#pragma once

#include <arpa/inet.h>
#include <assert.h>
#include <errno.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>

#include "tcp_session.h"
#include "debuglog.h"
#include "http_request.h"
#include "http_parser.h"
#include "http_parser_settings.h"
#include "vec.h"

#define HTTP_SESSION_DEFAULT_REQUEST_RESPONSE_SIZE (PAGE_SIZE)

#define u8 uint8_t
VEC(u8)

struct http_session {
	struct sockaddr     client_address; /* client requesting connection! */
	int                 socket;
	struct http_parser  http_parser;
	struct http_request http_request;
	struct vec_u8       request_buffer;
	struct vec_u8       response_buffer;
};

/**
 * @param session sandbox that we want to init
 * @returns 0 on success, -1 on error
 */
static inline int
http_session_init(struct http_session *session, int socket_descriptor, const struct sockaddr *socket_address)
{
	assert(session != NULL);
	assert(socket_descriptor >= 0);
	assert(socket_address != NULL);

	session->socket = socket_descriptor;
	memcpy(&session->client_address, socket_address, sizeof(struct sockaddr));

	http_parser_init(&session->http_parser, HTTP_REQUEST);

	/* Set the http_request member as the data pointer the http_parser callbacks receive */
	session->http_parser.data = &session->http_request;

	memset(&session->http_request, 0, sizeof(struct http_parser));

	int rc = vec_u8_init(&session->request_buffer, HTTP_SESSION_DEFAULT_REQUEST_RESPONSE_SIZE);
	if (rc < 0) return -1;

	/* Defer allocating response until we've matched a route */
	session->response_buffer.buffer = NULL;

	return 0;
}

static inline int
http_session_init_response_buffer(struct http_session *session, size_t capacity)
{
	assert(session != NULL);
	assert(session->response_buffer.buffer == NULL);

	int rc = vec_u8_init(&session->response_buffer, capacity);
	if (rc < 0) {
		vec_u8_deinit(&session->request_buffer);
		return -1;
	}

	return 0;
}

static inline struct http_session *
http_session_alloc(int socket_descriptor, const struct sockaddr *socket_address)
{
	assert(socket_descriptor >= 0);
	assert(socket_address != NULL);

	struct http_session *session = calloc(sizeof(struct http_session), 1);
	if (session == NULL) return NULL;

	int rc = http_session_init(session, socket_descriptor, socket_address);
	if (rc != 0) {
		free(session);
		return NULL;
	}

	return session;
}

/**
 * Deinitialize Linear Memory, cleaning up the backing buffer
 * @param sandbox
 */
static inline void
http_session_deinit(struct http_session *session)
{
	assert(session);

	vec_u8_deinit(&session->request_buffer);
	vec_u8_deinit(&session->response_buffer);
}

static inline void
http_session_free(struct http_session *session)
{
	assert(session);

	http_session_deinit(session);
	free(session);
}

/**
 * Writes buffer to the client socket
 * @param session - the HTTP session we want to send a 500 to
 * @param on_eagain - cb to execute when client socket returns EAGAIN. If NULL, error out
 * @returns 0 on success, -1 on error.
 */
static inline int
http_session_send_err(struct http_session *session, int status_code, void_cb on_eagain)
{
	assert(session != NULL);
	assert(status_code >= 100 && status_code <= 599);

	return tcp_session_send(session->socket, http_header_build(status_code), http_header_len(status_code),
	                        on_eagain);
}

static inline int
http_session_send_err_oneshot(struct http_session *session, int status_code)
{
	assert(session != NULL);
	assert(status_code >= 100 && status_code <= 599);

	return tcp_session_send_oneshot(session->socket, http_header_build(status_code), http_header_len(status_code));
}

static inline int
http_session_send_response(struct http_session *session, const char *response_content_type, void_cb on_eagain)
{
	assert(session != NULL);
	assert(session->response_buffer.buffer != NULL);
	assert(response_content_type != NULL);

	int rc = 0;

	struct vec_u8 *response_buffer = &session->response_buffer;

	/* Send HTTP Response Header and Body */
	rc = http_header_200_write(session->socket, response_content_type, response_buffer->length);
	if (rc < 0) goto err;

	rc = tcp_session_send(session->socket, (const char *)response_buffer->buffer, response_buffer->length,
	                      on_eagain);
	if (rc < 0) goto err;

	http_total_increment_2xx();
	rc = 0;

done:
	return rc;
err:
	debuglog("Error sending to client: %s", strerror(errno));
	rc = -1;
	goto done;
}

static inline void
http_session_close(struct http_session *session)
{
	assert(session != NULL);

	return tcp_session_close(session->socket, &session->client_address);
}


/**
 * Receive and Parse the Request for the current sandbox
 * @return 0 if message parsing complete, -1 on error, -2 if buffers run out of space
 */
static inline int
http_session_receive_request(struct http_session *session, void_cb on_eagain)
{
	assert(session != NULL);

	int rc = 0;

	struct vec_u8 *request_buffer = &session->request_buffer;
	assert(request_buffer->capacity > 0);
	assert(request_buffer->length < request_buffer->capacity);

	while (!session->http_request.message_end) {
		/* Read from the Socket */

		/* Structured to closely follow usage example at https://github.com/nodejs/http-parser */
		http_parser                *parser   = &session->http_parser;
		const http_parser_settings *settings = http_parser_settings_get();

