#include <sys/socket.h>
#include <sys/un.h>

#include <errno.h>
#include <stdio.h>
#include <unistd.h>

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

#define LIBNAME "client"

#ifndef VERSION
#define VERSION "(unknown)"
#endif

#ifndef DEFAULT_SOCKET_PATH
#define DEFAULT_SOCKET_PATH "/var/run/privsep/root.sock"
#endif

#define BUFSIZE 32768

static int pusherror(lua_State *L, const char *info)
{
	lua_pushnil(L);
	if (info == NULL)
		lua_pushstring(L, strerror(errno));
	else
		lua_pushfstring(L, "%s: %s", info, strerror(errno));
	lua_pushinteger(L, errno);
	return 3;
}

static int Pconnect(lua_State *L)
{
	const char *socket_path = luaL_optstring(L, 1, DEFAULT_SOCKET_PATH);
	struct sockaddr_un sun;
	int fd, ret;

	memset(&sun, 0, sizeof(sun));
	sun.sun_family = AF_UNIX;
	strncpy(sun.sun_path, socket_path, sizeof(sun.sun_path));

	fd = socket(AF_UNIX, SOCK_STREAM, 0);
	if (fd < 0)
		return pusherror(L, "socket");

	if (connect(fd, (struct sockaddr *) &sun, sizeof(sun)) < 0) {
		ret = pusherror(L, socket_path);
		goto close_err;
	}

	lua_pushinteger(L, fd);
	return 1;

close_err:
	close(fd);
	return ret;
}

static int push_err_or_int(lua_State *L, ssize_t n)
{
	if (n < 0)
		return pusherror(L, NULL);
	lua_pushinteger(L, n);
	return 1;
}

static int Pwrite(lua_State *L)
{
	int fd = luaL_checkinteger(L, 1);
	size_t len = 0;
	const char *msg = luaL_checklstring(L, 2, &len);
	return push_err_or_int(L, write(fd, msg, len));
}

static int Precv(lua_State *L)
{
	int fd = luaL_checkinteger(L, 1);
	static char buf[BUFSIZE];
	ssize_t n = recv(fd, buf, sizeof(buf), 0);
	if (n < 0)
		return pusherror(L, NULL);
	lua_pushlstring(L, buf, n);
	return 1;
}

static int Pclose(lua_State *L)
{
	int fd = luaL_checkinteger(L, 1);
	return push_err_or_int(L, close(fd));
}

static const luaL_reg reg_client_methods[] = {
	{"connect",	Pconnect},
	{"write",	Pwrite},
	{"recv",	Precv},
	{"close",	Pclose},
	{NULL,	NULL},
};


LUALIB_API int luaopen_client(lua_State *L)
{
	luaL_register(L, LIBNAME, reg_client_methods);
	lua_pushliteral(L, "version");
	lua_pushliteral(L, VERSION);
	lua_settable(L, -3);
	return 1;
}