/*
 *  rhnop
 *
 *  Copyright (C) 2011-2016 Christian Pointner <equinox@helsinki.at>
 *
 *  This file is part of rhnop.
 *
 *  rhnop 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.
 *
 *  rhnop 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 rhnop. If not, see <http://www.gnu.org/licenses/>.
 */

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

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

#include "l_pipe.h"

static int pipefds_[2];

int pipe_init()
{
  return pipe(pipefds_);
}

void pipe_close()
{
  close(pipefds_[0]);
  close(pipefds_[1]);
}

static int l_pipe_signal(lua_State *L)
{
  size_t len = 0, written = 0;
  const char* data = luaL_checklstring(L, 1, &len);
  len++; // also send trailing zero

  int ret = 0;
  for(;;) {
    ret = write(pipefds_[1], &(data[written]), len - written);
    if(!ret) continue;
    if(ret == -1 && (errno == EAGAIN || errno == EINTR)) continue;

    written += ret;
    if(written == len) break;

    break;
  }

  lua_pushinteger(L, ret);
  return 1;
}

static int l_pipe_getfd(lua_State *L)
{
  if(!lua_istable(L, -1))
    luaL_error(L, "can't retreive pipe fd");

  lua_pushliteral(L, "fd");
  lua_gettable(L, -2);
  return 1;
}

static int l_pipe_dirty(lua_State *L)
{
  lua_pushboolean(L, 0);
  return 1;
}

static int l_pipe_getreadfd(lua_State *L)
{
  lua_newtable(L);
  lua_pushliteral(L, "fd");
  lua_pushinteger(L, pipefds_[0]);
  lua_settable(L, -3);
  lua_pushliteral(L, "getfd");
  lua_pushcfunction(L, l_pipe_getfd);
  lua_settable(L, -3);
  lua_pushliteral(L, "dirty");
  lua_pushcfunction(L, l_pipe_dirty);
  lua_settable(L, -3);
  return 1;
}

static int l_pipe_consume(lua_State *L)
{
  char data[17]; // 17 should be sufficient
  size_t len = 0;

  int ret = 0;
  for(;;) {
    ret = read(pipefds_[0], &(data[len]), 1);
    if(ret == 0) break;
    if(ret == -1 && (errno == EAGAIN || errno == EINTR)) continue;

    if(data[len] == 0)
      break;

    len += ret;
    if(len >= sizeof(data)) {
      ret = 0;
      break;
    }
  }

  if(ret)
    lua_pushstring(L, data);
  else
    lua_pushnil(L);

  return 1;
}

static const struct luaL_Reg pipe_funcs [] = {
  { "signal", l_pipe_signal },
  { "getreadfd", l_pipe_getreadfd },
  { "consume", l_pipe_consume },
  { NULL, NULL }
};

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