ÿþ/* jalali.js  Gregorian to Jalali and inverse date convertor

 * Copyright (C) 2001  Roozbeh Pournader <roozbeh@sharif.edu>

 * Copyright (C) 2001  Mohammad Toossi <mohammad@bamdad.org>

 * Copyright (C) 2003,2008  Behdad Esfahbod <js@behdad.org>

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 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

 * Lesser General Public License for more details.

 *

 * You can receive a copy of GNU Lesser General Public License at the

 * World Wide Web address <http://www.gnu.org/licenses/lgpl.html>.

 *

 * For licensing issues, contact The FarsiWeb Project Group,

 * Computing Center, Sharif University of Technology,

 * PO Box 11365-8515, Tehran, Iran, or contact us the

 * email address <FWPG@sharif.edu>.

 */



/* Changes:

 * 

 * 2008-Jul-32:

 *	Use a remainder() function to fix conversion of ancient dates

 *	(before 1600 gregorian).  Reported by Shamim Rezaei.

 *

 * 2003-Mar-29:

 *      Ported to javascript by Behdad Esfahbod

 *

 * 2001-Sep-21:

 *	Fixed a bug with "30 Esfand" dates, reported by Mahmoud Ghandi

 *

 * 2001-Sep-20:

 *	First LGPL release, with both sides of conversions

 */

 

g_days_in_month = new Array(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);

j_days_in_month = new Array(31, 31, 31, 31, 31, 31, 30, 30, 30, 30, 30, 29);



month_name = new Array(

"A1H1/JF",

"'1/J(G4*",

".1/'/",

"*J1",

"E1/'/",

"4G1JH1",

"EG1",

""('F",

""01",

"/Ì",

"(GEF",

"'3AF/"

);

 

function div(a,b) {

  return Math.floor(a/b);

}



function remainder(a,b) {

  return a - div(a,b)*b;

}



function gregorian_to_jalali(g /* array containing year, month, day*/ )

{

   var gy, gm, gd;

   var jy, jm, jd;

   var g_day_no, j_day_no;

   var j_np;

 

   var i;



   gy = g[0]-1600;

   gm = g[1]-1;

   gd = g[2]-1;



   g_day_no = 365*gy+div((gy+3),4)-div((gy+99),100)+div((gy+399),400);

   for (i=0;i<gm;++i)

      g_day_no += g_days_in_month[i];

   if (gm>1 && ((gy%4==0 && gy%100!=0) || (gy%400==0)))

      /* leap and after Feb */

      ++g_day_no;

   g_day_no += gd;

 

   j_day_no = g_day_no-79;

 

   j_np = div(j_day_no, 12053);

   j_day_no = remainder (j_day_no, 12053);

 

   jy = 979+33*j_np+4*div(j_day_no,1461);

   j_day_no = remainder (j_day_no, 1461);

 

   if (j_day_no >= 366) {

      jy += div((j_day_no-1),365);

      j_day_no = remainder ((j_day_no-1), 365);

   }

 

   for (i = 0; i < 11 && j_day_no >= j_days_in_month[i]; ++i) {

      j_day_no -= j_days_in_month[i];

   }

   jm = i+1;

   jd = j_day_no+1;



   return new Array(jy, jm, jd);

}



function jalali_to_gregorian(j /* array containing year, month, day*/ )

{

   var gy, gm, gd;

   var jy, jm, jd;

   var g_day_no, j_day_no;

   var leap;



   var i;



   jy = j[0]-979;

   jm = j[1]-1;

   jd = j[2]-1;



   j_day_no = 365*jy + div(jy,33)*8 + div((remainder (jy, 33)+3),4);

   for (i=0; i < jm; ++i)

      j_day_no += j_days_in_month[i];



   j_day_no += jd;



   g_day_no = j_day_no+79;



   gy = 1600 + 400*div(g_day_no,146097); /* 146097 = 365*400 + 400/4 - 400/100 + 400/400 */

   g_day_no = remainder (g_day_no, 146097);



   leap = 1;

   if (g_day_no >= 36525) /* 36525 = 365*100 + 100/4 */

   {

      g_day_no--;

      gy += 100*div(g_day_no,36524); /* 36524 = 365*100 + 100/4 - 100/100 */

      g_day_no = remainder (g_day_no, 36524);

      

      if (g_day_no >= 365)

         g_day_no++;

      else

         leap = 0;

   }



   gy += 4*div(g_day_no,1461); /* 1461 = 365*4 + 4/4 */

   g_day_no = remainder (g_day_no, 1461);



   if (g_day_no >= 366) {

      leap = 0;



      g_day_no--;

      gy += div(g_day_no, 365);

      g_day_no = remainder (g_day_no, 365);

   }



   for (i = 0; g_day_no >= g_days_in_month[i] + (i == 1 && leap); i++)

      g_day_no -= g_days_in_month[i] + (i == 1 && leap);

   gm = i+1;

   gd = g_day_no+1;



   return new Array(gy, gm, gd);

}



function jalali_today() {

  Today = new Date();

  j = gregorian_to_jalali(new Array(

                          Today.getFullYear(),

                          Today.getMonth()+1,

                          Today.getDate()

                          ));

  return j[2]+" "+month_name[j[1]-1]+" "+j[0];

}