		/* If header parsing is complete, resize using content-length */
		if (session->http_request.header_end && session->http_request.body != NULL) {
			int header_size = (uint8_t *)session->http_request.body - session->request_buffer.buffer;
			assert(header_size > 0);
			int required_size = header_size + session->http_request.body_length;

			assert(required_size > 0);

			if (required_size > request_buffer->capacity) {
				uint8_t *old_buffer = request_buffer->buffer;
				if (vec_u8_resize(request_buffer, required_size) != 0) {
					debuglog("Failed to resize request vector to %d bytes\n", required_size);
					goto err_nobufs;
				}

				if (old_buffer != request_buffer->buffer) {
					/* buffer moved, so invalidate to reparse */
					memset(&session->http_request, 0, sizeof(struct http_request));
					http_parser_init(&session->http_parser, HTTP_REQUEST);
					/* Set the session as the data the http-parser has access to */
					session->http_parser.data = &session->http_request;
				}
			}
		} else if (request_buffer->length == request_buffer->capacity) {
			/* Otherwise, we have a huge header and should just grow */
			uint8_t *old_buffer = request_buffer->buffer;

			if (vec_u8_grow(request_buffer) != 0) {
				debuglog("Failed to grow request buffer\n");
				goto err_nobufs;
			}

			if (old_buffer != request_buffer->buffer) {
				/* buffer moved, so invalidate to reparse */
				memset(&session->http_request, 0, sizeof(struct http_request));
				http_parser_init(&session->http_parser, HTTP_REQUEST);
				/* Set the session as the data the http-parser has access to */
				session->http_parser.data = &session->http_request;
			}
		}

		ssize_t bytes_received = recv(session->socket, &request_buffer->buffer[request_buffer->length],
		                              request_buffer->capacity - request_buffer->length, 0);

		if (bytes_received < 0) {
			if (errno == EAGAIN) {
				if (on_eagain == NULL) {
					goto err_eagain;
				} else {
					on_eagain();
					continue;
				}
			} else {
				debuglog("Error reading socket %d - %s\n", session->socket, strerror(errno));
				goto err;
			}
		}

		/* If we received an EOF before we were able to parse a complete HTTP header, request is malformed */
		if (bytes_received == 0 && !session->http_request.message_end) {
			char client_address_text[INET6_ADDRSTRLEN] = {};
			if (unlikely(inet_ntop(AF_INET, &session->client_address, client_address_text, INET6_ADDRSTRLEN)
			             == NULL)) {
				debuglog("Failed to log client_address: %s", strerror(errno));
			}

			debuglog("recv returned 0 before a complete request was received: socket: %d. Address: %s\n",
			         session->socket, client_address_text);
			http_request_print(&session->http_request);
			goto err;
		}

		assert(bytes_received > 0);
		request_buffer->length += bytes_received;

#ifdef LOG_HTTP_PARSER
		debuglog("http_parser_execute(%p, %p, %p, %zu\n)", parser, settings,
		         &session->request_buffer.buffer[session->request_buffer.length], bytes_received);
#endif
		size_t bytes_parsed =
		  http_parser_execute(parser, settings,
		                      (const char *)&request_buffer->buffer[session->http_request.length_parsed],
		                      (size_t)request_buffer->length - session->http_request.length_parsed);

		if (bytes_parsed < (size_t)bytes_received) {
			debuglog("Error: %s, Description: %s\n",
			         http_errno_name((enum http_errno)session->http_parser.http_errno),
			         http_errno_description((enum http_errno)session->http_parser.http_errno));
			debuglog("Length Parsed %zu, Length Read %zu\n", bytes_parsed, (size_t)bytes_received);
			debuglog("Error parsing socket %d\n", session->socket);
			goto err;
		}

		session->http_request.length_parsed += bytes_parsed;
	}

#ifdef LOG_HTTP_PARSER
	for (int i = 0; i < session->http_request.query_params_count; i++) {
		debuglog("Argument %d, Len: %d, %.*s\n", i, session->http_request.query_params[i].value_length,
		         session->http_request.query_params[i].value_length,
		         session->http_request.query_params[i].value);
	}
#endif

	rc = 0;
done:
	return rc;
err_eagain:
	rc = -3;
	goto done;
err_nobufs:
	rc = -2;
	goto done;
err:
	rc = -1;
	goto done;
}

/**
 * Writes to the HTTP response buffer
 * On success, the number of bytes written is returned.  On error, -1 is returned,
 */
static inline int
http_session_write_response(struct http_session *session, const uint8_t *source, size_t n)
{
	assert(session);
	assert(session->response_buffer.buffer != NULL);
	assert(source);

	int rc = 0;

	if (session->response_buffer.capacity - session->response_buffer.length < n) {
		rc = vec_u8_grow(&session->response_buffer);
		if (rc != 0) goto DONE;
	}

	assert(session->response_buffer.capacity - session->response_buffer.length >= n);

	memcpy(&session->response_buffer.buffer[session->response_buffer.length], source, n);
	session->response_buffer.length += n;
	rc = n;

DONE:
	return rc;
}