var datePicker = new Class({
	initialize: function(dp){
		this.dayChars = 3;
		this.dayNames = ['Domingo', 'Segunda', 'Terça', 'Quarta', 'Quinta', 'Sexta', 'Sábado'];
		this.daysInMonth = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
		this.format = 'dd/mm/yyyy';
		this.monthNames = ['Janeiro', 'Fevereiro', 'Março', 'Abril', 'Maio', 'Junho', 'Julho', 'Agosto', 'Setembro', 'Outubro', 'Novembro', 'Dezembro'];
		this.startDay = 7;
		this.yearOrder = 'asc';
		this.yearRange = 1;
		this.yearStart = (new Date().getFullYear());

		if(dp.value != '') {
			dp.then = new Date(dp.value);
			dp.today = new Date();
		} else {
			dp.then = dp.today = new Date();
		}
		dp.oldYear = dp.year = dp.then.getFullYear();
		dp.oldMonth = dp.month = dp.then.getMonth();
		dp.oldDay = dp.then.getDate();
		dp.nowYear = dp.today.getFullYear();
		dp.nowMonth = dp.today.getMonth();
		dp.nowDay = dp.today.getDate();

		if(dp.alt) {
			options = Json.evaluate(dp.alt);
		} else {
			options = [];
		}
		dp.options = {
			monthNames: (options.monthNames && options.monthNames.length == 12 ? options.monthNames : this.monthNames) || this.monthNames, 
			daysInMonth: (options.daysInMonth && options.daysInMonth.length == 12 ? options.daysInMonth : this.daysInMonth) || this.daysInMonth, 
			dayNames: (options.dayNames && options.dayNames.length == 7 ? options.dayNames : this.dayNames) || this.dayNames,
			startDay : options.startDay || this.startDay,
			dayChars : options.dayChars || this.dayChars, 
			format: options.format || this.format,
			yearStart: options.yearStart || this.yearStart,
			yearRange: options.yearRange || this.yearRange,
			yearOrder: options.yearOrder || this.yearOrder
		};
		dp.setProperties({'id':dp.getProperty('name'), 'readonly':true});
		dp.container = false;
		dp.calendar = false;
		dp.interval = null;
		dp.active = false;
		dp.onclick = dp.onfocus = this.create.pass(dp, this);
	},

	create: function(dp){
		if (dp.calendar) return false;

