/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
    /*$RCSfile: validateCreditCard.js,v $ $Rev: 478676 $ $Date: 2006-11-23 22:35:44 +0100 (Thu, 23 Nov 2006) $ */
    /**
    * Check to see if fields are a valid creditcard number based on Luhn checksum.
    * Fields are not checked if they are disabled.
    * @param form The form validation is taking place on.
    */
    function validateCreditCard(form) {
        var bValid = true;
        var focusField = null;
        var i = 0;
        var fields = new Array();
 
        var oCreditCard = eval('new ' + jcv_retrieveFormName(form) +  '_creditCard()');

        for (var x in oCreditCard) {
            if (!jcv_verifyArrayElement(x, oCreditCard[x])) {
                continue;
            }
            var field = form[oCreditCard[x][0]];
            if (!jcv_isFieldPresent(field)) {
              continue;
            }
            if ((field.type == 'text' ||
                 field.type == 'textarea') &&
                (field.value.length > 0)) {
                if (!jcv_luhnCheck(field.value)) {
                    if (i == 0) {
                        focusField = field;
                    }
                    fields[i++] = oCreditCard[x][1];
                    bValid = false;
                }
            }
        }
        if (fields.length > 0) {
            jcv_handleErrors(fields, focusField);
        }
        return bValid;
    }

    /**
     * Checks whether a given credit card number has a valid Luhn checksum.
     * This allows you to spot most randomly made-up or garbled credit card numbers immediately.
     * Reference: http://www.speech.cs.cmu.edu/~sburke/pub/luhn_lib.html
     */
    function jcv_luhnCheck(cardNumber) {
        if (jcv_isLuhnNum(cardNumber)) {
            var no_digit = cardNumber.length;
            var oddoeven = no_digit & 1;
            var sum = 0;
            for (var count = 0; count < no_digit; count++) {
                var digit = parseInt(cardNumber.charAt(count));
                if (!((count & 1) ^ oddoeven)) {
                    digit *= 2;
                    if (digit > 9) digit -= 9;
                };
                sum += digit;
            };
            if (sum == 0) return false;
            if (sum % 10 == 0) return true;
        };
        return false;
    }

    function jcv_isLuhnNum(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;
            }
        }
        return true;
    }
