(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(format) {
		var r = format || Date.format;
		return r
			.split('yyyy').join(this.getFullYear())
			.split('yy').join((this.getFullYear() + '').substring(2))
			.split('MMMM').join(this.getMonthName(false))
			.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 mLength = 0;
		var iM = f.indexOf('MMMM');
		if (iM > -1) {
			for (var i=0; i<Date.monthNames.length; i++) {
				var mStr = s.substr(iM, Date.monthNames[i].length);
				if (Date.monthNames[i] == mStr) {
					mLength = Date.monthNames[i].length - 4;
					break;
				}
			}
			d.setMonth(i);
		} else {
			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);
			}
		}
		
		var iY = f.indexOf('yyyy');

		if (iY > -1) {
			if (iM < iY)
			{
				iY += mLength;
			}
			d.setFullYear(Number(s.substr(iY, 4)));
		} else {
			if (iM < iY)
			{
				iY += mLength;
			}
			// 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 iD = f.indexOf('dd');
		if (iM < iD)
		{
			iD += mLength;
		}
		d.setDate(Number(s.substr(iD, 2)));
		if (isNaN(d.getTime())) {
			return false;
		}
		return d;
	};



    //Input:
    //S, date string
    //T, time string
    //Returns: 
    //combines the date and time, taking Date.Format into account to work for different
    //locales, it returns the UTC value (num milliseconds from 01/01/1970)
    //ex input:  s = "04/15/2009"
    //           t = "12:25 PM"
    //ex input:  s = "25/01/2009"
    //           t = "15:25 "
	Date.LocalizedUTCFromString = function(s,t)
    {
        return (Date.parse(new Date.fromString(s))+Date.parse("01/01/1970 "+t+" GMT"));
    };
    

    Date.monthDays          = { 1 : 31,       //Jan
                                3 : 31,       //Mar
                                4 : 30,       //Apr
                                5 : 31,       //May
                                6 : 30,       //Jun
                                7 : 31,       //Jul
                                8 : 31,       //Aug
                                9 : 30,       //Sep
                                10 : 31,      //Oct
                                11 : 30,      //Nov
                                12 : 31};     //Dec
    
    Date.parseExact       = function(s, fmt) 
    {
        if (fmt == null)    fmt = Date.shortFormat;
        var re = /\W+/i;
        var sep = s.match(re);
        var dtPart = s.split(sep);
        var fmtPart = fmt.split(sep);
        this.setMonth(parseInt(fmtPart[0].substring(0,1).toUpperCase() == "M" ? dtPart[0] : fmtPart[1].substring(0,1).toUpperCase() == "M" ? dtPart[1] : dtPart[2])-1);
        this.setDate(fmtPart[0].substring(0,1).toUpperCase() == "D" ? dtPart[0] : fmtPart[1].substring(0,1).toUpperCase() == "D" ? dtPart[1] : dtPart[2]);
        this.setYear(fmtPart[0].substring(0,1).toUpperCase() == "Y" ? dtPart[0] : fmtPart[1].substring(0,1).toUpperCase() == "Y" ? dtPart[1] : dtPart[2]);    
        return this.getTime();
        //var d = new Date(); d.parseExact("01/10/2008","dd/mm/yy"); alert(d);
    };    
    
    Date.isDate                 = function(str) 
    {
        var re = /\W+/i;
        var sep = Date.shortFormat.match(re);
      
        var dtparts = str.split(sep);
        if (dtparts.length != 3) 
        {
			//Commented out because it is causing duplicate alert messages in the Daily Report with entering in an incorrect date (i.e. "1245554")
            //alert("Date entered must be in the format '" + Date.shortFormat + "'");
            return false;
        }
      
        var dtFmt = Date.shortFormat.split(sep);
       
        var mPt = dtFmt[0].substring(0,1).toUpperCase() == "M" ? 0 : dtFmt[1].substring(0,1).toUpperCase() == "M" ? 1 : 2;
        var dPt = dtFmt[0].substring(0,1).toUpperCase() == "D" ? 0 : dtFmt[1].substring(0,1).toUpperCase() == "D" ? 1 : 2;
        var yPt = dtFmt[0].substring(0,1).toUpperCase() == "Y" ? 0 : dtFmt[1].substring(0,1).toUpperCase() == "Y" ? 1 : 2;

        //alert(str + "..." + Date.shortFormat + "..." + "MonthPt: " + mPt + "..." + "DayPt: " + dPt + "..." + "YearPt: " + yPt);
        //alert("Month: " + dtparts[mPt] + "..." + "Day: " + dtparts[dPt] + "..." + "Year: " + dtparts[yPt]);
        var newDt;

        // Exit now for incorrect MONTHS
        var intMonth = parseInt(dtparts[mPt], 10);
        if (intMonth > 12 || intMonth < 1) 
	    {
		    return false;
	    }

        var intDay = parseInt(dtparts[dPt], 10);   //Tell parseInt to use base 10
	    //alert("Day: " + intDay);

	    //create a lookup for months not equal to Feb.
        //check if month value and day value agree
        
        var daysPerMonth = Date.monthDays[intMonth];
        //alert(intMonth + "..." + daysPerMonth);
	    if(daysPerMonth != null) 
	    {
		    if ((intDay <= daysPerMonth) && (intDay >= 1))
		    {
			    return true;	//found in lookup table, good date
		    }
	    }
    	
        //check for February
        var intYear = parseInt(dtparts[yPt], 10);
	    var booLeapYear = (intYear % 4 == 0 && intYear != 00 && intYear % 100 != 0);
        if( ((booLeapYear && intDay <= 29) || (!booLeapYear && intDay <=28)) && intDay !=0)
		    return true; //Feb. had valid number of days

        //alert("The date submitted is not valid.\n\nPlease ensure a valid date is submitted in the form '" + Date.shortFormat + "'");
        return false;        
    };


    
	
	// 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 :(
	};
	
})();