// Check that the number of characters in a string is between a max and a min
function isValidLength(string, min, max) {
	if (string.length < min || string.length > max) return false;
	else return true;
}

// Check that a credit card number is valid based using the LUHN formula (mod10 is 0)
function isValidCreditCard(number) {
	number = '' + number;
	
	if (number.length > 16 || number.length < 13 ) return false;
	else if (getMod10(number) != 0) return false;
	else if (arguments[1]) {
		var type = arguments[1];
		var first2digits = number.substring(0, 2);
		var first4digits = number.substring(0, 4);
		
		if (type.toLowerCase() == 'visa' && number.substring(0, 1) == 4 &&
			(number.length == 16 || number.length == 13 )) return true;
		else if (type.toLowerCase() == 'mastercard' && number.length == 16 &&
			(first2digits == '51' || first2digits == '52' || first2digits == '53' || first2digits == '54' || first2digits == '55')) return true;
		else if (type.toLowerCase() == 'american express' && number.length == 15 && 
			(first2digits == '34' || first2digits == '37')) return true;
		else if (type.toLowerCase() == 'diners club' && number.length == 14 && 
			(first2digits == '30' || first2digits == '36' || first2digits == '38')) return true;
		else if (type.toLowerCase() == 'discover' && number.length == 16 && first4digits == '6011') return true;
		else if (type.toLowerCase() == 'enroute' && number.length == 15 && 
			(first4digits == '2014' || first4digits == '2149')) return true;
		else if (type.toLowerCase() == 'jcb' && number.length == 16 &&
			(first4digits == '3088' || first4digits == '3096' || first4digits == '3112' || first4digits == '3158' || first4digits == '3337' || first4digits == '3528')) return true;
		else return true;
	}
	else return true;
}

// Check that an email address is valid based on RFC 821 (?)
function isValidEmail(address) {
	if (address.indexOf('@') < 2) return false;
	var name = address.substring(0, address.indexOf('@'));
	var domain = address.substring(address.indexOf('@') + 1);
	if (name.indexOf('(') != -1 || name.indexOf(')') != -1 || name.indexOf('<') != -1 || name.indexOf('>') != -1 || name.indexOf(',') != -1 || name.indexOf(';') != -1 || name.indexOf(':') != -1 || name.indexOf('\\') != -1 || name.indexOf('"') != -1 || name.indexOf('[') != -1 || name.indexOf(']') != -1 || name.indexOf(' ') != -1) return false;
	if (domain=="" || domain.indexOf('@') != -1 || domain.indexOf('(') != -1 || domain.indexOf(')') != -1 || domain.indexOf('<') != -1 || domain.indexOf('>') != -1 || domain.indexOf(',') != -1 || domain.indexOf(';') != -1 || domain.indexOf(':') != -1 || domain.indexOf('\\') != -1 || domain.indexOf('"') != -1 || domain.indexOf('[') != -1 || domain.indexOf(']') != -1 || domain.indexOf(' ') != -1) return false;
	return true;
}

	function ValidateEmail( Email )
	{
		var atCharPresent = false;
		var dotPresent = false;

		for ( var Idx = 0; Idx < Email.length; Idx++ )
		{
			if ( Email.charAt ( Idx ) == '@' )
				atCharPresent = true;
			if ( Email.charAt ( Idx ) == '.' )
				dotPresent = true;
		}

		if ( !atCharPresent || !dotPresent )
			return false;

		return true;
	}



// Check that a US zip code is valid
function isValidZipcode(zipcode) {
	zipcode = removeSpaces(zipcode);
	if (!(zipcode.length == 5) || !isNumeric(zipcode)) return false;
	return true;
}


// Check that a Canadian postal code is valid
function isValidPostalcode(postalcode) {
	if (postalcode.search) {
		postalcode = removeSpaces(postalcode);
		if (postalcode.length == 6 && postalcode.search(/^\w\d\w\d\w\d$/) != -1) return true;
		else if (postalcode.length == 7 && postalcode.search(/^\w\d\w\-d\w\d$/) != -1) return true;
		else return false;
	}
	return true;
}

