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/*
* Copyright 2020 Adobe. All rights reserved.
* This file is licensed to you under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License. You may obtain a copy
* of the License at http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under
* the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
* OF ANY KIND, either express or implied. See the License for the specific language
* governing permissions and limitations under the License.
*/
// Portions of the code in this file are based on code from ICU.
// Original licensing can be found in the NOTICE file in the root directory of this source tree.
import {AnyCalendarDate, CalendarIdentifier} from '../types';
import {CalendarDate} from '../CalendarDate';
import {fromExtendedYear, GregorianCalendar, gregorianToJulianDay, isLeapYear} from './GregorianCalendar';
// Starts in 78 AD,
const INDIAN_ERA_START = 78;
// The Indian year starts 80 days later than the Gregorian year.
const INDIAN_YEAR_START = 80;
/**
* The Indian National Calendar is similar to the Gregorian calendar, but with
* years numbered since the Saka era in 78 AD (Gregorian). There are 12 months
* in each year, with either 30 or 31 days. Only one era identifier is supported: 'saka'.
*/
export class IndianCalendar extends GregorianCalendar {
identifier: CalendarIdentifier = 'indian';
fromJulianDay(jd: number): CalendarDate {
// Gregorian date for Julian day
let date = super.fromJulianDay(jd);
// Year in Saka era
let indianYear = date.year - INDIAN_ERA_START;
// Day number in Gregorian year (starting from 0)
let yDay = jd - gregorianToJulianDay(date.era, date.year, 1, 1);
let leapMonth: number;
if (yDay < INDIAN_YEAR_START) {
// Day is at the end of the preceding Saka year
indianYear--;
// Days in leapMonth this year, previous Gregorian year
leapMonth = isLeapYear(date.year - 1) ? 31 : 30;
yDay += leapMonth + (31 * 5) + (30 * 3) + 10;
} else {
// Days in leapMonth this year
leapMonth = isLeapYear(date.year) ? 31 : 30;
yDay -= INDIAN_YEAR_START;
}
let indianMonth: number;
let indianDay: number;
if (yDay < leapMonth) {
indianMonth = 1;
indianDay = yDay + 1;
} else {
let mDay = yDay - leapMonth;
if (mDay < (31 * 5)) {
indianMonth = Math.floor(mDay / 31) + 2;
indianDay = (mDay % 31) + 1;
} else {
mDay -= 31 * 5;
indianMonth = Math.floor(mDay / 30) + 7;
indianDay = (mDay % 30) + 1;
}
}
return new CalendarDate(this, indianYear, indianMonth, indianDay);
}
toJulianDay(date: AnyCalendarDate): number {
let extendedYear = date.year + INDIAN_ERA_START;
let [era, year] = fromExtendedYear(extendedYear);
let leapMonth: number;
let jd: number;
if (isLeapYear(year)) {
leapMonth = 31;
jd = gregorianToJulianDay(era, year, 3, 21);
} else {
leapMonth = 30;
jd = gregorianToJulianDay(era, year, 3, 22);
}
if (date.month === 1) {
return jd + date.day - 1;
}
jd += leapMonth + Math.min(date.month - 2, 5) * 31;
if (date.month >= 8) {
jd += (date.month - 7) * 30;
}
jd += date.day - 1;
return jd;
}
getDaysInMonth(date: AnyCalendarDate): number {
if (date.month === 1 && isLeapYear(date.year + INDIAN_ERA_START)) {
return 31;
}
if (date.month >= 2 && date.month <= 6) {
return 31;
}
return 30;
}
getYearsInEra(): number {
// 9999-12-31 gregorian is 9920-10-10 indian.
// Round down to 9919 for the last full year.
return 9919;
}
getEras(): string[] {
return ['saka'];
}
balanceDate(): void {}
}
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