#include "plop.h"

#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.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"

struct plop plop = {
	.handler = PLOP_DEFAULT_HANDLER,
	.L = NULL,
	.fds = NULL,
	.data = NULL,
	.nfds = 0,
};

/// 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 open_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_pushliteral(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_pushliteral(L, "handler");
	lua_pushvalue(L, -2);
	lua_rawset(L, -4);
	lua_setglobal(L, "handler");
	lua_pop(L, 1);

	return LUA_OK;
}

/// Drops Lua thread referenced by *ref* in the registry of main Lua state.
void plop_drop_thread(const int ref)
{
	if (LUA_NOREF != ref)
		luaL_unref(plop.L, LUA_REGISTRYINDEX, ref);
}

/// Handles client events.
/// \param c Connection associated with the client
/// \return -1 if an error occured, 1 if expecting to continue
int plop_handle_client(struct connection * c)
{
	int nargs = 0;

	if (c->push)
	{
		lua_getglobal(c->L, "handler");
		stream_push_new(c->L, c->fd);
		nargs = 1;
		c->push = 0;
	}

	int nresults = 0;
	int result = lua_resume(c->L, NULL, nargs, &nresults);

	switch (result)
	{
		case LUA_OK:
		{
			// TODO: If keep-alive, then reset c->push?
			plop_drop_thread(c->ref);
			connection_free(c);
			return 0;
		}
		case LUA_YIELD:
		{
			return 1;
		}
		default:
		{
			const char * err = lua_tostring(c->L, -1);

			if (NULL == err)
			{
				err = "Unknown error ocurred";
			}

			dprintf(2, "%s\n", err);
			lua_pop(c->L, 1);
			plop_drop_thread(c->ref);
			connection_free(c);
			return -1;
		}
	}
}

/// Accepts awaiting connections if any.
/// \param server File descriptor for server socket
/// \return -1 if an error occured
int plop_handle_server(const int server)
{
	int i = 1;  // Always skip server descriptor.
	for (; i <= plop.nfds; ++i)
	{
		if (-1 == plop.fds[i].fd)
			break;
		if (plop.nfds == i)
			return 0;
	}

	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: Revisit error handling in server.
	}

	struct connection * connection = connection_new(client);
	if (NULL == connection)
		return -1;
	connection->L = lua_newthread(plop.L);
	if (NULL == connection->L)
		return -1;  // TODO: Revisit error handling.
	connection->ref = luaL_ref(plop.L, LUA_REGISTRYINDEX);
	connection->fd = client;
	connection->push = 1;
	plop.fds[i].fd = client;
	plop.data[i] = connection;

	return 0;
}