    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;
    018
    019import java.io.Serializable;
    020
    021import org.apache.commons.validator.routines.checkdigit.CheckDigitException;
    022import org.apache.commons.validator.routines.checkdigit.EAN13CheckDigit;
    023import org.apache.commons.validator.routines.checkdigit.ISSNCheckDigit;
    024
    025/**
    026 * International Standard Serial Number (ISSN)
    027 * is an eight-digit serial number used to
    028 * uniquely identify a serial publication.
    029 * <pre>
    030 * The format is:
    031 *
    032 * ISSN dddd-dddC
    033 * where:
    034 * d = decimal digit (0-9)
    035 * C = checksum (0-9 or X)
    036 *
    037 * The checksum is formed by adding the first 7 digits multiplied by
    038 * the position in the entire number (counting from the right).
    039 *
    040 * For example, abcd-efg would be 8a + 7b + 6c + 5d + 4e +3f +2g.
    041 * The check digit is modulus 11, where the value 10 is represented by 'X'
    042 * For example:
    043 * ISSN 0317-8471
    044 * ISSN 1050-124X
    045 *
    046 * This class strips off the 'ISSN ' prefix if it is present before passing
    047 * the remainder to the checksum routine.
    048 *
    049 * </pre>
    050 * <p>
    051 * Note: the {@link #isValid(String)} and {@link #validate(String)} methods strip off any leading
    052 * or trailing spaces before doing the validation.
    053 * To ensure that only a valid code (without 'ISSN ' prefix) is passed to a method,
    054 * use the following code:
    055 * </p>
    056 * <pre>
    057 * Object valid = validator.validate(input);
    058 * if (valid != null) {
    059 *    some_method(valid.toString());
    060 * }
    061 * </pre>
    062 * @since 1.5.0
    063 */
    064public class ISSNValidator implements Serializable {
    065
    066    private static final long serialVersionUID = 4319515687976420405L;
    067
    068    private static final String ISSN_REGEX = "(?:ISSN )?(\\d{4})-(\\d{3}[0-9X])$"; // We don't include the '-' in the code, so it is 8 chars
    069
    070    private static final int ISSN_LEN = 8;
    071
    072    private static final String ISSN_PREFIX = "977";
    073
    074    private static final String EAN_ISSN_REGEX = "^(977)(?:(\\d{10}))$";
    075
    076    private static final int EAN_ISSN_LEN = 13;
    077
    078    private static final CodeValidator VALIDATOR = new CodeValidator(ISSN_REGEX, ISSN_LEN, ISSNCheckDigit.ISSN_CHECK_DIGIT);
    079
    080    private static final CodeValidator EAN_VALIDATOR = new CodeValidator(EAN_ISSN_REGEX, EAN_ISSN_LEN, EAN13CheckDigit.EAN13_CHECK_DIGIT);
    081
    082    /** ISSN Code Validator. */
    083    private static final ISSNValidator ISSN_VALIDATOR = new ISSNValidator();
    084
    085    /**
    086     * Gets the singleton instance of the ISSN validator.
    087     *
    088     * @return A singleton instance of the ISSN validator.
    089     */
    090    public static ISSNValidator getInstance() {
    091        return ISSN_VALIDATOR;
    092    }
    093
    094    /**
    095     * Constructs a new instance.
    096     */
    097    public ISSNValidator() {
    098        // empty
    099    }
    100
    101    /**
    102     * Converts an ISSN code to an EAN-13 code.
    103     * <p>
    104     * This method requires a valid ISSN code.
    105     * It may contain a leading 'ISSN ' prefix,
    106     * as the input is passed through the {@link #validate(String)}
    107     * method.
