// The DatePicker constructor
// oDate : Date Optional argument representing the date to select
function DatePicker( oDate ) {
	// check arguments
	if ( arguments.length == 0 ) {
		this._selectedDate = new Date;
		this._none = false;
	}
	else {
		this._selectedDate = oDate || new Date();
		this._none = oDate == null;
	}

	this._matrix = [[],[],[],[],[],[],[]];
	this._showNone = true;
	this._showToday = true;
	this._firstWeekDay = 0;	// start week with monday according to standards
	this._redWeekDay = 6;	// sunday is the default red day.

	this._dontChangeNone = false;
}

// static fields describing the name of the months and days
DatePicker.days = ["m", "t", "w", "t", "f", "s", "s"];
DatePicker.none = "None";
DatePicker.today = "Today";
DatePicker.months = [
	"January", "February", "March", "April",
	"May", "June", "July", "August",
	"September", "October", "November", "December"];

DatePicker.prototype.onchange = function () {};

DatePicker.prototype.onselect = function () {};

// create the nodes inside the date picker
DatePicker.prototype.create = function ( doc ) {
	if ( doc == null ) doc = document;

	this._document = doc;

	// create elements
	this._el = doc.createElement( "div" );
	this._el.className = "datePicker";

	// header
	var div = doc.createElement( "div" );
	div.className = "header";
	this._el.appendChild( div );

	var headerTable = doc.createElement( "table" );
	headerTable.className = "headerTable";
	headerTable.cellSpacing = 0;
	div.appendChild( headerTable );

	var tBody = doc.createElement( "tbody" );
	headerTable.appendChild( tBody );

	var tr = doc.createElement( "tr" );
	tBody.appendChild( tr );

	var td = doc.createElement( "td" );
	this._previousMonth = doc.createElement( "button" );
	this._previousMonth.className = "previousButton";
	this._previousMonth.setAttribute("type", "button");
	td.appendChild( this._previousMonth );
	tr.appendChild( td );

	td = doc.createElement( "td" );
	td.className = "labelContainer";
	td.noWrap = true;
	tr.appendChild( td );

	this._month = doc.createElement( "a" );
	this._month.className = "topLabel";
	this._month.href = "#";
	this._month.appendChild( doc.createTextNode( String.fromCharCode( 160 ) ) );
	td.appendChild( this._month );

	this._year = doc.createElement( "a" );
	this._year.className = "topLabel";
	this._year.href = "#";
	this._year.appendChild( doc.createTextNode( String.fromCharCode( 160 ) ) );
	td.appendChild( this._year );

	this._labelPopup = doc.createElement( "div" );
	this._labelPopup.className = "labelPopup";
	// no insertion

	td = doc.createElement( "td" );
	this._nextMonth = doc.createElement( "button" );
	this._nextMonth.className = "nextButton";
	this._nextMonth.setAttribute("type", "button");
	td.appendChild( this._nextMonth );
	tr.appendChild( td );

	// grid
	div = doc.createElement( "div" );
	div.className = "grid";
	this._el.appendChild( div );
	this._table = div;

	// footer
	div = doc.createElement( "div" );
	div.className = "dpfooter";
	this._el.appendChild( div );

	var footerTable = doc.createElement( "table" );
	footerTable.className = "footerTable";
	footerTable.cellSpacing = 0;
	div.appendChild( footerTable );

	tBody = doc.createElement( "tbody" );
	footerTable.appendChild( tBody );

	tr = doc.createElement( "tr" );
	tBody.appendChild( tr );

	td = doc.createElement( "td" );
	this._todayButton = doc.createElement( "button" );
	this._todayButton.className = "todayButton";
	this._todayButton.setAttribute("type", "button");
	this._todayButton.appendChild( doc.createTextNode( DatePicker.today ) );
	td.appendChild( this._todayButton );
	tr.appendChild( td );

	td = doc.createElement( "td" );
	td.className = "filler";
	td.appendChild( doc.createTextNode( String.fromCharCode( 160 ) ) );
	tr.appendChild( td );

	td = doc.createElement( "td" );
	this._noneButton = doc.createElement( "button" );
	this._noneButton.className = "noneButton";
	this._noneButton.setAttribute("type", "button");
	this._noneButton.appendChild( doc.createTextNode( DatePicker.none ) );
	td.appendChild( this._noneButton );
	tr.appendChild( td );



	this._createTable( doc );

	this._updateTable();
	this._setMonthYear();

	if ( !this._showNone )
		this._noneButton.style.visibility = "hidden";
	if ( !this._showToday )
		this._todayButton.style.visibility = "hidden";