		if(window.ie6){
			$$('select').addClass('dpHide');
		}
		dp.container = new Element('div', {'class':'dpContainer'}).injectBefore(dp);
		dp.container.onmouseover = dp.onmouseover = function(){
			$clear(dp.interval);
		};
		dp.container.onmouseout = dp.onmouseout = function(){
			dp.interval = setInterval(function(){
				if (!dp.active) this.remove(dp);
			}.bind(this), 500);
		}.bind(this);
		dp.calendar = new Element('div', {'class':'dpCal'}).injectInside(dp.container);
		var date = new Date();
		if (dp.month && dp.year) {
			date.setFullYear(dp.year, dp.month, 1);
		} else {
			dp.month = date.getMonth();
			dp.year = date.getFullYear();
			date.setDate(1);
		}
		dp.year % 4 == 0 ? dp.options.daysInMonth[1] = 29 : dp.options.daysInMonth[1] = 28;
		var firstDay = (1-(7+date.getDay()-dp.options.startDay)%7);
		monthSel = new Element('select', {'id':dp.id + '_monthSelect'});
		for (var m = 0; m < dp.options.monthNames.length; m++){
			monthSel.options[m] = new Option(dp.options.monthNames[m], m);
			if (dp.month == m) monthSel.options[m].selected = true;
		}
		yearSel = new Element('select', {'id':dp.id + '_yearSelect'});
		i = 0;
		dp.options.yearStart ? dp.options.yearStart : dp.options.yearStart = date.getFullYear();
		if (dp.options.yearOrder == 'desc'){
			for (var y = dp.options.yearStart; y > (dp.options.yearStart - dp.options.yearRange - 1); y--){
				yearSel.options[i] = new Option(y, y);
				if (dp.year == y) yearSel.options[i].selected = true;
				i++;
			}
		} else {
			for (var y = dp.options.yearStart; y < (dp.options.yearStart + dp.options.yearRange + 1); y++){
				yearSel.options[i] = new Option(y, y);
				if (dp.year == y) yearSel.options[i].selected = true;
				i++;
			}
		}
		calTable = new Element('table');
		calTableThead = new Element('thead');
		calSelRow = new Element('tr');
		calSelCell = new Element('th', {'colspan':'7'});
		monthSel.injectInside(calSelCell);
		yearSel.injectInside(calSelCell);
		calSelCell.injectInside(calSelRow);
		calSelRow.injectInside(calTableThead);
		calTableTbody = new Element('tbody');
		calDayNameRow = new Element('tr');
		for (var i = 0; i < dp.options.dayNames.length; i++) {
			calDayNameCell = new Element('th');
			calDayNameCell.appendText(dp.options.dayNames[(dp.options.startDay+i)%7].substr(0, dp.options.dayChars)); 
			calDayNameCell.injectInside(calDayNameRow);
		}
		calDayNameRow.injectInside(calTableTbody);
		while (firstDay <= dp.options.daysInMonth[dp.month]){
			calDayRow = new Element('tr');
			for (i = 0; i < 7; i++){
				if ((firstDay <= dp.options.daysInMonth[dp.month]) && (firstDay > 0)){
					calDayCell = new Element('td', {'class':dp.id + '_calDay', 'axis':dp.year + '|' + (parseInt(dp.month) + 1) + '|' + firstDay}).appendText(firstDay).injectInside(calDayRow);
				} else {
					calDayCell = new Element('td', {'class':'dpEmpty'}).appendText(' ').injectInside(calDayRow);
				}
				if ( (firstDay == dp.oldDay) && (dp.month == dp.oldMonth ) && (dp.year == dp.oldYear) ) {
					calDayCell.addClass('dpSelected');
				}
				if ( (firstDay == dp.nowDay) && (dp.month == dp.nowMonth ) && (dp.year == dp.nowYear) ) {
					calDayCell.addClass('dpToday');
				}
				firstDay++;
			}
			calDayRow.injectInside(calTableTbody);
		}
		calTableThead.injectInside(calTable);
		calTableTbody.injectInside(calTable);
		calTable.injectInside(dp.calendar);
		$$('td.' + dp.id + '_calDay').each(function(el){
			el.onmouseover = function(){
				el.addClass('dpRoll');
			}.bind(this);
		}.bind(this));
		$$('td.' + dp.id + '_calDay').each(function(el){
			el.onmouseout = function(){
				el.removeClass('dpRoll');
			}.bind(this);
		}.bind(this));
		$$('td.' + dp.id + '_calDay').each(function(el){
			el.onclick = function(){
				ds = el.axis.split('|');
				dp.value = this.formatValue(dp, ds[0], ds[1], ds[2]);
				this.remove(dp);
			}.bind(this);
		}.bind(this));
		monthSel.onfocus = function(){ dp.active = true; };
		monthSel.onchange = function(){
			dp.month = monthSel.value;
			dp.year = yearSel.value;
			this.remove(dp);
			this.create(dp);
		}.bind(this);
		
		yearSel.onfocus = function(){ dp.active = true; };
		yearSel.onchange = function(){
			dp.month = monthSel.value;
			dp.year = yearSel.value;
			this.remove(dp);
			this.create(dp);
		}.bind(this);
	},

	formatValue: function(dp, year, month, day){
		var dateStr = '';
		if (day < 10) day = '0' + day;
		if (month < 10) month = '0' + month;
		dateStr = dp.options.format.replace( /dd/i, day ).replace( /mm/i, month ).replace( /yyyy/i, year );
		dp.month = dp.oldMonth = '' + (month - 1) + '';
		dp.year = dp.oldYear = year;
		dp.oldDay = day;
		return dateStr;
	},
	remove: function(dp){
		$clear(dp.interval);
		dp.active = false;
		if (window.opera) dp.container.empty();
		else if (dp.container) dp.container.remove();
		dp.calendar = false;
		dp.container = false;
		$$('select.dpHide').removeClass('dpHide');
	}
});
window.addEvent('domready', function(){
	$$('input.datePicker').each( function(el){
		new datePicker(el);
	});
});