/*

 *   SONEWS News Server

 *   see AUTHORS for the list of contributors

 *

 *   This program is free software: you can redistribute it and/or modify

 *   it under the terms of the GNU 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 General Public License for more details.

 *

 *   You should have received a copy of the GNU General Public License

 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

package org.sonews.util;

import java.util.HashMap;

import java.util.HashSet;

import java.util.Map;

import java.util.Set;

import java.util.concurrent.ConcurrentHashMap;

/**

 * Implementation of a Map that will loose its stored values after a 

 * configurable amount of time.

 * This class may be used to cache config values for example.

 * @author Christian Lins

 * @since sonews/0.5.0

 */

public class TimeoutMap<K, V> extends ConcurrentHashMap<K, V>

{

	private static final long serialVersionUID = 453453467700345L;

	private int timeout = 60000; // 60 sec

	private transient Map<K, Long> timeoutMap = new HashMap<K, Long>();

	/**

	 * Constructor.

	 * @param timeout Timeout in milliseconds

	 */

	public TimeoutMap(final int timeout)

	{

		this.timeout = timeout;

	}

	/**

	 * Uses default timeout (60 sec).

	 */

	public TimeoutMap()

	{

	}

	/**

	 *

	 * @param key

	 * @return true if key is still valid.

	 */

	protected boolean checkTimeOut(Object key)

	{

		synchronized (this.timeoutMap) {

			if (this.timeoutMap.containsKey(key)) {

				long keytime = this.timeoutMap.get(key);

				if ((System.currentTimeMillis() - keytime) < this.timeout) {

					return true;

				} else {

					remove(key);

					return false;

				}

			} else {

				return false;

			}

		}

	}

	@Override

	public boolean containsKey(Object key)

	{

		return checkTimeOut(key);

	}

	@Override

	public synchronized V get(Object key)

	{

		if (checkTimeOut(key)) {

			return super.get(key);

		} else {

			return null;

		}

	}

	@Override

	public V put(K key, V value)

	{

		synchronized (this.timeoutMap) {

			removeStaleKeys();

			this.timeoutMap.put(key, System.currentTimeMillis());

			return super.put(key, value);

		}

	}

	/**

	 * @param arg0

	 * @return

	 */

	@Override

	public V remove(Object arg0)

	{

		synchronized (this.timeoutMap) {

			this.timeoutMap.remove(arg0);

			V val = super.remove(arg0);

			return val;

		}

	}

	protected void removeStaleKeys()

	{

		synchronized (this.timeoutMap) {

			Set<Object> keySet = new HashSet<Object>(this.timeoutMap.keySet());

			for (Object key : keySet) {

				// The key/value is removed by the checkTimeOut() method if true

				checkTimeOut(key);

			}

		}

	}

}