/*
* IslamicCal.js - Represent a Islamic calendar object.
*
* Copyright © 2012-2015, 2018, JEDLSoft
*
* Licensed 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 CONDITIONS OF ANY KIND, either express or implied.
*
* See the License for the specific language governing permissions and
* limitations under the License.
*/
var MathUtils = require("./MathUtils.js");
var Calendar = require("./Calendar.js");
/**
* @class
* Construct a new Islamic calendar object. This class encodes information about
* the civil Islamic calendar. The civil Islamic calendar is a tabular islamic
* calendar where the dates are calculated by arithmetic rules. This differs from
* the religious Islamic calendar which is used to mark the beginning of particular
* holidays. The religious calendar depends on the first sighting of the new
* crescent moon to determine the first day of the new month. Because humans and
* weather are both involved, the actual time of sighting varies, so it is not
* really possible to precalculate the religious calendar. Certain groups, such
* as the Islamic Society of North America, decreed in in 2007 that they will use
* a calendar based on calculations rather than observations to determine the
* beginning of lunar months, and therefore the dates of holidays.<p>
*
* @param {Object=} options Options governing the construction of this instance
* @constructor
* @extends Calendar
*/
var IslamicCal = function(options) {
this.type = "islamic";
if (options && typeof(options.onLoad) === "function") {
options.onLoad(this);
}
};
/**
* the lengths of each month
* @private
* @const
* @type Array.<number>
*/
IslamicCal.monthLengths = [
30, /* Muharram */
29, /* Saffar */
30, /* Rabi'I */
29, /* Rabi'II */
30, /* Jumada I */
29, /* Jumada II */
30, /* Rajab */
29, /* Sha'ban */
30, /* Ramadan */
29, /* Shawwal */
30, /* Dhu al-Qa'da */
29 /* Dhu al-Hijja */
];
/**
* Return the number of months in the given year. The number of months in a year varies
* for luni-solar calendars because in some years, an extra month is needed to extend the
* days in a year to an entire solar year. The month is represented as a 1-based number
* where 1=first month, 2=second month, etc.
*
* @param {number} year a year for which the number of months is sought
*/
IslamicCal.prototype.getNumMonths = function(year) {
return 12;
};
/**
* Return the number of days in a particular month in a particular year. This function
* can return a different number for a month depending on the year because of things
* like leap years.
*
* @param {number} month the month for which the length is sought
* @param {number} year the year within which that month can be found
* @return {number} the number of days within the given month in the given year
*/
IslamicCal.prototype.getMonLength = function(month, year) {
if (month !== 12) {
return IslamicCal.monthLengths[month-1];
} else {
return this.isLeapYear(year) ? 30 : 29;
}
};
/**
* Return true if the given year is a leap year in the Islamic calendar.
* The year parameter may be given as a number, or as a IslamicDate object.
* @param {number} year the year for which the leap year information is being sought
* @return {boolean} true if the given year is a leap year
*/
IslamicCal.prototype.isLeapYear = function(year) {
return (MathUtils.mod((14 + 11 * year), 30) < 11);
};
/**
* Return the type of this calendar.
*
* @return {string} the name of the type of this calendar
*/
IslamicCal.prototype.getType = function() {
return this.type;
};
/*register this calendar for the factory method */
Calendar._constructors["islamic"] = IslamicCal;
module.exports = IslamicCal;
Source