/* Copyright (C) 2004 MySQL AB

   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; version 2 of the License.

   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, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */


#ifdef USE_PRAGMA_INTERFACE
#pragma interface			/* gcc class interface */
#endif

/**
  This class represents abstract time zone and provides 
  basic interface for DRIZZLE_TIME <-> my_time_t conversion.
  Actual time zones which are specified by DB, or via offset 
  or use system functions are its descendants.
*/
class Time_zone: public Sql_alloc 
{
public:
  Time_zone() {}                              /* Remove gcc warning */
  /**
    Converts local time in broken down DRIZZLE_TIME representation to 
    my_time_t (UTC seconds since Epoch) represenation.
    Returns 0 in case of error. Sets in_dst_time_gap to true if date provided
    falls into spring time-gap (or lefts it untouched otherwise).
  */
  virtual my_time_t TIME_to_gmt_sec(const DRIZZLE_TIME *t, 
                                    bool *in_dst_time_gap) const = 0;
  /**
    Converts time in my_time_t representation to local time in
    broken down DRIZZLE_TIME representation.
  */
  virtual void   gmt_sec_to_TIME(DRIZZLE_TIME *tmp, my_time_t t) const = 0;
  /**
    Because of constness of String returned by get_name() time zone name 
    have to be already zeroended to be able to use String::ptr() instead
    of c_ptr().
  */
  virtual const String * get_name() const = 0;

  /** 
    We need this only for surpressing warnings, objects of this type are
    allocated on MEM_ROOT and should not require destruction.
  */
  virtual ~Time_zone() {};
};

extern Time_zone * my_tz_UTC;
extern Time_zone * my_tz_SYSTEM;
extern Time_zone * my_tz_OFFSET0;
extern Time_zone * my_tz_find(THD *thd, const String *name);
extern bool     my_tz_init(THD *org_thd, const char *default_tzname, bool bootstrap);
extern void        my_tz_free();
extern my_time_t   sec_since_epoch_TIME(DRIZZLE_TIME *t);