package com.atlassian.cache.ehcache;
   
   import java.util.SortedMap;
   
   import javax.annotation.Nonnull;
   import javax.annotation.Nullable;
   
   import com.atlassian.cache.CacheException;
   import com.atlassian.cache.CacheSettings;
  import com.atlassian.cache.CacheStatisticsKey;
  import com.atlassian.cache.CachedReference;
  import com.atlassian.cache.CachedReferenceListener;
  import com.atlassian.cache.impl.CachedReferenceListenerSupport;
  import com.atlassian.cache.impl.LazyCachedReferenceListenerSupport;
  import com.atlassian.cache.impl.ReferenceKey;
  import com.atlassian.util.concurrent.Supplier;
  
  import net.sf.ehcache.Ehcache;
  import net.sf.ehcache.Element;
  import net.sf.ehcache.event.CacheEventListener;
  
  import static com.atlassian.cache.ehcache.DelegatingCacheStatistics.toStatistics;
  
  /**
   * A Lazy Reference that delegates to EhCache.
   *
   * @since 2.0
   */
  class DelegatingCachedReference<V> extends ManagedCacheSupport implements CachedReference<V>
  {
      private final Ehcache delegate;
      private final CachedReferenceListenerSupport<V> listenerSupport = new LazyCachedReferenceListenerSupport<V>()
      {
          @Override
          protected void init()
          {
              delegate.getCacheEventNotificationService().registerListener(new DelegatingReferenceCacheEventListener());
          }
      };
  
      private DelegatingCachedReference(final Ehcache delegate, CacheSettings settings)
      {
          super(delegate, settings);
          this.delegate = delegate;
      }
  
      static <V> DelegatingCachedReference<V> create(final Ehcache delegate, CacheSettings settings)
      {
          return new DelegatingCachedReference<V>(delegate, settings);
      }
  
      @Nonnull
      @SuppressWarnings("unchecked")
      @Override
      public V get()
      {
          try
          {
              Element element = delegate.get(ReferenceKey.KEY);
              return element == null ? null : (V) element.getObjectValue();
          }
          catch (net.sf.ehcache.CacheException e)
          {
              throw new CacheException(e.getCause());
          }
          catch (Exception e)
          {
              throw new CacheException(e);
          }
      }
  
      @Override
      public void reset()
      {
          try
          {
              try
              {
                  delegate.get(ReferenceKey.KEY);
              }
              finally
              {
                  delegate.remove(ReferenceKey.KEY);
              }
          }
          catch (Exception e)
          {
              throw new CacheException(e);
          }
      }
  
      @Override
      public void clear()
      {
          reset();
      }
  
      public boolean equals(@Nullable final Object other)
      {
         if (other instanceof DelegatingCachedReference)
         {
             DelegatingCachedReference<?> otherDelegatingReference = (DelegatingCachedReference<?>) other;
             if (delegate.equals(otherDelegatingReference.delegate))
             {
                 return true;
             }
         }
         return false;
     }
 
     @Override
     public int hashCode()
     {
         return 3 + delegate.hashCode();
     }
 
     @Nonnull
     @Override
     public SortedMap<CacheStatisticsKey,Supplier<Long>> getStatistics()
     {
         return toStatistics(delegate.getStatistics());
     }
 
     @Override
     public void addListener(@Nonnull CachedReferenceListener<V> listener, boolean includeValues)
     {
         listenerSupport.add(listener, includeValues);
     }
 
     @Override
     public void removeListener(@Nonnull CachedReferenceListener<V> listener)
     {
         listenerSupport.remove(listener);
     }
 
     private class DelegatingReferenceCacheEventListener implements CacheEventListener
     {
         @Override
         public void notifyElementRemoved(Ehcache ehcache, Element element) throws net.sf.ehcache.CacheException
         {
             listenerSupport.notifyReset((V) element.getObjectValue());
         }
 
         @Override
         public void notifyElementPut(Ehcache ehcache, Element element) throws net.sf.ehcache.CacheException
         {
             listenerSupport.notifySet((V) element.getObjectValue());
         }
 
         @Override
         public void notifyElementUpdated(Ehcache ehcache, Element element) throws net.sf.ehcache.CacheException
         {
             listenerSupport.notifySet((V) element.getObjectValue());
         }
 
         @Override
         public void notifyElementExpired(Ehcache ehcache, Element element)
         {
             listenerSupport.notifyEvict((V) element.getObjectValue());
         }
 
         @Override
         public void notifyElementEvicted(Ehcache ehcache, Element element)
         {
             listenerSupport.notifyEvict((V) element.getObjectValue());
         }
 
         @Override
         public void notifyRemoveAll(Ehcache ehcache)
         {
             listenerSupport.notifyReset((V) null);
         }
 
         @Override
         public void dispose()
         {
             // We don't hold onto any resources so there is nothing to be done.
         }
 
         public Object clone() throws CloneNotSupportedException
         {
             throw new CloneNotSupportedException();
         }
     }
 }