// date field validation
// usage: add onBlur="checkDate(this)" event to textbox input widget
// example: 
//	<input type="text" name="tbDate" onBlur="checkDate(this)">
// accepts the following date formats:
//	mm-dd-yyyy, mm/dd/yyyy, mm.dd.yyyy, mm dd yyyy, mmm dd yyyy, 
//	mmddyyyy, m-d-yyyy, m/d/yyyy, m.d.yyyy, m d yyyy, mmm d yyyy, 
//	m-d-yy, m/d/yy, m.d.yy, m d yy, mmm d yy


	function checkDate(objName) 
	{
		var datefield = objName;
		if (chkdate(objName) == false) 
		{
			alert("That date is invalid. Date should be in the form of mm/dd/yyyy. Please try again.");
			datefield.select();
			//datefield.value = '';
			//datefield.focus();
			return false;
		}
		else 
		{
			return true;
		}
	}
	
	function chkdate(objName) 
	{
		var strDatestyle = "US"; //United States date style
		//var strDatestyle = "EU";  //European date style
		var strDate;
		var strDateArray;
		var strDay;
		var strMonth;
		var strYear;
		var intday;
		var intMonth;
		var intYear;
		var booFound = false;
		var datefield = objName;
		var strSeparatorArray = new Array("-"," ","/",".");
		var intElementNr;
		var err = 0;
		var strMonthArray = new Array(12);
		strMonthArray[0] = "Jan";
		strMonthArray[1] = "Feb";
		strMonthArray[2] = "Mar";
		strMonthArray[3] = "Apr";
		strMonthArray[4] = "May";
		strMonthArray[5] = "Jun";
		strMonthArray[6] = "Jul";
		strMonthArray[7] = "Aug";
		strMonthArray[8] = "Sep";
		strMonthArray[9] = "Oct";
		strMonthArray[10] = "Nov";
		strMonthArray[11] = "Dec";
		strDate = datefield.value;
		var minYear = 1900;
		
		if (strDate.length < 1) 
		{
			return true;
		}		
		for (intElementNr = 0; intElementNr < strSeparatorArray.length; intElementNr++) 
		{
			if (strDate.indexOf(strSeparatorArray[intElementNr]) != -1) 
			{
				strDateArray = strDate.split(strSeparatorArray[intElementNr]);
				if (strDateArray.length != 3) 
				{
					err = 1;
					return false;
				}
				else 
				{
					strDay = strDateArray[0];
					strMonth = strDateArray[1];
					strYear = strDateArray[2];
				}
				booFound = true;
	   		}
		}
		if (booFound == false) 
		{
			if (strDate.length>5) 
			{
				strDay = strDate.substr(0, 2);
				strMonth = strDate.substr(2, 2);
				strYear = strDate.substr(4);
		   }
		}
		if ((strYear == null) || (strMonth == null) || (strDay == null))
		{
			return false;
		}
		if (strYear.length == 2) 
		{
			if (parseInt(strYear, 10) >= 80)
				strYear = '19' + strYear;
			else
				strYear = '20' + strYear;
		}
		// US style
		if (strDatestyle == "US") 
		{
			strTemp = strDay;
			strDay = strMonth;
			strMonth = strTemp;
		}
		intday = parseInt(strDay, 10);
		if (isNaN(intday)) 
		{
			err = 2;
			return false;
		}
		intMonth = parseInt(strMonth, 10);
		if (isNaN(intMonth)) 
		{
			for (i = 0;i<12;i++) 
			{
				if (strMonth.toUpperCase() == strMonthArray[i].toUpperCase()) 
				{
					intMonth = i+1;
					strMonth = strMonthArray[i];
					i = 12;
			   }
			}
			if (isNaN(intMonth)) 
			{
				err = 3;
				return false;
			}
		}
		intYear = parseInt(strYear, 10);
		if (isNaN(intYear)) 
		{
			err = 4;
			return false;
		}
		if (intYear < minYear)
		{
			err = 11
			return false;
		}
		if (intMonth>12 || intMonth<1) 
		{
			err = 5;
			return false;
		}
		if ((intMonth == 1 || intMonth == 3 || intMonth == 5 || intMonth == 7 || intMonth == 8 || intMonth == 10 || intMonth == 12) && (intday > 31 || intday < 1)) 
		{
			err = 6;
			return false;
		}
		if ((intMonth == 4 || intMonth == 6 || intMonth == 9 || intMonth == 11) && (intday > 30 || intday < 1)) 
		{
			err = 7;
			return false;
		}
		if (intMonth == 2) 
		{
			if (intday < 1) 
			{
				err = 8;
				return false;
			}
			if (LeapYear(intYear) == true) 
			{
				if (intday > 29) 
				{
					err = 9;
					return false;
				}
			}
			else 
			{
				if (intday > 28) 
				{
					err = 10;
					return false;
				}
			}
		}
		if (strDatestyle == "US") 
		{
			if (intMonth < 10)
				strMonth = '0' + intMonth.toString();
			else
				strMonth = intMonth.toString();			
			if (intday < 10)
				strDay = '0' + intday.toString();
			else
				strDay = intday.toString();
			datefield.value = strMonth + "/" + strDay + "/" + intYear;
		}
		else 
		{
			datefield.value = intday + " " + strMonthArray[intMonth-1] + " " + intYear;
		}
		return true;
	}
	
	function LeapYear(intYear) 
	{
		if (intYear % 100 == 0) 
		{
			if (intYear % 400 == 0) { return true; }
		}
		else 
		{
			if ((intYear % 4) == 0) { return true; }
		}
		return false;
	}