	// IE55+ extension
	this._previousMonth.hideFocus = true;
	this._nextMonth.hideFocus = true;
	this._todayButton.hideFocus = true;
	this._noneButton.hideFocus = true;
	// end IE55+ extension

	// hook up events
	var dp = this;
	// buttons
	this._previousMonth.onclick = function () {
		dp._dontChangeNone = true;
		dp.goToPreviousMonth();
		dp._dontChangeNone = false;
	};
	this._nextMonth.onclick = function () {
		dp._dontChangeNone = true;
		dp.goToNextMonth();
		dp._dontChangeNone = false;
	};
	this._todayButton.onclick = function () {
		dp.goToToday();
		if ( typeof dp.onselect == "function" )
			dp.onselect();
	};
	this._noneButton.onclick = function () {
		dp.setDate( null );
		if ( typeof dp.onselect == "function" )
			dp.onselect();
	};

	this._el.onselectstart = function () {
		return false;
	};

	this._table.onclick = function ( e ) {
		// find event
		if ( e == null ) e = doc.parentWindow.event;

		// find td
		var el = e.target != null ? e.target : e.srcElement;
		while ( el.nodeType != 1 )
			el = el.parentNode;
		while ( el != null && el.tagName && el.tagName.toLowerCase() != "td" )
			el = el.parentNode;

		// if no td found, return
		if ( el == null || el.tagName == null || el.tagName.toLowerCase() != "td" )
			return;

		var d = new Date( dp._selectedDate );
		var n = Number( el.firstChild.data );
		if ( isNaN( n ) || n <= 0 || n == null )
			return;

		d.setDate( n );
		dp.setDate( d );
		
		if ( typeof dp.onselect == "function" )
			dp.onselect();
	};

	// show popup
	this._year.onclick = function ( e ) 
	{
		middleYear = 0;
		dp._showYearPopup();
		return false;
	};

	this._month.onclick = function ( e ) 
	{
		dp._showMonthPopup();
		return false;
	};

	this._el.onkeydown = function ( e ) {
		if ( e == null ) e = doc.parentWindow.event;
		var kc = e.keyCode != null ? e.keyCode : e.charCode;

		if ( kc < 37 || kc > 40 ) return true;

		var d = new Date( dp._selectedDate ).valueOf();
		if ( kc == 37 ) // left
			d -= 24 * 60 * 60 * 1000;
		else if ( kc == 39 ) // right
			d += 24 * 60 * 60 * 1000;
		else if ( kc == 38 ) // up
			d -= 7 * 24 * 60 * 60 * 1000;
		else if ( kc == 40 ) // down
			d += 7 * 24 * 60 * 60 * 1000;

		dp.setDate( new Date( d ) );
		return false;
	}

	// ie6 extension
	this._el.onmousewheel = function ( e ) {
		if ( e == null ) e = doc.parentWindow.event;
		var n = - e.wheelDelta / 120;
		var d = new Date( dp._selectedDate );
		var m = d.getMonth() + n;
		d.setMonth( m );


		dp._dontChangeNone = true;
		dp.setDate( d );
		dp._dontChangeNone = false;

		return false;
	}

	return this._el;
};

DatePicker.prototype.setDate = function ( oDate ) {

	this._hideLabelPopup();

	// if null then set None
	if ( oDate == null ) {
		if ( !this._none ) {
			this._none = true;
			this._setMonthYear();
			this._updateTable();

			if ( typeof this.onchange == "function" )
				this.onchange();
		}
		return;
	}

	// if string or number create a Date object
	if ( typeof oDate == "string" || typeof oDate == "number" ) {
		oDate = new Date( oDate );
	}


