/* Copyright (C) 2008  Emmanuel Varoquaux

   This file is part of XOS.

   This program 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
   (at your option) any later version.

   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>. */

#include "time.h"

#include <string.h>
#include <stdlib.h>

static const struct dst_struct cet_dst = {"CEST", -7200, {2, 5, 0, 7200}, {9, 5, 0, 10800}};

static const struct tz_struct tz_table[] = {
  /* UTC */
  {"UTC", 0, NULL},

  /* GMT */
  {"GMT", 0, NULL},

  /* CET */
  {"CET", -3600, &cet_dst}
};
static const size_t tz_table_size = sizeof tz_table / sizeof tz_table[0];
const struct tz_struct *const __utc_tz = &tz_table[0];
static const struct tz_struct *const gmt_tz = &tz_table[1];

const struct tz_struct *__current_tz;

static char __tzname[TZNAME_MAX + 1][2];
char *tzname[2] __attribute__ ((weak, visibility ("default")));
long timezone __attribute__ ((weak, visibility ("default")));
int daylight __attribute__ ((weak, visibility ("default")));

static void set_vars()
{
  strcpy(__tzname[0], __current_tz->name);
  strcpy(__tzname[1], __current_tz->dst ? __current_tz->dst->name : __current_tz->name);
  tzname[0] = __tzname[0];
  tzname[1] = __tzname[1];
  timezone = __current_tz->offset;
  daylight = __current_tz->dst ? 1 : 0;
}

static void set_current_tz(const char *s)
{
  __current_tz = tz_table;
  while (__current_tz < tz_table + tz_table_size) {
    if (!strcmp(__current_tz->name, s))
      goto set_vars;
    __current_tz++;
  }
  __current_tz = __utc_tz;
 set_vars:
  set_vars();
}

void __tz_init()
{
  __current_tz = gmt_tz;
  set_vars();
}

void __attribute__ ((weak, visibility ("default"))) tzset()
{
  const char *_timezone;

  if ((_timezone = getenv("TZ")))
    set_current_tz(_timezone);
  else
    set_current_tz("UTC");
}
typeof (tzset) __tzset __attribute__ ((alias ("tzset")));