#include "http.h"

#include "log.h"
#include "mem.h"
#include "util.js.h"

#include "picohttpparser.h"
#include "uv.h"

#include <assert.h>
#include <stdlib.h>
#include <string.h>

#if !defined(__APPLE__) && !defined(__OpenBSD__) && !defined(_WIN32)
#include <alloca.h>
#endif

typedef struct _tf_http_connection_t
{
	tf_http_t* http;
	uv_tcp_t tcp;

	const char* method;
	const char* path;
	int minor_version;

	char headers_buffer[8192];
	size_t headers_buffer_length;
	int parsed_length;

	char buffer[8192];
	size_t buffer_length;

	struct phr_header headers[32];
	int headers_length;
	bool headers_done;

	tf_http_callback_t* callback;
	void* user_data;

	void* body;
	size_t body_length;
	size_t content_length;
	bool connection_close;
} tf_http_connection_t;

typedef struct _tf_http_handler_t
{
	const char* pattern;
	tf_http_callback_t* callback;
	void* user_data;
} tf_http_handler_t;

typedef struct _tf_http_t
{
	uv_tcp_t** listeners;
	int listeners_count;

	tf_http_connection_t** connections;
	int connections_count;

	tf_http_handler_t* handlers;
	int handlers_count;

	int pending_closes;
	uv_loop_t* loop;
} tf_http_t;

static void _http_connection_destroy(tf_http_connection_t* connection);
static const char* _http_status_text(int status);

tf_http_t* tf_http_create(uv_loop_t* loop)
{
	tf_http_t* http = tf_malloc(sizeof(tf_http_t));
	*http = (tf_http_t)
	{
		.loop = loop,
	};
	return http;
}

void _http_allocate_buffer(uv_handle_t* handle, size_t suggestedSize, uv_buf_t* buf)
{
	tf_http_connection_t* connection = handle->data;
	if (!connection->headers_done)
	{
		*buf = uv_buf_init(connection->headers_buffer + connection->headers_buffer_length, sizeof(connection->headers_buffer) - connection->headers_buffer_length);
	}
	else
	{
		*buf = uv_buf_init(connection->buffer + connection->buffer_length, sizeof(connection->buffer) - connection->buffer_length);
	}
}

bool _http_find_handler(tf_http_t* http, const char* path, tf_http_callback_t** out_callback, void** out_user_data)
{
	for (int i = 0; i < http->handlers_count; i++)
	{
		if (!http->handlers[i].pattern ||
			strcmp(path, http->handlers[i].pattern) == 0 ||
			(strncmp(path, http->handlers[i].pattern, strlen(http->handlers[i].pattern)) == 0 && path[strlen(http->handlers[i].pattern)] == '/'))
		{
			*out_callback = http->handlers[i].callback;
			*out_user_data = http->handlers[i].user_data;
			return true;
		}
	}
	return false;
}

static void _http_on_write(uv_write_t* write, int status)
{
	tf_free(write);
}

static void _http_connection_on_close(uv_handle_t* handle)
{
	tf_http_connection_t* connection = handle->data;
	handle->data = NULL;
	_http_connection_destroy(connection);
}

static void _http_connection_destroy(tf_http_connection_t* connection)
{
	if (connection->tcp.data)
	{
		uv_close((uv_handle_t*)&connection->tcp, _http_connection_on_close);
	}
	else
	{
		tf_http_t* http = connection->http;
		for (int i = 0; i < http->connections_count; i++)
		{
			if (http->connections[i] == connection)
			{
				http->connections[i] = http->connections[--http->connections_count];
			}
		}
		if (connection->body)
		{
			tf_free(connection->body);
			connection->body = NULL;
		}
		tf_free(connection);
	}
}

static void _http_builtin_404_handler(tf_http_request_t* request)
{
	const char* k_payload = _http_status_text(404);
	tf_http_respond(request, 404, NULL, 0, k_payload, strlen(k_payload));
}

static void _http_reset_connection(tf_http_connection_t* connection)
{
	connection->headers_done = false;
	connection->headers_buffer_length = 0;
	connection->body_length = 0;
	connection->content_length = 0;
}

static void _http_add_body_bytes(tf_http_connection_t* connection, const void* data, size_t size)
{
	size_t fit = tf_min(connection->content_length - connection->body_length, size);
	if (fit > 0)
	{
		memcpy((char*)connection->body + connection->body_length, data, fit);
		connection->body_length += fit;
	}

	if (connection->body_length == connection->content_length)
	{
		tf_http_request_t* request = tf_malloc(sizeof(tf_http_request_t));
		*request = (tf_http_request_t)
		{
			.connection = connection,
			.phase = k_http_callback_phase_headers_received,
			.method = connection->method,
			.path = connection->path,
			.headers = connection->headers,
			.headers_count = connection->headers_length,
			.user_data = connection->user_data,
		};
		connection->callback(request);
		_http_reset_connection(connection);
	}
}

