var V = function (id) {
	return "string" == typeof id ? document.getElementById(id) : id;
};

function addEventHandler(oTarget, sEventType, fnHandler) {
	if (oTarget.addEventListener) {
		oTarget.addEventListener(sEventType, fnHandler, false);
	} else if (oTarget.attachEvent) {
		oTarget.attachEvent("on" + sEventType, fnHandler);
	} else {
		oTarget["on" + sEventType] = fnHandler;
	}
};

var Class = {
  create: function() {
	return function() {
	  this.initialize.apply(this, arguments);
	}
  }
}

var Extend = function(destination, source) {
	for (var property in source) {
		destination[property] = source[property];
	}
	return destination;
}

var DateSelector = Class.create();
DateSelector.prototype = {
  initialize: function(oYear, oMonth, oDay, options) {
	this.SelYear = V(oYear);
	this.SelMonth = V(oMonth);
	this.SelDay = V(oDay);
	
	this.SetOptions(options);
	
	var dt = new Date(), iMonth = parseInt(this.options.Month), iDay = parseInt(this.options.Day), iMinYear = parseInt(this.options.MinYear), iMaxYear = parseInt(this.options.MaxYear);
	
	this.Year = parseInt(this.options.Year) || dt.getFullYear();
	this.Month = 1 <= iMonth && iMonth <= 12 ? iMonth : dt.getMonth() + 1;
	this.Day = iDay > 0 ? iDay : dt.getDate();
	this.MinYear = iMinYear && iMinYear < this.Year ? iMinYear : this.Year;
	this.MaxYear = iMaxYear && iMaxYear > this.Year ? iMaxYear : this.Year;
	this.onChange = this.options.onChange;
	
	this.SetSelect(this.SelYear, this.MinYear, this.MaxYear - this.MinYear + 1, this.Year - this.MinYear);
	this.SetSelect(this.SelMonth, 1, 12, this.Month - 1);
	this.SetDay();
	
	var oThis = this;
	addEventHandler(this.SelYear, "change", function(){
		oThis.Year = oThis.SelYear.value; oThis.SetDay(); oThis.onChange();
	});
	addEventHandler(this.SelMonth, "change", function(){
		oThis.Month = oThis.SelMonth.value; oThis.SetDay(); oThis.onChange();
	});
	addEventHandler(this.SelDay, "change", function(){ oThis.Day = oThis.SelDay.value; oThis.onChange(); });
  },
  SetOptions: function(options) {
	this.options = {
		Year:		0,
		Month:		0,
		Day:		0,
		MinYear:	0,
		MaxYear:	0,
		onChange:	function(){}
	};
	Extend(this.options, options || {});
  },
  SetDay: function() {
	var daysInMonth = new Date(this.Year, this.Month, 0).getDate();
	if (this.Day > daysInMonth) { this.Day = daysInMonth; };
	this.SetSelect(this.SelDay, 1, daysInMonth, this.Day - 1);
  },
  SetSelect: function(oSelect, iStart, iLength, iIndex) {
	oSelect.options.length = iLength;
	var month_arr = new Array();
	month_arr[1] = "Jan";
	month_arr[2] = "Feb";
    month_arr[3] = "Mar";
    month_arr[4] = "Apr";
    month_arr[5] = "May";
    month_arr[6] = "June";
    month_arr[7] = "July";
    month_arr[8] = "Aug";
    month_arr[9] = "Sept";
    month_arr[10] = "Oct";
    month_arr[11] = "Nov";
    month_arr[12] = "Dec";
	for (var i = 0; i < iLength; i++) { if(oSelect.id=="idMonth"){oSelect.options[i].value = iStart + i;oSelect.options[i].text = month_arr[oSelect.options[i].value]}else{oSelect.options[i].text = oSelect.options[i].value = iStart + i;} }
	oSelect.selectedIndex = iIndex;
  }
};