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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Diagnostics;
namespace System.Globalization
{
/// <summary>
/// Modern Persian calendar is a solar observation based calendar. Each new year begins on the day when the vernal equinox occurs before noon.
/// The epoch is the date of the vernal equinox prior to the epoch of the Islamic calendar (March 19, 622 Julian or March 22, 622 Gregorian)
/// There is no Persian year 0. Ordinary years have 365 days. Leap years have 366 days with the last month (Esfand) gaining the extra day.
/// </summary>
/// <remarks>
/// Calendar support range:
/// Calendar Minimum Maximum
/// ========== ========== ==========
/// Gregorian 0622/03/22 9999/12/31
/// Persian 0001/01/01 9378/10/13
/// </remarks>
public class PersianCalendar : Calendar
{
public static readonly int PersianEra = 1;
private static readonly long s_persianEpoch = new DateTime(622, 3, 22).Ticks / TimeSpan.TicksPerDay;
private const int ApproximateHalfYear = 180;
private const int DatePartYear = 0;
private const int DatePartDayOfYear = 1;
private const int DatePartMonth = 2;
private const int DatePartDay = 3;
private const int MonthsPerYear = 12;
private static ReadOnlySpan<int> DaysToMonth => [0, 31, 62, 93, 124, 155, 186, 216, 246, 276, 306, 336, 366];
private const int MaxCalendarYear = 9378;
private const int MaxCalendarMonth = 10;
private const int MaxCalendarDay = 13;
// Persian calendar (year: 1, month: 1, day:1 ) = Gregorian (year: 622, month: 3, day: 22)
// This is the minimal Gregorian date that we support in the PersianCalendar.
private static readonly DateTime s_minDate = new DateTime(622, 3, 22);
private static readonly DateTime s_maxDate = DateTime.MaxValue;
public override DateTime MinSupportedDateTime => s_minDate;
public override DateTime MaxSupportedDateTime => s_maxDate;
public override CalendarAlgorithmType AlgorithmType => CalendarAlgorithmType.SolarCalendar;
public PersianCalendar()
{
}
internal override CalendarId BaseCalendarID => CalendarId.GREGORIAN;
internal override CalendarId ID => CalendarId.PERSIAN;
private static long GetAbsoluteDatePersian(int year, int month, int day)
{
if (year < 1 || year > MaxCalendarYear || month < 1 || month > 12)
{
throw new ArgumentOutOfRangeException(null, SR.ArgumentOutOfRange_BadYearMonthDay);
}
// day is one based, make 0 based since this will be the number of days we add to beginning of year below
int ordinalDay = DaysInPreviousMonths(month) + day - 1;
int approximateDaysFromEpochForYearStart = (int)(CalendricalCalculationsHelper.MeanTropicalYearInDays * (year - 1));
long yearStart = CalendricalCalculationsHelper.PersianNewYearOnOrBefore(s_persianEpoch + approximateDaysFromEpochForYearStart + ApproximateHalfYear);
yearStart += ordinalDay;
return yearStart;
}
internal static void CheckTicksRange(long ticks)
{
if (ticks < s_minDate.Ticks || ticks > s_maxDate.Ticks)
{
throw new ArgumentOutOfRangeException(
"time",
ticks,
SR.Format(SR.ArgumentOutOfRange_CalendarRange, s_minDate, s_maxDate));
}
}
internal static void CheckEraRange(int era)
{
if (era != CurrentEra && era != PersianEra)
{
throw new ArgumentOutOfRangeException(nameof(era), era, SR.ArgumentOutOfRange_InvalidEraValue);
}
}
internal static void CheckYearRange(int year, int era)
{
CheckEraRange(era);
if (year < 1 || year > MaxCalendarYear)
{
throw new ArgumentOutOfRangeException(
nameof(year),
year,
SR.Format(SR.ArgumentOutOfRange_Range, 1, MaxCalendarYear));
}
}
internal static void CheckYearMonthRange(int year, int month, int era)
{
CheckYearRange(year, era);
if (year == MaxCalendarYear)
{
if (month > MaxCalendarMonth)
{
throw new ArgumentOutOfRangeException(
nameof(month),
month,
SR.Format(SR.ArgumentOutOfRange_Range, 1, MaxCalendarMonth));
}
}
if (month < 1 || month > 12)
{
ThrowHelper.ThrowArgumentOutOfRange_Month(month);
}
}
private static int MonthFromOrdinalDay(int ordinalDay)
{
Debug.Assert(ordinalDay <= 366);
int index = 0;
while (ordinalDay > DaysToMonth[index])
{
index++;
}
return index;
}
private static int DaysInPreviousMonths(int month)
{
Debug.Assert(1 <= month && month <= 12);
// months are one based but for calculations use 0 based
--month;
return DaysToMonth[month];
}
private int GetDatePart(long ticks, int part)
{
CheckTicksRange(ticks);
// Get the absolute date. The absolute date is the number of days from January 1st, 1 A.D.