	// do not update if not really changed
	if ( this._selectedDate.getDate() != oDate.getDate() ||
		this._selectedDate.getMonth() != oDate.getMonth() ||
		this._selectedDate.getFullYear() != oDate.getFullYear() ||
		this._none ) {

		if ( !this._dontChangeNone )
			this._none = false;

		this._selectedDate = new Date( oDate );

		this._setMonthYear();
		this._updateTable();

		if ( typeof this.onchange == "function" )
			this.onchange();
	}

	if ( !this._dontChangeNone )
		this._none = false;
}


DatePicker.prototype.getDate = function () {
	if ( this._none ) return null;
	return new Date( this._selectedDate );	// create a new instance
}

// creates the table elements and inserts them into the date picker
DatePicker.prototype._createTable = function ( doc ) {
	var str, i;
	var rows = 6;
	var cols = 7;
	var currentWeek = 0;

	var table = doc.createElement( "table" );
	table.className = "gridTable";
	table.cellSpacing = 0;

	var tBody = doc.createElement( "tbody" );
	table.appendChild( tBody );

	// days row
	var tr = doc.createElement( "tr" );
	tr.className = "daysRow";

	var td, tn;
	var nbsp = String.fromCharCode( 160 );
	for ( i = 0; i < cols; i++ ) {
		td = doc.createElement( "td" );
		td.appendChild( doc.createTextNode( nbsp ) );
		tr.appendChild( td );
	}
	tBody.appendChild( tr );

	// upper line
	tr = doc.createElement( "tr" );
	td = doc.createElement( "td" );
	td.className = "upperLine";
	td.colSpan = 7;
	tr.appendChild( td );
	tBody.appendChild( tr );

	// rest
	for ( i = 0; i < rows; i++ ) {
		tr = doc.createElement( "tr" );
		for ( var j = 0; j < cols; j++ ) {
			td = doc.createElement( "td" );
			td.appendChild( doc.createTextNode( nbsp ) );
			tr.appendChild( td );
		}
		tBody.appendChild( tr );
	}
	str += "</table>";

	if ( this._table != null )
		this._table.appendChild( table )
};
// this method updates all the text nodes inside the table as well
// as all the classNames on the tds
DatePicker.prototype._updateTable = function () {
	// if no element no need to continue
	if ( this._table == null ) return;

	var i;
	var str = "";
	var rows = 6;
	var cols = 7;
	var currentWeek = 0;

	var cells = new Array( rows );
	this._matrix = new Array( rows )
	for ( i = 0; i < rows; i++ ) {
		cells[i] = new Array( cols );
		this._matrix[i] = new Array( cols );
	}

	// Set the tmpDate to this month
	var tmpDate = new Date( this._selectedDate.getFullYear(),
							this._selectedDate.getMonth(), 1 );
	var today = new Date();
	// go thorugh all days this month and store the text
	// and the class name in the cells matrix
	var weekDay;
	for ( i = 1; i < 32; i++ ) 
	{
		tmpDate.setDate( i );
		// convert to ISO, Monday is 0 and 6 is Sunday
		if( i == 1 )
			weekDay = ( tmpDate.getDay() + 6 ) % 7;
		else
		{
			weekDay = ( ++weekDay ) % 7;
		}

		var colIndex = ( weekDay - this._firstWeekDay + 7 ) % 7;
		if ( tmpDate.getMonth() == this._selectedDate.getMonth() ) {

			var isToday = tmpDate.getDate() == today.getDate() &&
						tmpDate.getMonth() == today.getMonth() &&
						tmpDate.getFullYear() == today.getFullYear();

			cells[currentWeek][colIndex] = { text: "", className: "" };

			if ( this._selectedDate.getDate() == tmpDate.getDate() && !this._none )
				cells[currentWeek][colIndex].className += "selected ";
			if ( isToday )
				cells[currentWeek][colIndex].className += "today ";
			if ( ( tmpDate.getDay() + 6 ) % 7 == this._redWeekDay ) // ISO
				cells[currentWeek][colIndex].className += "red";

			cells[currentWeek][colIndex].text =
				this._matrix[currentWeek][colIndex] = i;

			if ( colIndex == 6 )
				currentWeek++;
		}
	}

	// fix day letter order if not standard
	var weekDays = DatePicker.days;
	if (this._firstWeekDay != 0) {
		weekDays = new Array(7);
		for ( i = 0; i < 7; i++)
			weekDays[i] = DatePicker.days[ (i + this._firstWeekDay) % 7];
	}

