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 */
017
018package org.apache.commons.validator.routines.checkdigit;
019
020import org.apache.commons.validator.GenericValidator;
021import org.apache.commons.validator.routines.CodeValidator;
022
023/**
024 * Modulus 11 <strong>EC number</strong> Check Digit calculation/validation.
025 *
026 * <p>
027 * The European Community number (EC number) is a unique seven-digit identifier that is assigned to chemical substances. For example, the EC number of arsenic
028 * is 231-148-6:
029 * </p>
030 *
031 * <p>
032 * Check digit calculation is based on <em>modulus 11</em> with digits being weighted based on their position (from left to right).
033 * </p>
034 *
035 * <p>
036 * For further information see <a href="https://en.wikipedia.org/wiki/European_Community_number">Wikipedia - EC number</a>.
037 * </p>
038 *
039 * @since 1.9.0
040 */
041public final class ECNumberCheckDigit extends ModulusCheckDigit {
042
043    private static final long serialVersionUID = 7265356024784308367L;
044
045    /** Singleton Check Digit instance. */
046    private static final ECNumberCheckDigit INSTANCE = new ECNumberCheckDigit();
047
048    /**
049     * EC number consists of 3 groups of numbers separated dashes (-). Example: dexamethasone is 200-003-9
050     */
051    private static final String GROUP = "(\\d{3})";
052
053    private static final String DASH = "(?:\\-)";
054
055    static final String EC_REGEX = "^(?:" + GROUP + DASH + GROUP + DASH + "(\\d))$";
056
057    private static final int EC_LEN = 7;
058
059    static final CodeValidator REGEX_VALIDATOR = new CodeValidator(EC_REGEX, EC_LEN, null);
060
061    /**
062     * Gets the singleton instance of this validator.
063     *
064     * @return A singleton instance of the EC Number validator.
065     */
066    public static CheckDigit getInstance() {
067        return INSTANCE;
068    }
069
070    /**
071     * Constructs a modulus 11 Check Digit routine.
072     */
073    private ECNumberCheckDigit() {
074        super(MODULUS_11);
075    }
076
077    /**
078     * {@inheritDoc}
079     */
080    @Override
081    public String calculate(final String code) throws CheckDigitException {
082        if (GenericValidator.isBlankOrNull(code)) {
083            throw new CheckDigitException("Code is missing");
084        }
085        final int modulusResult = INSTANCE.calculateModulus(code, false);
086        return toCheckDigit(modulusResult);
087    }
088
089    /**
090     * {@inheritDoc}
091     */
092    @Override
093    public boolean isValid(final String code) {
094        if (GenericValidator.isBlankOrNull(code)) {
095            return false;
096        }
097        final Object cde = REGEX_VALIDATOR.validate(code);
098        if (!(cde instanceof String)) {
099            return false;
100        }
101        final String validated = (String) cde;
102        try {
103            return INSTANCE.calculateModulus(validated, true) == Character.getNumericValue(validated.charAt(validated.length() - 1));
104        } catch (final CheckDigitException e) {
105            return false;
106        }
107    }
108
109    /**
110     * Calculates the <em>weighted</em> value of a character in the code at a specified position.
111     *
112     * <p>
113     * For EC number digits are weighted by their position from left to right.
114     * </p>
115     *
116     * @param charValue The numeric value of the character.
117     * @param leftPos   The position of the character in the code, counting from left to right.
118     * @param rightPos  The position of the character in the code, counting from right to left.
119     * @return The weighted value of the character.
120     */
121    @Override
122    protected int weightedValue(final int charValue, final int leftPos, final int rightPos) {
123        return leftPos >= EC_LEN ? 0 : charValue * leftPos;
124    }
125}