/*
 *  gcsd
 *
 *  gcsd the generic command sequencer daemon can be used to serialize
 *  commands sent over various paralell communication channels to a
 *  single command output. It can be seen as a multiplexer for any
 *  kind of communication between a single resource and various clients
 *  which want to submit commands to it or query information from it.
 *  gcsd is written in C and Lua. The goal is to provide an easy to
 *  understand high level API based on Lua which can be used to
 *  implement the business logic of the so formed multiplexer daemon.
 *
 *
 *  Copyright (C) 2009-2010 Markus Grueneis <gimpf@spreadspace.org>
 *                          Christian Pointner <equinox@spreadspace.org>
 *
 *  This file is part of gcsd.
 *
 *  gcsd is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  any later version.
 *
 *  gcsd is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with gcsd. If not, see <http://www.gnu.org/licenses/>.
 */

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

#include <sys/time.h>
#include <string.h>
#include <errno.h>

#include "l_timer.h"

typedef struct timeval timer_t;
#define LUA_TIMER_UDATA_NAME "timer_t"

static int l_timer_add(lua_State *L);
static int l_timer_sub(lua_State *L);

static timer_t* newtimerudata(lua_State *L)
{
  timer_t* tv = (timer_t*)lua_newuserdata(L, sizeof(timer_t));
  if(luaL_newmetatable(L, LUA_TIMER_UDATA_NAME)) {
    lua_pushliteral(L, "__add");
    lua_pushcfunction(L, l_timer_add);
    lua_settable(L, -3);
    lua_pushliteral(L, "__sub");
    lua_pushcfunction(L, l_timer_sub);
    lua_settable(L, -3);
  }
  lua_setmetatable(L, -2);
  return tv;
}

static int l_timer_new(lua_State *L)
{
  int ms = luaL_optint(L, 1, 0);
  timer_t* tv = newtimerudata(L);
  tv->tv_sec = ms/1000;
  tv->tv_usec = (ms%1000)*1000;
  return 1;
}

static int l_timer_now(lua_State *L)
{
  timer_t* now = newtimerudata(L);
  int ret = gettimeofday(now, NULL);
  if(ret) {
    lua_pushnil(L);
    lua_pushstring(L, strerror(errno)); // FIXXXXXME: strerror is not threadsafe!!!
    return 2;
  }
  return 1;
}

static int l_timer_add(lua_State *L)
{
  timer_t* a = (timer_t*)luaL_checkudata(L, 1, LUA_TIMER_UDATA_NAME);
  timer_t* b = (timer_t*)luaL_checkudata(L, 2, LUA_TIMER_UDATA_NAME);
  timer_t* res = newtimerudata(L);
  timeradd(a, b, res);
  return 1;
}

static int l_timer_sub(lua_State *L)
{
  timer_t* a = (timer_t*)luaL_checkudata(L, 1, LUA_TIMER_UDATA_NAME);
  timer_t* b = (timer_t*)luaL_checkudata(L, 2, LUA_TIMER_UDATA_NAME);
  timer_t* res = newtimerudata(L);
  timersub(a, b, res);
  return 1;
}

static int l_timer_cmp(lua_State *L)
{
  timer_t* a = (timer_t*)luaL_checkudata(L, 1, LUA_TIMER_UDATA_NAME);
  timer_t* b = (timer_t*)luaL_checkudata(L, 2, LUA_TIMER_UDATA_NAME);
  if(timercmp(a, b, <))
    lua_pushinteger(L, -1);
  else if(timercmp(a, b, >))
    lua_pushinteger(L, 1);
  else
    lua_pushinteger(L, 0);

  return 1;
}

static const struct luaL_Reg timer_funcs [] = {
  { "new", l_timer_new },
  { "now", l_timer_now },
  { "add", l_timer_add },
  { "sub", l_timer_sub },
  { "cmp", l_timer_cmp },
  { NULL, NULL }
};

LUALIB_API int luaopen_timer(lua_State *L)
{
#if LUA_VERSION_NUM > 501
  lua_newtable(L);
  luaL_setfuncs(L, timer_funcs, 0);
  lua_pushvalue(L, -1);
  lua_setglobal(L, LUA_TIMERLIBNAME);
#else
   luaL_register(L, LUA_TIMERLIBNAME, timer_funcs);
#endif
  return 1;
}