GIslamicDate - header, take two

[Ali Abdin <aliabdin aucegypt edu>]

Okay,

This is my second take at a GIslamicDate header. Mainly, I fixed a few issues
in it. Also, I took out a lot of stuff that I just "copied" from GDate and
which might not need to apply to GIslamicDate (I picture GIslamicDate just as
a convenient way to represent Islamic Dates, and to convert to/from the
gregorian dates. We don't need to do any "complex" computations with them
(i.e. add/subtract days, months, years, etc. - We can use GDate for that, and
then convert into GIslamicDate).

There are still some FIXME's in there which I would appreciate comments on.

Regards,
Ali

/* GLIB - Library of useful routines for C programming
 *
 * Copyright (C) 2000 Ali Abdin <aliabdin aucegypt edu>
 *
 * 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 2 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 */

#ifndef __G_ISLAMIC_DATE_H
#define __G_ISLAMIC_DATE_H

G_BEGIN_DECLS

/* GIslamicDate
 *
 * This is basically an implmentation for the Islamic lunar calendar. It
 * is a deterministic calendar which means it can not ever be 100%
 * accurate. This implementation is based on the GNU Emacs lisp implementation
 * of the Islamic lunar calendar. It is discussed in a paper found at this
 * website: http://emr.cs.uiuc.edu/~reingold/calendars.shtml
 */

typedef guint16 GIslamicDateYear;
typedef guint8  GIslamicDateDay;
typedef struct _GIslamicDate GIslamicDate;
/* To recognize struct tm withotu including time.h */
struct tm;

typedef enum
{
  G_ISLAMIC_DATE_BAD_MONTH    = 0,
  G_ISLAMIC_DATE_MUHARRAM     = 1,
  G_ISLAMIC_DATE_SAFAR	      = 2,
  G_ISLAMIC_DATE_RABI1	      = 3,
  G_ISLAMIC_DATE_RABI2	      = 4,
  G_ISLAMIC_DATE_JUMADA1      = 5,
  G_ISLAMIC_DATE_JUMADA2      = 6,
  G_ISLAMIC_DATE_RAJAB	      = 7,
  G_ISLAMIC_DATE_SHAABAN      = 8,
  G_ISLAMIC_DATE_RAMADAN      = 9,
  G_ISLAMIC_DATE_SHAWAL	      = 10,
  G_ISLAMIC_DATE_DHU_AL_QHADA = 11,
  G_ISLAMIC_DATE_DHU_AL_HIJJA = 12
} GIslamicDateMonth;

typedef enum
{
  G_ISLAMIC_RAMADAN_EARLY     = 0, /* Ramadan was one day early */
  G_ISLAMIC_RAMADAN_NORMAL    = 1, /* Default: Ramadan is on schedule */
  G_ISLAMIC_RAMADAN_LATE      = 2  /* Ramadan is one day late	*/
} GIslamicRamadanSchedule;

#define G_ISLAMIC_DATE_BAD_DAY 0U
#define G_ISLAMIC_DATE_BAD_YEAR 0U

/* Don't access the struct directly */
struct _GIslamicDate
{
  GIslamicRamadanSchedule ramadan_sched;
  
  guint day    	: 6;
  guint month	: 4;
  guint year   	: 16;
};

GIslamicDate*		g_islamic_date_new		(void);
/* dmy is in Islamic month/day/year (not gregorian!) */
GIslamicDate*		g_islamic_date_new_dmy		(GIslamicDateDay     day,
							 GIslamicDateMonth   month,
							 GIslamicDateYear    year);
GIslamicDate*		g_islamic_date_new_struct_tm	(GIslamicDate	     *date,
							 struct tm	     tm);
/* New GIslamicDate from an existing GDate */
GIslamicDate*		g_islamic_date_new_gdate	(GDate 		     *date);
void 			g_islamic_date_free		(GIslamicDate 	     *date);

/* Always check for an operation that could fail */
gboolean		g_islamic_date_valid		(GIslamicDate 	     *date);
gboolean		g_islamic_date_valid_day	(GIslamicDateDay     day) G_GNUC_CONST;
gboolean		g_islamic_date_valid_month	(GIslamicDateMonth   month) G_GNUC_CONST;
gboolean		g_islamic_date_valid_year	(GIslamicDateYear    year) G_GNUC_CONST;
/* Islamic dmy - not gregorian */
gboolean		g_islamic_date_valid_dmy	(GIslamicDateDay     day,
							 GIslamicDateMonth   month,
							 GIslamicDateYear    year) G_GNUC_CONST;

GIslamicDateMonth	g_islamic_date_month		(GIslamicDate	     *date);
GIslamicDateYear	g_islamic_date_year		(GIslamicDate	     *date);
GIslamicDateDay		g_islamic_date_day		(GIslamicDate 	     *date);

/* If you create a static date struct you need to clear it to get it
 * in a sane state before use. You can clear a whole array at
 * once with the ndates argument.
 */
void			g_islamic_date_clear		(GIslamicDate	     *date,
                                           		 guint        	     n_dates);

void			g_islamic_date_set_month	(GIslamicDate	     *date,
							 GIslamicDateMonth   month);
void			g_islamic_date_set_day		(GIslamicDate	     *date,
							 GIslamicDateDay     day);
void			g_islamic_date_set_year		(GIslamicDate	     *date,
							 GIslamicDateYear    year);
void			g_islamic_date_set_dmy		(GIslamicDate	     *date,
							 GIslamicDateDay     day,
							 GIslamicDateMonnth  month,
							 GIslamicDateYear    year);
							 		
gboolean		g_islamic_date_is_leap_year	(GIslamicDateYear    year) G_GNUC_CONST;
/* If the year == current year then take ramadan setting into account */
guint8			g_islamic_date_days_in_month	(GIslamicDateMonth   month,
							 GIslamicDateYear    year) G_GNUC_CONST;
/* q-sort friendly with a cast */
gint			g_islamic_date_compare		(GIslamicDate 	     *lhs,
							 GIslamicDate	     *rhs);

void			g_islamic_date_to_struct_tm	(GIslamicDate 	     *date,
							 struct tm	     *tm);
/* FIXME: Should this be g_date_new_islamic? (like g_date_new_julians and
 * g_islamic_date_new_gdate)?
 */
void			g_islamic_date_to_gdate		(GIslamicDate	     *date,
							 GDate		     *norm_gdate);
/* FIXME: Should we add conversion functions to/from time_t ? */

/* FIXME: Should we add a function that returns an i18n'd dup'd string based on
 * the GIslamicDateMonth
 */

G_END_DECLS

#endif /* __G_ISLAMIC_DATE_H__ */