Htk.Calendar = new Class
({
	Extends: Htk.Field
	,Tag: 'htk-calendar'
	
	,tds: []
	,selectedTd: null
	,todayTd: null
	,year: null
	,month: null

	,initialize: function (props)
	{
		this.parent (props);
		var len = Vn.Date.WDays.length;
		
		this.createElement ('div');
		this.node.className = 'htk-calendar';
		
		var table = document.createElement ('table');
		this.node.appendChild (table);

		var colgroup = document.createElement ('colgroup');
		table.appendChild (colgroup);
		
		for (var i = 0; i < len; i++)
			colgroup.appendChild (document.createElement ('col'));
		
		var thead = document.createElement ('thead');
		table.appendChild (thead);

		var tr = document.createElement ('tr');
		thead.appendChild (tr);

		var th = document.createElement ('th');
		th.appendChild (document.createTextNode ('<'));
		th.className = 'button';
		th.addEventListener ('click', this.prevMonthClicked.bind (this));
		tr.appendChild (th);

		var monthNode = document.createElement ('th');
		monthNode.colSpan = 5;
		tr.appendChild (monthNode);

		var th = document.createElement ('th');
		th.appendChild (document.createTextNode ('>'));
		th.className = 'button';
		th.addEventListener ('click', this.nextMonthClicked.bind (this));
		tr.appendChild (th);
		
		var tr = document.createElement ('tr');
		thead.appendChild (tr);
		
		for (i = 1; i <= len; i++)
		{
			var th = document.createElement ('th');
			tr.appendChild (th);
			
			var weekday = Vn.Date.AbrWDays [i%len];
			th.appendChild (document.createTextNode (weekday));
		}

		var tfoot = document.createElement ('tfoot');
		table.appendChild (tfoot);

		var tr = document.createElement ('tr');
		tfoot.appendChild (tr);

		var th = document.createElement ('th');
		th.appendChild (document.createTextNode ('<'));
		th.className = 'button';
		th.addEventListener ('click', this.prevYearClicked.bind (this));
		tr.appendChild (th);

		var yearNode = document.createElement ('th');
		yearNode.colSpan = 5;
		tr.appendChild (yearNode);

		var th = document.createElement ('th');
		th.appendChild (document.createTextNode ('>'));
		th.className = 'button';
		th.addEventListener ('click', this.nextYearClicked.bind (this));
		tr.appendChild (th);
		
		var tbody = document.createElement ('tbody');
		table.appendChild (tbody);
		
		for (i = 0; i < 6; i++)
		{
			tr = document.createElement ('tr');
			tbody.appendChild (tr);

			for (j = 0; j < len; j++)
			{
				td = document.createElement ('td');
				td.addEventListener ('click', this.dayClicked.bind (this, td, i*len+j));
				tr.appendChild (td);
				this.tds.push (td);
			}
		}

		this.monthNode = monthNode;
		this.yearNode = yearNode;
		this.goToCurrentMonth ();
	}

	,getFirstWeekDay: function ()
	{
		var weekDay = new Date (this.year, this.month, 1).getDay ();
		return (weekDay != 0) ? weekDay - 1 : 6;
	}

	,getMonthDays: function ()
	{
		if (this.month > 6)
			return (this.month % 2 != 0) ? 31 : 30;
		else if (this.month != 1)
			return (this.month % 2 != 1) ? 31 : 30;
		else
			return (this.year % 4 != 0) ? 28 : 29;
	}
	
	,goToMonth: function (year, month)
	{
		if (year)
			this.year = year;
		if (!isNaN (month))
			this.month = month;

		this.refresh ();
	}
	
	,goToSelectedMonth: function ()
	{
		var date = this._value;
		
		if (date instanceof Date)
			this.goToMonth (date.getFullYear (), date.getMonth ());
		else
			this.goToCurrentMonth ();			
	}

	,goToCurrentMonth: function ()
	{
		var date = new Date ();
		this.goToMonth (date.getFullYear (), date.getMonth ());
	}

	,refresh: function ()
	{
		Vn.Node.setText (this.yearNode, this.year);
		Vn.Node.setText (this.monthNode, Vn.Date.Months[this.month]);

		var firstWeekDay = this.getFirstWeekDay ();
		var monthDays = this.getMonthDays ();

		var day = 1;

		for (i = 0; i < this.tds.length; i++)
		{
			if (firstWeekDay <= i && day <= monthDays)
				Vn.Node.setText (this.tds[i], day++);
			else
				Vn.Node.removeChilds (this.tds[i]);
		}
		
		// Marks the current day
		
		var today = new Date ();
		
		if (this.year == today.getFullYear ()
		&& this.month == today.getMonth ())
		{
			var tdIndex = (firstWeekDay + today.getDate ()) - 1;
			this.tds[tdIndex].style.fontWeight = 'bold';
			this.todayTd = this.tds[tdIndex];
		}
		else if (this.todayTd)
		{
			this.todayTd.style.fontWeight = '';
			this.todayTd = null;
		}
		
		// Marks the selected day
		
		var date = this._value;

		if (date instanceof Date
		&& this.year == date.getFullYear ()
		&& this.month == date.getMonth ())
		{
			var tdIndex = (firstWeekDay + date.getDate ()) - 1;
			this.selectTd (this.tds[tdIndex]);
		}
		else
			this.selectTd (null);
	}

	,selectTd: function (td)
	{
		if (this.selectedTd)
			this.selectedTd.className = undefined;
		if (td)
			td.className = 'highlight';

		this.selectedTd = td;
	}

	,putValue: function (value)
	{
		this.goToSelectedMonth ();
	}

	,dayClicked: function (td, tdIndex)
	{
		var monthDay = (tdIndex - this.getFirstWeekDay ()) + 1;

		if (monthDay >= 1 && monthDay <= this.getMonthDays ())
		{
			this.selectTd (td);

			var newDate = new Date (this.year, this.month, monthDay);
			this.valueChanged (newDate);
		}
	}

	,prevMonthClicked: function ()
	{
		if (this.month > 0)
			this.month--;
		else
		{
			this.month = 11;
			this.year--;
		}
		
		this.refresh ();
	}

	,nextMonthClicked: function ()
	{
		if (this.month < 11)
			this.month++;
		else
		{
			this.month = 0;
			this.year++;
		}
		
		this.refresh ();
	}

	,prevYearClicked: function ()
	{
		this.year--;
		this.refresh ();
	}

	,nextYearClicked: function ()
	{
		this.year++;
		this.refresh ();
	}
});