/*
 * 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 Jörn 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 = ['Domenica', 'Lunedi', 'Martedi', 'Mercoledi', 'Giovedi', 'Venerdi', 'Sabato'];

/**
 * An Array of abbreviated day names starting with Sun.
 *
 * @example abbrDayNames[0]
 * @result 'Sun'
 *
 * @name abbrDayNames
 * @type Array
 * @cat Plugins/Methods/Date
 */
Date.abbrDayNames = ['Dom', 'Lun', 'Mar', 'Merc', 'Gio', 'Ven', 'Sab'];

/**
 * An Array of month names starting with Janurary.
 *
 * @example monthNames[0]
 * @result 'January'
 *
 * @name monthNames
 * @type Array
 * @cat Plugins/Methods/Date
 */
Date.monthNames = ['Gennaio', 'Febbraio', 'Marzo', 'Aprile', 'Maggio', 'Giugno', 'Luglio', 'Agosto', 'Settembre', 'Ottobre', 'Novembre', 'Dicembre'];

/**
 * 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);
                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() {
                var r = Date.format;
                return r
                        .split('yyyy').join(this.getFullYear())
                        .split('yy').join((this.getFullYear() + '').substring(2))
                        .split('mmm').join(this.getMonthName(true))
                        .split('mm').join(_zeroPad(this.getMonth()+1))
                        .split('dd').join(_zeroPad(this.getDate()));
        });

        /**
         * 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('01/01/1977');
                var iY = f.indexOf('yyyy');
                if (iY > -1) {
                        d.setFullYear(Number(s.substr(iY, 4)));
                } else {
                        // TODO - this doesn't work very well - are there any rules for what is meant by a two digit year?
                        d.setFullYear(Number(Date.fullYearStart + s.substr(f.indexOf('yy'), 2)));
                }
                var iM = f.indexOf('mmm');
                if (iM > -1) {
                        var mStr = s.substr(iM, 3);
                        for (var i=0; i<Date.abbrMonthNames.length; i++) {
                                if (Date.abbrMonthNames[i] == mStr) break;
                        }
                        d.setMonth(i);
                } else {
                        d.setMonth(Number(s.substr(f.indexOf('mm'), 2)) - 1);
                }
                d.setDate(Number(s.substr(f.indexOf('dd'), 2)));
                if (isNaN(d.getTime())) {
                        return false;
                }
                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 :(
        };

})();