StackGenVis/frontend/node_modules/world-calendars/dist/calendars/julian.js

/*
 * World Calendars
 * https://github.com/alexcjohnson/world-calendars
 *
 * Batch-converted from kbwood/calendars
 * Many thanks to Keith Wood and all of the contributors to the original project!
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

/* http://keith-wood.name/calendars.html
   Julian calendar for jQuery v2.0.2.
   Written by Keith Wood (wood.keith{at}optusnet.com.au) August 2009.
   Available under the MIT (http://keith-wood.name/licence.html) license. 
   Please attribute the author if you use it. */

var main = require('../main');
var assign = require('object-assign');


/** Implementation of the Julian calendar.
    Based on code from <a href="http://www.fourmilab.ch/documents/calendar/">http://www.fourmilab.ch/documents/calendar/</a>.
    See also <a href="http://en.wikipedia.org/wiki/Julian_calendar">http://en.wikipedia.org/wiki/Julian_calendar</a>.
    @class JulianCalendar
    @augments BaseCalendar
    @param [language=''] {string} The language code (default English) for localisation. */
function JulianCalendar(language) {
    this.local = this.regionalOptions[language || ''] || this.regionalOptions[''];
}

JulianCalendar.prototype = new main.baseCalendar;

assign(JulianCalendar.prototype, {
    /** The calendar name.
        @memberof JulianCalendar */
    name: 'Julian',
    /** Julian date of start of Julian epoch: 1 January 0001 AD = 30 December 0001 BCE.
        @memberof JulianCalendar */
    jdEpoch: 1721423.5,
    /** Days per month in a common year.
        @memberof JulianCalendar */
    daysPerMonth: [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31],
    /** <code>true</code> if has a year zero, <code>false</code> if not.
        @memberof JulianCalendar */
    hasYearZero: false,
    /** The minimum month number.
        @memberof JulianCalendar */
    minMonth: 1,
    /** The first month in the year.
        @memberof JulianCalendar */
    firstMonth: 1,
    /** The minimum day number.
        @memberof JulianCalendar */
    minDay: 1,

    /** Localisations for the plugin.
        Entries are objects indexed by the language code ('' being the default US/English).
        Each object has the following attributes.
        @memberof JulianCalendar
        @property name {string} The calendar name.
        @property epochs {string[]} The epoch names.
        @property monthNames {string[]} The long names of the months of the year.
        @property monthNamesShort {string[]} The short names of the months of the year.
        @property dayNames {string[]} The long names of the days of the week.
        @property dayNamesShort {string[]} The short names of the days of the week.
        @property dayNamesMin {string[]} The minimal names of the days of the week.
        @property dateFormat {string} The date format for this calendar.
                See the options on <a href="BaseCalendar.html#formatDate"><code>formatDate</code></a> for details.
        @property firstDay {number} The number of the first day of the week, starting at 0.
        @property isRTL {number} <code>true</code> if this localisation reads right-to-left. */
    regionalOptions: { // Localisations
        '': {
            name: 'Julian',
            epochs: ['BC', 'AD'],
            monthNames: ['January', 'February', 'March', 'April', 'May', 'June',
            'July', 'August', 'September', 'October', 'November', 'December'],
            monthNamesShort: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
            dayNames: ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'],
            dayNamesShort: ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'],
            dayNamesMin: ['Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa'],
            digits: null,
            dateFormat: 'mm/dd/yyyy',
            firstDay: 0,
            isRTL: false
        }
    },

    /** Determine whether this date is in a leap year.
        @memberof JulianCalendar
        @param year {CDate|number} The date to examine or the year to examine.
        @return {boolean} <code>true</code> if this is a leap year, <code>false</code> if not.
        @throws Error if an invalid year or a different calendar used. */
    leapYear: function(year) {
        var date = this._validate(year, this.minMonth, this.minDay, main.local.invalidYear);
        var year = (date.year() < 0 ? date.year() + 1 : date.year()); // No year zero
        return (year % 4) === 0;
    },

    /** Determine the week of the year for a date - ISO 8601.
        @memberof JulianCalendar
        @param year {CDate|number} The date to examine or the year to examine.
        @param [month] {number} The month to examine.
        @param [day] {number} The day to examine.
        @return {number} The week of the year.
        @throws Error if an invalid date or a different calendar used. */
    weekOfYear: function(year, month, day) {
        // Find Thursday of this week starting on Monday
        var checkDate = this.newDate(year, month, day);
        checkDate.add(4 - (checkDate.dayOfWeek() || 7), 'd');
        return Math.floor((checkDate.dayOfYear() - 1) / 7) + 1;
    },

    /** Retrieve the number of days in a month.
        @memberof JulianCalendar
        @param year {CDate|number} The date to examine or the year of the month.
        @param [month] {number} The month.
        @return {number} The number of days in this month.
        @throws Error if an invalid month/year or a different calendar used. */
    daysInMonth: function(year, month) {
        var date = this._validate(year, month, this.minDay, main.local.invalidMonth);
        return this.daysPerMonth[date.month() - 1] +
            (date.month() === 2 && this.leapYear(date.year()) ? 1 : 0);
    },

    /** Determine whether this date is a week day.
        @memberof JulianCalendar
        @param year {CDate|number} The date to examine or the year to examine.
        @param [month] {number} The month to examine.
        @param [day] {number} The day to examine.
        @return {boolean} True if a week day, false if not.
        @throws Error if an invalid date or a different calendar used. */
    weekDay: function(year, month, day) {
        return (this.dayOfWeek(year, month, day) || 7) < 6;
    },

    /** Retrieve the Julian date equivalent for this date,
        i.e. days since January 1, 4713 BCE Greenwich noon.
        @memberof JulianCalendar
        @param year {CDate|number} The date to convert or the year to convert.
        @param [month] {number} The month to convert.
        @param [day] {number} The day to convert.
        @return {number} The equivalent Julian date.
        @throws Error if an invalid date or a different calendar used. */
    toJD: function(year, month, day) {
        var date = this._validate(year, month, day, main.local.invalidDate);
        year = date.year();
        month = date.month();
        day = date.day();
        if (year < 0) { year++; } // No year zero
        // Jean Meeus algorithm, "Astronomical Algorithms", 1991
        if (month <= 2) {
            year--;
            month += 12;
        }
        return Math.floor(365.25 * (year + 4716)) +
            Math.floor(30.6001 * (month + 1)) + day - 1524.5;
    },

    /** Create a new date from a Julian date.
        @memberof JulianCalendar
        @param jd {number} The Julian date to convert.
        @return {CDate} The equivalent date. */
    fromJD: function(jd) {
        // Jean Meeus algorithm, "Astronomical Algorithms", 1991
        var a = Math.floor(jd + 0.5);
        var b = a + 1524;
        var c = Math.floor((b - 122.1) / 365.25);
        var d = Math.floor(365.25 * c);
        var e = Math.floor((b - d) / 30.6001);
        var month = e - Math.floor(e < 14 ? 1 : 13);
        var year = c - Math.floor(month > 2 ? 4716 : 4715);
        var day = b - d - Math.floor(30.6001 * e);
        if (year <= 0) { year--; } // No year zero
        return this.newDate(year, month, day);
    }
});

// Julian calendar implementation
main.calendars.julian = JulianCalendar;