form = document.generated_form;

var Cards = new makeArray(8);

Cards[0] = new CardType("MasterCard", "51,52,53,54,55", "16");
var MasterCard = Cards[0];

Cards[1] = new CardType("VisaCard", "4", "13,16");
var VisaCard = Cards[1];

Cards[2] = new CardType("AmExCard", "34,37", "15");
var AmExCard = Cards[2];

Cards[3] = new CardType("DinersClubCard", "30,36,38", "14");
var DinersClubCard = Cards[3];

Cards[4] = new CardType("DiscoverCard", "6011", "16");
var DiscoverCard = Cards[4];

Cards[5] = new CardType("enRouteCard", "2014,2149", "15");
var enRouteCard = Cards[5];

Cards[6] = new CardType("JCBCard", "3088,3096,3112,3158,3337,3528", "16");
var JCBCard = Cards[6];

var LuhnCheckSum = Cards[7] = new CardType();




/*************************************************************************\

	checkCardNumber(form)
	function called when users click the "check" button.

\*************************************************************************/

function checkCardNumber(form)
{
	var tmpyear;			
	
	if (form.x_card_num.value.length == 0)
	{
		alert("Please enter a Card Number.");
		form.x_card_num.focus();
		return;
	}
	
	if (form.x_exp_year.value.length == 0)
	{
		alert("Please enter the Expiration Year.");
		form.x_exp_year.focus();
		return;
	}
	
	if (form.x_exp_year.value > 96) 		tmpyear = "19" + form.x_exp_year.value;
	else if (form.x_exp_month.value < 21) 	tmpyear = "20" + form.x_exp_year.value;
	else
	{
		alert("The Expiration Year is not valid.");
		return;
	}
	tmpmonth = form.x_exp_month.options[form.x_exp_month.selectedIndex].value;
	
	// The following line doesnt work in IE3, you need to change it
	// to something like "(new CardType())...".
	// if (!CardType().isExpiryDate(tmpyear, tmpmonth)) {
	
	if (!(new CardType()).isExpiryDate(tmpyear, tmpmonth))
	{
		alert("This card has already expired.");
		return;
	}
	
	
	card = form.CardType.options[form.CardType.selectedIndex].value;
	
	var retval = eval(card + ".checkCardNumber(\"" + form.x_card_num.value + "\", " + tmpyear + ", " + tmpmonth + ");");
	cardname = "";
	if (retval)
	{
		// comment this out if used on an order form
		alert("This card number appears to be valid.");
	}
	else
	{
		// The x_card_num has the valid luhn checksum, but we want to know which
		// cardtype it belongs to.
		for (var n = 0; n < Cards.size; n++)
		{
			if (Cards[n].checkCardNumber(form.x_card_num.value, tmpyear, tmpmonth))
			{
				cardname = Cards[n].getCardType();
				break;
			}
		}
	}
	
	if (cardname.length > 0)
	{
		alert("This looks like a " + cardname + " number, not a " + card + " number.");
	}
	else
	{
		alert("This card number is not valid.");
	}
}





/*************************************************************************\

	Object CardType([String cardtype, String rules, String len, int year, int month])
	cardtype    : type of card, eg: MasterCard, Visa, etc.
	rules       : rules of the x_card_num, eg: "4", "6011", "34,37".
	len         : valid length of x_card_num, eg: "16,19", "13,16".
	year        : year of expiry date.
	month       : month of expiry date.
	eg:
	var VisaCard = new CardType("Visa", "4", "16");
	var AmExCard = new CardType("AmEx", "34,37", "15");

\*************************************************************************/

function CardType() {
	var n;
	var argv = CardType.arguments;
	var argc = CardType.arguments.length;
	
	this.objname = "object CardType";
	
	var tmpcardtype = (argc > 0) ? argv[0] : "CardObject";
	var tmprules = (argc > 1) ? argv[1] : "0,1,2,3,4,5,6,7,8,9";
	var tmplen = (argc > 2) ? argv[2] : "13,14,15,16,19";
	
	this.setCardNumber = setCardNumber;  // set x_card_num method.
	this.setCardType = setCardType;  // setCardType method.
	this.setLen = setLen;  // setLen method.
	this.setRules = setRules;  // setRules method.
	this.setExpiryDate = setExpiryDate;  // setExpiryDate method.
	
	this.setCardType(tmpcardtype);
	this.setLen(tmplen);
	this.setRules(tmprules);
	if (argc > 4) this.setExpiryDate(argv[3], argv[4]);
	
	this.checkCardNumber = checkCardNumber;  // checkCardNumber method.
	this.getExpiryDate = getExpiryDate;  // getExpiryDate method.
	this.getCardType = getCardType;  // getCardType method.
	this.isCardNumber = isCardNumber;  // isCardNumber method.
	this.isExpiryDate = isExpiryDate;  // isExpiryDate method.
	this.luhnCheck = luhnCheck;// luhnCheck method.
	return this;
}




/*************************************************************************\

	boolean checkCardNumber([String x_card_num, int year, int month])
	return true if x_card_num pass the luhncheck and the expiry date is
	valid, else return false.

\*************************************************************************/

function checkCardNumber() {
	var argv = checkCardNumber.arguments;
	var argc = checkCardNumber.arguments.length;
	var x_card_num = (argc > 0) ? argv[0] : this.x_card_num;
	var year = (argc > 1) ? argv[1] : this.year;
	var month = (argc > 2) ? argv[2] : this.month;
	
	this.setCardNumber(x_card_num);
	this.setExpiryDate(year, month);
	
	if (!this.isCardNumber())
	return false;
	if (!this.isExpiryDate())
	return false;
	
	return true;
}




/*************************************************************************\

	String getCardType()
	return the cardtype.

