#include "plop.h"

#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>

#include <lauxlib.h>
#include <lua.h>
#include <lualib.h>

#include "connection.h"
#include "stream.h"
#include "response.h"

/// Initializes new Lua state for the server.
/// \return Lua state
lua_State * plop_initialize_lua(void)
{
	lua_State * L = luaL_newstate();

	if (NULL == L)
	{
		return NULL;
	}

	luaL_openlibs(L);

	return L;
}

/// Tries to create, bind and start listening on INET server socket.
/// \param node Hostname
/// \param service Port
/// \return File descriptor of the socket or -1 in case of an error
/// \see getaddrinfo(3)
// TODO: Handle UNIX sockets
int plop_make_server(const char * node, const char * service)
{
	struct addrinfo hints = {
		.ai_family = AF_UNSPEC,
		.ai_socktype = SOCK_STREAM,
		.ai_flags = AI_PASSIVE,
	};

	struct addrinfo * result;
	struct addrinfo * it;

	if (0 != getaddrinfo(node, service, &hints, &result))
	{
		return -1; // TODO: Handle errors properly
	}

	int server;
	int optval = 1;

	for (it = result; it != NULL; it = it->ai_next)
	{
		server = socket(it->ai_family, it->ai_socktype, it->ai_protocol);

		if (-1 == server)
			continue;

		if (-1 == setsockopt(server, SOL_SOCKET, SO_REUSEADDR, (char *) &optval, sizeof(optval)))
		{
			close(server);
			continue;
		}

		if (-1 == fcntl(server, F_SETFL, (fcntl(server, F_GETFL, 0) | O_NONBLOCK)))
		{
			close(server);
			continue;
		}

		if (0 == bind(server, it->ai_addr,it->ai_addrlen))
			break;

		close(server);
	}

	if (it == NULL)
	{
		server = -1; // TODO: Handle errors properly
	}

	freeaddrinfo(result);

	if (-1 == server || -1 == listen(server, 5))
	{
		return -1; // TODO: Handle errors properly
	}

	return server;
}

/// Loads a file in path, executes it, then puts first result into package.loaded table and into global table.
/// \param L Lua state to load the handler into
/// \param path Path the script that returns handle is located at
/// \param LUA_OK if successful, appropriate Lua error otherwise
int plop_load_handler(lua_State * L, const char * path)
{
	lua_getglobal(L, "package");
	lua_pushstring(L, "loaded");
	int result = lua_rawget(L, -2);

	if (LUA_TTABLE != result)
	{
		lua_pop(L, 2);
		return LUA_ERRRUN;
	}

	result = luaL_loadfile(L, path) || lua_pcall(L, 0, 1, 0);

	if (LUA_OK != result)
	{
		lua_pop(L, 3);
		return result;
	}

	lua_pushstring(L, "handler");
	lua_pushvalue(L, -2);
	lua_rawset(L, -4);
	lua_setglobal(L, "handler");
	lua_pop(L, 1);

	return LUA_OK;
}

/// Handles client events.
/// \param L Server's Lua state
/// \param event Event for client
/// \return -1 if an error occured
int plop_handle_client(lua_State * L, struct epoll_event * event)
{
	struct connection * c = (struct connection *) event->data.ptr;
	int nargs = 0;

	if (NULL == c->L)
	{
		c->L = lua_newthread(L);

		if (NULL == c->L)
		{
			return -1; // TODO: Fail only this connection?
		}

		c->ref = luaL_ref(L, LUA_REGISTRYINDEX);

		lua_getglobal(c->L, "handler");
		stream_push_new(c->L, c->fd);
		nargs = 1;
	}

	int result = lua_resume(c->L, NULL, nargs);

	switch (result)
	{
		case LUA_OK:
		{
			int n = lua_gettop(c->L);

			if (0 == n)
			{
				lua_pushnil(c->L);
			}

			response_send(c->L, c->fd);
			connection_free(L, c);

			return 0;
		}
		case LUA_YIELD:
		{
			connection_free(L, c); // TODO: This shouldn't be the case... Right?
			return 0;
		}
		default:
		{
			connection_free(L, c);
			return -1;
		}
	}
}

/// Accepts awaiting connections if any.
/// \param L Server's Lua state
/// \param efd File descriptor for epoll's context
/// \param server File descriptor for server socket
/// \return -1 if an error occured
int plop_handle_server(lua_State * L, const int efd, const int server)
{
	struct epoll_event e;
	e.events = EPOLLIN; // TODO: Add EPOLLOUT?

	const int client = accept(server, NULL, NULL);
	if (-1 == client)
	{
		switch (errno)
		{
			case EAGAIN:
#if EWOULDBLOCK != EAGAIN
			case EWOULDBLOCK:
#endif
			case ENETDOWN:
			case EPROTO:
			case ENOPROTOOPT:
			case EHOSTDOWN:
			case ENONET:
			case EHOSTUNREACH:
			case EOPNOTSUPP:
			case ENETUNREACH:
			case ECONNABORTED:
			case EMFILE:
			case ENFILE:
			case ENOBUFS:
			case ENOMEM:
			{
				return 0;
			}
			default:
			{
				return -1;
			}
		}
	}

	if (-1 == fcntl(client, F_SETFL, (fcntl(client, F_GETFL, 0) | O_NONBLOCK)))
	{
		close(client);
		return 0; // TODO: Retriage this error at some point.
	}

	struct connection * connection = connection_new(L, client);
	if (NULL == connection)
	{
		return -1;
	}

	connection->fd = client;
	e.data.ptr = connection;

	if (-1 == epoll_ctl(efd, EPOLL_CTL_ADD, client, &e))
	{
		return -1;
	}

	return 0;
}