unit HijriLib;

{
**************************************************
  First part of this lib which is in charge of
  converting to and from Hijri Calendar is
  reproduced form YSE Hijridate PHP Script:
    http://www.yse-uk.com


  For any possible future update or change see:
    http://pmc.khone.ir

**************************************************
  This lib is licensed under the GNU LESSER
  GENERAL PUBLIC LICENSE
**************************************************
}


interface

  uses
    jalaliLib, dialogs, SysUtils, dateutils;

{  type
    datePack = record
      Year : Word;
      Month : Word;
      Day : Word;
    end;
}

  function gregorian_to_hijri(g_y, g_m, g_d : Word): datePack; overload;
  function gregorian_to_hijri(iDate : datePack): datePack; overload;
  function get_hmonth_name(j_m: Word) : WideString;
  function ConvToFarDigit(inp: Integer): WideString; overload;
  function ConvToFarDigit(inp: WideString): WideString; overload;
  procedure setHijriOffset(ofs : Integer);
  function getHijriOffset() : Integer;
  function hNow() : datePack;

implementation

  var
    cnvAr : array[0..9] of WideChar = ('۰','۱','۲','۳','۴','۵','۶','۷','۸','۹');
    hDayOffset : Integer = 0;

  function getHijriOffset() : Integer;
  begin
    Result := hDayOffset;
  end;

  procedure setHijriOffset(ofs : Integer);
  begin
    hDayOffset := ofs;
  end;

  function ConvToFarDigit(inp: WideString): WideString; overload;
  var
    i : Word;
  begin
    for i := 1 to Length(inp) do
      if (Ord(inp[i]) >= 48) and (Ord(inp[i]) <= 57) then
        inp[i] := cnvAr[ord(inp[i]) - 48];

    Result := inp;
  end;

  function ConvToFarDigit(inp: Integer): WideString; overload;
  begin
    Result := ConvToFarDigit(IntToStr(inp));
  end;

  function greg2jd(g_y, g_m, g_d : Integer) : Extended;
  begin
	  Result := (1461 * (g_y + 4800 + (g_m - 14) / 12)) / 4 +
	        (367 * (g_m - 2 - 12 * ((g_m - 14) / 12))) / 12 -
	        (3 * ((g_y + 4900 + (g_m - 14) / 12) / 100 )) / 4 +
	        g_d - 32075;

  end;

  function jd2hijri(jd : Extended) : datePack;
  var
    h_n, h_j : Integer;
  begin
  	jd := jd - 1948440 + 10632;
  	h_n := Trunc((jd - 1) / 10631);
	  jd := jd - 10631 * h_n + 354;
  	h_j := (Trunc ((10985 - jd) / 5316)) *
	    (Trunc (50 * jd / 17719)) +
    	(Trunc (jd / 5670)) *
    	(Trunc (43 * jd / 15238));
  	jd := jd - (Trunc ((30 - h_j) / 15)) *
    	(Trunc ((17719 * h_j) / 50)) -
    	(Trunc (h_j / 16)) *
    	(Trunc ((15238 * h_j) / 43)) + 29;
      
  	Result.Month := Trunc(24 * jd / 709);
	  Result.Day := Round(jd - Trunc(709 * Result.Month / 24)) + hDayOffset;
  	Result.Year := 30 * h_n + h_j - 30;

  end;


  function gregorian_to_hijri(g_y, g_m, g_d : Word): datePack; overload;
  begin
    Result := jd2hijri(greg2jd(g_y, g_m, g_d));
  end;

  function gregorian_to_hijri(iDate : datePack): datePack; overload;
  begin
    Result := gregorian_to_hijri(iDate.Year, iDate.Month, iDate.Day);
  end;

  function get_hmonth_name(j_m: Word) : WideString;
  begin
    case j_m of
      1 : Result := 'محرّم';
      2 : Result := 'صفر';
      3 : Result := 'ربيع الأول';
      4 : Result := 'ربيع الآخر';
      5 : Result := 'جمادى الأول';
      6 : Result := 'جمادى الآخر';
      7 : Result := 'رجب';
      8 : Result := 'شعبان';
      9 : Result := 'رمضان';
      10 : Result := 'شوّال';
      11 : Result := 'ذو القعدة';
      12 : Result := 'ذو الحجة';
    end;
  end;

  function hNow() : datePack;
  begin
    Result := gregorian_to_hijri(YearOf(Now), MonthOf(Now), DayOf(Now));
  end;

end.