err); break;
            case '\'': escaped_v = value_from_str(S("&#x27;"), arena, err); break;
        }
        if (escaped_v == VALUE_ERROR) return -1;

        if (num == max) {
            REPORT(err, "Escape buffer limit reached");
            return -1;
        }
        out[num++] = escaped_v;
    }

    return num;
}

static int value_escape(Value v, Value *out, int max, WL_Arena *arena, Error *err)
{
    Type t = value_type(v);

    if (t == TYPE_ARRAY)
        return array_escape(v, out, max, arena, err);

    if (t == TYPE_STRING)
        return string_escape(v, out, max, arena, err);

    if (max < 1)
        return -1;
    out[0] = v;
    return 1;
}

static Value value_escape_packed(Value v, WL_Arena *arena, Error *err)
{
    Value tmp[32];
    int num = value_escape(v, tmp, COUNT(tmp), arena, err);
    if (num < 0) return VALUE_ERROR;

    Value escaped_v;

    if (num > 1) {

        Value packed = value_empty_array(num, arena, err);
        if (packed == VALUE_ERROR)
            return VALUE_ERROR;

        for (int j = 0; j < num; j++)
            if (!value_append(packed, tmp[j], arena, err))
                return VALUE_ERROR;
        escaped_v = packed;

    } else {

        ASSERT(num == 1);
        escaped_v = tmp[0];
    }

    return escaped_v;
}

#undef TYPE_PAIR

/////////////////////////////////////////////////////////////////////////
// RUNTIME
/////////////////////////////////////////////////////////////////////////

#define MAX_STACK 1024
#define MAX_FRAMES 1024
#define MAX_GROUPS 8

typedef struct {
    int retaddr;
    int varbase;
} Frame;

typedef enum {
    RUNTIME_BEGIN,
    RUNTIME_LOOP,
    RUNTIME_DONE,
    RUNTIME_ERROR,
    RUNTIME_OUTPUT,
    RUNTIME_SYSVAR,
    RUNTIME_SYSCALL,
} RuntimeState;

struct WL_Runtime {

    RuntimeState state;

    String code;
    String data;
    int off;

    int vars;
    int stack;
    Value values[MAX_STACK];

    int num_frames;
    Frame frames[MAX_FRAMES];

    int num_groups;
    int groups[MAX_GROUPS];

    WL_Arena *arena;

    char  msg[128];
    Error err;

    int stack_before_user;
    String str_for_user;
    int num_output;
    int cur_output;
    char buf[128];
};

WL_Runtime *wl_runtime_init(WL_Arena *arena, WL_Program program)
{
    if (program.len < 3 * sizeof(uint32_t))
        return NULL;

    uint32_t magic;
    uint32_t code_len;
    uint32_t data_len;

    memcpy(&magic   , program.ptr + 0, sizeof(uint32_t));
    memcpy(&code_len, program.ptr + 4, sizeof(uint32_t));
    memcpy(&data_len, program.ptr + 8, sizeof(uint32_t));

    if (magic != WL_MAGIC)
        return NULL;

    String code = { program.ptr + sizeof(uint32_t) * 3           , code_len };
    String data = { program.ptr + sizeof(uint32_t) * 3 + code_len, data_len };

    WL_Runtime *rt = alloc(arena, SIZEOF(WL_Runtime), ALIGNOF(WL_Runtime));
    if (rt == NULL)
        return NULL;

    *rt = (WL_Runtime) {
        .state      = RUNTIME_BEGIN,
        .code       = code,
        .data       = data,
        .off        = 0,
        .stack      = 0,
        .vars       = MAX_STACK-1,
        .num_frames = 0,
        .arena      = arena,
        .err        = { NULL, 0, false },
    };
    rt->err.buf = rt->msg;
    rt->err.cap = SIZEOF(rt->msg);

    rt->frames[rt->num_frames++] = (Frame) {
        .retaddr = 0,
        .varbase = rt->vars,
    };

    return rt;
}

WL_String wl_runtime_error(WL_Runtime *rt)
{
    return rt->err.yes
        ? (WL_String) { rt->msg, strlen(rt->msg) }
        : (WL_String) { NULL, 0 };
}

static void rt_read_mem(WL_Runtime *r, void *dst, int len)
{
    ASSERT(r->off + len <= r->code.len);
    memcpy(dst, r->code.ptr + r->off, len);
    r->off += len;
}

static uint8_t rt_read_u8(WL_Runtime *rt)
{
    ASSERT(rt->state == RUNTIME_LOOP);

    uint8_t x;
    rt_read_mem(rt, &x, SIZEOF(x));

    return x;
}

static uint32_t rt_read_u32(WL_Runtime *rt)
{
    ASSERT(rt->state == RUNTIME_LOOP);

    uint32_t x;
    rt_read_mem(rt, &x, SIZEOF(x));

    return x;
}

static int64_t rt_read_s64(WL_Runtime *rt)
{
    ASSERT(rt->state == RUNTIME_LOOP);

    int64_t x;
    rt_read_mem(rt, &x, SIZEOF(x));

    return x;
}

static double rt_read_f64(WL_Runtime *rt)
{
    ASSERT(rt->state == RUNTIME_LOOP);

    double x;
    rt_read_mem(rt, &x, SIZEOF(x));

    return x;
}

static String rt_read_str(WL_Runtime *rt)
{
    ASSERT(rt->state == RUNTIME_LOOP);
    uint32_t off = rt_read_u32(rt);
    uint32_t len = rt_read_u32(rt);
    ASSERT(off + len <= (uint32_t) rt->data.len);
    return (String) { rt->data.ptr + off, len };
}

static Value *rt_variable(WL_Runtime *rt, uint8_t x)
{
    ASSERT(rt->num_frames > 0);

    Frame *frame = &rt->frames[rt->num_frames-1];

    ASSERT(frame->varbase - x >= 0
        && frame->varbase - x < MAX_STACK);

    return &rt->values[frame->varbase - x];
}

static int values_usage(WL_Runtime *rt)
{
    int num_vars = (MAX_STACK - rt->vars - 1);
    return rt->stack + num_vars;
}

static bool rt_check_stack(WL_Runtime *rt, int min)
{
    if (MAX_STACK - values_usage(rt) < min) {
        REPORT(&rt->err, "Out of stack");
        rt->state = RUNTIME_ERROR;
        return false;
    }
    return true;
}

static bool rt_push_frame(WL_Runtime *rt, uint8_t args)
{
    if (rt->num_frames == MAX_FRAMES) {
        REPORT(&rt->err, "Call stack limit reached");
        rt->state = RUNTIME_ERROR;
        return false;
    }

    if (MAX_STACK - values_usage(rt) < args) {
        REPORT(&rt->err, "Stack limit reached");
        rt->state = RUNTIME_ERROR;
        return false;
    }

    Frame *frame = &rt->frames[rt->num_frames++];
    frame->retaddr = rt->off;
    frame->varbase = rt->vars;

    for (int i = 0; i < args; i++)
        rt->values[rt->vars--] = rt->values[--rt->stack];

    return true;
}

static void rt_pop_frame(WL_Runtime *rt)
{
    ASSERT(rt->num_frames > 0);
    Frame *frame = &rt->frames[rt->num_frames-1];
    rt->off  = frame->retaddr;
    rt->vars = frame->varbase;
    rt->num_frames--;
}

static void rt_set_frame_vars(WL_Runtime *rt, uint8_t num)
{
    ASSERT(rt->num_frames > 0);
    Frame *frame = &rt->frames[rt->num_frames-1];
    int num_vars = frame->varbase - rt->vars;
    if (num_vars < num)
        for (int i = 0; i < num - num_vars; i++)
            rt->values[rt->vars - i] = VALUE_NONE;
    rt->vars = frame->varbase - num;
}

static void rt_push_group(WL_Runtime *rt)
{
    if (rt->num_groups == MAX_GROUPS) {
        REPORT(&rt->err, "Out of memory");
        rt->state = RUNTIME_ERROR;
        return;
    }
    rt->groups[rt->num_groups++] = rt->stack;
}

static void rt_pack_group(WL_Runtime *rt)
{
    if (!rt_check_stack(rt, 1))
        return;

    ASSERT(rt->num_groups > 0);
    int start = rt->groups[--rt->num_groups];
    int end = rt->stack;

    if (end - start > 1) {

        Value set = value_empty_array(end - start, rt->arena, &rt->err);
        if (set == VALUE_ERROR)
            return;

        for (int i = start; i < end; i++)
            if (!value_append(set, rt->values[i], rt->arena, &rt->err))
                return;

        rt->stack = start;
        rt->values[rt->stack++] = set;
    }
}

static void rt_pop_group(WL_Runtime *rt)
{
    ASSERT(rt->num_groups > 0);
    rt->stack = rt->groups[--rt->num_groups];
}

static void value_print(Value v)
{
    char buf[1<<8];
    int len = value_convert_to_str(v, buf, SIZEOF(buf));
    if (len < SIZEOF(buf))
        fwrite(buf, 1, len, stdout);
    else {
        len = SIZEOF(buf)-1;
        fwrite(buf, 1, len, stdout);
        fprintf(stdout, " [...]");
    }
    putc('\n', stdout);
    fflush(stdout);
}

static void step(WL_Runtime *rt)
{
    switch (rt_read_u8(rt)) {

        Type t;
        Value v1;
        Value v2;
        Value v3;
        uint32_t o;
        uint8_t  b1;
        uint8_t  b2;
        uint8_t  b3;
        int64_t  i;
        double   f;
        String   s;

        case OPCODE_NOPE:
        break;

        case OPCODE_JUMP:
        rt->off = rt_read_u32(rt);
        break;

        case OPCODE_JIFP:
        ASSERT(rt->stack > 0);
        o = rt_read_u32(rt);
        v1 = rt->values[--rt->stack];
        if (v1 == VALUE_FALSE)
            rt->off = o;
        else if (value_type(v1) != TYPE_BOOL) {
            REPORT(&rt->err, "Invalid non-boolean condition");
            rt->state = RUNTIME_ERROR;
            break;
        }
        break;

        case OPCODE_VARS:
        b1 = rt_read_u8(rt);
        rt_set_frame_vars(rt, b1);
        break;

        case OPCODE_OUTPUT:
        if (rt->stack > 0) {
            rt->cur_output = 0;
            rt->num_output = rt->stack;
            rt->state = RUNTIME_OUTPUT;
        }
        break;

        case OPCODE_SYSVAR:
        s = rt_read_str(rt);
        rt_push_frame(rt, 0);
        rt->stack_before_user = rt->stack;
        rt->str_for_user = s;
        rt->state = RUNTIME_SYSVAR;
        break;

        case OPCODE_SYSCALL:
        b1 = rt_read_u8(rt);
        s = rt_read_str(rt);
        rt_push_frame(rt, b1);
        rt->stack_before_user = rt->stack;
        rt->str_for_user = s;
        rt->state = RUNTIME_SYSCALL;
        break;

        case OPCODE_CALL:
        b1 = rt_read_u8(rt);
        o = rt_read_u32(rt);
        rt_push_frame(rt, b1);
        rt->off = o;
        break;

        case OPCODE_RET:
        rt_pop_frame(rt);
        break;

        case OPCODE_GROUP:
        rt_push_group(rt);
        break;

        case OPCODE_ESCAPE:
        {
            ASSERT(rt->num_groups > 0);
            int start = rt->groups[--rt->num_groups];
            int end = rt->stack;

