/// <summary>
/// Sets the current Jewish date to the date represented by the given "Absolute Date" -
/// which is the number of days after/before December 31st, 1 BCE.
/// The logic here was translated from the C code - which in turn were translated
/// from the Lisp code in ''Calendrical Calculations'' by Nachum Dershowitz and Edward M. Reingold in
/// Software---Practice & Experience, vol. 20, no. 9 (September, 1990), pp. 899--928.
/// </summary>
/// <param name="absoluteDate"></param>
private void SetFromAbsoluteDate(int absoluteDate)
{
this._absoluteDate = absoluteDate;
//To save on calculations, start with an estimation of a few years before date
this._year = 3761 + (absoluteDate / (absoluteDate > 0 ? 366 : 300));
//The following is from the original code; it starts the calculations way back when and takes almost as long to calculate all of them...
//this._year = ((absoluteDate + JewishDateCalculations.HEBREW_EPOCH) / 366); // Approximation from below.
// Search forward for year from the approximation.
while (absoluteDate >= JewishDateCalculations.GetAbsoluteFromJewishDate((this._year + 1), 7, 1))
{
this._year++;
}
// Search forward for month from either Tishrei or Nissan.
if (absoluteDate < JewishDateCalculations.GetAbsoluteFromJewishDate(this._year, 1, 1))
{
this._month = 7; // Start at Tishrei
}
else
{
this._month = 1; // Start at Nissan
}
while (absoluteDate > JewishDateCalculations.GetAbsoluteFromJewishDate(
this._year,
this._month,
(JewishDateCalculations.DaysInJewishMonth(this._year, this._month))))
{
this._month++;
}
// Calculate the day by subtraction.
this._day = (absoluteDate - JewishDateCalculations.GetAbsoluteFromJewishDate(this._year, this._month, 1) + 1);
}
private Sedra(int year, bool inIsrael)
{
//If the last call is within the same year as this one, we reuse the data.
//If memory is an issue, remove these next few lines
if (_lastSedraCalculated != null && _lastSedraCalculated._year == year && _lastSedraCalculated._inIsrael == inIsrael)
{
this._firstSatInYear = _lastSedraCalculated._firstSatInYear;
this._sedraArray = _lastSedraCalculated._sedraArray;
return;
}
//Save the data in case the next call is for the same year
_lastSedraCalculated = this;
bool longCheshvon = JewishDateCalculations.IsLongCheshvan(year);
bool shortKislev = JewishDateCalculations.IsShortKislev(year);
int roshHashana = JewishDateCalculations.GetAbsoluteFromJewishDate(year, 7, 1);
DayOfWeek roshHashanaDOW = (DayOfWeek)Math.Abs(roshHashana % 7);
YearType yearType;
if (longCheshvon && !shortKislev)
{
yearType = YearType.Complete;
}
else if (!longCheshvon && shortKislev)
{
yearType = YearType.Incomplete;
}
else
{
yearType = YearType.Regular;
}
this._year = year;
this._inIsrael = inIsrael;
/* find and save the first shabbos on or after Rosh Hashana */
this._firstSatInYear = GetDayOnOrBefore(6, roshHashana + 6);
if (!JewishDateCalculations.IsJewishLeapYear(year))
{
switch (roshHashanaDOW)
{
case DayOfWeek.Saturday:
if (yearType == YearType.Incomplete)
{
this._sedraArray = shabbos_short;
}
else if (yearType == YearType.Complete)
{
this._sedraArray = shabbos_long;
}
break;
case DayOfWeek.Monday:
if (yearType == YearType.Incomplete)
{
this._sedraArray = mon_short;
}
else if (yearType == YearType.Complete)
{
this._sedraArray = this._inIsrael ? mon_short : mon_long;
}
break;
case DayOfWeek.Tuesday:
if (yearType == YearType.Regular)
{
this._sedraArray = this._inIsrael ? mon_short : mon_long;
}
break;
case DayOfWeek.Thursday:
if (yearType == YearType.Regular)
{
this._sedraArray = this._inIsrael ? thu_normal_Israel : thu_normal;
}
else if (yearType == YearType.Complete)
{
this._sedraArray = thu_long;
}
break;
default:
throw new Exception("improper sedra year type calculated.");
}
}
else /* leap year */
{
switch (roshHashanaDOW)
{
case DayOfWeek.Saturday:
if (yearType == YearType.Incomplete)
{
this._sedraArray = shabbos_short_leap;
}
else if (yearType == YearType.Complete)
{
this._sedraArray = this._inIsrael ? shabbos_short_leap : shabbos_long_leap;
}
break;
case DayOfWeek.Monday:
if (yearType == YearType.Incomplete)
{
this._sedraArray = this._inIsrael ? mon_short_leap_Israel : mon_short_leap;
}
else if (yearType == YearType.Complete)
{
this._sedraArray = this._inIsrael ? mon_long_leap_Israel : mon_long_leap;
}
break;
case DayOfWeek.Tuesday:
if (yearType == YearType.Regular)
{
this._sedraArray = this._inIsrael ? mon_long_leap_Israel : mon_long_leap;
}
break;
case DayOfWeek.Thursday:
if (yearType == YearType.Incomplete)
{
this._sedraArray = thu_short_leap;
}
else if (yearType == YearType.Complete)
{
this._sedraArray = thu_long_leap;
}
break;
default:
throw new Exception("improper sedra year type calculated.");
}
}
}
/// <summary>
/// Creates a new JewishDate with the specified Hebrew year, month and day
/// </summary>
/// <param name="year">The year - counted from the creation of the world</param>
/// <param name="month">The Jewish month. As it is in the Torah, Nissan is 1.</param>
/// <param name="day">The day of the month</param>
public JewishDate(int year, int month, int day) :
this(year, month, day, JewishDateCalculations.GetAbsoluteFromJewishDate(year, month, day))
{
}
