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/**
 * COOS - Connected Objects Operating System (www.connectedobjects.org).
 *
 * Copyright (C) 2009 Telenor ASA and Tellu AS. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see .
 *
 * You may also contact one of the following for additional information:
 * Telenor ASA, Snaroyveien 30, N-1331 Fornebu, Norway (www.telenor.no)
 * Tellu AS, Hagalokkveien 13, N-1383 Asker, Norway (www.tellu.no)
 */
package org.coos.messaging.util;

/**
 * @author Knut Eilif Husa, Tellu AS Generator of UUIDs
 */

public class UuidGenerator {

	private static final String UNIQUE_STUB;
	private static int instanceCount;
	private static String hostName;
	private String seed;
	private long sequence;
	public static final String UUID = "UUID-";

	static {
		String stub = "";

		hostName = "localhost";
		stub = "-1-" + System.currentTimeMillis() + "-";

		UNIQUE_STUB = stub;
	}

	/**
	 * Construct an IdGenerator
	 */

	public UuidGenerator(String prefix) {
		synchronized (UNIQUE_STUB) {
			this.seed = prefix + UNIQUE_STUB + (instanceCount++) + "-";
		}
	}

	public UuidGenerator() {
		this(UUID + hostName);
	}

	/**
	 * As we have to find the hostname as a side-affect of generating a unique
	 * stub, we allow it's easy retrevial here
	 * 
	 * @return the local host name
	 */

	public static String getHostName() {
		return hostName;
	}

	/**
	 * Generate a unqiue id
	 * 
	 * @return a unique id
	 */

	public synchronized String generateId() {
		return this.seed + (this.sequence++);
	}

	/**
	 * Generate a unique ID - that is friendly for a URL or file system
	 * 
	 * @return a unique id
	 */
	public String generateSanitizedId() {
		String result = generateId();
		result = result.replace(':', '-');
		result = result.replace('_', '-');
		result = result.replace('.', '-');
		return result;
	}

}