/*
** $Id: loslib.c,v $
** Standard Operating System library
** See Copyright Notice in lua.h
*/


#include <errno.h>
#include <locale.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#define loslib_c
#define LUA_LIB

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"


static int pushresult (lua_State *L, int i, const char *filename) {
  if (i) {
    lua_pushboolean(L, 1);
    return 1;
  }
  else {
    lua_pushnil(L);
    if (filename)
      lua_pushfstring(L, "%s: %s", filename, strerror(errno));
    else
      lua_pushfstring(L, "%s", strerror(errno));
    lua_pushinteger(L, errno);
    return 3;
  }
}


static int io_execute (lua_State *L) {
  lua_pushinteger(L, system(luaL_checkstring(L, 1)));
  return 1;
}


static int io_remove (lua_State *L) {
  const char *filename = luaL_checkstring(L, 1);
  return pushresult(L, remove(filename) == 0, filename);
}


static int io_rename (lua_State *L) {
  const char *fromname = luaL_checkstring(L, 1);
  const char *toname = luaL_checkstring(L, 2);
  return pushresult(L, rename(fromname, toname) == 0, fromname);
}


static int io_tmpname (lua_State *L) {
#if !USE_TMPNAME
  luaL_error(L, "`tmpname' not supported");
  return 0;
#else
  char buff[L_tmpnam];
  if (tmpnam(buff) != buff)
    return luaL_error(L, "unable to generate a unique filename in `tmpname'");
  lua_pushstring(L, buff);
  return 1;
#endif
}


static int io_getenv (lua_State *L) {
  lua_pushstring(L, getenv(luaL_checkstring(L, 1)));  /* if NULL push nil */
  return 1;
}


static int io_clock (lua_State *L) {
  lua_pushnumber(L, ((lua_Number)clock())/(lua_Number)CLOCKS_PER_SEC);
  return 1;
}


/*
** {======================================================
** Time/Date operations
** { year=%Y, month=%m, day=%d, hour=%H, min=%M, sec=%S,
**   wday=%w+1, yday=%j, isdst=? }
** =======================================================
*/

static void setfield (lua_State *L, const char *key, int value) {
  lua_pushstring(L, key);
  lua_pushinteger(L, value);
  lua_rawset(L, -3);
}

static void setboolfield (lua_State *L, const char *key, int value) {
  lua_pushstring(L, key);
  lua_pushboolean(L, value);
  lua_rawset(L, -3);
}

static int getboolfield (lua_State *L, const char *key) {
  int res;
  lua_getfield(L, -1, key);
  res = lua_isnil(L, -1) ? -1 : lua_toboolean(L, -1);
  lua_pop(L, 1);
  return res;
}


static int getfield (lua_State *L, const char *key, int d) {
  int res;
  lua_getfield(L, -1, key);
  if (lua_isnumber(L, -1))
    res = (int)lua_tointeger(L, -1);
  else {
    if (d < 0)
      return luaL_error(L, "field `%s' missing in date table", key);
    res = d;
  }
  lua_pop(L, 1);
  return res;
}


static int io_date (lua_State *L) {
  const char *s = luaL_optstring(L, 1, "%c");
  lua_Number n = luaL_optnumber(L, 2, -1);
  time_t t = (n == -1) ? time(NULL) : (time_t)n;
  struct tm *stm;
  if (*s == '!') {  /* UTC? */
    stm = gmtime(&t);
    s++;  /* skip `!' */
  }
  else
    stm = localtime(&t);
  if (stm == NULL)  /* invalid date? */
    lua_pushnil(L);
  else if (strcmp(s, "*t") == 0) {
    lua_createtable(L, 0, 9);  /* 9 = number of fields */
    setfield(L, "sec", stm->tm_sec);
    setfield(L, "min", stm->tm_min);
    setfield(L, "hour", stm->tm_hour);
    setfield(L, "day", stm->tm_mday);
    setfield(L, "month", stm->tm_mon+1);
    setfield(L, "year", stm->tm_year+1900);
    setfield(L, "wday", stm->tm_wday+1);
    setfield(L, "yday", stm->tm_yday+1);
    setboolfield(L, "isdst", stm->tm_isdst);
  }
  else {
    char b[256];
    if (strftime(b, sizeof(b), s, stm))
      lua_pushstring(L, b);
    else
      return luaL_error(L, "`date' format too long");
  }
  return 1;
}


static int io_time (lua_State *L) {
  if (lua_isnoneornil(L, 1))  /* called without args? */
    lua_pushnumber(L, time(NULL));  /* return current time */
  else {
    time_t t;
    struct tm ts;
    luaL_checktype(L, 1, LUA_TTABLE);
    lua_settop(L, 1);  /* make sure table is at the top */
    ts.tm_sec = getfield(L, "sec", 0);
    ts.tm_min = getfield(L, "min", 0);
    ts.tm_hour = getfield(L, "hour", 12);
    ts.tm_mday = getfield(L, "day", -1);
    ts.tm_mon = getfield(L, "month", -1) - 1;
    ts.tm_year = getfield(L, "year", -1) - 1900;
    ts.tm_isdst = getboolfield(L, "isdst");
    t = mktime(&ts);
    if (t == (time_t)(-1))
      lua_pushnil(L);
    else
      lua_pushnumber(L, t);
  }
  return 1;
}


static int io_difftime (lua_State *L) {
  lua_pushnumber(L, difftime((time_t)(luaL_checknumber(L, 1)),
                             (time_t)(luaL_optnumber(L, 2, 0))));
  return 1;
}

/* }====================================================== */


static int io_setloc (lua_State *L) {
  static const int cat[] = {LC_ALL, LC_COLLATE, LC_CTYPE, LC_MONETARY,
                      LC_NUMERIC, LC_TIME};
  static const char *const catnames[] = {"all", "collate", "ctype", "monetary",
     "numeric", "time", NULL};
  const char *l = lua_tostring(L, 1);
  int op = luaL_findstring(luaL_optstring(L, 2, "all"), catnames);
  luaL_argcheck(L, l || lua_isnoneornil(L, 1), 1, "string expected");
  luaL_argcheck(L, op != -1, 2, "invalid option");
  lua_pushstring(L, setlocale(cat[op], l));
  return 1;
}


static int io_exit (lua_State *L) {
  exit(luaL_optint(L, 1, EXIT_SUCCESS));
  return 0;  /* to avoid warnings */
}

static const luaL_reg syslib[] = {
  {"clock",     io_clock},
  {"date",      io_date},
  {"difftime",  io_difftime},
  {"execute",   io_execute},
  {"exit",      io_exit},
  {"getenv",    io_getenv},
  {"remove",    io_remove},
  {"rename",    io_rename},
  {"setlocale", io_setloc},
  {"time",      io_time},
  {"tmpname",   io_tmpname},
  {NULL, NULL}
};

/* }====================================================== */



LUALIB_API int luaopen_os (lua_State *L) {
  luaL_openlib(L, LUA_OSLIBNAME, syslib, 0);
  return 1;
}