function CalendarJS()
{
	this.now = new Date();
	this.dayname = ["Mo","Tu","We","Th","Fr","Sa","Su"];
	this.monthname = ["January","February","March","April","May","June","Juli","August","September","October","November","December"];	
	this.tooltip = ["previous Month","next Month"];
	this.monthCell = document.createElement("th");
	this.tableHead = null;
	this.parEl = null;
	
	this.init = function( id )
	{
		this.date = this.now.getDate();
		this.month = this.mm = this.now.getMonth();
		this.year = this.yy = this.now.getFullYear();
		this.monthCell.colSpan = 5;
		this.monthCell.appendChild(document.createTextNode( this.monthname[this.mm]+" "+this.yy ));
		this.tableHead = this.createTableHead();
		this.parEl = document.getElementById( id );
		this.show();
	}
	
	this.removeElements = function( Obj )
	{
		for (var i=0; i<Obj.childNodes.length; i++)
			Obj.removeChild(Obj.childNodes[i]);
		return Obj;
	}
		
	this.show = function()
	{
		this.parEl = this.removeElements( this.parEl );
		this.monthCell.firstChild.replaceData(0, this.monthCell.firstChild.nodeValue.length, this.monthname[this.mm]+" "+this.yy);
		var table = document.createElement("table");
		table.appendChild( this.createTableBody() );
		table.appendChild( this.tableHead );
		this.parEl.appendChild( table );
	}
			
	this.createTableHead = function()
	{
		var thead = document.createElement("thead");
		var tr = document.createElement("tr");
		var th = document.createElement("th");
		th.appendChild(document.createTextNode( "\u00AB" ));
		th.Instanz = this;
		th.onclick = function() { this.Instanz.switchMonth("prev"); };
		th.title = this.tooltip[0];
		try { th.style.cursor = "pointer"; } catch(e){ th.style.cursor = "hand"; }
		tr.appendChild( th );
		tr.appendChild( this.monthCell );			
		th = document.createElement("th");
		th.appendChild(document.createTextNode( "\u00BB" ));
		th.Instanz = this;
		th.onclick = function() { this.Instanz.switchMonth("next"); };
		th.title = this.tooltip[1];
		try { th.style.cursor = "pointer"; } catch(e){ th.style.cursor = "hand"; }
		tr.appendChild( th );
		thead.appendChild( tr );
		tr = document.createElement('tr');
		for (var i=0; i<this.dayname.length; i++)
			tr.appendChild( this.getCell("th", this.dayname[i], "weekday" ) );
		thead.appendChild( tr );
		return thead;
	}
	
	this.createTableBody = function()
	{
		var dayspermonth = [31,28,31,30,31,30,31,31,30,31,30,31];
		var sevendaysaweek = 0;
		var begin = new Date(this.yy, this.mm, 1);
		var firstday = begin.getDay()-1;
		if (firstday < 0)
			firstday = 6;
		if ((this.yy%4==0) && ((this.yy%100!=0) || (this.yy%400==0)))
			dayspermonth[1] = 29;
		var tbody = document.createElement("tbody");
		var tr = document.createElement('tr');
		
		for (var i=0; i<firstday; i++, sevendaysaweek++)
			tr.appendChild( this.getCell( "td", " ", null ) );

		for (var i=1; i<=dayspermonth[this.mm]; i++, sevendaysaweek++)
		{
			if (this.dayname.length == sevendaysaweek)
			{
				tbody.appendChild( tr );
				tr = document.createElement('tr');
				sevendaysaweek = 0;
			}
			if (i==this.date && this.mm==this.month && this.yy==this.year && (sevendaysaweek == 5 || sevendaysaweek == 6))
				tr.appendChild( this.getCell( "td", i, "today weekend" ) );
			else if (i==this.date && this.mm==this.month && this.yy==this.year)
				tr.appendChild( this.getCell( "td", i, "today" ) );
			else if (sevendaysaweek == 5)
				tr.appendChild( this.getCell( "td", i, "saturday weekend" ) );
			else if (sevendaysaweek == 6)
				tr.appendChild( this.getCell( "td", i, "sunday weekend" ) );
			else
				tr.appendChild( this.getCell( "td", i, null ) );
		}

		for (var i=sevendaysaweek; i<this.dayname.length; i++)
			tr.appendChild( this.getCell( "td", " ", null  ) );

		tbody.appendChild( tr );
		return tbody;
		
	}
	
	this.getCell = function(tag, str, cssClass)
	{
		var El = document.createElement( tag );
		El.appendChild(document.createTextNode( str ));
		if (cssClass != null)
			El.className = cssClass;
		return El;
	}
	
	this.switchMonth = function( s )
	{
		switch (s)
		{
			case "prev": 
				this.yy = (this.mm == 0)?this.yy-1:this.yy;
				this.mm = (this.mm == 0)?11:this.mm-1;
			break;
			
			case "next":
				this.yy = (this.mm == 11)?this.yy+1:this.yy;
				this.mm = (this.mm == 11)?0:this.mm+1;
			break;
		}
		this.show();
	}
}

var DOMContentLoaded = false;
function addContentLoadListener (func)
{
	if (document.addEventListener)
	{
		var DOMContentLoadFunction = function ()
		{
			window.DOMContentLoaded = true;
			func();
		};
		document.addEventListener("DOMContentLoaded", DOMContentLoadFunction, false);
	}
	var oldfunc = (window.onload || new Function());
	window.onload = function ()
	{
		if (!window.DOMContentLoaded)
		{
			oldfunc();
			func();
		}
	};
}

addContentLoadListener( function()
{ 
		new CalendarJS().init("calendar");
}
);