\*************************************************************************/

function getCardType() {
return this.cardtype;
}



/*************************************************************************\

	String getExpiryDate()
	return the expiry date.

\*************************************************************************/
function getExpiryDate() {
	return this.month + "/" + this.year;
}



/*************************************************************************\

	boolean isCardNumber([String x_card_num])
	return true if x_card_num pass the luhncheck and the rules, else return
	false.
	
\*************************************************************************/

function isCardNumber() {
var argv = isCardNumber.arguments;
var argc = isCardNumber.arguments.length;
var x_card_num = (argc > 0) ? argv[0] : this.x_card_num;
if (!this.luhnCheck())
	return false;

for (var n = 0; n < this.len.size; n++)
	if (x_card_num.toString().length == this.len[n]) {
		for (var m = 0; m < this.rules.size; m++) {
		var headdigit = x_card_num.substring(0, this.rules[m].toString().length);
			if (headdigit == this.rules[m])
			return true;
		}
			return false;
	}
	return false;
}



/*************************************************************************\
boolean isExpiryDate([int year, int month])
return true if the date is a valid expiry date,
else return false.
\*************************************************************************/
function isExpiryDate() {
	var argv = isExpiryDate.arguments;
	var argc = isExpiryDate.arguments.length;
	
	year = argc > 0 ? argv[0] : this.year;
	month = argc > 1 ? argv[1] : this.month;
	
	if (!isNum(year+"")) return false;
	if (!isNum(month+""))
	{
		return false;
		today = new Date();
		expiry = new Date(year, month);
	}
	if (today.getTime() > expiry.getTime()) return false;
	else return true;
}




/*************************************************************************\
boolean isNum(String argvalue)
return true if argvalue contains only numeric characters,
else return false.
\*************************************************************************/
function isNum(argvalue)
{
	argvalue = argvalue.toString();
	if (argvalue.length == 0) return false;
	for (var n = 0; n < argvalue.length; n++)
	{
		if (argvalue.substring(n, n+1) < "0" || argvalue.substring(n, n+1) > "9") return false;
		else return true;
	}
}





/*************************************************************************\
boolean luhnCheck([String x_card_num])
return true if x_card_num pass the luhn check else return false.
Reference: http://www.ling.nwu.edu/~sburke/pub/luhn_lib.pl
\*************************************************************************/
function luhnCheck() {
	var argv = luhnCheck.arguments;
	var argc = luhnCheck.arguments.length;
	
	var x_card_num = argc > 0 ? argv[0] : this.x_card_num;
	
	if (! isNum(x_card_num)) return false;
	
	var no_digit = x_card_num.length;
	var oddoeven = no_digit & 1;
	var sum = 0;
	
	for (var count = 0; count < no_digit; count++)
	{
		var digit = parseInt(x_card_num.charAt(count));
		if (!((count & 1) ^ oddoeven)) digit *= 2;
		if (digit > 9) digit -= 9;
	}
	sum += digit;
	if (sum % 10 == 0) return true;
	else return false;
}


/*************************************************************************\
ArrayObject makeArray(int size)
return the array object in the size specified.
\*************************************************************************/
function makeArray(size) {
	this.size = size;
	return this;
}



/*************************************************************************\
CardType setCardNumber(x_card_num)
return the CardType object.
\*************************************************************************/
function setCardNumber(x_card_num) {
	this.x_card_num = x_card_num;
	return this;
}



/*************************************************************************\
CardType setCardType(cardtype)
return the CardType object.
\*************************************************************************/
function setCardType(cardtype) {
	this.cardtype = cardtype;
	return this;
}




/*************************************************************************\
CardType setExpiryDate(year, month)
return the CardType object.
\*************************************************************************/
function setExpiryDate(year, month) {
	this.year = year;
	this.month = month;
	return this;
}




/*************************************************************************\
CardType setLen(len)
return the CardType object.
\*************************************************************************/
function setLen(len) {
	// Create the len array.
	if (len.length == 0 || len == null) len = "13,14,15,16,19";

	var tmplen = len;
	n = 1;
	while (tmplen.indexOf(",") != -1)
	{
		tmplen = tmplen.substring(tmplen.indexOf(",") + 1, tmplen.length);
		n++;
	}
	
	this.len = new makeArray(n);
	n = 0;
	while (len.indexOf(",") != -1)
	{
		var tmpstr = len.substring(0, len.indexOf(","));
		this.len[n] = tmpstr;
		len = len.substring(len.indexOf(",") + 1, len.length);
		n++;
	}
	
	this.len[n] = len;
	return this;
}




/*************************************************************************\
CardType setRules()
return the CardType object.
\*************************************************************************/
function setRules(rules){
	// Create the rules array.
	if (rules.length == 0 || rules == null)	rules = "0,1,2,3,4,5,6,7,8,9";
	  
	var tmprules = rules;
	n = 1;
	while (tmprules.indexOf(",") != -1)
	{
		tmprules = tmprules.substring(tmprules.indexOf(",") + 1, tmprules.length);
		n++;
	}
	
	this.rules = new makeArray(n);
	n = 0;
	while (rules.indexOf(",") != -1)
	{
		var tmpstr = rules.substring(0, rules.indexOf(","));
		this.rules[n] = tmpstr;
		rules = rules.substring(rules.indexOf(",") + 1, rules.length);
		n++;
	}
	
	this.rules[n] = rules;
	return this;
}