Date.dayNames = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];


Date.abbrDayNames = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];


Date.monthNames = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];


Date.abbrMonthNames = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];


Date.firstDayOfWeek = 1;


Date.format = 'dd/mm/yyyy';


(function() {


	function add(name, method) {
		if( !Date.prototype[name] ) {
			Date.prototype[name] = method;
		}
	};
	
	add("isLeapYear", function() {
		var y = this.getFullYear();
		return (y%4==0 && y%100!=0) || y%400==0;
	});
	
	add("isWeekend", function() {
		return this.getDay()==0 || this.getDay()==6;
	});
	
	add("isWeekDay", function() {
		return !this.isWeekend();
	});
	
	add("getDaysInMonth", function() {
		return [31,(this.isLeapYear() ? 29:28),31,30,31,30,31,31,30,31,30,31][this.getMonth()];
	});
	

	add("getDayName", function(abbreviated) {
		return abbreviated ? Date.abbrDayNames[this.getDay()] : Date.dayNames[this.getDay()];
	});

	add("getMonthName", function(abbreviated) {
		return abbreviated ? Date.abbrMonthNames[this.getMonth()] : Date.monthNames[this.getMonth()];
	});

	add("getDayOfYear", function() {
		var tmpdtm = new Date("1/1/" + this.getFullYear());
		return Math.floor((this.getTime() - tmpdtm.getTime()) / 86400000);
	});
	

	add("getWeekOfYear", function() {
		return Math.ceil(this.getDayOfYear() / 7);
	});


	add("setDayOfYear", function(day) {
		this.setMonth(0);
		this.setDate(day);
		return this;
	});
	

	add("addYears", function(num) {
		this.setFullYear(this.getFullYear() + num);
		return this;
	});


	add("addMonths", function(num) {
		var tmpdtm = this.getDate();
		
		this.setMonth(this.getMonth() + num);
		
		if (tmpdtm > this.getDate())
			this.addDays(-this.getDate());
		
		return this;
	});
	

	add("addDays", function(num) {
		this.setDate(this.getDate() + num);
		return this;
	});
	

	add("addHours", function(num) {
		this.setHours(this.getHours() + num);
		return this;
	});


	add("addMinutes", function(num) {
		this.setMinutes(this.getMinutes() + num);
		return this;
	});
	

	add("addSeconds", function(num) {
		this.setSeconds(this.getSeconds() + num);
		return this;
	});
	

	add("zeroTime", function() {
		this.setMilliseconds(0);
		this.setSeconds(0);
		this.setMinutes(0);
		this.setHours(0);
		return this;
	});
	

	add("asString", function() {
		var r = Date.format;
		return r
			.split('yyyy').join(this.getFullYear())
			.split('yy').join(this.getYear())
			.split('mmm').join(this.getMonthName(true))
			.split('mm').join(_zeroPad(this.getMonth()+1))
			.split('dd').join(_zeroPad(this.getDate()));
	});
	

	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.setYear(Number(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 :(
	};
	
})();
		
function rightYearBtnOn() {
	document.getElementById("dp-nav-next-year").style.backgroundPosition = "0px -14px"
}
function rightYearBtnOff() {
	document.getElementById("dp-nav-next-year").style.backgroundPosition = "0px 0px"
}

function rightMonthBtnOn() {
	document.getElementById("dp-nav-next-month").style.backgroundPosition = "0px -14px"
}
function rightMonthBtnOff() {
	document.getElementById("dp-nav-next-month").style.backgroundPosition = "0px 0px"
}



function leftYearBtnOn() {
	document.getElementById("dp-nav-prev-year").style.backgroundPosition = "0px -14px"
}
function leftYearBtnOff() {
	document.getElementById("dp-nav-prev-year").style.backgroundPosition = "0px 0px"
}

function leftMonthBtnOn() {
	document.getElementById("dp-nav-prev-month").style.backgroundPosition = "0px -14px"
}
function leftMonthBtnOff() {
	document.getElementById("dp-nav-prev-month").style.backgroundPosition = "0px 0px"
}



