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}