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 *
063 * @since 1.5.0
064 */
065public class ISSNValidator implements Serializable {
066
067    private static final long serialVersionUID = 4319515687976420405L;
068
069    private static final String ISSN_REGEX = "(?:ISSN )?(\\d{4})-(\\d{3}[0-9X])$"; // We don't include the '-' in the code, so it is 8 chars
070
071    private static final int ISSN_LEN = 8;
072
073    private static final String ISSN_PREFIX = "977";
074
075    private static final String EAN_ISSN_REGEX = "^(977)(?:(\\d{10}))$";
076
077    private static final int EAN_ISSN_LEN = 13;
078
079    private static final CodeValidator VALIDATOR = new CodeValidator(ISSN_REGEX, ISSN_LEN, ISSNCheckDigit.ISSN_CHECK_DIGIT);
080
081    private static final CodeValidator EAN_VALIDATOR = new CodeValidator(EAN_ISSN_REGEX, EAN_ISSN_LEN, EAN13CheckDigit.EAN13_CHECK_DIGIT);
082
083    /** ISSN Code Validator. */
084    private static final ISSNValidator ISSN_VALIDATOR = new ISSNValidator();
085
086    /**
087     * Gets the singleton instance of the ISSN validator.
088     *
089     * @return A singleton instance of the ISSN validator.
090     */
091    public static ISSNValidator getInstance() {
092        return ISSN_VALIDATOR;
093    }
094
095    /**
096     * Constructs a new instance.
097     */
098    public ISSNValidator() {
099        // empty
100    }
101
102    /**
103     * Converts an ISSN code to an EAN-13 code.
104     * <p>
105     * This method requires a valid ISSN code.
106     * It may contain a leading 'ISSN ' prefix,
107     * as the input is passed through the {@link #validate(String)}
108     * method.
109     * </p>
110     *
111     * @param issn The ISSN code to convert
112     * @param suffix the two digit suffix, for example, "00"
113     * @return A converted EAN-13 code or {@code null}
114     * if the input ISSN code is not valid
115     */
116    public String convertToEAN13(final String issn, final String suffix) {
117        if (suffix == null || !suffix.matches("\\d\\d")) {
118            throw new IllegalArgumentException("Suffix must be two digits: '" + suffix + "'");
119        }
120        final Object result = validate(issn);
121        if (result == null) {
122            return null;
123        }
124        // Calculate the new EAN-13 code
125        final String input = result.toString();
126        String ean13 = ISSN_PREFIX + input.substring(0, input.length() - 1) + suffix;
127        try {
128            final String checkDigit = EAN13CheckDigit.EAN13_CHECK_DIGIT.calculate(ean13);
129            ean13 += checkDigit;
130            return ean13;
131        } catch (final CheckDigitException e) { // Should not happen
132            throw new IllegalArgumentException("Check digit error for '" + ean13 + "' - " + e.getMessage());
133        }
134    }
135
136    /**
137     * Extracts an ISSN code from an ISSN-EAN-13 code.
138     * <p>
139     * This method requires a valid ISSN-EAN-13 code with NO formatting
140     * characters.
141     * That is a 13 digit EAN-13 code with the '977' prefix.
142     * </p>
143     *
144     * @param ean13 The ISSN code to convert
145     * @return A valid ISSN code or {@code null}
146     * if the input ISSN EAN-13 code is not valid
147     * @since 1.7
148     */
149    public String extractFromEAN13(final String ean13) {
150        String input = ean13.trim();
151        if (input.length() != EAN_ISSN_LEN) {
152            throw new IllegalArgumentException("Invalid length " + input.length() + " for '" + input + "'");
153        }
154        if (!input.startsWith(ISSN_PREFIX)) {
155            throw new IllegalArgumentException("Prefix must be " + ISSN_PREFIX + " to contain an ISSN: '" + ean13 + "'");
156        }
157        final Object result = validateEan(input);
158        if (result == null) {
159            return null;
160        }
161        // Calculate the ISSN code
162        input = result.toString();
163        try {
164            //CHECKSTYLE:OFF: MagicNumber
165            final String issnBase = input.substring(3, 10); // TODO: how to derive these
166            //CHECKSTYLE:ON: MagicNumber
167            final String checkDigit = ISSNCheckDigit.ISSN_CHECK_DIGIT.calculate(issnBase);
168            return issnBase + checkDigit;
169        } catch (final CheckDigitException e) { // Should not happen
170            throw new IllegalArgumentException("Check digit error for '" + ean13 + "' - " + e.getMessage());
171        }
172    }
173
174    /**
175     * Tests whether the code is a valid ISSN code after any transformation
176     * by the validate routine.
177     *
178     * @param code The code to validate.
179     * @return {@code true} if a valid ISSN
180     * code, otherwise {@code false}.
181     */
182    public boolean isValid(final String code) {
183        return VALIDATOR.isValid(code);
184    }
185
186    /**
187     * Checks the code is valid ISSN code.
188     * <p>
189     * If valid, this method returns the ISSN code with
190     * the 'ISSN ' prefix removed (if it was present)
191     * </p>
192     *
193     * @param code The code to validate.
194     * @return A valid ISSN code if valid, otherwise {@code null}.
195     */
196    public Object validate(final String code) {
197        return VALIDATOR.validate(code);
198    }
199
200    /**
201     * Checks the code is a valid EAN code.
202     * <p>
203     * If valid, this method returns the EAN code
204     * </p>
205     *
206     * @param code The code to validate.
207     * @return A valid EAN code if valid, otherwise {@code null}.
208     * @since 1.7
209     */
210    public Object validateEan(final String code) {
211        return EAN_VALIDATOR.validate(code);
212    }
213}