static void _http_on_read(uv_stream_t* stream, ssize_t read_size, const uv_buf_t* buffer)
{
	tf_http_connection_t* connection = stream->data;
	if (read_size > 0)
	{
		if (!connection->headers_done)
		{
			connection->headers_buffer_length += read_size;

			const char* method = NULL;
			size_t method_length = 0;
			const char* path = NULL;
			size_t path_length = 0;
			size_t header_count = sizeof(connection->headers) / sizeof(*connection->headers);

			int parse_result = phr_parse_request(connection->headers_buffer, connection->headers_buffer_length, &method, &method_length, &path, &path_length, &connection->minor_version, connection->headers, &header_count, connection->parsed_length);
			connection->parsed_length = connection->headers_buffer_length;
			if (parse_result > 0)
			{
				connection->headers_done = true;
				connection->method = method;
				((char*)connection->method)[method_length] = '\0';
				connection->path = path;
				((char*)connection->path)[path_length] = '\0';

				connection->connection_close = connection->minor_version == 0;

				for (int i = 0; i < (int)header_count; i++)
				{
					((char*)connection->headers[i].name)[connection->headers[i].name_len] = '\0';
					((char*)connection->headers[i].value)[connection->headers[i].value_len] = '\0';
					if (strcasecmp(connection->headers[i].name, "content-length") == 0)
					{
						connection->content_length = strtoull(connection->headers[i].value, NULL, 10);
					}
					else if (strcasecmp(connection->headers[i].name, "connection") == 0)
					{
						if (strcasecmp(connection->headers[i].value, "close") == 0)
						{
							connection->connection_close = true;
						}
					}
				}

				if (connection->content_length)
				{
					connection->body = tf_malloc(connection->content_length);
				}

				if (!_http_find_handler(connection->http, connection->path, &connection->callback, &connection->user_data) || !connection->callback)
				{
					connection->callback = _http_builtin_404_handler;
				}

				_http_add_body_bytes(connection, connection->headers_buffer + parse_result, connection->headers_buffer_length - parse_result);
			}
			else if (parse_result == -2)
			{
				/* Incomplete.  Will try again next time. */
			}
			else
			{
				tf_printf("phr_parse_request: %d\n", parse_result);
				_http_connection_destroy(connection);
			}
		}
		else
		{
			connection->buffer_length += read_size;
			_http_add_body_bytes(connection, connection->buffer, connection->buffer_length);
		}
	}
	else
	{
		_http_connection_destroy(connection);
	}
}

static void _http_on_connection(uv_stream_t* stream, int status)
{
	tf_http_t* http = stream->data;
	tf_http_connection_t* connection = tf_malloc(sizeof(tf_http_connection_t));
	*connection = (tf_http_connection_t) { .http = http, .tcp = { .data = connection } };
	int r = uv_tcp_init(connection->http->loop, &connection->tcp);
	if (r)
	{
		tf_printf("uv_tcp_init: %s\n", uv_strerror(r));
		tf_free(connection);
		return;
	}

	r = uv_accept(stream, (uv_stream_t*)&connection->tcp);
	if (r)
	{
		tf_printf("uv_accept: %s\n", uv_strerror(r));
		uv_close((uv_handle_t*)&connection->tcp, NULL);
		tf_free(connection);
		return;
	}

	r = uv_read_start((uv_stream_t*)&connection->tcp, _http_allocate_buffer, _http_on_read);
	if (r)
	{
		tf_printf("uv_read-start: %s\n", uv_strerror(r));
		uv_close((uv_handle_t*)&connection->tcp, NULL);
		tf_free(connection);
		return;
	}

	http->connections = tf_realloc(http->connections, http->connections_count + 1);
	http->connections[http->connections_count++] = connection;
}

void tf_http_listen(tf_http_t* http, int port)
{
	uv_tcp_t* tcp = tf_malloc(sizeof(uv_tcp_t));
	*tcp = (uv_tcp_t) { .data = http };
	int r = uv_tcp_init(http->loop, tcp);
	if (r)
	{
		tf_printf("uv_tcp_init: %s\n", uv_strerror(r));
	}

	if (r == 0)
	{
		struct sockaddr_in addr =
		{
			.sin_family = AF_INET,
			.sin_addr = { .s_addr = INADDR_ANY },
			.sin_port = ntohs(port),
		};
		r = uv_tcp_bind(tcp, (struct sockaddr*)&addr, 0);
		if (r)
		{
			tf_printf("uv_tcp_bind: %s\n", uv_strerror(r));
		}
	}

	if (r == 0)
	{
		r = uv_listen((uv_stream_t*)tcp, 16, _http_on_connection);
		if (r)
		{
			tf_printf("uv_listen: %s\n", uv_strerror(r));
		}
	}

