/*
* Date prototype extensions. Doesn't depend on any
* other code. Doens't overwrite existing methods.
*
* Adds dayNames, abbrDayNames, monthNames and abbrMonthNames static properties and isLeapYear,
* isWeekend, isWeekDay, getDaysInMonth, getDayName, getMonthName, getDayOfYear, getWeekOfYear,
* setDayOfYear, addYears, addMonths, addDays, addHours, addMinutes, addSeconds methods
*
* Copyright (c) 2006 J枚rn Zaefferer and Brandon Aaron (brandon.aaron@gmail.com || http://brandonaaron.net)
*
* Additional methods and properties added by Kelvin Luck: firstDayOfWeek, dateFormat, zeroTime, asString, fromString -
* I've added my name to these methods so you know who to blame if they are broken!
* 
* Dual licensed under the MIT and GPL licenses:
*   http://www.opensource.org/licenses/mit-license.php
*   http://www.gnu.org/licenses/gpl.html
*
*/

/**
* An Array of day names starting with Sunday.
* 
* @example dayNames[0]
* @result 'Sunday'
*
* @name dayNames
* @type Array
* @cat Plugins/Methods/Date
*/
Date.dayNames = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];

/**
* An Array of abbreviated day names starting with Sun.
* 
* @example abbrDayNames[0]
* @result 'Sun'
*
* @name abbrDayNames
* @type Array
* @cat Plugins/Methods/Date
*/
Date.abbrDayNames = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];

/**
* An Array of month names starting with Janurary.
* 
* @example monthNames[0]
* @result 'January'
*
* @name monthNames
* @type Array
* @cat Plugins/Methods/Date
*/
Date.monthNames = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];

/**
* An Array of abbreviated month names starting with Jan.
* 
* @example abbrMonthNames[0]
* @result 'Jan'
*
* @name monthNames
* @type Array
* @cat Plugins/Methods/Date
*/
Date.abbrMonthNames = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];

/**
* The first day of the week for this locale.
*
* @name firstDayOfWeek
* @type Number
* @cat Plugins/Methods/Date
* @author Kelvin Luck
*/
Date.firstDayOfWeek = 1;

/**
* The format that string dates should be represented as (e.g. 'dd/mm/yyyy' for UK, 'mm/dd/yyyy' for US, 'yyyy-mm-dd' for Unicode etc).
*
* @name format
* @type String
* @cat Plugins/Methods/Date
* @author Kelvin Luck
*/
//Date.format = 'dd/mm/yyyy';
//Date.format = 'mm/dd/yyyy';
Date.format = 'yyyy-mm-dd';
//Date.format = 'dd mmm yy';

/**
* The first two numbers in the century to be used when decoding a two digit year. Since a two digit year is ambiguous (and date.setYear
* only works with numbers < 99 and so doesn't allow you to set years after 2000) we need to use this to disambiguate the two digit year codes.
*
* @name format
* @type String
* @cat Plugins/Methods/Date
* @author Kelvin Luck
*/
Date.fullYearStart = '20';

(function () {

    /**
    * Adds a given method under the given name 
    * to the Date prototype if it doesn't
    * currently exist.
    *
    * @private
    */
    function add(name, method) {
        if (!Date.prototype[name]) {
            Date.prototype[name] = method;
        }
    };

    /**
    * Checks if the year is a leap year.
    *
    * @example var dtm = new Date("01/12/2008");
    * dtm.isLeapYear();
    * @result true
    *
    * @name isLeapYear
    * @type Boolean
    * @cat Plugins/Methods/Date
    */
    add("isLeapYear", function () {
        var y = this.getFullYear();
        return (y % 4 == 0 && y % 100 != 0) || y % 400 == 0;
    });

    /**
    * Checks if the day is a weekend day (Sat or Sun).
    *
    * @example var dtm = new Date("01/12/2008");
    * dtm.isWeekend();
    * @result false
    *
    * @name isWeekend
    * @type Boolean
    * @cat Plugins/Methods/Date
    */
    add("isWeekend", function () {
        return this.getDay() == 0 || this.getDay() == 6;
    });

    /**
    * Check if the day is a day of the week (Mon-Fri)
    * 
    * @example var dtm = new Date("01/12/2008");
    * dtm.isWeekDay();
    * @result false
    * 
    * @name isWeekDay
    * @type Boolean
    * @cat Plugins/Methods/Date
    */
    add("isWeekDay", function () {
        return !this.isWeekend();
    });

    /**
    * Gets the number of days in the month.
    * 
    * @example var dtm = new Date("01/12/2008");
    * dtm.getDaysInMonth();
    * @result 31
    * 
    * @name getDaysInMonth
    * @type Number
    * @cat Plugins/Methods/Date
    */
    add("getDaysInMonth", function () {
        return [31, (this.isLeapYear() ? 29 : 28), 31, 30, 31, 30, 31, 31, 30, 31, 30, 31][this.getMonth()];
    });

