001/*
002 * (C) Copyright 2006-2016 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 *
016 * Contributors:
017 *     Nuxeo - initial API and implementation
018 */
019package org.nuxeo.common.utils;
020
021import java.security.SecureRandom;
022import java.util.ArrayList;
023import java.util.List;
024import java.util.Random;
025import java.util.regex.Pattern;
026
027/**
028 * Utils for identifier generation.
029 *
030 * @author <a href="mailto:at@nuxeo.com">Anahide Tchertchian</a>
031 */
032public final class IdUtils {
033
034    private static final String WORD_SPLITTING_REGEXP = "[^a-zA-Z0-9]+";
035
036    public static final String UUID_TYPE_4_REGEXP = "[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}";
037
038    private static final Random RANDOM = new SecureRandom();
039
040    // This is an utility class.
041    private IdUtils() {
042    }
043
044    /**
045     * Generates an unique string identifier.
046     */
047    public static String generateStringId() {
048        return String.valueOf(generateLongId());
049    }
050
051    /**
052     * Generates an unique long identifier.
053     */
054    public static long generateLongId() {
055        long r = RANDOM.nextLong();
056        if (r < 0) {
057            r = -r;
058        }
059        return r;
060    }
061
062    /**
063     * Generates an id from a non-null String.
064     * <p>
065     * Replaces accented characters from a string by their ascii equivalent, removes non alphanumerical characters and
066     * replaces spaces by the given wordSeparator character.
067     *
068     * @param s the original String
069     * @param wordSeparator the word separator to use (usually '-')
070     * @param lower if lower is true, remove upper case
071     * @param maxChars maximum longer of identifier characters
072     * @return the identifier String
073     */
074    public static String generateId(String s, String wordSeparator, boolean lower, int maxChars) {
075        s = StringUtils.toAscii(s);
076        s = s.trim();
077        if (lower) {
078            s = s.toLowerCase();
079        }
080        String[] words = s.split(WORD_SPLITTING_REGEXP);
081        // remove blank chars from words, did not get why they're not filtered
082        List<String> wordsList = new ArrayList<>();
083        for (String word : words) {
084            if (word != null && word.length() > 0) {
085                wordsList.add(word);
086            }
087        }
088        if (wordsList.isEmpty()) {
089            return generateStringId();
090        }
091        StringBuilder sb = new StringBuilder();
092        String id;
093        if (maxChars > 0) {
094            // be sure at least one word is used
095            sb.append(wordsList.get(0));
096            for (int i = 1; i < wordsList.size(); i++) {
097                String newWord = wordsList.get(i);
098                if (sb.length() + newWord.length() > maxChars) {
099                    break;
100                } else {
101                    sb.append(wordSeparator).append(newWord);
102                }
103            }
104            id = sb.toString();
105            id = id.substring(0, Math.min(id.length(), maxChars));
106        } else {
107            id = String.join(wordSeparator, wordsList);
108        }
109
110        return id;
111    }
112
113    /**
114     * Check if a given string has the pattern for UUID type 4
115     *
116     * @since 5.7
117     */
118    public static boolean isValidUUID(String uuid) {
119        return Pattern.compile(UUID_TYPE_4_REGEXP).matcher(uuid).matches();
120    }
121
122}