	if (r == 0)
	{
		http->listeners = tf_realloc(http->listeners, sizeof(uv_tcp_t*) * (http->listeners_count + 1));
		http->listeners[http->listeners_count++] = tcp;
	}
}

void tf_http_add_handler(tf_http_t* http, const char* pattern, tf_http_callback_t* callback, void* user_data)
{
	http->handlers = tf_realloc(http->handlers, sizeof(tf_http_handler_t) * (http->handlers_count + 1));
	http->handlers[http->handlers_count++] = (tf_http_handler_t)
	{
		.pattern = tf_strdup(pattern),
		.callback = callback,
		.user_data = user_data,
	};
}

static void _http_free_on_close(uv_handle_t* handle)
{
	handle->data = NULL;
	tf_free(handle);
}

void tf_http_destroy(tf_http_t* http)
{
	for (int i = 0; i < http->listeners_count; i++)
	{
		uv_close((uv_handle_t*)http->listeners[i], _http_free_on_close);
	}
	tf_free(http->listeners);
	http->listeners = NULL;
	http->listeners_count = 0;

	for (int i = 0; i < http->handlers_count; i++)
	{
		if (http->handlers[i].pattern)
		{
			tf_free((void*)http->handlers[i].pattern);
			http->handlers[i].pattern = NULL;
		}
	}
	tf_free(http->handlers);
	http->handlers_count = 0;

	tf_free(http->connections);
	http->connections_count = 0;

	tf_free(http);
}

static const char* _http_status_text(int status)
{
	switch (status)
	{
	case 101: return "Switching Protocols";
	case 200: return "OK";
	case 303: return "See other";
	case 304: return "Not Modified";
	case 400: return "Bad Request";
	case 401: return "Unauthorized";
	case 403: return "Forbidden";
	case 404: return "File not found";
	case 500: return "Internal server error";
	default: return "Unknown";
	}
}

static void _http_on_shutdown(uv_shutdown_t* request, int status)
{
	tf_free(request);
}

void tf_http_respond(tf_http_request_t* request, int status, const char** headers, int headers_count, const void* body, size_t content_length)
{
	const char* status_text = _http_status_text(status);
	/* HTTP/1.x 200 OK\r\n */
	bool sent_content_length = false;
	int headers_length = 8 + 1 + 3 + 1 + strlen(status_text) + 2;
	for (int i = 0; i < headers_count; i += 2)
	{
		/* Key: Value\r\n */
		headers_length += strlen(headers[i]) + 2 + strlen(headers[i + 1]) + 2;
		if (strcasecmp(headers[i], "content-length") == 0)
		{
			sent_content_length = true;
		}
	}
	/* \r\n */
	headers_length += 2;

	char content_length_buffer[32] = { 0 };
	int content_length_buffer_length = 0;
	if (!sent_content_length)
	{
		content_length_buffer_length = snprintf(content_length_buffer, sizeof(content_length_buffer), "Content-Length: %zd\r\n", content_length);
		headers_length += content_length_buffer_length;
	}

	uv_write_t* write = tf_malloc(sizeof(uv_write_t) + headers_length + content_length + 1);
	*write = (uv_write_t) { .data = request->connection };
	char* buffer = (char*)(write + 1);
	int offset = snprintf(buffer, headers_length + 1, "HTTP/1.%d %03d %s\r\n", request->connection->minor_version, status, status_text);
	for (int i = 0; i < headers_count; i += 2)
	{
		offset += snprintf(buffer + offset, headers_length + 1 - offset, "%s: %s\r\n", headers[i], headers[i + 1]);
	}
	if (!sent_content_length)
	{
		memcpy(buffer + offset, content_length_buffer, content_length_buffer_length);
		offset += content_length_buffer_length;
	}
	offset += snprintf(buffer + offset, headers_length + 1 - offset, "\r\n");
	assert(offset == headers_length);
	if (content_length)
	{
		memcpy(buffer + offset, body, content_length);
	}
	int r = uv_write(write, (uv_stream_t*)&request->connection->tcp, &(uv_buf_t) { .base = buffer, .len = headers_length + content_length }, 1, _http_on_write);
	if (r)
	{
		tf_printf("uv_write: %s\n", uv_strerror(r));
	}

	if (request->connection->connection_close)
	{
		uv_shutdown_t* shutdown_request = tf_malloc(sizeof(uv_shutdown_t));
		*shutdown_request = (uv_shutdown_t) { .data = request };
		uv_shutdown(shutdown_request, (uv_stream_t*)&request->connection->tcp, _http_on_shutdown);
	}
	tf_free(request);
}

size_t tf_http_get_body(const tf_http_request_t* request, const void** out_data)
{
	*out_data = request->connection->body;
	return request->connection->content_length;
}