    /**
    * Gets the name of the day.
    * 
    * @example var dtm = new Date("01/12/2008");
    * dtm.getDayName();
    * @result 'Saturday'
    * 
    * @example var dtm = new Date("01/12/2008");
    * dtm.getDayName(true);
    * @result 'Sat'
    * 
    * @param abbreviated Boolean When set to true the name will be abbreviated.
    * @name getDayName
    * @type String
    * @cat Plugins/Methods/Date
    */
    add("getDayName", function (abbreviated) {
        return abbreviated ? Date.abbrDayNames[this.getDay()] : Date.dayNames[this.getDay()];
    });

    /**
    * Gets the name of the month.
    * 
    * @example var dtm = new Date("01/12/2008");
    * dtm.getMonthName();
    * @result 'Janurary'
    *
    * @example var dtm = new Date("01/12/2008");
    * dtm.getMonthName(true);
    * @result 'Jan'
    * 
    * @param abbreviated Boolean When set to true the name will be abbreviated.
    * @name getDayName
    * @type String
    * @cat Plugins/Methods/Date
    */
    add("getMonthName", function (abbreviated) {
        return abbreviated ? Date.abbrMonthNames[this.getMonth()] : Date.monthNames[this.getMonth()];
    });

    /**
    * Get the number of the day of the year.
    * 
    * @example var dtm = new Date("01/12/2008");
    * dtm.getDayOfYear();
    * @result 11
    * 
    * @name getDayOfYear
    * @type Number
    * @cat Plugins/Methods/Date
    */
    add("getDayOfYear", function () {
        var tmpdtm = new Date("1/1/" + this.getFullYear());
        return Math.floor((this.getTime() - tmpdtm.getTime()) / 86400000);
    });

    /**
    * Get the number of the week of the year.
    * 
    * @example var dtm = new Date("01/12/2008");
    * dtm.getWeekOfYear();
    * @result 2
    * 
    * @name getWeekOfYear
    * @type Number
    * @cat Plugins/Methods/Date
    */
    add("getWeekOfYear", function () {
        return Math.ceil(this.getDayOfYear() / 7);
    });

    /**
    * Set the day of the year.
    * 
    * @example var dtm = new Date("01/12/2008");
    * dtm.setDayOfYear(1);
    * dtm.toString();
    * @result 'Tue Jan 01 2008 00:00:00'
    * 
    * @name setDayOfYear
    * @type Date
    * @cat Plugins/Methods/Date
    */
    add("setDayOfYear", function (day) {
        this.setMonth(0);
        this.setDate(day);
        return this;
    });

    /**
    * Add a number of years to the date object.
    * 
    * @example var dtm = new Date("01/12/2008");
    * dtm.addYears(1);
    * dtm.toString();
    * @result 'Mon Jan 12 2009 00:00:00'
    * 
    * @name addYears
    * @type Date
    * @cat Plugins/Methods/Date
    */
    add("addYears", function (num) {
        this.setFullYear(this.getFullYear() + num);
        return this;
    });

    /**
    * Add a number of months to the date object.
    * 
    * @example var dtm = new Date("01/12/2008");
    * dtm.addMonths(1);
    * dtm.toString();
    * @result 'Tue Feb 12 2008 00:00:00'
    * 
    * @name addMonths
    * @type Date
    * @cat Plugins/Methods/Date
    */
    add("addMonths", function (num) {
        var tmpdtm = this.getDate();

        this.setMonth(this.getMonth() + num);

        if (tmpdtm > this.getDate())
            this.addDays(-this.getDate());

        return this;
    });

    /**
    * Add a number of days to the date object.
    * 
    * @example var dtm = new Date("01/12/2008");
    * dtm.addDays(1);
    * dtm.toString();
    * @result 'Sun Jan 13 2008 00:00:00'
    * 
    * @name addDays
    * @type Date
    * @cat Plugins/Methods/Date
    */
    add("addDays", function (num) {
        //this.setDate(this.getDate() + num);
        this.setTime(this.getTime() + (num * 86400000));
        return this;
    });

    /**
    * Add a number of hours to the date object.
    * 
    * @example var dtm = new Date("01/12/2008");
    * dtm.addHours(24);
    * dtm.toString();
    * @result 'Sun Jan 13 2008 00:00:00'
    * 
    * @name addHours
    * @type Date
    * @cat Plugins/Methods/Date
    */
    add("addHours", function (num) {
        this.setHours(this.getHours() + num);
        return this;
    });