function closeBtnOn() {
	document.getElementById("dp-close").style.backgroundPosition = "0px -14px"
}
function closeBtnOff() {
	document.getElementById("dp-close").style.backgroundPosition = "0px 0px"
}



var dateFormat = function () {
	var	token        = /d{1,4}|m{1,4}|yy(?:yy)?|([HhMsTt])\1?|[LloZ]|"[^"]*"|'[^']*'/g,
		timezone     = /\b(?:[PMCEA][SDP]T|(?:Pacific|Mountain|Central|Eastern|Atlantic) (?:Standard|Daylight|Prevailing) Time|(?:GMT|UTC)(?:[-+]\d{4})?)\b/g,
		timezoneClip = /[^-+\dA-Z]/g,
		pad = function (value, length) {
			value = String(value);
			length = parseInt(length) || 2;
			while (value.length < length)
				value = "0" + value;
			return value;
		};

	// Regexes and supporting functions are cached through closure
	return function (date, mask) {
		// Treat the first argument as a mask if it doesn't contain any numbers
		if (
			arguments.length == 1 &&
			(typeof date == "string" || date instanceof String) &&
			!/\d/.test(date)
		) {
			mask = date;
			date = undefined;
		}

		date = date ? new Date(date) : new Date();
		if (isNaN(date))
			throw "invalid date";

		var dF = dateFormat;
		mask   = String(dF.masks[mask] || mask || dF.masks["default"]);

		var	d = date.getDate(),
			D = date.getDay(),
			m = date.getMonth(),
			y = date.getFullYear(),
			H = date.getHours(),
			M = date.getMinutes(),
			s = date.getSeconds(),
			L = date.getMilliseconds(),
			o = date.getTimezoneOffset(),
			flags = {
				d:    d,
				dd:   pad(d),
				ddd:  dF.i18n.dayNames[D],
				dddd: dF.i18n.dayNames[D + 7],
				m:    m + 1,
				mm:   pad(m + 1),
				mmm:  dF.i18n.monthNames[m],
				mmmm: dF.i18n.monthNames[m + 12],
				yy:   String(y).slice(2),
				yyyy: y,
				h:    H % 12 || 12,
				hh:   pad(H % 12 || 12),
				H:    H,
				HH:   pad(H),
				M:    M,
				MM:   pad(M),
				s:    s,
				ss:   pad(s),
				l:    pad(L, 3),
				L:    pad(L > 99 ? Math.round(L / 10) : L),
				t:    H < 12 ? "a"  : "p",
				tt:   H < 12 ? "am" : "pm",
				T:    H < 12 ? "A"  : "P",
				TT:   H < 12 ? "AM" : "PM",
				Z:    (String(date).match(timezone) || [""]).pop().replace(timezoneClip, ""),
				o:    (o > 0 ? "-" : "+") + pad(Math.floor(Math.abs(o) / 60) * 100 + Math.abs(o) % 60, 4)
			};

		return mask.replace(token, function ($0) {
			return ($0 in flags) ? flags[$0] : $0.slice(1, $0.length - 1);
		});
	};
}();

// Some common format strings
dateFormat.masks = {
	"default":       "ddd mmm d yyyy HH:MM:ss",
	shortDate:       "m/d/yy",
	mediumDate:      "mmm d, yyyy",
	longDate:        "mmmm d, yyyy",
	fullDate:        "dddd, mmmm d, yyyy",
	shortTime:       "h:MM TT",
	mediumTime:      "h:MM:ss TT",
	longTime:        "h:MM:ss TT Z",
	isoDate:         "yyyy-mm-dd",
	isoTime:         "HH:MM:ss",
	isoDateTime:     "yyyy-mm-dd'T'HH:MM:ss",
	isoFullDateTime: "yyyy-mm-dd'T'HH:MM:ss.lo"
};

// Internationalization strings
dateFormat.i18n = {
	dayNames: [
		"Sun", "Mon", "Tue", "Wed", "Thr", "Fri", "Sat",
		"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
	],
	monthNames: [
		"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec",
		"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"
	]
};

// For convenience...
Date.prototype.format = function (mask) {
	return dateFormat(this, mask);
}