            Value escaped[256];
            int num_escaped = 0;

            for (int i = start; i < end; i++) {
                Value v = rt->values[i];
                int num = value_escape(v, escaped + num_escaped, COUNT(escaped) - num_escaped, rt->arena, &rt->err);
                if (num < 0) break;
                num_escaped += num;
            }

            if (num_escaped > COUNT(escaped)) {
                REPORT(&rt->err, "Escape buffer limit reached");
                rt->state = RUNTIME_ERROR;
                break;
            }

            rt->stack = start;
            if (!rt_check_stack(rt, num_escaped)) break;

            for (int i = 0; i < num_escaped; i++)
                rt->values[rt->stack + i] = escaped[i];
            rt->stack += num_escaped;
        }
        break;

        case OPCODE_PACK:
        rt_pack_group(rt);
        break;

        case OPCODE_GPOP:
        rt_pop_group(rt);
        break;

        case OPCODE_FOR:
        b1 = rt_read_u8(rt);
        b2 = rt_read_u8(rt);
        b3 = rt_read_u8(rt);
        o  = rt_read_u32(rt);

        v1 = *rt_variable(rt, b3);
        ASSERT(value_type(v1) == TYPE_INT);
        i = value_to_s64(v1);

        v2 = *rt_variable(rt, b1);

        if (value_length(v2)-1 == i) {
            rt->off = o;
            break;
        }
        i++;

        v1 = value_select_by_index(v2, i, &rt->err);
        if (v1 == VALUE_ERROR) break;

        *rt_variable(rt, b2) = v1;

        v1 = value_from_s64(i, rt->arena, &rt->err); // TODO: this could be in-place
        *rt_variable(rt, b3) = v1;
        break;

        case OPCODE_EXIT:
        rt->state = RUNTIME_DONE;
        break;

        case OPCODE_POP:
        ASSERT(rt->stack > 0);
        rt->stack--;
        break;

        case OPCODE_SETV:
        ASSERT(rt->stack > 0);
        b1 = rt_read_u8(rt);
        *rt_variable(rt, b1) =  rt->values[rt->stack-1];
        break;

        case OPCODE_PUSHV:
        if (!rt_check_stack(rt, 1)) break;
        b1 = rt_read_u8(rt);
        rt->values[rt->stack++] = *rt_variable(rt, b1);
        break;

        case OPCODE_PUSHI:
        if (!rt_check_stack(rt, 1)) break;
        i = rt_read_s64(rt);
        v1 = value_from_s64(i, rt->arena, &rt->err);
        rt->values[rt->stack++] = v1;
        break;

        case OPCODE_PUSHF:
        if (!rt_check_stack(rt, 1)) break;
        f = rt_read_f64(rt);
        v1 = value_from_f64(f, rt->arena, &rt->err);
        rt->values[rt->stack++] = v1;
        break;

        case OPCODE_PUSHS:
        if (!rt_check_stack(rt, 1)) break;
        s = rt_read_str(rt);
        v1 = value_from_str(s, rt->arena, &rt->err);
        rt->values[rt->stack++] = v1;
        break;

        case OPCODE_PUSHA:
        if (!rt_check_stack(rt, 1)) break;
        o = rt_read_u32(rt);
        v1 = value_empty_array(o, rt->arena, &rt->err);
        rt->values[rt->stack++] = v1;
        break;

        case OPCODE_PUSHM:
        if (!rt_check_stack(rt, 1)) break;
        o = rt_read_u32(rt);
        v1 = value_empty_map(o, rt->arena, &rt->err);
        rt->values[rt->stack++] = v1;
        break;

        case OPCODE_PUSHN:
        if (!rt_check_stack(rt, 1)) break;
        rt->values[rt->stack++] = VALUE_NONE;
        break;

        case OPCODE_PUSHT:
        if (!rt_check_stack(rt, 1)) break;
        rt->values[rt->stack++] = VALUE_TRUE;
        break;

        case OPCODE_PUSHFL:
        if (!rt_check_stack(rt, 1)) break;
        rt->values[rt->stack++] = VALUE_FALSE;
        break;

        case OPCODE_LEN:
        ASSERT(rt->stack > 0);
        v1 = rt->values[rt->stack-1];
        t = value_type(v1);
        if (t != TYPE_ARRAY && t != TYPE_MAP) {
            REPORT(&rt->err, "Invalid operation 'len' on non-aggregate value");
            rt->state = RUNTIME_ERROR;
            break;
        }
        v2 = value_from_s64(value_length(v1), rt->arena, &rt->err);
        rt->values[rt->stack-1] = v2;
        break;

        case OPCODE_NEG:
        ASSERT(rt->stack > 0);
        v1 = rt->values[rt->stack-1];
        v2 = value_neg(v1, rt->arena, &rt->err);
        rt->values[rt->stack-1] = v2;
        break;

        case OPCODE_EQL:
        ASSERT(rt->stack > 1);
        v1 = rt->values[--rt->stack];
        v2 = rt->values[--rt->stack];
        v3 = value_eql(v2, v1) ? VALUE_TRUE : VALUE_FALSE;
        rt->values[rt->stack++] = v3;
        break;

        case OPCODE_NQL:
        ASSERT(rt->stack > 1);
        v1 = rt->values[--rt->stack];
        v2 = rt->values[--rt->stack];
        v3 = value_nql(v2, v1) ? VALUE_TRUE : VALUE_FALSE;
        rt->values[rt->stack++] = v3;
        break;

        case OPCODE_LSS:
        ASSERT(rt->stack > 1);
        v1 = rt->values[--rt->stack];
        v2 = rt->values[--rt->stack];
        v3 = value_lower(v2, v1, &rt->err) ? VALUE_TRUE : VALUE_FALSE;
        rt->values[rt->stack++] = v3;
        break;

        case OPCODE_GRT:
        ASSERT(rt->stack > 1);
        v1 = rt->values[--rt->stack];
        v2 = rt->values[--rt->stack];
        v3 = value_greater(v2, v1, &rt->err) ? VALUE_TRUE : VALUE_FALSE;
        rt->values[rt->stack++] = v3;
        break;

        case OPCODE_ADD:
        ASSERT(rt->stack > 1);
        v1 = rt->values[--rt->stack];
        v2 = rt->values[--rt->stack];
        v3 = value_add(v2, v1, rt->arena, &rt->err);
        rt->values[rt->stack++] = v3;
        break;

        case OPCODE_SUB:
        ASSERT(rt->stack > 1);
        v1 = rt->values[--rt->stack];
        v2 = rt->values[--rt->stack];
        v3 = value_sub(v2, v1, rt->arena, &rt->err);
        rt->values[rt->stack++] = v3;
        break;

        case OPCODE_MUL:
        ASSERT(rt->stack > 1);
        v1 = rt->values[--rt->stack];
        v2 = rt->values[--rt->stack];
        v3 = value_mul(v2, v1, rt->arena, &rt->err);
        rt->values[rt->stack++] = v3;
        break;

        case OPCODE_DIV:
        ASSERT(rt->stack > 1);
        v1 = rt->values[--rt->stack];
        v2 = rt->values[--rt->stack];
        v3 = value_div(v2, v1, rt->arena, &rt->err);
        rt->values[rt->stack++] = v3;
        break;

        case OPCODE_MOD:
        ASSERT(rt->stack > 1);
        v1 = rt->values[--rt->stack];
        v2 = rt->values[--rt->stack];
        v3 = value_mod(v2, v1, rt->arena, &rt->err);
        rt->values[rt->stack++] = v3;
        break;

        case OPCODE_APPEND:
        ASSERT(rt->stack > 1);
        v2 = rt->values[--rt->stack];
        v1 = rt->values[rt->stack-1];
        value_append(v1, v2, rt->arena, &rt->err);
        break;

        case OPCODE_INSERT1:
        ASSERT(rt->stack > 2);
        v1 = rt->values[--rt->stack];
        v2 = rt->values[--rt->stack];
        v3 = rt->values[rt->stack-1];
        value_insert(v3, v1, v2, rt->arena, &rt->err);
        break;

        case OPCODE_INSERT2:
        ASSERT(rt->stack > 2);
        v1 = rt->values[--rt->stack];
        v2 = rt->values[--rt->stack];
        v3 = rt->values[rt->stack-1];
        value_insert(v2, v1, v3, rt->arena, &rt->err);
        break;

        case OPCODE_SELECT:
        ASSERT(rt->stack > 1);
        v1 = rt->values[--rt->stack];
        v2 = rt->values[--rt->stack];
        v3 = value_select(v2, v1, &rt->err);
        rt->values[rt->stack++] = v3;
        break;

        default:
        UNREACHABLE;
    }
}

WL_EvalResult wl_runtime_eval(WL_Runtime *rt)
{
    if (rt->state != RUNTIME_OUTPUT || rt->cur_output == rt->num_output) {

        switch (rt->state) {

            case RUNTIME_BEGIN:
            break;

            case RUNTIME_DONE:
            return (WL_EvalResult) { .type=WL_EVAL_DONE };

            case RUNTIME_ERROR:
            return (WL_EvalResult) { .type=WL_EVAL_ERROR };

            case RUNTIME_OUTPUT:
            rt->stack -= rt->num_output;
            break;

            case RUNTIME_SYSVAR:
            {
                ASSERT(rt->stack >= rt->stack_before_user);

                int pushed_by_user = rt->stack - rt->stack_before_user;
                if (pushed_by_user > 1) {
                    REPORT(&rt->err, "Invalid API usage");
                    rt->state = RUNTIME_ERROR;
                    return (WL_EvalResult) { .type=WL_EVAL_ERROR };
                }

                if (rt->stack == rt->stack_before_user) {
                    // User didn't push anything on the stack
                    if (!rt_check_stack(rt, 1))
                        return (WL_EvalResult) { .type=WL_EVAL_ERROR };
                    rt->values[rt->stack++] = VALUE_NONE;
                }

                rt_pop_frame(rt);
            }
            break;

            case RUNTIME_SYSCALL:
            ASSERT(rt->stack >= rt->stack_before_user);
            rt_pop_frame(rt);
            break;

            default:
            UNREACHABLE;
        }

        rt->state = RUNTIME_LOOP;

        do {

            step(rt);

            if (rt->err.yes)
                rt->state = RUNTIME_ERROR;

