package org.apache.commons.jcs3.engine;
   
   /*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF 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.
   */
  
  import java.io.IOException;
  import java.util.Collections;
  import java.util.Set;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import java.util.concurrent.CopyOnWriteArraySet;
  
  import org.apache.commons.jcs3.engine.behavior.ICacheListener;
  import org.apache.commons.jcs3.engine.behavior.ICacheObserver;
  import org.apache.commons.jcs3.log.Log;
  import org.apache.commons.jcs3.log.LogManager;
  
  /**
   * Intercepts the requests to the underlying ICacheObserver object so that the listeners can be
   * recorded locally for remote connection recovery purposes. (Durable subscription like those in JMS
   * is not implemented at this stage for it can be too expensive.)
   */
  public class CacheWatchRepairable
      implements ICacheObserver
  {
      /** The logger */
      private static final Log log = LogManager.getLog( CacheWatchRepairable.class );
  
      /** the underlying ICacheObserver. */
      private ICacheObserver cacheWatch;
  
      /** Map of cache regions. */
      private final ConcurrentMap<String, Set<ICacheListener<?, ?>>> cacheMap =
          new ConcurrentHashMap<>();
  
      /**
       * Replaces the underlying cache watch service and re-attaches all existing listeners to the new
       * cache watch.
       * <p>
       * @param cacheWatch The new cacheWatch value
       */
      public void setCacheWatch( final ICacheObserver cacheWatch )
      {
          this.cacheWatch = cacheWatch;
          cacheMap.forEach((cacheName, value) -> value.forEach(listener -> {
                  try
                  {
                      log.info( "Adding listener to cache watch. ICacheListener = "
                              + "{0} | ICacheObserver = {1}", listener, cacheWatch );
                      cacheWatch.addCacheListener( cacheName, listener );
                  }
                  catch ( final IOException ex )
                  {
                      log.error( "Problem adding listener. ICacheListener = {0} | "
                              + "ICacheObserver = {1}", listener, cacheWatch, ex );
                  }
          }));
      }
  
      /**
       * Adds a feature to the CacheListener attribute of the CacheWatchRepairable object
       * <p>
       * @param cacheName The feature to be added to the CacheListener attribute
       * @param obj The feature to be added to the CacheListener attribute
       * @throws IOException
       */
      @Override
      public <K, V> void addCacheListener( final String cacheName, final ICacheListener<K, V> obj )
          throws IOException
      {
          // Record the added cache listener locally, regardless of whether the
          // remote add-listener operation succeeds or fails.
          cacheMap.computeIfAbsent(cacheName, key -> new CopyOnWriteArraySet<>(Collections.singletonList(obj)));
  
          log.info( "Adding listener to cache watch. ICacheListener = {0} | "
                  + "ICacheObserver = {1} | cacheName = {2}", obj, cacheWatch,
                  cacheName );
          cacheWatch.addCacheListener( cacheName, obj );
      }
  
      /**
       * Adds a feature to the CacheListener attribute of the CacheWatchRepairable object
       * <p>
      * @param obj The feature to be added to the CacheListener attribute
      * @throws IOException
      */
     @Override
     public <K, V> void addCacheListener( final ICacheListener<K, V> obj )
         throws IOException
     {
         // Record the added cache listener locally, regardless of whether the
         // remote add-listener operation succeeds or fails.
         cacheMap.values().forEach(set -> set.add(obj));
 
         log.info( "Adding listener to cache watch. ICacheListener = {0} | "
                 + "ICacheObserver = {1}", obj, cacheWatch );
         cacheWatch.addCacheListener( obj );
     }
 
     /**
      * Tell the server to release us.
      * <p>
      * @param cacheName
      * @param obj
      * @throws IOException
      */
     @Override
     public <K, V> void removeCacheListener( final String cacheName, final ICacheListener<K, V> obj )
         throws IOException
     {
         log.info( "removeCacheListener, cacheName [{0}]", cacheName );
         // Record the removal locally, regardless of whether the remote
         // remove-listener operation succeeds or fails.
         final Set<ICacheListener<?, ?>> listenerSet = cacheMap.get( cacheName );
         if ( listenerSet != null )
         {
             listenerSet.remove( obj );
         }
         cacheWatch.removeCacheListener( cacheName, obj );
     }
 
     /**
      * @param obj
      * @throws IOException
      */
     @Override
     public <K, V> void removeCacheListener( final ICacheListener<K, V> obj )
         throws IOException
     {
         log.info( "removeCacheListener, ICacheListener [{0}]", obj );
 
         // Record the removal locally, regardless of whether the remote
         // remove-listener operation succeeds or fails.
         cacheMap.values().forEach(set -> {
             log.debug("Before removing [{0}] the listenerSet = {1}", obj, set);
             set.remove( obj );
         });
         cacheWatch.removeCacheListener( obj );
     }
 }