/*'--isDate.js---------------------------------------------------------------------------------------
 - Purpose : verifies that an input string is a valid date format
 - Parameters : 
 		-	dtStr = string to be verified as a date value
 - Author : Ryan Putman
  - Updates : 3/17/2004 - comments updated
  ---------------------------------------------------------------------------------------------------*/
  
  /* variables used in the isDate function and its children functions */
	var dtCh= "/";
	var minYear=1900;
	var maxYear=2100;
	
	function isDate(dtStr,field){
		var strError = "";
		if(dtStr != '')
		{
			if(isInteger(dtStr))
			{
				dtStr = addSlashesValue(dtStr);
				document.getElementById(field).value = dtStr
			}
			var daysInMonth = DaysArray(12)
			var pos1=dtStr.indexOf(dtCh)
			var pos2=dtStr.indexOf(dtCh,pos1+1)
			var strMonth=dtStr.substring(0,pos1)
			var strDay=dtStr.substring(pos1+1,pos2)
			var strYear=dtStr.substring(pos2+1)
			strYr=strYear
			if (strDay.charAt(0)=="0" && strDay.length>1) strDay=strDay.substring(1)
			if (strMonth.charAt(0)=="0" && strMonth.length>1) strMonth=strMonth.substring(1)
			for (var i = 1; i <= 3; i++) {
				if (strYr.charAt(0)=="0" && strYr.length>1) strYr=strYr.substring(1)
			}
			month=parseInt(strMonth)
			day=parseInt(strDay)
			year=parseInt(strYr)
			if (pos1==-1 || pos2==-1)
				strError = "The date format should be : mm/dd/yyyy";
	
			if (strMonth.length<1 || month<1 || month>12)
				strError = "Please enter a valid month";
	
			if (strDay.length<1 || day<1 || day>31 || (month==2 && day>daysInFebruary(year)) || day > daysInMonth[month])
				strError = "Please enter a valid day of the month";
	
			if (year==0 || year.length<2)
				strError = "Please enter a valid year.";
	
			if (dtStr.indexOf(dtCh,pos2+1)!=-1 || isInteger(stripCharsInBag(dtStr, dtCh))==false)
				strError = "Please enter a valid date";
		}//end if
		return strError;

	}
	
		/* returns the maximum days that can be in the coordinating month */
	function DaysArray(n) {
		for (var i = 1; i <= n; i++) {
			this[i] = 31
			if (i==4 || i==6 || i==9 || i==11) {this[i] = 30}
			if (i==2) {this[i] = 29}
	   } 
	   return this
	}
	
		/* s is your string input, and bag is a character that you want taken out of that input string */	
	function stripCharsInBag(s, bag){
		var i;
		var returnString = "";
		for (i = 0; i < s.length; i++){   
			var c = s.charAt(i);
			if (bag.indexOf(c) == -1) returnString += c;
		}
		return returnString;
	}
	
	/* determines the number of days for February based on leap year credentials */
	function daysInFebruary (year){
		return (((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0))) ? 29 : 28 );
	}
	
	/* checks the input to verify that it is a number */
	function isInteger(s){
		var i;
		for (i = 0; i < s.length; i++){   
			var c = s.charAt(i);
			if (((c < "0") || (c > "9"))) return false;
		}
		return true;
	}