        } while (rt->state == RUNTIME_LOOP);

    }

    switch (rt->state) {

        case RUNTIME_BEGIN:
        case RUNTIME_LOOP:
        UNREACHABLE;

        case RUNTIME_DONE:
        break;

        case RUNTIME_ERROR:
        return (WL_EvalResult) { .type=WL_EVAL_ERROR };

        case RUNTIME_OUTPUT:
        {
            ASSERT(rt->cur_output < rt->num_output);

            Value v = rt->values[rt->stack - rt->num_output + rt->cur_output];
            Type type = value_type(v);

            String str;
            if (type == TYPE_STRING)
                str = value_to_str(v);
            else {
                int len = value_convert_to_str(v, rt->buf, SIZEOF(rt->buf));
                if (len > SIZEOF(rt->buf)) {
                    char *p = alloc(rt->arena, len, 1);
                    if (p == NULL) {
                        REPORT(&rt->err, "Out of memory");
                        rt->state = RUNTIME_ERROR;
                        return (WL_EvalResult) { .type=WL_EVAL_ERROR };
                    }
                    len = value_convert_to_str(v, p, len);
                    str = (String) { p, len };
                } else {
                    str = (String) { rt->buf, len };
                }
            }

            rt->cur_output++;
            return (WL_EvalResult) { .type=WL_EVAL_OUTPUT, .str={ str.ptr, str.len } };
        }

        case RUNTIME_SYSVAR:
        return (WL_EvalResult) { .type=WL_EVAL_SYSVAR, .str=(WL_String) { rt->str_for_user.ptr, rt->str_for_user.len } };

        case RUNTIME_SYSCALL:
        return (WL_EvalResult) { .type=WL_EVAL_SYSCALL, .str=(WL_String) { rt->str_for_user.ptr, rt->str_for_user.len } };
    }

    return (WL_EvalResult) { .type=WL_EVAL_DONE };
}

bool wl_streq(WL_String a, char *b, int blen)
{
    if (b == NULL) b = "";
    if (blen < 0) blen = strlen(b);
    return streq((String) { a.ptr, a.len }, (String) { b, blen });
}

int wl_arg_count(WL_Runtime *rt)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return -1;

    ASSERT(rt->num_frames > 0);
    return rt->frames[rt->num_frames-1].varbase - rt->vars; // TODO: is this right?
}

static Value user_arg(WL_Runtime *rt, int idx, Type type)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return -1;

    int tot = wl_arg_count(rt);
    if (idx < 0 || idx >= tot)
        return false;

    Value v = *rt_variable(rt, tot - idx - 1);
    if (value_type(v) != type)
        return VALUE_ERROR;

    return v;
}

bool wl_arg_none(WL_Runtime *rt, int idx)
{
    Value v = user_arg(rt, idx, TYPE_NONE);
    if (v == VALUE_ERROR)
        return false;
    return true;
}

bool wl_arg_bool(WL_Runtime *rt, int idx, bool *x)
{
    Value v = user_arg(rt, idx, TYPE_BOOL);
    if (v == VALUE_ERROR)
        return false;
    *x = (v == VALUE_TRUE);
    return true;
}

bool wl_arg_s64(WL_Runtime *rt, int idx, int64_t *x)
{
    Value v = user_arg(rt, idx, TYPE_INT);
    if (v == VALUE_ERROR)
        return false;
    *x = value_to_s64(v);
    return true;
}

bool wl_arg_f64(WL_Runtime *rt, int idx, double *x)
{
    Value v = user_arg(rt, idx, TYPE_FLOAT);
    if (v == VALUE_ERROR)
        return false;
    *x = value_to_f64(v);
    return true;
}

bool wl_arg_str(WL_Runtime *rt, int idx, WL_String *x)
{
    Value v = user_arg(rt, idx, TYPE_STRING);
    if (v == VALUE_ERROR)
        return false;
    String s = value_to_str(v);
    *x = (WL_String) { s.ptr, s.len };
    return true;
}

bool wl_arg_array(WL_Runtime *rt, int idx)
{
    Value v = user_arg(rt, idx, TYPE_ARRAY);
    if (v == VALUE_ERROR)
        return false;
    return true;
}

bool wl_arg_map(WL_Runtime *rt, int idx)
{
    Value v = user_arg(rt, idx, TYPE_MAP);
    if (v == VALUE_ERROR)
        return false;
    return true;
}

static Value user_peek(WL_Runtime *rt, int off, Type type)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return VALUE_ERROR;

    if (rt->stack + off < rt->stack_before_user || off >= 0)
        return VALUE_ERROR;

    Value v = rt->values[rt->stack + off];
    if (value_type(v) != type)
        return VALUE_ERROR;

    return v;
}

bool wl_peek_none(WL_Runtime *rt, int off)
{
    Value v = user_peek(rt, off, TYPE_NONE);
    if (v == VALUE_ERROR)
        return false;
    return true;
}

bool wl_peek_bool(WL_Runtime *rt, int off, bool *x)
{
    Value v = user_peek(rt, off, TYPE_BOOL);
    if (v == VALUE_ERROR)
        return false;
    *x = (v == VALUE_TRUE);
    return true;
}

bool wl_peek_s64(WL_Runtime *rt, int off, int64_t *x)
{
    Value v = user_peek(rt, off, TYPE_INT);
    if (v == VALUE_ERROR)
        return false;
    *x = value_to_s64(v);
    return true;
}

bool wl_peek_f64(WL_Runtime *rt, int off, double *x)
{
    Value v = user_peek(rt, off, TYPE_FLOAT);
    if (v == VALUE_ERROR)
        return false;
    *x = value_to_f64(v);
    return true;
}

bool wl_peek_str(WL_Runtime *rt, int off, WL_String *x)
{
    Value v = user_peek(rt, off, TYPE_STRING);
    if (v == VALUE_ERROR)
        return false;
    String s = value_to_str(v);
    *x = (WL_String) { s.ptr, s.len };
    return true;
}

bool wl_pop_any(WL_Runtime *rt)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return VALUE_ERROR;

    if (rt->stack == rt->stack_before_user)
        return false;

    ASSERT(rt->stack > 0);
    rt->stack--;
    return true;
}

static Value user_pop(WL_Runtime *rt, Type type)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return VALUE_ERROR;

    if (rt->stack == rt->stack_before_user)
        return VALUE_ERROR;

    ASSERT(rt->stack > 0);
    Value v = rt->values[rt->stack-1];
    if (value_type(v) != type)
        return VALUE_ERROR;

    rt->stack--;
    return v;
}

bool wl_pop_none(WL_Runtime *rt)
{
    Value v = user_pop(rt, TYPE_NONE);
    if (v == VALUE_ERROR)
        return false;
    return true;
}

bool wl_pop_bool(WL_Runtime *rt, bool *x)
{
    Value v = user_pop(rt, TYPE_BOOL);
    if (v == VALUE_ERROR)
        return false;
    *x = (v == VALUE_TRUE);
    return true;
}

bool wl_pop_s64(WL_Runtime *rt, int64_t *x)
{
    Value v = user_pop(rt, TYPE_INT);
    if (v == VALUE_ERROR)
        return false;
    *x = value_to_s64(v);
    return true;
}

bool wl_pop_f64(WL_Runtime *rt, double *x)
{
    Value v = user_pop(rt, TYPE_FLOAT);
    if (v == VALUE_ERROR)
        return false;
    *x = value_to_f64(v);
    return true;
}

bool wl_pop_str(WL_Runtime *rt, WL_String *x)
{
    Value v = user_pop(rt, TYPE_STRING);
    if (v == VALUE_ERROR)
        return false;
    String s = value_to_str(v);
    *x = (WL_String) { s.ptr, s.len };
    return true;
}

void wl_push_none(WL_Runtime *rt)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return;

    if (!rt_check_stack(rt, 1))
        return;

    rt->values[rt->stack++] = VALUE_NONE;
}

void wl_push_true(WL_Runtime *rt)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return;

    if (!rt_check_stack(rt, 1))
        return;

    rt->values[rt->stack++] = VALUE_TRUE;
}

void wl_push_false(WL_Runtime *rt)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return;

    if (!rt_check_stack(rt, 1))
        return;

    rt->values[rt->stack++] = VALUE_FALSE;
}

void wl_push_s64(WL_Runtime *rt, int64_t x)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return;

    if (!rt_check_stack(rt, 1))
        return;

    Value v = value_from_s64(x, rt->arena, &rt->err);
    if (v == VALUE_ERROR) {
        rt->state = RUNTIME_ERROR;
        return;
    }

    rt->values[rt->stack++] = v;
}

void wl_push_f64(WL_Runtime *rt, double x)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return;

    if (!rt_check_stack(rt, 1))
        return;

    Value v = value_from_f64(x, rt->arena, &rt->err);
    if (v == VALUE_ERROR) {
        rt->state = RUNTIME_ERROR;
        return;
    }

    rt->values[rt->stack++] = v;
}

void wl_push_str(WL_Runtime *rt, WL_String x)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return;

    if (!rt_check_stack(rt, 1))
        return;

    Value v = value_from_str((String) { x.ptr, x.len }, rt->arena, &rt->err);
    if (v == VALUE_ERROR) {
        rt->state = RUNTIME_ERROR;
        return;
    }

    rt->values[rt->stack++] = v;
}

void wl_push_array(WL_Runtime *rt, int cap)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return;

    if (!rt_check_stack(rt, 1))
        return;

    Value v = value_empty_array(cap, rt->arena, &rt->err);
    if (v == VALUE_ERROR) {
        rt->state = RUNTIME_ERROR;
        return;
    }

    rt->values[rt->stack++] = v;
}

void wl_push_map(WL_Runtime *rt, int cap)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return;

    if (!rt_check_stack(rt, 1))
        return;

    Value v = value_empty_map(cap, rt->arena, &rt->err);
    if (v == VALUE_ERROR) {
        rt->state = RUNTIME_ERROR;
        return;
    }

    rt->values[rt->stack++] = v;
}

void wl_push_arg(WL_Runtime *rt, int idx)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return;

    if (!rt_check_stack(rt, 1))
        return;

    int tot = wl_arg_count(rt);
    if (idx < 0 || idx >= tot) {
        REPORT(&rt->err, "Invalid API usagge");
        rt->state = RUNTIME_ERROR;
        return;
    }

    rt->values[rt->stack++] = *rt_variable(rt, tot - idx - 1);
}

void wl_insert(WL_Runtime *rt)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return;

    if (rt->stack - rt->stack_before_user < 3) {
        REPORT(&rt->err, "Invalid API usagge");
        rt->state = RUNTIME_ERROR;
        return;
    }