// 1/1/0001 is absolute date 1.
long numDays = ticks / TimeSpan.TicksPerDay + 1;
// Calculate the appromixate Persian Year.
long yearStart = CalendricalCalculationsHelper.PersianNewYearOnOrBefore(numDays);
int y = (int)(Math.Floor(((yearStart - s_persianEpoch) / CalendricalCalculationsHelper.MeanTropicalYearInDays) + 0.5)) + 1;
Debug.Assert(y >= 1);
if (part == DatePartYear)
{
return y;
}
// Calculate the Persian Month.
int ordinalDay = (int)(numDays - CalendricalCalculationsHelper.GetNumberOfDays(this.ToDateTime(y, 1, 1, 0, 0, 0, 0, 1)));
if (part == DatePartDayOfYear)
{
return ordinalDay;
}
int m = MonthFromOrdinalDay(ordinalDay);
Debug.Assert(ordinalDay >= 1);
Debug.Assert(m >= 1 && m <= 12);
if (part == DatePartMonth)
{
return m;
}
int d = ordinalDay - DaysInPreviousMonths(m);
Debug.Assert(1 <= d);
Debug.Assert(d <= 31);
// Calculate the Persian Day.
if (part == DatePartDay)
{
return d;
}
// Incorrect part value.
throw new InvalidOperationException(SR.InvalidOperation_DateTimeParsing);
}
// Exactly the same as GetDatePart, except computing all of
// year/month/day rather than just one of them. Used when all three
// are needed rather than redoing the computations for each.
internal void GetDate(long ticks, out int year, out int month, out int day)
{
CheckTicksRange(ticks);
// Get the absolute date. The absolute date is the number of days from January 1st, 1 A.D.
// 1/1/0001 is absolute date 1.
long numDays = ticks / TimeSpan.TicksPerDay + 1;
// Calculate the appromixate Persian Year.
long yearStart = CalendricalCalculationsHelper.PersianNewYearOnOrBefore(numDays);
year = (int)(Math.Floor(((yearStart - s_persianEpoch) / CalendricalCalculationsHelper.MeanTropicalYearInDays) + 0.5)) + 1;
Debug.Assert(year >= 1);
// Calculate the Persian Month.
int ordinalDay = (int)(numDays - CalendricalCalculationsHelper.GetNumberOfDays(this.ToDateTime(year, 1, 1, 0, 0, 0, 0, 1)));
month = MonthFromOrdinalDay(ordinalDay);
Debug.Assert(ordinalDay >= 1);
Debug.Assert(month >= 1 && month <= 12);
day = ordinalDay - DaysInPreviousMonths(month);
Debug.Assert(1 <= day);
Debug.Assert(day <= 31);
}
public override DateTime AddMonths(DateTime time, int months)
{
if (months < -120000 || months > 120000)
{
throw new ArgumentOutOfRangeException(
nameof(months),
months,
SR.Format(SR.ArgumentOutOfRange_Range, -120000, 120000));
}
// Get the date in Persian calendar.
