Date class for Morebits

morebits-date.js

/*************** Morebits.date ********************/

/**
 * @constructor
 * Create a date object. MediaWiki timestamp format is also acceptable,
 * in addition to everything that JS Date() accepts.
 */
Morebits.date = function() {
	var args = Array.prototype.slice.call(arguments);

	this._d = new (Function.prototype.bind.apply(Date, [Date].concat(args)));

	if (isNaN(this._d.getTime()) && typeof args[0] === 'string') {
		// Try again after removing a comma, to get MediaWiki timestamps to parse
		this._d = new (Function.prototype.bind.call(Date, Date, args[0].replace(/(\d\d:\d\d),/, '$1')));
	}

};

Morebits.date.prototype = {

	/** @param {(Date|Morebits.date)} date */
	isBefore: function(date) {
		return this.getTime() < date.getTime();
	},
	isAfter: function(date) {
		return this.getTime() > date.getTime();
	},

	/**
	 * Add a given number of minutes, hours, days, months or years to the date.
	 * This is done in-place. The modified date object is also returned, allowing chaining.
	 * @param {number} number
	 * @param {string} unit
	 * @throws {Error} if invalid or unsupported unit is given
	 * @returns {Morebits.date}
	 */
	add: function(number, unit) {
		// mapping time units with getter/setter function names
		var unitMap = {
			minutes: 'Minutes',
			hours: 'Hours',
			days: 'Date',
			months: 'Month',
			years: 'FullYear'
		};
		var unitNorm = unitMap[unit] || unitMap[unit + 's'];
		if (unitNorm) {
			this['set' + unitNorm](this['get' + unitNorm]() + number);
			return this;
		}
		throw new Error('Invalid unit "' + unit + '": Only ' + Object.keys(unitMap).join(', ') + ' are allowed.');
	},

	/**
	 * Subtracts a given number of minutes, hours, days, months or years to the date.
	 * This is done in-place. The modified date object is also returned, allowing chaining.
	 * @param {number} number
	 * @param {string} unit
	 * @throws {Error} if invalid or unsupported unit is given
	 * @returns {Morebits.date}
	 */
	subtract: function(number, unit) {
		return this.add(-number, unit);
	},

	/**
	 * Formats the date into a string per the given format string, and as per a given time zone,
	 * text between square brackets is kept as is.
	 * @param {string} formatstr
	 * @param {string|number} [zone=system] - 'system' (for browser-default time zone), 'utc' (for UTC),
	 * or 'user' (for time zone according to user's site preferences), or just specify a timezone as number
	 * of minutes past UTC.
	 * @returns {string}
	 * @requires mediawiki.user - if 'user' zone is used
	 */
	format: function(formatstr, zone) {
		zone = zone || 'system';
		var udate = this;
		// create a new date object that will contain the date to display as system time
		if (zone === 'utc') {
			udate = new Morebits.date(this.getTime()).add(this.getTimezoneOffset(), 'minutes');
		} else if (zone === 'user') {
			var offset = parseInt(mw.user.options.get('timecorrection').split('|')[1]);
			udate = new Morebits.date(this.getTime()).add(offset, 'minutes');
		} else if (typeof zone === 'number') {
			var offset = this.getTimezoneOffset() /* convert to utc */ + zone; /* add the utc offset */
			udate = new Morebits.date(this.getTime()).add(offset, 'minutes');
		}
		var pad = function(num) {
			return num < 10 ? '0' + num : num;
		};
		var unbinder = new Morebits.unbinder(formatstr); // escape stuff between [...]
		unbinder.unbind('\\[', '\\]');
		unbinder.content = unbinder.content
			.replace(/HH/g, pad(udate.getHours()))
			.replace(/H/g, udate.getHours())
			.replace(/mm/g, pad(udate.getMinutes()))
			.replace(/SS/g, pad(udate.getSeconds()))
			.replace(/DD/g, pad(udate.getDate()))
			.replace(/D/g, udate.getDate())
			.replace(/MMMM/g, mw.config.get('wgMonthNames')[udate.getMonth() + 1])
			.replace(/MMM/g, mw.config.get('wgMonthNamesShort')[udate.getMonth() + 1])
			.replace(/MM/g, pad(udate.getMonth() + 1))
			.replace(/M/g, udate.getMonth() + 1)
			.replace(/YYYY/g, udate.getFullYear());
		return unbinder.rebind().replace(/\[(.*?)\]/g, '$1');
	},