    Value key = rt->values[--rt->stack];
    Value val = rt->values[--rt->stack];
    Value set = rt->values[rt->stack-1];

    if (!value_insert(set, key, val, rt->arena, &rt->err)) {
        rt->state = RUNTIME_ERROR;
        return;
    }
}

void wl_append(WL_Runtime *rt)
{
    if (rt->state != RUNTIME_SYSVAR &&
        rt->state != RUNTIME_SYSCALL)
        return;

     if (rt->stack - rt->stack_before_user < 2) {
        REPORT(&rt->err, "Invalid API usagge");
        rt->state = RUNTIME_ERROR;
        return;
    }

    Value val = rt->values[--rt->stack];
    Value set = rt->values[rt->stack-1];

    if (!value_append(set, val, rt->arena, &rt->err)) {
        rt->state = RUNTIME_ERROR;
        return;
    }
}

void wl_runtime_dump(WL_Runtime *rt)
{
    for (int i = 0; i < rt->num_frames; i++) {
        printf("=== frame %d ===\n", i);
        
        Frame *frame = &rt->frames[i];

        int num_vars;
        if (i+1 < rt->num_frames)
            num_vars = frame->varbase - rt->frames[i+1].varbase;
        else
            num_vars = frame->varbase - rt->vars;

        for (int j = 0; j < num_vars; j++) {
            printf("  %d = ", j);
            value_print(rt->values[frame->varbase - j]);
        }
    }
    printf("===============\n");
}

////////////////////////////////////////////////////////////////////////////////////////
// src/main.c
////////////////////////////////////////////////////////////////////////////////////////

#include "sqlite3.h"
#include "wl.h"
#include "chttp.h"
#include "cweb.h"

#ifdef __linux__
#include <errno.h>
#include <sys/random.h>
#endif

#ifdef _WIN32
#include <windows.h>
#endif

typedef struct {
    char           path[1<<8];
    int            pathlen;
    WL_Program     program;
} CachedProgram;

typedef struct {
    int count;
    int capacity_log2;
    CachedProgram pool[];
} TemplateCache;

static TemplateCache *template_cache_init(int capacity_log2);
static void           template_cache_free(TemplateCache *cache);

typedef struct SessionStorage SessionStorage;
typedef struct SQLiteCache SQLiteCache;

static SQLiteCache* sqlite_cache_init(sqlite3 *db, int capacity_log2);
static void         sqlite_cache_free(SQLiteCache *cache);
static sqlite3*     sqlite_cache_getdb(SQLiteCache *cache);

static int sqlite3utils_prepare(SQLiteCache *cache,
    sqlite3_stmt **pstmt, char *fmt, int fmtlen);

static int sqlite3utils_prepare_and_bind_impl(SQLiteCache *cache,
    sqlite3_stmt **pstmt, char *fmt, CWEB_VArgs args);

#define sqlite3utils_prepare_and_bind(cache, pstmt, fmt, ...) \
    sqlite3utils_prepare_and_bind_impl((cache), (pstmt), (fmt), VARGS(__VA_ARGS__))

struct CWEB {

    HTTP_Server *server;
    int pool_cap;
    char *pool;

    // Login
    SessionStorage *session_storage;

    // Database
    sqlite3 *db;
    SQLiteCache *dbcache;

    // Template
    TemplateCache *tpcache;

    bool allow_insecure_login;

    CWEB_Request req;
};

struct CWEB_Request {

    CWEB *cweb;

    WL_Arena arena;

    HTTP_Request *req;
    HTTP_ResponseBuilder builder;

    // Session
    bool just_created_session;
    int  user_id;
    CWEB_String sess;
    CWEB_String csrf;
};

///////////////////////////

bool cweb_streq(CWEB_String a, CWEB_String b)
{
    return http_streq((HTTP_String) { a.ptr, a.len }, (HTTP_String) { b.ptr, b.len });
}

CWEB_String cweb_trim(CWEB_String s)
{
    HTTP_String s2 = http_trim((HTTP_String) { s.ptr, s.len });
    return (CWEB_String) { s2.ptr, s2.len };
}

CWEB_VArg cweb_varg_from_c    (char c)            { return (CWEB_VArg) { CWEB_VARG_TYPE_C,    .c=c       }; }
CWEB_VArg cweb_varg_from_s    (short s)           { return (CWEB_VArg) { CWEB_VARG_TYPE_S,    .s=s       }; }
CWEB_VArg cweb_varg_from_i    (int i)             { return (CWEB_VArg) { CWEB_VARG_TYPE_I,    .i=i       }; }
CWEB_VArg cweb_varg_from_l    (long l)            { return (CWEB_VArg) { CWEB_VARG_TYPE_L,    .l=l       }; }
CWEB_VArg cweb_varg_from_ll   (long long ll)      { return (CWEB_VArg) { CWEB_VARG_TYPE_LL,   .ll=ll     }; }
CWEB_VArg cweb_varg_from_sc   (char sc)           { return (CWEB_VArg) { CWEB_VARG_TYPE_SC,   .sc=sc     }; }
CWEB_VArg cweb_varg_from_ss   (short ss)          { return (CWEB_VArg) { CWEB_VARG_TYPE_SS,   .ss=ss     }; }
CWEB_VArg cweb_varg_from_si   (int si)            { return (CWEB_VArg) { CWEB_VARG_TYPE_SI,   .si=si     }; }
CWEB_VArg cweb_varg_from_sl   (long sl)           { return (CWEB_VArg) { CWEB_VARG_TYPE_SL,   .sl=sl     }; }
CWEB_VArg cweb_varg_from_sll  (long long sll)     { return (CWEB_VArg) { CWEB_VARG_TYPE_SLL,  .sll=sll   }; }
CWEB_VArg cweb_varg_from_uc   (char uc)           { return (CWEB_VArg) { CWEB_VARG_TYPE_UC,   .uc=uc     }; }
CWEB_VArg cweb_varg_from_us   (short us)          { return (CWEB_VArg) { CWEB_VARG_TYPE_US,   .us=us     }; }
CWEB_VArg cweb_varg_from_ui   (int ui)            { return (CWEB_VArg) { CWEB_VARG_TYPE_UI,   .ui=ui     }; }
CWEB_VArg cweb_varg_from_ul   (long ul)           { return (CWEB_VArg) { CWEB_VARG_TYPE_UL,   .ul=ul     }; }
CWEB_VArg cweb_varg_from_ull  (long long ull)     { return (CWEB_VArg) { CWEB_VARG_TYPE_ULL,  .ull=ull   }; }
CWEB_VArg cweb_varg_from_f    (float f)           { return (CWEB_VArg) { CWEB_VARG_TYPE_F,    .f=f       }; }
CWEB_VArg cweb_varg_from_d    (double d)          { return (CWEB_VArg) { CWEB_VARG_TYPE_D,    .d=d       }; }
CWEB_VArg cweb_varg_from_b    (bool b)            { return (CWEB_VArg) { CWEB_VARG_TYPE_B,    .b=b       }; }
CWEB_VArg cweb_varg_from_str  (CWEB_String str)   { return (CWEB_VArg) { CWEB_VARG_TYPE_STR,  .str=str   }; }
CWEB_VArg cweb_varg_from_hash (CWEB_PasswordHash hash) { return (CWEB_VArg) { CWEB_VARG_TYPE_HASH, .hash=hash }; }
CWEB_VArg cweb_varg_from_pc   (char *pc)          { return (CWEB_VArg) { CWEB_VARG_TYPE_PC,   .pc=pc     }; }
CWEB_VArg cweb_varg_from_ps   (short *ps)         { return (CWEB_VArg) { CWEB_VARG_TYPE_PS,   .ps=ps     }; }
CWEB_VArg cweb_varg_from_pi   (int *pi)           { return (CWEB_VArg) { CWEB_VARG_TYPE_PI,   .pi=pi     }; }
CWEB_VArg cweb_varg_from_pl   (long *pl)          { return (CWEB_VArg) { CWEB_VARG_TYPE_PL,   .pl=pl     }; }
CWEB_VArg cweb_varg_from_pll  (long long *pll)    { return (CWEB_VArg) { CWEB_VARG_TYPE_PLL,  .pll=pll   }; }
CWEB_VArg cweb_varg_from_psc  (char *psc)         { return (CWEB_VArg) { CWEB_VARG_TYPE_PSC,  .psc=psc   }; }
CWEB_VArg cweb_varg_from_pss  (short *pss)        { return (CWEB_VArg) { CWEB_VARG_TYPE_PSS,  .pss=pss   }; }
CWEB_VArg cweb_varg_from_psi  (int *psi)          { return (CWEB_VArg) { CWEB_VARG_TYPE_PSI,  .psi=psi   }; }
CWEB_VArg cweb_varg_from_psl  (long *psl)         { return (CWEB_VArg) { CWEB_VARG_TYPE_PSL,  .psl=psl   }; }
CWEB_VArg cweb_varg_from_psll (long long *psll)   { return (CWEB_VArg) { CWEB_VARG_TYPE_PSLL, .psll=psll }; }
CWEB_VArg cweb_varg_from_puc  (char *puc)         { return (CWEB_VArg) { CWEB_VARG_TYPE_PUC,  .puc=puc   }; }
CWEB_VArg cweb_varg_from_pus  (short *pus)        { return (CWEB_VArg) { CWEB_VARG_TYPE_PUS,  .pus=pus   }; }
CWEB_VArg cweb_varg_from_pui  (int *pui)          { return (CWEB_VArg) { CWEB_VARG_TYPE_PUI,  .pui=pui   }; }
CWEB_VArg cweb_varg_from_pul  (long *pul)         { return (CWEB_VArg) { CWEB_VARG_TYPE_PUL,  .pul=pul   }; }
CWEB_VArg cweb_varg_from_pull (long long *pull)   { return (CWEB_VArg) { CWEB_VARG_TYPE_PULL, .pull=pull }; }
CWEB_VArg cweb_varg_from_pf   (float *pf)         { return (CWEB_VArg) { CWEB_VARG_TYPE_PF,   .pf=pf     }; }
CWEB_VArg cweb_varg_from_pd   (double *pd)        { return (CWEB_VArg) { CWEB_VARG_TYPE_PD,   .pd=pd     }; }
CWEB_VArg cweb_varg_from_pb   (bool *pb)          { return (CWEB_VArg) { CWEB_VARG_TYPE_PB,   .pb=pb     }; }
CWEB_VArg cweb_varg_from_pstr (CWEB_String *pstr) { return (CWEB_VArg) { CWEB_VARG_TYPE_PSTR, .pstr=pstr }; }
CWEB_VArg cweb_varg_from_phash(CWEB_PasswordHash *phash) { return (CWEB_VArg) { CWEB_VARG_TYPE_PHASH, .phash=phash }; }

