/*

  *   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);

       }

     }

   }

 }