/*
 * jQuery creditcard2 extension for the jQuery Validation plugin (http://plugins.jquery.com/project/validate).
 * Ported from http://www.braemoor.co.uk/software/creditcard.shtml by John Gardner, with some enhancements.
 *
 * Author: Jack Killpatrick
 * Copyright (c) 2008 iHwy, Inc.
 *
 * Version 1.0.0 (11/17/2008)
 * Tested with jquery 1.2.6, but will probably work with earlier versions.
 *
 * History	:
 * 1.0.0 - released 2008-11-17
 *
 * Visit http://www.ihwy.com/labs/jquery-validate-credit-card-extension.aspx for usage information
 *
 * Dual licensed under the MIT and GPL licenses:
 *   http://www.opensource.org/licenses/mit-license.php
 *   http://www.gnu.org/licenses/gpl.html
*/
 
jQuery.validator.addMethod("creditcard2", function(value, element, param) {
	var cardName = param;
	
	var cards = new Array();
	cards [0] = {cardName: "Visa", lengths: "13,16", prefixes: "4", checkdigit: true};
	cards [1] = {cardName: "MasterCard", lengths: "16", prefixes: "51,52,53,54,55", checkdigit: true};
	cards [2] = {cardName: "American Express", lengths: "15", prefixes: "34,37", checkdigit: true};
	cards [3] = {cardName: "Discover", lengths: "16", prefixes: "6011,650", checkdigit: true};
				   
	var cardType = -1;
	for (var i=0; i<cards.length; i++) {
		if (cardName.toLowerCase() == cards[i].cardName.toLowerCase()) {
			cardType = i;
			break;
		}
	}
	if (cardType == -1) { return false; } // card type not found

	value = value.replace (/[\s-]/g, ""); // remove spaces and dashes
	if (value.length == 0) { return false; } // no length

	var cardNo = value;
	var cardexp = /^[0-9]{13,19}$/;
	if (!cardexp.exec(cardNo)) { return false; } // has chars or wrong length
	
	cardNo = cardNo.replace(/\D/g, ""); // strip down to digits

	if (cards[cardType].checkdigit){
		var checksum = 0;
		var mychar = "";
		var j = 1;

		var calc;
		for (i = cardNo.length - 1; i >= 0; i--) {
			calc = Number(cardNo.charAt(i)) * j;
			if (calc > 9) {
				checksum = checksum + 1;
				calc = calc - 10;
			}
			checksum = checksum + calc;
			if (j ==1) {j = 2} else {j = 1};
		} 

		if (checksum % 10 != 0) { return false; } // not mod10
	}  

	var lengthValid = false;
	var prefixValid = false; 
	var prefix = new Array ();
	var lengths = new Array ();

	prefix = cards[cardType].prefixes.split(",");
	for (i=0; i<prefix.length; i++) {
		var exp = new RegExp ("^" + prefix[i]);
		if (exp.test (cardNo)) prefixValid = true;
	}
	if (!prefixValid) { return false; } // invalid prefix

	lengths = cards[cardType].lengths.split(",");
	for (j=0; j<lengths.length; j++) {
		if (cardNo.length == lengths[j]) lengthValid = true;
	}
	if (!lengthValid) { return false; } // wrong length

	return true;
}, jQuery.validator.messages.creditcard);