/////////////////////////////////////////////////////////////////
// RANDOM
////////////////////////////////////////////////////////////////

static int generate_random_bytes(char *dst, int cap)
{
#ifdef __linux__
    int copied = 0;
    while (copied < cap) {
        int ret = getrandom(dst, (size_t) cap, 0);
        if (ret < 0) {
            if (errno == EINTR)
                continue;
            return -1;
        }
        copied += ret;
    }
    return 0;
#endif

#ifdef _WIN32
    NTSTATUS status = BCryptGenRandom(NULL, (unsigned char*) dst, (ULONG) cap, BCRYPT_USE_SYSTEM_PREFERRED_RNG);
    return BCRYPT_SUCCESS(status) ? 0 : -1;
#endif
}

////////////////////////////////////////////////////////////////
// PASSWORD
////////////////////////////////////////////////////////////////

int cweb_hash_password(char *pass, int passlen, int cost, CWEB_PasswordHash *hash)
{
    char passzt[128];
    if (passlen >= (int) sizeof(passzt))
        return -1;
    memcpy(passzt, pass, passlen);
    passzt[passlen] = '\0';

    char random[16];
    int ret = generate_random_bytes(random, (int) sizeof(random));
    if (ret) return -1;

    char salt[30];
    if (_crypt_gensalt_blowfish_rn("$2b$", cost, random, sizeof(random), salt, sizeof(salt)) == NULL)
        return -1;

    if (_crypt_blowfish_rn(passzt, salt, hash->data, (int) sizeof(hash->data)) == NULL)
        return -1;

    return 0;
}

int cweb_check_password(char *pass, int passlen, CWEB_PasswordHash hash)
{
    char passzt[128];
    if (passlen >= (int) sizeof(passzt))
        return -1;
    memcpy(passzt, pass, passlen);
    passzt[passlen] = '\0';

    CWEB_PasswordHash new_hash;
    if (_crypt_blowfish_rn(passzt, hash.data, new_hash.data, sizeof(new_hash.data)) == NULL)
        return -1;

    if (strcmp(hash.data, new_hash.data)) // TODO: should be constant-time
        return 1;

    return 0;
}

/////////////////////////////////////////////////////////////////
// SESSION
////////////////////////////////////////////////////////////////

#define CSRF_RAW_TOKEN_SIZE 32
#define SESS_RAW_TOKEN_SIZE 32

#define CSRF_TOKEN_SIZE (2 * CSRF_RAW_TOKEN_SIZE)
#define SESS_TOKEN_SIZE (2 * SESS_RAW_TOKEN_SIZE)

typedef struct {
    int  user;
    char csrf[CSRF_TOKEN_SIZE];
    char sess[SESS_TOKEN_SIZE];
} Session;

struct SessionStorage {
    int count;
    int capacity;
    Session items[];
};

static bool is_hex_digit(char c)
{
    return (c >= '0' && c <= '9') || (c >= 'A' && c <= 'F') || (c >= 'a' && c <= 'f');
}

static int hex_digit_to_int(char c)
{
    if (c >= 'A' && c <= 'F')
        return c - 'A' + 10;
    if (c >= 'a' && c <= 'f')
        return c - 'a' + 10;
    return c - '0';
}

static void unpack_token(char *src, int srclen, char *dst, int dstlen)
{
    assert(2 * srclen == dstlen);

    for (int i = 0; i < srclen; i++) {
        static const char table[] = "0123456789abcdef";
        int low  = (src[i] & 0x0F) >> 0;
        int high = (src[i] & 0xF0) >> 4;
        dst[(i << 1) | 0] = table[high];
        dst[(i << 1) | 1] = table[low];
    }
}

static int pack_token(char *src, int srclen, char *dst, int dstlen)
{
    if (srclen & 1)
        return -1;

    assert(srclen == 2 * dstlen);

    for (int i = 0; i < srclen; i += 2) {
        int high = src[i+0];
        int low  = src[i+1];
        if (!is_hex_digit(high) || !is_hex_digit(low))
            return -1;
        dst[i] = (hex_digit_to_int(high) << 4) | (hex_digit_to_int(low) << 0);
    }

    return 0;
}

static SessionStorage *session_storage_init(int max_sessions)
{
    int capacity = 2 * max_sessions;
    SessionStorage *storage = malloc(sizeof(SessionStorage) + capacity * sizeof(Session));
    if (storage == NULL)
        return NULL;
    storage->count = 0;
    storage->capacity = capacity;
    for (int i = 0; i < capacity; i++)
        storage->items[i].user = -1;
    return storage;
}

static void session_storage_free(SessionStorage *storage)
{
    free(storage);
}

static Session *lookup_session_slot(SessionStorage *storage, CWEB_String sess, bool find_unused)
{
    if (find_unused && 2 * storage->count + 2 > storage->capacity)
        return NULL;

    if (sess.len != SESS_TOKEN_SIZE)
        return NULL;

    uint64_t key;
    if (sess.len < (int) (2 * sizeof(key)))
        return NULL;
    for (int i = 0; i < (int) sizeof(key); i++) {

        int high = sess.ptr[(i << 1) | 0];
        int low  = sess.ptr[(i << 1) | 1];

        if (!is_hex_digit(sess.ptr[i+0]) ||
            !is_hex_digit(sess.ptr[i+1]))
            return NULL;

        key <<= 4;
        key |= hex_digit_to_int(high);

        key <<= 4;
        key |= hex_digit_to_int(low);
    }
    int i = key % storage->capacity;

    for (int j = 0; j < storage->capacity; j++) {

        if (find_unused) {

            if (storage->items[i].user < 0)
                return &storage->items[i]; // Unused slot

        } else {

            if (storage->items[i].user == -1)
                return NULL;

            if (storage->items[i].user != -2)
                if (!memcmp(storage->items[i].sess, sess.ptr, SESS_TOKEN_SIZE))
                    return &storage->items[i];
        }

        i++;
        if (i == storage->capacity)
            i = 0;
    }

    return NULL;
}

static int create_session(SessionStorage *storage, int user, CWEB_String *psess, CWEB_String *pcsrf)
{
    int ret;
    char raw_sess[SESS_RAW_TOKEN_SIZE];
    char raw_csrf[CSRF_RAW_TOKEN_SIZE];

    ret = generate_random_bytes(raw_sess, SESS_RAW_TOKEN_SIZE);
    if (ret) return -1;

    ret = generate_random_bytes(raw_csrf, CSRF_RAW_TOKEN_SIZE);
    if (ret) return -1;

    char sess[SESS_TOKEN_SIZE];
    char csrf[CSRF_TOKEN_SIZE];
    unpack_token(raw_sess, SESS_RAW_TOKEN_SIZE, sess, SESS_TOKEN_SIZE);
    unpack_token(raw_csrf, CSRF_RAW_TOKEN_SIZE, csrf, CSRF_TOKEN_SIZE);

    Session *found = lookup_session_slot(storage, (CWEB_String) { sess, SESS_TOKEN_SIZE }, true);
    if (found == NULL) return -1;

    found->user = user;
    memcpy(found->sess, sess, SESS_TOKEN_SIZE);
    memcpy(found->csrf, csrf, CSRF_TOKEN_SIZE);

    *psess = (CWEB_String) { found->sess, SESS_TOKEN_SIZE };
    *pcsrf = (CWEB_String) { found->csrf, CSRF_TOKEN_SIZE };

    storage->count++;
    return 0;
}

static int delete_session(SessionStorage *storage, CWEB_String sess)
{
    char raw_sess[SESS_RAW_TOKEN_SIZE];
    if (sess.len != SESS_TOKEN_SIZE || pack_token(sess.ptr, sess.len, raw_sess, (int) sizeof(raw_sess)) < 0)
        return -1;
    Session *found = lookup_session_slot(storage, sess, false);
    if (found == NULL)
        return false;
    assert(found->user >= 0);
    found->user = -2;
    storage->count--;
    return 0;
}

static int find_session(SessionStorage *storage, CWEB_String sess, CWEB_String *pcsrf, int *puser)
{
    Session *found = lookup_session_slot(storage, sess, false);
    if (found == NULL)
        return -1;
    assert(found->user >= 0);
    *pcsrf = (CWEB_String) { found->csrf, CSRF_TOKEN_SIZE };
    *puser = found->user;
    return 0;
}

/////////////////////////////////////////////////////////////////
// DATABASE
////////////////////////////////////////////////////////////////

typedef struct {
    char *str;
    int   len;
    sqlite3_stmt *stmt;
} Prepped;

struct SQLiteCache {
    sqlite3 *db;
    int count;
    int capacity_log2;
    Prepped items[];
};

static SQLiteCache *sqlite_cache_init(sqlite3 *db, int capacity_log2)
{
    SQLiteCache *cache = malloc(sizeof(SQLiteCache) + (1 << capacity_log2) * sizeof(Prepped));
    if (cache == NULL)
        return NULL;

    cache->db = db;
    cache->count = 0;
    cache->capacity_log2 = capacity_log2;

    for (int i = 0; i < (1 << capacity_log2); i++)
        cache->items[i].stmt = NULL;

    return cache;
}

static void sqlite_cache_free(SQLiteCache *cache)
{
    for (int i = 0; i < (1 << cache->capacity_log2); i++) {
        sqlite3_stmt *stmt = cache->items[i].stmt;
        if (stmt) {
            free(cache->items[i].str);
            sqlite3_finalize(stmt);
        }
    }
    free(cache);
}

static sqlite3 *sqlite_cache_getdb(SQLiteCache *cache)
{
    return cache->db;
}

static unsigned long djb2(char *src, int len)
{
    char *ptr = src;
    char *end = src + len;

    unsigned long hash = 5381;
    int c;
    while (ptr < end && (c = *ptr++))
        hash = ((hash << 5) + hash) + c; // hash * 33 + c
    return hash;
}

static int lookup(SQLiteCache *cache, char *fmt, int fmtlen)
{
    int mask = (1 << cache->capacity_log2) - 1;
    int hash = djb2(fmt, fmtlen);
    int i = hash & mask;
    int perturb = hash;
    for (;;) {

        if (cache->items[i].stmt == NULL)
            return i;

        if (cache->items[i].len == fmtlen && !memcmp(cache->items[i].str, fmt, fmtlen))
            return i;

        perturb >>= 5;
        i = (i * 5 + 1 + perturb) & mask;
    }

    return -1;
}

static int sqlite3utils_prepare(SQLiteCache *cache, sqlite3_stmt **pstmt, char *fmt, int fmtlen)
{
    if (fmtlen < 0)
        fmtlen = strlen(fmt);

    int i = lookup(cache, fmt, fmtlen);
    if (cache->items[i].stmt == NULL) {

        sqlite3_stmt *stmt;
        int ret = sqlite3_prepare_v2(cache->db, fmt, -1, &stmt, NULL);
        if (ret != SQLITE_OK) {
            //fprintf(stderr, "Failed to prepare statement: %s (%s:%d)\n", sqlite3_errmsg(db), __FILE__, __LINE__);
            return ret;
        }

        char *cpy = malloc(fmtlen);
        if (cpy == NULL) {
            sqlite3_finalize(stmt);
            return SQLITE_NOMEM;
        }
        memcpy(cpy, fmt, fmtlen);

        cache->items[i].str = cpy;
        cache->items[i].len = fmtlen;
        cache->items[i].stmt = stmt;
    }
    sqlite3_stmt *stmt = cache->items[i].stmt;