	// Redundant to `format`, hence probably unnecessary:

	// /**
	//  * Returns a "HH:mm, D MMMM YYYY" UTC timestamp. The default MediaWiki timestamp format.
	//  * @returns {string}
	//  */
	// toTimestamp: function() {
	// 	var h = this.getUTCHours(), m = this.getUTCMinutes();
	// 	return (h < 10 ? '0' + h : h) + ':' + (m < 10 ? '0' + m : m) + ', ' +
	// 		this.getUTCDate() + ' ' + this.getUTCMonthName() + ' ' + this.getUTCFullYear();
	// },

	// /**
	//  * @param {string} [format=dmy] - 'dmy', 'mdy' or 'ymd'
	//  * @returns {string}
	//  */
	// dateString: function(format) {
	// 	var D = this.getUTCDate(), M = this.getUTCMonthName(), Y = this.getUTCFullYear();
	// 	switch (format) {
	// 		case 'ymd':
	// 			return Y + ' ' + M + ' ' + D;
	// 		case 'mdy':
	// 			return M + ' ' + D + ', ' + Y;
	// 		default: // dmy
	// 			return D + ' ' + M + ' ' + Y;
	// 	}
	// },

	/**
	 * Gives a readable relative time string such as "Yesterday at 6:43 PM" or "Last Thursday at 11:45 AM".
	 * @returns {string}
	 */
	calendar: function() {
		var days = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];
		var now = new Date(), thisdate = new Morebits.date(this.getTime()); // create a copy
		now.setHours(0, 0, 0, 0); // zero out the hours, minutes, seconds and milliseconds - keeping only the date
		thisdate.setHours(0, 0, 0, 0);
		var datediff = Math.abs((now.getTime() - thisdate.getTime())) / 86400000;
		if (datediff >= 7) {
			return thisdate.format('DD/MM/YYYY');
		}
		var result;
		if (datediff === 0) {
			result = 'Today';
		} else if (datediff === 1) {
			result = thisdate.isBefore(now) ? 'Yesterday' : 'Tomorrow';
		} else if (datediff < 7) {
			result = (thisdate.isBefore(now) ? 'Last ' : '') + days[thisdate.getDay()];
		}
		var h = this.getHours(), m = this.getMinutes();
		result += ' at ' + (h > 12 ? h - 12 : h) + ':' + (m < 10 ? '0' + m : m) + ' ' + (h >= 12 ? 'PM' : 'AM');
		return result;
	},

	/**
	 * Returns a regex that matches wikitext section titles such as ==December 2019== or
	 * === Jan 2018 ===
	 * @returns {RegExp}
	 */
	monthHeaderRegex: function() {
		return new RegExp('^==+\\s*(?:' + this.getUTCMonthName() + '|' + this.getUTCMonthNameAbbrev() +
			')\\s+' + this.getUTCFullYear() + '\\s*==+', 'mg');
	},

	/**
	 * Creates a wikitext section header with the month and year.
	 * @param {number} [level=2] - Header level (default 2)
	 * @returns {string}
	 */
	monthHeader: function(level) {
		level = level || 2;
		var header = '';  // String.prototype.repeat is not supported in IE 11, so...
		for (var i = 0; i < level; i++) {
			header += '=';
		}
		return header + ' ' + this.getUTCMonthName() + ' ' + this.getUTCFullYear() + ' ' + header;
	}

};

// Allow native Date.prototype methods to be used on Morebits.date objects
// Note that this includes getUTCMonthName() and getUTCMonthNameAbbrev(), which should probably be removed
// from Date.prototype and moved above.
Object.getOwnPropertyNames(Date.prototype).forEach(function(func) {
	Morebits.date.prototype[func] = function() {
		return this._d[func].apply(this._d, Array.prototype.slice.call(arguments));
	};
});