    /**
    * Add a number of minutes to the date object.
    * 
    * @example var dtm = new Date("01/12/2008");
    * dtm.addMinutes(60);
    * dtm.toString();
    * @result 'Sat Jan 12 2008 01:00:00'
    * 
    * @name addMinutes
    * @type Date
    * @cat Plugins/Methods/Date
    */
    add("addMinutes", function (num) {
        this.setMinutes(this.getMinutes() + num);
        return this;
    });

    /**
    * Add a number of seconds to the date object.
    * 
    * @example var dtm = new Date("01/12/2008");
    * dtm.addSeconds(60);
    * dtm.toString();
    * @result 'Sat Jan 12 2008 00:01:00'
    * 
    * @name addSeconds
    * @type Date
    * @cat Plugins/Methods/Date
    */
    add("addSeconds", function (num) {
        this.setSeconds(this.getSeconds() + num);
        return this;
    });

    /**
    * Sets the time component of this Date to zero for cleaner, easier comparison of dates where time is not relevant.
    * 
    * @example var dtm = new Date();
    * dtm.zeroTime();
    * dtm.toString();
    * @result 'Sat Jan 12 2008 00:01:00'
    * 
    * @name zeroTime
    * @type Date
    * @cat Plugins/Methods/Date
    * @author Kelvin Luck
    */
    add("zeroTime", function () {
        this.setMilliseconds(0);
        this.setSeconds(0);
        this.setMinutes(0);
        this.setHours(0);
        return this;
    });

    /**
    * Returns a string representation of the date object according to Date.format.
    * (Date.toString may be used in other places so I purposefully didn't overwrite it)
    * 
    * @example var dtm = new Date("01/12/2008");
    * dtm.asString();
    * @result '12/01/2008' // (where Date.format == 'dd/mm/yyyy'
    * 
    * @name asString
    * @type Date
    * @cat Plugins/Methods/Date
    * @author Kelvin Luck
    */
    add("asString", function (format) {
        var r = format || Date.format;
        if (r.split('mm').length > 1) { // ugly workaround to make sure we don't replace the m's in e.g. noveMber
            r = r.split('mmmm').join(this.getMonthName(false))
				.split('mmm').join(this.getMonthName(true))
				.split('mm').join(_zeroPad(this.getMonth() + 1))
        } else {
            r = r.split('m').join(this.getMonth() + 1);
        }
        r = r.split('yyyy').join(this.getFullYear())
			.split('yy').join((this.getFullYear() + '').substring(2))
			.split('dd').join(_zeroPad(this.getDate()))
			.split('d').join(this.getDate());
        return r;
    });

    /**
    * Returns a new date object created from the passed String according to Date.format or false if the attempt to do this results in an invalid date object
    * (We can't simple use Date.parse as it's not aware of locale and I chose not to overwrite it incase it's functionality is being relied on elsewhere)
    *
    * @example var dtm = Date.fromString("12/01/2008");
    * dtm.toString();
    * @result 'Sat Jan 12 2008 00:00:00' // (where Date.format == 'dd/mm/yyyy'
    * 
    * @name fromString
    * @type Date
    * @cat Plugins/Methods/Date
    * @author Kelvin Luck
    */
    Date.fromString = function (s) {
        var f = Date.format;

        var d = new Date('01/01/1970');

        if (s == '') return d;

        s = s.toLowerCase();
        var matcher = '';
        var order = [];
        var r = /(dd?d?|mm?m?|yy?yy?)+([^(m|d|y)])?/g;
        var results;
        while ((results = r.exec(f)) != null) {
            switch (results[1]) {
                case 'd':
                case 'dd':
                case 'm':
                case 'mm':
                case 'yy':
                case 'yyyy':
                    matcher += '(\\d+\\d?\\d?\\d?)+';
                    order.push(results[1].substr(0, 1));
                    break;
                case 'mmm':
                    matcher += '([a-z]{3})';
                    order.push('M');
                    break;
            }
            if (results[2]) {
                matcher += results[2];
            }

        }
        var dm = new RegExp(matcher);
        var result = s.match(dm);
        for (var i = 0; i < order.length; i++) {
            var res = result[i + 1];
            switch (order[i]) {
                case 'd':
                    d.setDate(res);
                    break;
                case 'm':
                    d.setMonth(Number(res) - 1);
                    break;
                case 'M':
                    for (var j = 0; j < Date.abbrMonthNames.length; j++) {
                        if (Date.abbrMonthNames[j].toLowerCase() == res) break;
                    }
                    d.setMonth(j);
                    break;
                case 'y':
                    d.setYear(res);
                    break;
            }
        }

        return d;
    };

    // utility method
    var _zeroPad = function (num) {
        var s = '0' + num;
        return s.substring(s.length - 2)
        //return ('0'+num).substring(-2); // doesn't work on IE :(
    };

})();