    *pstmt = stmt;
    return SQLITE_OK;
}

static int sqlite3utils_prepare_and_bind_impl(SQLiteCache *cache,
    sqlite3_stmt **pstmt, char *fmt, CWEB_VArgs args)
{
    sqlite3_stmt *stmt;
    int ret = sqlite3utils_prepare(cache, &stmt, fmt, strlen(fmt));
    if (ret != SQLITE_OK)
        return ret;

    for (int i = 0; i < args.len; i++) {
        CWEB_VArg arg = args.ptr[i];
        switch (arg.type) {
            case CWEB_VARG_TYPE_C  : ret = sqlite3_bind_text  (stmt, i+1, &arg.c, 1, NULL); break;
            case CWEB_VARG_TYPE_S  : ret = sqlite3_bind_int   (stmt, i+1, arg.s);   break;
            case CWEB_VARG_TYPE_I  : ret = sqlite3_bind_int   (stmt, i+1, arg.i);   break;
            case CWEB_VARG_TYPE_L  : ret = sqlite3_bind_int64 (stmt, i+1, arg.l);   break;
            case CWEB_VARG_TYPE_LL : ret = sqlite3_bind_int64 (stmt, i+1, arg.ll);  break;
            case CWEB_VARG_TYPE_SC : ret = sqlite3_bind_int   (stmt, i+1, arg.sc);  break;
            case CWEB_VARG_TYPE_SS : ret = sqlite3_bind_int   (stmt, i+1, arg.ss);  break;
            case CWEB_VARG_TYPE_SI : ret = sqlite3_bind_int   (stmt, i+1, arg.si);  break;
            case CWEB_VARG_TYPE_SL : ret = sqlite3_bind_int64 (stmt, i+1, arg.sl);  break;
            case CWEB_VARG_TYPE_SLL: ret = sqlite3_bind_int   (stmt, i+1, arg.sll); break;
            case CWEB_VARG_TYPE_UC : ret = sqlite3_bind_int   (stmt, i+1, arg.uc);  break;
            case CWEB_VARG_TYPE_US : ret = sqlite3_bind_int   (stmt, i+1, arg.us);  break;
            case CWEB_VARG_TYPE_UI : ret = sqlite3_bind_int64 (stmt, i+1, arg.ui);  break;
            case CWEB_VARG_TYPE_UL : ret = sqlite3_bind_int64 (stmt, i+1, arg.ul);  break;
            case CWEB_VARG_TYPE_ULL: ret = sqlite3_bind_int64 (stmt, i+1, arg.ull); break;
            case CWEB_VARG_TYPE_F  : ret = sqlite3_bind_double(stmt, i+1, arg.f);   break;
            case CWEB_VARG_TYPE_D  : ret = sqlite3_bind_double(stmt, i+1, arg.d);   break;
            case CWEB_VARG_TYPE_B  : ret = sqlite3_bind_int   (stmt, i+1, arg.b);   break;
            case CWEB_VARG_TYPE_STR: ret = sqlite3_bind_text  (stmt, i+1, arg.str.ptr, arg.str.len, NULL); break;
        }
        if (ret != SQLITE_OK) {
            sqlite3_reset(stmt);
            return ret;
        }
    }

    *pstmt = stmt;
    return SQLITE_OK;
}

int64_t cweb_database_insert_impl(CWEB *cweb, const char *fmt, CWEB_VArgs args)
{
    sqlite3_stmt *stmt;
    int ret = sqlite3utils_prepare_and_bind_impl(cweb->dbcache, &stmt, fmt, args);
    if (ret != SQLITE_OK)
        return -1;

    ret = sqlite3_step(stmt);
    if (ret != SQLITE_DONE) {
        sqlite3_reset(stmt);
        return -1;
    }

    int64_t insert_id = sqlite3_last_insert_rowid(cweb->db);
    if (insert_id < 0) {
        sqlite3_reset(stmt);
        return -1;
    }

    sqlite3_reset(stmt);
    return insert_id;
}

CWEB_QueryResult cweb_database_select_impl(CWEB *cweb, const char *fmt, CWEB_VArgs args)
{
    sqlite3_stmt *stmt;
    int ret = sqlite3utils_prepare_and_bind_impl(cweb->dbcache, &stmt, fmt, args);
    if (ret != SQLITE_OK)
        return (CWEB_QueryResult) { NULL };

    return (CWEB_QueryResult) { stmt };
}

int cweb_next_query_row_impl(CWEB_QueryResult *res, CWEB_VArgs args)
{
    if (res->handle == NULL)
        return -1;

    int ret = sqlite3_step(res->handle);

    if (ret == SQLITE_DONE)
        return 0;

    if (ret != SQLITE_ROW) {
        sqlite3_reset(res->handle);
        res->handle = NULL;
        return -1;
    }

    if (sqlite3_column_count(res->handle) != args.len) {
        sqlite3_reset(res->handle);
        res->handle = NULL;
        return -1;
    }

    for (int i = 0; i < args.len; i++) {
        switch (args.ptr[i].type) {

            case CWEB_VARG_TYPE_PI:
            {
                int64_t x = sqlite3_column_int64(res->handle, i);
                if (x < INT_MIN || x > INT_MAX) {
                    sqlite3_reset(res->handle);
                    res->handle = NULL;
                    return -1;
                }
                *args.ptr[i].pi = (int) x;
            }
            break;

            case CWEB_VARG_TYPE_PL:
            {
                int64_t x = sqlite3_column_int64(res->handle, i);
                if (x < LONG_MIN || x > LONG_MAX) {
                    sqlite3_reset(res->handle);
                    res->handle = NULL;
                    return -1;
                }
                *args.ptr[i].pl = (long) x;
            }
            break;

            case CWEB_VARG_TYPE_PLL:
            {
                int64_t x = sqlite3_column_int64(res->handle, i);
                *args.ptr[i].pll = (int) x;
            }
            break;

            case CWEB_VARG_TYPE_PF:
            {
                double x = sqlite3_column_double(res->handle, i);
                *args.ptr[i].pf = (float) x;
            }
            break;

            case CWEB_VARG_TYPE_PD:
            {
                double x = sqlite3_column_double(res->handle, i);
                *args.ptr[i].pf = (float) x;
            }
            break;

            case CWEB_VARG_TYPE_PSTR:
            {
                *args.ptr[i].pstr = (CWEB_String) {
                    sqlite3_column_text(res->handle, i),
                    sqlite3_column_bytes(res->handle, i),
                };
            }
            break;

            default:
            sqlite3_reset(res->handle);
            res->handle = NULL;
            return -1;
        }
    }

    return 1;
}

void cweb_free_query_result(CWEB_QueryResult *res)
{
    if (res->handle) {
        sqlite3_reset(res->handle);
        res->handle = NULL;
    }
}

int cweb_global_init(void)
{
    http_global_init();
}

void cweb_global_free(void)
{
    http_global_free();
}

CWEB *web_init(CWEB_String addr, uint16_t port)
{
    // If set, allows logins and signups over HTTP, which is highly insecure.
    // This allows compiling the application without TLS when developing.
    bool allow_insecure_login = true;

    if (allow_insecure_login)
        printf("WARNING: allow_insecure_login is true\n");

    CWEB *cweb = malloc(sizeof(CWEB));
    if (cweb == NULL)
        return -1;

    cweb->pool_cap = 1<<20;
    cweb->pool = malloc(cweb->pool_cap);
    if (cweb->pool == NULL) {
        free(cweb);
        return -1;
    }

    cweb->tpcache = template_cache_init(4);
    if (cweb->tpcache == NULL) {
        free(cweb->pool);
        free(cweb);
        return -1;
    }

    cweb->session_storage = session_storage_init(1024);
    if (cweb->session_storage == NULL) {
        template_cache_free(cweb->tpcache);
        free(cweb->pool);
        free(cweb);
        return -1;
    }

    cweb->server = http_server_init((HTTP_String) { addr.ptr, addr.len }, port);
    if (cweb->server == NULL) {
        session_storage_free(cweb->session_storage);
        template_cache_free(cweb->tpcache);
        free(cweb->pool);
        free(cweb);
        return -1;
    }

    cweb->db = NULL;
    cweb->dbcache = NULL;

    cweb->allow_insecure_login = false;

    return 0;
}

void cweb_free(CWEB *cweb)
{
    http_server_free(cweb->server);
    session_storage_free(cweb->session_storage);
    template_cache_free(cweb->tpcache);
    if (cweb->db) {
        sqlite_cache_free(cweb->dbcache);
        sqlite3_close(cweb->db);
    }
    free(cweb);
}

void cweb_version(void)
{
    printf("%s\n", sqlite3_libversion());
}

int cweb_enable_database(CWEB *cweb, CWEB_String file)
{
    if (cweb->db != NULL)
        return -1; // Already enabled

    char file_copy[1<<12];
    if (file.len >= SIZEOF(file_copy))
        return -1;
    memcpy(file_copy, file.ptr, file.len);
    file_copy[file.len] = '\0';

    int ret = sqlite3_open(file_copy, &cweb->db);
    if (ret != SQLITE_OK) {
        sqlite3_close(cweb->db);
        cweb->db = NULL;
        return -1;
    }

    char *schema_data;
    long  schema_size;
    ret = load_file(file_copy, &schema_data, &schema_size);
    if (ret < 0) {
        sqlite3_close(cweb->db);
        cweb->db = NULL;
        return -1;
    }

    ret = sqlite3_exec(cweb->db, schema_data, NULL, NULL, NULL);
    if (ret != SQLITE_OK) {
        sqlite3_close(cweb->db);
        cweb->db = NULL;
        return -1;
    }

    free(schema_data);

    cweb->dbcache = sqlite_cache_init(cweb->db, 5);
    if (cweb->dbcache == NULL) {
        sqlite3_close(cweb->db);
        cweb->db = NULL;
        return -1;
    }

    return 0;
}

CWEB_Request *cweb_wait(CWEB *cweb)
{
    CWEB_Request *req = &cweb->req;

    int ret = http_server_wait(cweb->server, &req->req, &req->builder);
    if (ret < 0) return NULL;

