/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.elasticsearch.common;

import java.util.Random;

public class UUIDs {

    private static final RandomBasedUUIDGenerator RANDOM_UUID_GENERATOR = new RandomBasedUUIDGenerator();
    private static final UUIDGenerator TIME_UUID_GENERATOR = new TimeBasedUUIDGenerator();

    /** Generates a time-based UUID (similar to Flake IDs), which is preferred when generating an ID to be indexed into a Lucene index as
     *  primary key.  The id is opaque and the implementation is free to change at any time! */
    public static String base64UUID() {
        return TIME_UUID_GENERATOR.getBase64UUID();
    }

    /** Returns a Base64 encoded version of a Version 4.0 compatible UUID as defined here: http://www.ietf.org/rfc/rfc4122.txt, using the
     *  provided {@code Random} instance */
    public static String randomBase64UUID(Random random) {
        return RANDOM_UUID_GENERATOR.getBase64UUID(random);
    }

    /** Returns a Base64 encoded version of a Version 4.0 compatible UUID as defined here: http://www.ietf.org/rfc/rfc4122.txt, using a
     *  private {@code SecureRandom} instance */
    public static String randomBase64UUID() {
        return RANDOM_UUID_GENERATOR.getBase64UUID();
    }

}