	// update text in days row
	var tds = this._table.firstChild.tBodies[0].rows[0].cells;
	for ( i = 0; i < cols; i++ )
		tds[i].firstChild.data = weekDays[i];

	// update the text nodes and class names
	var trs = this._table.firstChild.tBodies[0].rows;
	var tmpCell;
	var nbsp = String.fromCharCode( 160 );
	for ( var y = 0; y < rows; y++ ) {
		for (var x = 0; x < cols; x++) {
			tmpCell = trs[y + 2].cells[x];
			if ( typeof cells[y][x] != "undefined" ) {
				tmpCell.className = cells[y][x].className;
				tmpCell.firstChild.data = cells[y][x].text;
			}
			else {
				tmpCell.className = "";
				tmpCell.firstChild.data = nbsp;
			}
		}
	}
}

// sets the label showing the year and selected month
DatePicker.prototype._setMonthYear = function () {
	if ( this._year != null )
		this._year.lastChild.data = this._selectedDate.getFullYear();
	if ( this._month != null )
		this._month.lastChild.data = " " + DatePicker.months[ this._selectedDate.getMonth() ];
}

DatePicker.prototype.goToNextMonth = function () {
	var d = new Date( this._selectedDate );
	d.setDate( Math.min(d.getDate(), DatePicker.getDaysPerMonth(d.getMonth() + 1,
		d.getFullYear())) ); // no need to catch dec -> jan for the year
	d.setMonth( d.getMonth() + 1 );
	this.setDate( d );
}

DatePicker.prototype.goToPreviousMonth = function () {
	var d = new Date( this._selectedDate );
	d.setDate( Math.min(d.getDate(), DatePicker.getDaysPerMonth(d.getMonth() - 1,
		d.getFullYear())) ); // no need to catch jan -> dec for the year
	d.setMonth( d.getMonth() - 1 );
	this.setDate( d );
}

DatePicker.prototype.goToToday = function () {
	if ( this._none )
		// change the selectedDate to force update if none was true
		this._selectedDate = new Date( this._selectedDate + 10000000000 );
	this._none = false;
	this.setDate( new Date() );
}

DatePicker.prototype.setShowToday = function ( bShowToday ) {
	if ( typeof bShowToday == "string" )
		bShowToday = !/false|0|no/i.test( bShowToday );

	if ( this._todayButton != null )
		this._todayButton.style.visibility = bShowToday ? "visible" : "hidden";
	this._showToday = bShowToday;
}

DatePicker.prototype.getShowToday = function () {
	return this._showToday;
}

DatePicker.prototype.setShowNone = function ( bShowNone ) {
	if ( typeof bShowNone == "string" )
		bShowNone = !/false|0|no/i.test( bShowNone );

	if ( this._noneButton != null )
		this._noneButton.style.visibility = bShowNone ? "visible" : "hidden";
	this._showNone = bShowNone;
}

DatePicker.prototype.getShowNone = function () {
	return this._showNone;
}

// 0 is monday and 6 is sunday as in the ISO standard
DatePicker.prototype.setFirstWeekDay = function ( nFirstWeekDay ) {
	if ( this._firstWeekDay != nFirstWeekDay ) {
		this._firstWeekDay = nFirstWeekDay;
		this._updateTable();
	}
}

DatePicker.prototype.getFirstWeekDay = function () {
	return this._firstWeekDay;
}

// 0 is monday and 6 is sunday as in the ISO standard
DatePicker.prototype.setRedWeekDay = function ( nRedWeekDay ) {
	if ( this._redWeekDay != nRedWeekDay ) {
		this._redWeekDay = nRedWeekDay;
		this._updateTable();
	}
}