    HTTP_String sess_token = http_get_cookie(req->req, HTTP_STR("sess_token"));

    req->arena = (WL_Arena) { cweb->pool, cweb->pool_cap, 0 };
    req->just_created_session = false;
    req->sess = (CWEB_String) { sess_token.ptr, sess_token.len };
    if (find_session(cweb->session_storage, req->sess, &req->csrf, &req->user_id) < 0) {
        req->user_id = -1;
        req->sess = (CWEB_String) { NULL, 0 };
        req->csrf = (CWEB_String) { NULL, 0 };
    }

    return req;
}

bool cweb_match_endpoint(CWEB_Request *req, CWEB_String str)
{
    return http_streq(req->req->url.path, (HTTP_String) { str.ptr, str.len });
}

CWEB_String cweb_get_param_s(CWEB_Request *req, CWEB_String name)
{
    HTTP_String res = http_get_param(req->req->body,
        (HTTP_String) { name.ptr, name.len },
        req->arena.ptr + req->arena.cur,
        req->arena.len - req->arena.cur
    );
    if (res.ptr >= req->arena.ptr && res.ptr < req->arena.ptr + req->arena.len)
        req->arena.cur += res.len;
    return (CWEB_String) { res.ptr, res.len };
}

int cweb_get_param_i(CWEB_Request *req, CWEB_String name)
{
    return http_get_param_i(req->req->body, (HTTP_String) { name.ptr, name.len });
}

static int set_auth_cookie_if_necessary(CWEB_Request *req)
{
    if (req->just_created_session) {
        char cookie[1<<9];
        int cookie_len = snprintf(cookie, sizeof(cookie), "Set-Cookie: sess_token=%.*s; Path=/; HttpOnly; Secure", req->sess.len, req->sess.ptr);
        if (cookie_len < 0 || cookie_len >= (int) sizeof(cookie))
            return -500;
        http_response_builder_header(req->builder, (HTTP_String) { cookie, cookie_len });
    }
    return 0;
}

void cweb_respond(CWEB_Request *req, int status, CWEB_String content)
{
    http_response_builder_status(req->builder, 200);
    int ret = set_auth_cookie_if_necessary(req);
    if (ret < 0) {
        http_response_builder_undo(req->builder);
        http_response_builder_status(req->builder, -ret);
        http_response_builder_done(req->builder);
        return;
    }
    http_response_builder_body(req->builder, (HTTP_String) { content.ptr, content.len });
    http_response_builder_done(req->builder);
}

typedef struct {
    char *dst;
    int   cap;
    int   len;
} StaticOutputBuffer;

static void append_to_output(StaticOutputBuffer *out, char *src, int len)
{
    int unused = out->cap - out->len;
    if (unused > 0)
        memcpy(out->dst + out->len, src, MIN(len, unused));
    out->len += len;
}

static void append_to_output_u64(StaticOutputBuffer *out, uint64_t n)
{
    // TODO
}

static void append_to_output_s64(StaticOutputBuffer *out, int64_t n)
{
    // TODO
}

static void append_to_output_ptr(StaticOutputBuffer *out, void *p)
{
    // TODO
}

static void value_to_output(StaticOutputBuffer *out, CWEB_VArg arg)
{
    switch (arg.type) {
        case CWEB_VARG_TYPE_C    : append_to_output(out, &arg.c, 1);     break;
        case CWEB_VARG_TYPE_S    : append_to_output_s64(out, arg.s);     break;
        case CWEB_VARG_TYPE_I    : append_to_output_s64(out, arg.i);     break;
        case CWEB_VARG_TYPE_L    : append_to_output_s64(out, arg.l);     break;
        case CWEB_VARG_TYPE_LL   : append_to_output_s64(out, arg.ll);    break;
        case CWEB_VARG_TYPE_SC   : append_to_output_s64(out, arg.sc);    break;
        case CWEB_VARG_TYPE_SS   : append_to_output_s64(out, arg.ss);    break;
        case CWEB_VARG_TYPE_SI   : append_to_output_s64(out, arg.si);    break;
        case CWEB_VARG_TYPE_SL   : append_to_output_s64(out, arg.sl);    break;
        case CWEB_VARG_TYPE_SLL  : append_to_output_s64(out, arg.sll);   break;
        case CWEB_VARG_TYPE_UC   : append_to_output_u64(out, arg.uc);    break;
        case CWEB_VARG_TYPE_US   : append_to_output_u64(out, arg.us);    break;
        case CWEB_VARG_TYPE_UI   : append_to_output_u64(out, arg.ui);    break;
        case CWEB_VARG_TYPE_UL   : append_to_output_u64(out, arg.ul);    break;
        case CWEB_VARG_TYPE_ULL  : append_to_output_u64(out, arg.ull);   break;
        case CWEB_VARG_TYPE_F    : append_to_output_f64(out, arg.f);     break;
        case CWEB_VARG_TYPE_D    : append_to_output_u64(out, arg.d);     break;
        case CWEB_VARG_TYPE_B    : append_to_output(out, arg.b ? "true" : "false", arg.b ? 4: 5);break;
        case CWEB_VARG_TYPE_STR  : append_to_output(out, arg.str.ptr, arg.str.len); break;
        case CWEB_VARG_TYPE_HASH : append_to_output(out, arg.hash.data, strlen(arg.hash.data)); break;
        case CWEB_VARG_TYPE_PC   : append_to_output_ptr(out, arg.pc);    break;
        case CWEB_VARG_TYPE_PS   : append_to_output_ptr(out, arg.ps);    break;
        case CWEB_VARG_TYPE_PI   : append_to_output_ptr(out, arg.pi);    break;
        case CWEB_VARG_TYPE_PL   : append_to_output_ptr(out, arg.pl);    break;
        case CWEB_VARG_TYPE_PLL  : append_to_output_ptr(out, arg.pll);   break;
        case CWEB_VARG_TYPE_PSC  : append_to_output_ptr(out, arg.psc);   break;
        case CWEB_VARG_TYPE_PSS  : append_to_output_ptr(out, arg.pss);   break;
        case CWEB_VARG_TYPE_PSI  : append_to_output_ptr(out, arg.psi);   break;
        case CWEB_VARG_TYPE_PSL  : append_to_output_ptr(out, arg.psl);   break;
        case CWEB_VARG_TYPE_PSLL : append_to_output_ptr(out, arg.psll);  break;
        case CWEB_VARG_TYPE_PUC  : append_to_output_ptr(out, arg.puc);   break;
        case CWEB_VARG_TYPE_PUS  : append_to_output_ptr(out, arg.pus);   break;
        case CWEB_VARG_TYPE_PUI  : append_to_output_ptr(out, arg.pui);   break;
        case CWEB_VARG_TYPE_PUL  : append_to_output_ptr(out, arg.pul);   break;
        case CWEB_VARG_TYPE_PULL : append_to_output_ptr(out, arg.pull);  break;
        case CWEB_VARG_TYPE_PF   : append_to_output_ptr(out, arg.pf);    break;
        case CWEB_VARG_TYPE_PD   : append_to_output_ptr(out, arg.pd);    break;
        case CWEB_VARG_TYPE_PB   : append_to_output_ptr(out, arg.pb);    break;
        case CWEB_VARG_TYPE_PSTR : append_to_output_ptr(out, arg.pstr);  break;
        case CWEB_VARG_TYPE_PHASH: append_to_output_ptr(out, arg.phash); break;
    }
}

static void evaluate_format(StaticOutputBuffer *out, CWEB_String format, CWEB_VArgs args)
{
    char *src = format.ptr;
    int   len = format.len;
    int   cur = 0;
    int   arg_idx = 0;

    for (;;) {

        int off = cur;
        while (cur < len && src[cur] != '{' && src[cur] != '\\')
            cur++;

        if (cur > off)
            append_to_output(out, src + off, cur - off);

        if (cur == len)
            break;
        cur++;

        if (src[cur-1] == '{') {

            while (cur < len && src[cur] != '}')
                cur++;

            if (cur < len) {
                assert(src[cur] == '}');
                cur++;
            }

            if (arg_idx < args.len) {
                value_to_output(out, args.ptr[arg_idx]);
                arg_idx++;
            }

        } else {
            assert(src[cur-1] == '\\');
            if (cur < len) {
                append_to_output(out, &src[cur], 1);
                cur++;
            }
        }
    }
}

CWEB_String cweb_format_impl(CWEB_Request *req, char *fmt, CWEB_VArgs args)
{
    StaticOutputBuffer out = { 
        .dst = req->arena.ptr + req->arena.cur,
        .cap = req->arena.len - req->arena.cur,
        .len = 0
    };
    evaluate_format(&out, (CWEB_String) { fmt, strlen(fmt) }, args);
    if (out.len > req->arena.len - req->arena.cur)
        return (CWEB_String) { NULL, 0 };
    req->arena.cur += out.len;
    return (CWEB_String) { out.dst, out.len };
}

void cweb_respond_redirect_impl(CWEB_Request *req, CWEB_String target)
{
    CWEB_String location_header = cweb_format(req, "Location: {}", target);
    if (location_header.len == 0) {
        http_response_builder_status(req->builder, 500);
        http_response_builder_done(req->builder);
        return;
    }

    http_response_builder_status(req->builder, 303);
    int ret = set_auth_cookie_if_necessary(req);
    if (ret < 0) {
        http_response_builder_undo(req->builder);
        http_response_builder_status(req->builder, -ret);
        http_response_builder_done(req->builder);
        return;
    }
    http_response_builder_header(req->builder, (HTTP_String) { location_header.ptr, location_header.len });
    http_response_builder_done(req->builder);
}

int cweb_set_user_id(CWEB_Request *req, int user_id)
{
    if (user_id != req->user_id) {

        if (!req->req->secure && !req->cweb->allow_insecure_login)
            return -1;

        int ret;
        if (user_id == -1) ret = delete_session(req->cweb->session_storage, req->sess);
        else               ret = create_session(req->cweb->session_storage, user_id, &req->sess, &req->csrf);

        if (ret < 0)
            return -1;