// Check that a string contains only letters and numbers
function isAlphanumeric(string, ignoreWhiteSpace) {
	if (string.search) {
		if ((ignoreWhiteSpace && string.search(/[^\w\s]/) != -1) || (!ignoreWhiteSpace && string.search(/\W/) != -1)) return false;
	}
	return true;
}

// Check that a string contains only letters
function isAlphabetic(string, ignoreWhiteSpace) {
	if (string.search) {
		if ((ignoreWhiteSpace && string.search(/[^a-zA-Z\s]/) != -1) || (!ignoreWhiteSpace && string.search(/[^a-zA-Z]/) != -1)) return false;
	}
	return true;
}

// Check that a string contains only numbers
function isNumeric(string, ignoreWhiteSpace) {
	if (string.search) {
		if ((ignoreWhiteSpace && string.search(/[^\d\s]/) != -1) || (!ignoreWhiteSpace && string.search(/\D/) != -1)) return false;
	}
	return true;
}

// Remove characters that might cause security problems from a string 
function removeBadCharacters(string) {
	if (string.replace) {
		string.replace(/[<>\"\'%;\)\(&\+]/, '');
	}
	return string;
}

// Remove all spaces from a string
function removeSpaces(string) {
	var newString = '';
	for (var i = 0; i < string.length; i++) {
		if (string.charAt(i) != ' ') newString += string.charAt(i);
	}
	return newString;
}

// Remove leading and trailing whitespace from a string
function trimWhitespace(string) {
	var newString  = '';
	var substring  = '';
	beginningFound = false;
	
	// copy characters over to a new string
	// retain whitespace characters if they are between other characters
	for (var i = 0; i < string.length; i++) {
		
		// copy non-whitespace characters
		if (string.charAt(i) != ' ' && string.charCodeAt(i) != 9) {
			
			// if the temporary string contains some whitespace characters, copy them first
			if (substring != '') {
				newString += substring;
				substring = '';
			}
			newString += string.charAt(i);
			if (beginningFound == false) beginningFound = true;
		}
		
		// hold whitespace characters in a temporary string if they follow a non-whitespace character
		else if (beginningFound == true) substring += string.charAt(i);
	}
	return newString;
}

// Returns a checksum digit for a number using mod 10
function getMod10(number) {
	
	// convert number to a string and check that it contains only digits
	// return -1 for illegal input
	number = '' + number;
	number = removeSpaces(number);
	if (!isNumeric(number)) return -1;
	
	// calculate checksum using mod10
	var checksum = 0;
	for (var i = number.length - 1; i >= 0; i--) {
		var isOdd = ((number.length - i) % 2 != 0) ? true : false;
		digit = number.charAt(i);
		
		if (isOdd) checksum += parseInt(digit);
		else {
			var evenDigit = parseInt(digit) * 2;
			if (evenDigit >= 10) checksum += 1 + (evenDigit - 10);
			else checksum += evenDigit;
		}
	}
	return (checksum % 10);
}



//Date Check functions
function checkdate(objName) {
var datefield = objName;
if (chkdate(objName) == false) {
datefield.select();
alert("That date is invalid.  Please try again.");
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;
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.length == 2) {
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 (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") {
datefield.value = strMonthArray[intMonth-1] + " " + intday+" " + strYear;
}
else {
datefield.value = intday + " " + strMonthArray[intMonth-1] + " " + strYear;
}
return true;
}
function LeapYear(intYear) {
if (intYear % 100 == 0) {
if (intYear % 400 == 0) { return true; }
}
else {
if ((intYear % 4) == 0) { return true; }
}
return false;
}

function doDateCheck(from, to) {
if (Date.parse(from.value) <= Date.parse(to.value)) {
alert("The dates are valid.");
}
else {
if (from.value == "" || to.value == "") 
alert("Both dates must be entered.");
else 
alert("To date must occur after the from date.");
   }
}