GetDate(time.Ticks, out int y, out int m, out int d);
int i = m - 1 + months;
if (i >= 0)
{
m = i % 12 + 1;
y += i / 12;
}
else
{
m = 12 + (i + 1) % 12;
y += (i - 11) / 12;
}
int days = GetDaysInMonth(y, m);
if (d > days)
{
d = days;
}
long ticks = GetAbsoluteDatePersian(y, m, d) * TimeSpan.TicksPerDay + time.Ticks % TimeSpan.TicksPerDay;
CheckAddResult(ticks, MinSupportedDateTime, MaxSupportedDateTime);
return new DateTime(ticks);
}
public override DateTime AddYears(DateTime time, int years)
{
return AddMonths(time, years * 12);
}
public override int GetDayOfMonth(DateTime time)
{
return GetDatePart(time.Ticks, DatePartDay);
}
public override DayOfWeek GetDayOfWeek(DateTime time) => time.DayOfWeek;
public override int GetDayOfYear(DateTime time)
{
return GetDatePart(time.Ticks, DatePartDayOfYear);
}
public override int GetDaysInMonth(int year, int month, int era)
{
CheckYearMonthRange(year, month, era);
if ((month == MaxCalendarMonth) && (year == MaxCalendarYear))
{
return MaxCalendarDay;
}
int daysInMonth = DaysToMonth[month] - DaysToMonth[month - 1];
if ((month == MonthsPerYear) && !IsLeapYear(year))
{
Debug.Assert(daysInMonth == 30);
--daysInMonth;
}
return daysInMonth;
}
public override int GetDaysInYear(int year, int era)
{
CheckYearRange(year, era);
if (year == MaxCalendarYear)
{
return DaysToMonth[MaxCalendarMonth - 1] + MaxCalendarDay;
}
return IsLeapYear(year, CurrentEra) ? 366 : 365;
}
public override int GetEra(DateTime time)
{
CheckTicksRange(time.Ticks);
return PersianEra;
}
public override int[] Eras => [PersianEra];
public override int GetMonth(DateTime time)
{
return GetDatePart(time.Ticks, DatePartMonth);
}
public override int GetMonthsInYear(int year, int era)
{
CheckYearRange(year, era);
if (year == MaxCalendarYear)
{
return MaxCalendarMonth;
}
return 12;
}
public override int GetYear(DateTime time)
{
return GetDatePart(time.Ticks, DatePartYear);
}
public override bool IsLeapDay(int year, int month, int day, int era)
{
// The year/month/era value checking is done in GetDaysInMonth().
int daysInMonth = GetDaysInMonth(year, month, era);
if (day < 1 || day > daysInMonth)
{
throw new ArgumentOutOfRangeException(
nameof(day),
day,
SR.Format(SR.ArgumentOutOfRange_Day, daysInMonth, month));
}
return IsLeapYear(year, era) && month == 12 && day == 30;
}
public override int GetLeapMonth(int year, int era)
{
CheckYearRange(year, era);
return 0;
}
public override bool IsLeapMonth(int year, int month, int era)
{
CheckYearMonthRange(year, month, era);
return false;
}
public override bool IsLeapYear(int year, int era)
{
CheckYearRange(year, era);
if (year == MaxCalendarYear)
{
return false;
}
return (GetAbsoluteDatePersian(year + 1, 1, 1) - GetAbsoluteDatePersian(year, 1, 1)) == 366;
}
public override DateTime ToDateTime(int year, int month, int day, int hour, int minute, int second, int millisecond, int era)
{
// The year/month/era checking is done in GetDaysInMonth().
int daysInMonth = GetDaysInMonth(year, month, era);
if (day < 1 || day > daysInMonth)
{
throw new ArgumentOutOfRangeException(
nameof(day),
day,
SR.Format(SR.ArgumentOutOfRange_Day, daysInMonth, month));
}
long lDate = GetAbsoluteDatePersian(year, month, day);
if (lDate < 0)
{
throw new ArgumentOutOfRangeException(null, SR.ArgumentOutOfRange_BadYearMonthDay);
}
return new DateTime(lDate * TimeSpan.TicksPerDay + TimeToTicks(hour, minute, second, millisecond));
}
private const int DefaultTwoDigitYearMax = 1410;
public override int TwoDigitYearMax
{
get
{
if (_twoDigitYearMax == -1)
{
_twoDigitYearMax = GetSystemTwoDigitYearSetting(ID, DefaultTwoDigitYearMax);
}
return _twoDigitYearMax;
}
set
{
VerifyWritable();
if (value < 99 || value > MaxCalendarYear)
{
throw new ArgumentOutOfRangeException(
nameof(value),
value,
SR.Format(SR.ArgumentOutOfRange_Range, 99, MaxCalendarYear));
}
_twoDigitYearMax = value;
}
}
public override int ToFourDigitYear(int year)
{
ArgumentOutOfRangeException.ThrowIfNegative(year);
if (year < 100)
{
return base.ToFourDigitYear(year);
}
if (year > MaxCalendarYear)
{
throw new ArgumentOutOfRangeException(
nameof(year),
year,
SR.Format(SR.ArgumentOutOfRange_Range, 1, MaxCalendarYear));
}
return year;
}
}
}
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