        req->just_created_session = true;
    }

    return 0;
}

int cweb_get_user_id(CWEB_Request *req)
{
    return req->user_id;
}

/////////////////////////////////////////////////////////////////
// TEMPLATE
////////////////////////////////////////////////////////////////

static TemplateCache *template_cache_init(int capacity_log2)
{
    TemplateCache *cache = malloc(sizeof(TemplateCache) + (1 << capacity_log2) * sizeof(CachedProgram));
    if (cache == NULL)
        return NULL;

    cache->count = 0;
    cache->capacity_log2 = capacity_log2;

    for (int i = 0; i < (1 << capacity_log2); i++)
        cache->pool[i].pathlen = -1;
    return cache;
}

static void template_cache_free(TemplateCache *cache)
{
    free(cache);
}

static unsigned long djb2(WL_String str)
{
    char *ptr = str.ptr;
    char *end = str.ptr + str.len;

    unsigned long hash = 5381;
    int c;
    while (ptr < end && (c = *ptr++))
        hash = ((hash << 5) + hash) + c; // hash * 33 + c
    return hash;
}

static int lookup(TemplateCache *cache, WL_String path)
{
    int mask = (1 << cache->capacity_log2) - 1;
    int hash = djb2(path);
    int i = hash & mask;
    int perturb = hash;
    for (;;) {

        if (cache->pool[i].pathlen == -1)
            return i;

        if (wl_streq(path, cache->pool[i].path, cache->pool[i].pathlen))
            return i;

        perturb >>= 5;
        i = (i * 5 + 1 + perturb) & mask;
    }

    return -1;
}

typedef struct LoadedFile LoadedFile;
struct LoadedFile {
    LoadedFile* next;
    int         len;
    char        data[];
};

static LoadedFile *load_file(WL_String path)
{
    char buf[1<<10];
    if (path.len >= (int) sizeof(buf))
        return NULL;
    memcpy(buf, path.ptr, path.len);
    buf[path.len] = '\0';

    FILE *stream = fopen(buf, "rb");
    if (stream == NULL)
        return NULL;

    int ret = fseek(stream, 0, SEEK_END);
    if (ret) {
        fclose(stream);
        return NULL;
    }

    long tmp = ftell(stream);
    if (tmp < 0 || tmp > INT_MAX) {
        fclose(stream);
        return NULL;
    }
    int len = (int) tmp;

    ret = fseek(stream, 0, SEEK_SET);
    if (ret) {
        fclose(stream);
        return NULL;
    }

    LoadedFile *result = malloc(sizeof(LoadedFile) + len + 1);
    if (result == NULL) {
        fclose(stream);
        return NULL;
    }
    result->next = NULL;
    result->len  = len;

    int read_len = fread(result->data, 1, len+1, stream);
    if (read_len != len || ferror(stream) || !feof(stream)) {
        fclose(stream);
        free(result);
        return NULL;
    }

    fclose(stream);
    return result;
}

static void free_loaded_files(LoadedFile *loaded_file)
{
    while (loaded_file) {
        LoadedFile *next = loaded_file->next;
        free(loaded_file);
        loaded_file = next;
    }
}

static int compile(WL_String path, WL_Program *program, WL_Arena *arena)
{
    WL_Compiler *compiler = wl_compiler_init(arena);
    if (compiler == NULL) {
        TRACE("Couldn't initialize WL compiler object");
        return -1;
    }

    LoadedFile *loaded_file_head = NULL;
    LoadedFile **loaded_file_tail = &loaded_file_head;

    for (int i = 0;; i++) {

        LoadedFile *loaded_file = load_file(path);
        if (loaded_file == NULL) {
            TRACE("Couldn't load file '%.*s'", path.len, path.ptr);
            free_loaded_files(loaded_file_head);
            return -1;
        }

        *loaded_file_tail = loaded_file;
        loaded_file_tail = &loaded_file->next;

        WL_String content = { loaded_file->data, loaded_file->len };
        WL_AddResult result = wl_compiler_add(compiler, content);

        if (result.type == WL_ADD_ERROR) {
            TRACE("Compilation failed (%s)", wl_compiler_error(compiler).ptr);
            free_loaded_files(loaded_file_head);
            return -1;
        }

        if (result.type == WL_ADD_LINK) break;

        assert(result.type == WL_ADD_AGAIN);
        path = result.path;
    }

    int ret = wl_compiler_link(compiler, program);
    if (ret < 0) {
        TRACE("Compilation failed (%s)", wl_compiler_error(compiler).ptr);
        return -1;
    }

    free_loaded_files(loaded_file_head);

    TRACE("Compilation succeded");
    return 0;
}

static int query_routine(WL_Runtime *rt, SQLiteCache *dbcache)
{
    int num_args = wl_arg_count(rt);
    if (num_args == 0)
        return 0;

    WL_String format;
    if (!wl_arg_str(rt, 0, &format))
        return -1;

    sqlite3_stmt *stmt;
    int ret = sqlite3utils_prepare(dbcache, &stmt, format.ptr, format.len);
    if (ret != SQLITE_OK)
        return -1;

    for (int i = 1; i < num_args; i++) {

        int64_t ival;
        double  fval;
        WL_String str;

        if (wl_arg_none(rt, i))
            ret = sqlite3_bind_null(stmt, i);
        else if (wl_arg_s64(rt, i, &ival))
            ret = sqlite3_bind_int64(stmt, i, ival);
        else if (wl_arg_f64(rt, i, &fval))
            ret = sqlite3_bind_double(stmt, i, fval);
        else if (wl_arg_str(rt, i, &str))
            ret = sqlite3_bind_text(stmt, i, str.ptr, str.len, NULL);
        else {
            assert(0); // TODO
        }

        if (ret != SQLITE_OK) {
            sqlite3_reset(stmt);
            return -1;
        }
    }

    wl_push_array(rt, 0);

    while (sqlite3_step(stmt) == SQLITE_ROW) {

        int num_cols = sqlite3_column_count(stmt);
        if (num_cols < 0) {
            sqlite3_reset(stmt);
            return -1;
        }

        wl_push_map(rt, num_cols);

        for (int i = 0; i < num_cols; i++) {
            ret = sqlite3_column_type(stmt, i);
            switch (ret) {

                case SQLITE_INTEGER:
                {
                    int64_t x = sqlite3_column_int64(stmt, i);
                    wl_push_s64(rt, x);
                }
                break;

                case SQLITE_FLOAT:
                {
                    double x = sqlite3_column_double(stmt, i);
                    wl_push_f64(rt, x);
                }
                break;

                case SQLITE_TEXT:
                {
                    const void *x = sqlite3_column_text(stmt, i);
                    int n = sqlite3_column_bytes(stmt, i);
                    wl_push_str(rt, (WL_String) { (char*) x, n });
                }
                break;

                case SQLITE_BLOB:
                {
                    const void *x = sqlite3_column_blob(stmt, i);
                    int n = sqlite3_column_bytes(stmt, i);
                    wl_push_str(rt, (WL_String) { (char*) x, n });
                }
                break;

                case SQLITE_NULL:
                {
                    wl_push_none(rt);
                }
                break;
            }

            const char *name = sqlite3_column_name(stmt, i);

            wl_push_str(rt, (WL_String) { (char*) name, strlen(name) });
            wl_insert(rt);
        }

        wl_append(rt);
    }

    sqlite3_reset(stmt);
    return 0;
}

static void push_sysvar(WL_Runtime *rt, WL_String name, SQLiteCache *dbcache, HTTP_String csrf, int user_id, int resource_id)
{
    (void) dbcache;

    if (wl_streq(name, "login_user_id", -1)) {

        if (user_id < 0)
            wl_push_none(rt);
        else
            wl_push_s64(rt, user_id);

    } else if (wl_streq(name, "resource_id", -1)) {

        if (resource_id < 0)
            wl_push_none(rt);
        else
            wl_push_s64(rt, resource_id);

    } else if (wl_streq(name, "csrf", -1)) {

        if (csrf.len == 0)
            wl_push_none(rt);
        else
            wl_push_str(rt, (WL_String) { csrf.ptr, csrf.len });
    }
}

static void push_syscall(WL_Runtime *rt, WL_String name, SQLiteCache *dbcache)
{
    if (wl_streq(name, "query", -1)) {
        query_routine(rt, dbcache);
        return;
    }
}

static int get_or_create_program(TemplateCache *cache, WL_String path, WL_Arena *arena, WL_Program *program)
{
    if (cache == NULL)
        return -1;

    int i = lookup(cache, path);
    if (cache->pool[i].pathlen == -1) {

        WL_Program program;
        int ret = compile(path, &program, arena);
        if (ret < 0) return -1;

        void *p = malloc(program.len);
        if (p == NULL)
            return -1;
        memcpy(p, program.ptr, program.len);
        program.ptr = p;

        if ((int) sizeof(cache->pool->path) <= path.len)
            return -1;
        memcpy(cache->pool[i].path, path.ptr, path.len);
        cache->pool[i].path[path.len] = '\0';
        cache->pool[i].pathlen = path.len;
        cache->pool[i].program = program;
    }

    *program = cache->pool[i].program;
    return 0;
}

void cweb_respond_template(CWEB_Request *req, int status, CWEB_String template_file, int resource_id)
{
    http_response_builder_status(req->builder, status);

    WL_Program program;
    int ret = get_or_create_program(req->cweb->tpcache, template_file, &req->arena, &program);
    if (ret < 0) {
        http_response_builder_undo(req->builder);
        http_response_builder_status(req->builder, 500);
        http_response_builder_done(req->builder);
        return;
    }

    //wl_dump_program(program);

    WL_Runtime *rt = wl_runtime_init(&req->arena, program);
    if (rt == NULL) {
        http_response_builder_undo(req->builder);
        http_response_builder_status(req->builder, 500);
        http_response_builder_done(req->builder);
        return;
    }

    for (bool done = false; !done; ) {

        WL_EvalResult result = wl_runtime_eval(rt);
        switch (result.type) {

            case WL_EVAL_DONE:
            http_response_builder_done(req->builder);
            done = true;
            break;

            case WL_EVAL_ERROR:
            // wl_runtime_error(rt)
            http_response_builder_undo(req->builder);
            http_response_builder_status(req->builder, 500);
            http_response_builder_done(req->builder);
            return;

            case WL_EVAL_SYSVAR:
            push_sysvar(rt, result.str, req->cweb->dbcache, req->csrf, req->user_id, resource_id);
            break;

            case WL_EVAL_SYSCALL:
            push_syscall(rt, result.str, req->cweb->dbcache);
            break;

            case WL_EVAL_OUTPUT:
            http_response_builder_body(req->builder, (HTTP_String) { result.str.ptr, result.str.len });
            break;

            default:
            break;
        }
    }
}