    108     * </p>
    109     *
    110     * @param issn The ISSN code to convert
    111     * @param suffix the two digit suffix, for example, "00"
    112     * @return A converted EAN-13 code or {@code null}
    113     * if the input ISSN code is not valid
    114     */
    115    public String convertToEAN13(final String issn, final String suffix) {
    116        if (suffix == null || !suffix.matches("\\d\\d")) {
    117            throw new IllegalArgumentException("Suffix must be two digits: '" + suffix + "'");
    118        }
    119        final Object result = validate(issn);
    120        if (result == null) {
    121            return null;
    122        }
    123        // Calculate the new EAN-13 code
    124        final String input = result.toString();
    125        String ean13 = ISSN_PREFIX + input.substring(0, input.length() - 1) + suffix;
    126        try {
    127            final String checkDigit = EAN13CheckDigit.EAN13_CHECK_DIGIT.calculate(ean13);
    128            ean13 += checkDigit;
    129            return ean13;
    130        } catch (final CheckDigitException e) { // Should not happen
    131            throw new IllegalArgumentException("Check digit error for '" + ean13 + "' - " + e.getMessage());
    132        }
    133    }
    134
    135    /**
    136     * Extracts an ISSN code from an ISSN-EAN-13 code.
    137     * <p>
    138     * This method requires a valid ISSN-EAN-13 code with NO formatting
    139     * characters.
    140     * That is a 13 digit EAN-13 code with the '977' prefix.
    141     * </p>
    142     *
    143     * @param ean13 The ISSN code to convert
    144     * @return A valid ISSN code or {@code null}
    145     * if the input ISSN EAN-13 code is not valid
    146     * @since 1.7
    147     */
    148    public String extractFromEAN13(final String ean13) {
    149        String input = ean13.trim();
    150        if (input.length() != EAN_ISSN_LEN) {
    151            throw new IllegalArgumentException("Invalid length " + input.length() + " for '" + input + "'");
    152        }
    153        if (!input.startsWith(ISSN_PREFIX)) {
    154            throw new IllegalArgumentException("Prefix must be " + ISSN_PREFIX + " to contain an ISSN: '" + ean13 + "'");
    155        }
    156        final Object result = validateEan(input);
    157        if (result == null) {
    158            return null;
    159        }
    160        // Calculate the ISSN code
    161        input = result.toString();
    162        try {
    163            //CHECKSTYLE:OFF: MagicNumber
    164            final String issnBase = input.substring(3, 10); // TODO: how to derive these
    165            //CHECKSTYLE:ON: MagicNumber
    166            final String checkDigit = ISSNCheckDigit.ISSN_CHECK_DIGIT.calculate(issnBase);
    167            return issnBase + checkDigit;
    168        } catch (final CheckDigitException e) { // Should not happen
    169            throw new IllegalArgumentException("Check digit error for '" + ean13 + "' - " + e.getMessage());
    170        }
    171    }
    172
    173    /**
    174     * Tests whether the code is a valid ISSN code after any transformation
    175     * by the validate routine.
    176     *
    177     * @param code The code to validate.
    178     * @return {@code true} if a valid ISSN
    179     * code, otherwise {@code false}.
    180     */
    181    public boolean isValid(final String code) {
    182        return VALIDATOR.isValid(code);
    183    }
    184
    185    /**
    186     * Checks the code is valid ISSN code.
    187     * <p>
    188     * If valid, this method returns the ISSN code with
    189     * the 'ISSN ' prefix removed (if it was present)
    190     * </p>
    191     *
    192     * @param code The code to validate.
    193     * @return A valid ISSN code if valid, otherwise {@code null}.
    194     */
    195    public Object validate(final String code) {
    196        return VALIDATOR.validate(code);
    197    }
    198
    199    /**
    200     * Checks the code is a valid EAN code.
    201     * <p>
    202     * If valid, this method returns the EAN code
    203     * </p>
    204     *
    205     * @param code The code to validate.
    206     * @return A valid EAN code if valid, otherwise {@code null}.
    207     * @since 1.7
    208     */
    209    public Object validateEan(final String code) {
    210        return EAN_VALIDATOR.validate(code);
    211    }
    212}