DatePicker.prototype.getRedWeekDay = function () {
	return this._redWeekDay;
}


DatePicker.prototype._showMonthPopup = function () 
{
	var dateContext = function ( dp, d ) {
		return function ( e ) {
			dp._dontChangeNone = true;
			dp._hideLabelPopup();
			dp.setDate( d );
			dp._dontChangeNone = false;
			return false;
		};
	};

	var dp = this;
	// clear all old elements in the popup
	while ( this._labelPopup.hasChildNodes() )
		this._labelPopup.removeChild( this._labelPopup.firstChild );

	this._labelPopup.onmousewheel = function( e )
	{ 
		if ( e == null ) e = document.parentWindow.event;
		e.cancelBubble = true;
		return false; 
	};
	
	var tmp;
	for ( var i = 0; i <= 11; i++ ) {
		tmp = new Date( this._selectedDate );
		tmp.setDate( Math.min(tmp.getDate(), DatePicker.getDaysPerMonth( i, tmp.getFullYear()) ) );
		tmp.setMonth( i );

		var a = this._document.createElement( "a" );
		a.href = "javascript:void 0;";
		a.onclick = dateContext( dp, tmp );
		a.appendChild( this._document.createTextNode( DatePicker.months[ i ] ) );
		if ( i == new Date( this._selectedDate ).getMonth() )
			a.className = "selected";
		this._labelPopup.appendChild( a );
	}

	this._month.parentNode.insertBefore( this._labelPopup, this._month.parentNode.firstChild );
};

var middleYear = 0;
DatePicker.prototype._showYearPopup = function () 
{
	var dateContext = function ( dp, d ) {
		return function ( e ) {
			dp._dontChangeNone = true;
			dp._hideLabelPopup();
			dp.setDate( d );
			dp._dontChangeNone = false;
			return false;
		};
	};

	var dp = this;

	// clear all old elements in the popup
	while ( this._labelPopup.hasChildNodes() )
		this._labelPopup.removeChild( this._labelPopup.firstChild );

	this._labelPopup.onmousewheel = function ( e ) {
		if ( e == null ) e = document.parentWindow.event;
		var n = - e.wheelDelta / 120;
		
		if( n >= 1 )
		{
			middleYear+=10;
			dp._showYearPopup();
		}
		
		if( n <= -1 )
		{
			middleYear-=10; 
			dp._showYearPopup();
		}

		return false;
	}


	var upArrow = this._document.createElement( "a" );
	upArrow.href = "javascript:void 0;";
	var imgUp = this._document.createElement( "img" );
	imgUp.src = imagesFolder + 'DPUpArrow.gif';
	imgUp.className = "Img";
	upArrow.appendChild( imgUp );
	upArrow.onclick = function() { middleYear-=10; dp._showYearPopup(); };
	this._labelPopup.appendChild( upArrow );

	var tmp;
	for ( var i = -5; i < 5; i++ ) {
		tmp = new Date( this._selectedDate );
		tmp.setDate( Math.min(tmp.getDate(), DatePicker.getDaysPerMonth( tmp.getMonth(), tmp.getFullYear() + i ) ) );
		tmp.setFullYear( tmp.getFullYear() + i + middleYear );

		var a = this._document.createElement( "a" );
		a.href = "javascript:void 0;";
		a.onclick = dateContext( dp, tmp );
		a.appendChild( this._document.createTextNode( tmp.getFullYear() ) );
		if ( new Date( this._selectedDate ).getFullYear() == tmp.getFullYear() )
			a.className = "selected";
		this._labelPopup.appendChild( a );
	}

	var downArrow = this._document.createElement( "a" );
	downArrow.href = "javascript:void 0;";
	var imgDown = this._document.createElement( "img" );
	imgDown.src = imagesFolder + 'DPDownArrow.gif';
	imgDown.className = "Img";
	downArrow.appendChild( imgDown );
	downArrow.onclick = function() { middleYear+=10; dp._showYearPopup(); };
	this._labelPopup.appendChild( downArrow );

	this._year.parentNode.insertBefore( this._labelPopup, this._year.parentNode.firstChild );
};

DatePicker.prototype._hideLabelPopup = function () {
	if ( this._labelPopup.parentNode )
		this._labelPopup.parentNode.removeChild( this._labelPopup );
};

DatePicker._daysPerMonth = [31,28,31,30,31,30,31,31,30,31,30,31];
DatePicker.getDaysPerMonth = function (nMonth, nYear) {
	nMonth = (nMonth + 12) % 12;
	var res = DatePicker._daysPerMonth[nMonth];
	if (nMonth == 1) {
		res += ( (nYear % 4 == 0) && !(nYear % 400 == 0) ) ? 1 : 0;
	}
	return res;
};