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 *      http://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     * Converts an ISSN code to an EAN-13 code.
096     * <p>
097     * This method requires a valid ISSN code.
098     * It may contain a leading 'ISSN ' prefix,
099     * as the input is passed through the {@link #validate(String)}
100     * method.
101     * </p>
102     *
103     * @param issn The ISSN code to convert
104     * @param suffix the two digit suffix, e.g. "00"
105     * @return A converted EAN-13 code or {@code null}
106     * if the input ISSN code is not valid
107     */
108    public String convertToEAN13(final String issn, final String suffix) {
109        if (suffix == null || !suffix.matches("\\d\\d")) {
110            throw new IllegalArgumentException("Suffix must be two digits: '" + suffix + "'");
111        }
112        final Object result = validate(issn);
113        if (result == null) {
114            return null;
115        }
116        // Calculate the new EAN-13 code
117        final String input = result.toString();
118        String ean13 = ISSN_PREFIX + input.substring(0, input.length() - 1) + suffix;
119        try {
120            final String checkDigit = EAN13CheckDigit.EAN13_CHECK_DIGIT.calculate(ean13);
121            ean13 += checkDigit;
122            return ean13;
123        } catch (final CheckDigitException e) { // Should not happen
124            throw new IllegalArgumentException("Check digit error for '" + ean13 + "' - " + e.getMessage());
125        }
126    }
127
128    /**
129     * Extracts an ISSN code from an ISSN-EAN-13 code.
130     * <p>
131     * This method requires a valid ISSN-EAN-13 code with NO formatting
132     * characters.
133     * That is a 13 digit EAN-13 code with the '977' prefix.
134     * </p>
135     *
136     * @param ean13 The ISSN code to convert
137     * @return A valid ISSN code or {@code null}
138     * if the input ISSN EAN-13 code is not valid
139     * @since 1.7
140     */
141    public String extractFromEAN13(final String ean13) {
142        String input = ean13.trim();
143        if (input.length() != EAN_ISSN_LEN ) {
144            throw new IllegalArgumentException("Invalid length " + input.length() + " for '" + input + "'");
145        }
146        if (!input.startsWith(ISSN_PREFIX)) {
147            throw new IllegalArgumentException("Prefix must be " + ISSN_PREFIX + " to contain an ISSN: '" + ean13 + "'");
148        }
149        final Object result = validateEan(input);
150        if (result == null) {
151            return null;
152        }
153        // Calculate the ISSN code
154        input = result.toString();
155        try {
156            //CHECKSTYLE:OFF: MagicNumber
157            final String issnBase = input.substring(3, 10); // TODO: how to derive these
158            //CHECKSTYLE:ON: MagicNumber
159            final String checkDigit = ISSNCheckDigit.ISSN_CHECK_DIGIT.calculate(issnBase);
160            return issnBase + checkDigit;
161        } catch (final CheckDigitException e) { // Should not happen
162            throw new IllegalArgumentException("Check digit error for '" + ean13 + "' - " + e.getMessage());
163        }
164    }
165
166    /**
167     * Tests whether the code is a valid ISSN code after any transformation
168     * by the validate routine.
169     *
170     * @param code The code to validate.
171     * @return {@code true} if a valid ISSN
172     * code, otherwise {@code false}.
173     */
174    public boolean isValid(final String code) {
175        return VALIDATOR.isValid(code);
176    }
177
178    /**
179     * Checks the code is valid ISSN code.
180     * <p>
181     * If valid, this method returns the ISSN code with
182     * the 'ISSN ' prefix removed (if it was present)
183     * </p>
184     *
185     * @param code The code to validate.
186     * @return A valid ISSN code if valid, otherwise {@code null}.
187     */
188    public Object validate(final String code) {
189        return VALIDATOR.validate(code);
190    }
191
192    /**
193     * Checks the code is a valid EAN code.
194     * <p>
195     * If valid, this method returns the EAN code
196     * </p>
197     *
198     * @param code The code to validate.
199     * @return A valid EAN code if valid, otherwise {@code null}.
200     * @since 1.7
201     */
202    public Object validateEan(final String code) {
203        return EAN_VALIDATOR.validate(code);
204    }
205}