001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      https://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.validator.routines.checkdigit;
018
019import java.io.Serializable;
020
021import org.apache.commons.validator.GenericValidator;
022
023/**
024 * Combined <strong>ISBN-10</strong> / <strong>ISBN-13</strong> Check Digit calculation/validation.
025 * <p>
026 * This implementation validates/calculates ISBN check digits
027 * based on the length of the code passed to it - delegating
028 * either to the {@link ISBNCheckDigit#ISBN10_CHECK_DIGIT} or the
029 * {@link ISBNCheckDigit#ISBN13_CHECK_DIGIT} routines to perform the actual
030 * validation/calculation.
031 * <p>
032 * <strong>N.B.</strong> From 1st January 2007 the book industry will start to use a new 13 digit
033 * ISBN number (rather than this 10 digit ISBN number) which uses the EAN-13 / UPC
034 * standard.
035 *
036 * @since 1.4
037 */
038public final class ISBNCheckDigit extends AbstractCheckDigit implements Serializable {
039
040    private static final long serialVersionUID = 1391849166205184558L;
041
042    /** Singleton ISBN-10 Check Digit instance */
043    public static final CheckDigit ISBN10_CHECK_DIGIT = ISBN10CheckDigit.ISBN10_CHECK_DIGIT;
044
045    /** Singleton ISBN-13 Check Digit instance */
046    public static final CheckDigit ISBN13_CHECK_DIGIT = EAN13CheckDigit.EAN13_CHECK_DIGIT;
047
048    /** Singleton combined ISBN-10 / ISBN-13 Check Digit instance */
049    public static final CheckDigit ISBN_CHECK_DIGIT = new ISBNCheckDigit();
050
051    /**
052     * Constructs a new instance.
053     */
054    public ISBNCheckDigit() {
055        // empty
056    }
057
058    /**
059     * Calculate an ISBN-10 or ISBN-13 check digit, depending
060     * on the length of the code.
061     * <p>
062     * If the length of the code is 9, it is treated as an ISBN-10
063     * code or if the length of the code is 12, it is treated as an ISBN-13
064     * code.
065     *
066     * @param code The ISBN code to validate (should have a length of
067     * 9 or 12)
068     * @return The ISBN-10 check digit if the length is 9 or an ISBN-13
069     * check digit if the length is 12.
070     * @throws CheckDigitException if the code is missing, or an invalid
071     * length (that is, not 9 or 12) or if there is an error calculating the
072     * check digit.
073     */
074    @Override
075    public String calculate(final String code) throws CheckDigitException {
076        if (GenericValidator.isBlankOrNull(code)) {
077            throw new CheckDigitException("ISBN Code is missing");
078        }
079        if (code.length() == 9) { // CHECKSTYLE IGNORE MagicNumber
080            return ISBN10_CHECK_DIGIT.calculate(code);
081        }
082        if (code.length() == 12) { // CHECKSTYLE IGNORE MagicNumber
083            return ISBN13_CHECK_DIGIT.calculate(code);
084        }
085        throw new CheckDigitException("Invalid ISBN Length = " + code.length());
086    }
087
088    /**
089     * <p>Validate an ISBN-10 or ISBN-13 check digit, depending
090     * on the length of the code.</p>
091     * <p>
092     * If the length of the code is 10, it is treated as an ISBN-10
093     * code or ff the length of the code is 13, it is treated as an ISBN-13
094     * code.
095     *
096     * @param code The ISBN code to validate (should have a length of
097     * 10 or 13)
098     * @return {@code true} if the code has a length of 10 and is
099     * a valid ISBN-10 check digit or the code has a length of 13 and is
100     * a valid ISBN-13 check digit - otherwise {@code false}.
101     */
102    @Override
103    public boolean isValid(final String code) {
104        if (code == null) {
105            return false;
106        }
107        if (code.length() == 10) { // CHECKSTYLE IGNORE MagicNumber
108            return ISBN10_CHECK_DIGIT.isValid(code);
109        }
110        if (code.length() == 13) { // CHECKSTYLE IGNORE MagicNumber
111            return ISBN13_CHECK_DIGIT.isValid(code);
112        }
113        return false;
114    }
115
116}