package com.atlassian.cache.ehcache;
   
   import java.util.Collection;
   import java.util.SortedMap;
   
   import javax.annotation.Nonnull;
   import javax.annotation.Nullable;
   
   import com.atlassian.cache.Cache;
  import com.atlassian.cache.CacheEntryListener;
  import com.atlassian.cache.CacheException;
  import com.atlassian.cache.CacheSettings;
  import com.atlassian.cache.CacheStatisticsKey;
  import com.atlassian.cache.impl.CacheEntryListenerSupport;
  import com.atlassian.cache.impl.LazyCacheEntryListenerSupport;
  import com.atlassian.instrumentation.caches.CacheCollector;
  import com.atlassian.util.concurrent.Supplier;
  
  import com.google.common.collect.ImmutableSortedMap;
  
  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 Cache that delegates to EhCache.
   *
   * @since 2.0
   */
  class DelegatingCache<K, V> extends ManagedCacheSupport implements Cache<K, V>
  {
      private final Ehcache delegate;
  
      private final CacheEntryListenerSupport<K, V> listenerSupport = new LazyCacheEntryListenerSupport<K, V>()
      {
          @Override
          protected void init()
          {
              delegate.getCacheEventNotificationService().registerListener(new DelegatingCacheEventListener());
          }
      };
  
      private DelegatingCache(final Ehcache delegate, CacheSettings settings)
      {
          super(delegate, settings);
          this.delegate = delegate;
      }
  
      static <K, V> DelegatingCache<K, V> create(final Ehcache delegate, CacheSettings settings)
      {
          return new DelegatingCache<K, V>(delegate, settings);
      }
  
      @Override
      public boolean containsKey(@Nonnull K key)
      {
          return delegate.isKeyInCache(key);
      }
  
      @Nonnull
      @SuppressWarnings("unchecked")
      @Override
      public Collection<K> getKeys()
      {
          try
          {
              return delegate.getKeys();
          }
          catch (Exception e)
          {
              throw new CacheException(e);
          }
      }
  
      @Override
      public void put(@Nonnull final K key, @Nonnull final V value)
      {
          try
          {
              delegate.put(new Element(key, value));
          }
          catch (Exception e)
          {
              throw new CacheException(e);
          }
      }
  
      @SuppressWarnings("unchecked")
      @Nullable
      @Override
      public V get(@Nonnull final K key)
      {
          try
          {
              Element element = delegate.get(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);
         }
     }
 
     @SuppressWarnings("unchecked")
     @Nonnull
     @Override
     public V get(@Nonnull final K key, @Nonnull final com.atlassian.cache.Supplier<? extends V> valueSupplier)
     {
         try
         {
             Element element = delegate.getWithLoader(key, new ReferenceCacheLoader(valueSupplier), null);
             return (V) element.getObjectValue();
         }
         catch (net.sf.ehcache.CacheException e)
         {
             throw new CacheException(e.getCause());
         }
         catch (Exception e)
         {
             throw new CacheException(e);
         }
     }
 
     @Override
     public void remove(@Nonnull final K key)
     {
         try
         {
             delegate.remove(key);
         }
         catch (Exception e)
         {
             throw new CacheException(e);
         }
     }
 
     @Override
     public void removeAll()
     {
         try
         {
             delegate.removeAll();
         }
         catch (Exception e)
         {
             throw new CacheException(e);
         }
     }
 
     @Override
     public void clear()
     {
         removeAll();
     }
 
     @Nullable
     @Override
     @SuppressWarnings("unchecked")
     public V putIfAbsent(@Nonnull K key, @Nonnull V value)
     {
         try
         {
             Element previous = delegate.putIfAbsent(new Element(key, value));
             if (previous != null)
             {
                 return (V) previous.getObjectValue();
             }
             else
             {
                 return null;
             }
         }
         catch (Exception e)
         {
             throw new CacheException(e);
         }
     }
 
     @Override
     public boolean remove(@Nonnull K key, @Nonnull V value)
     {
         try
         {
             return delegate.removeElement(new Element(key, value));
         }
         catch (Exception e)
         {
             throw new CacheException(e);
         }
     }
 
     @Override
     public boolean replace(@Nonnull K key, @Nonnull V oldValue, @Nonnull V newValue)
     {
         try
         {
             return delegate.replace(new Element(key, oldValue), new Element(key, newValue));
         }
         catch (Exception e)
         {
             throw new CacheException(e);
         }
     }
 
     @Nonnull
     @Override
     public SortedMap<CacheStatisticsKey,Supplier<Long>> getStatistics()
     {
         if (isStatisticsEnabled())
         {
             return toStatistics(delegate.getStatistics());
         }
         else
         {
             return ImmutableSortedMap.of();
         }
     }
 
     @Nullable
     @Override
     public CacheCollector getCacheCollector()
     {
         // Not implemented.
         return null;
     }
 
     @Override
     public boolean equals(@Nullable final Object other)
     {
         if (other instanceof DelegatingCache)
         {
             DelegatingCache<?,?> otherDelegatingCache = (DelegatingCache<?,?>)other;
             if (delegate.equals(otherDelegatingCache.delegate))
             {
                 return true;
             }
         }
         return false;
     }
 
     @Override
     public int hashCode()
     {
         return 3 + delegate.hashCode();
     }
 
     @Override
     public void addListener(@Nonnull CacheEntryListener<K, V> listener, boolean includeValues)
     {
         listenerSupport.add(listener, includeValues);
     }
 
     @Override
     public void removeListener(@Nonnull CacheEntryListener<K, V> listener)
     {
         listenerSupport.remove(listener);
     }
 
     private class DelegatingCacheEventListener implements CacheEventListener
     {
         @Override
         public void notifyElementRemoved(Ehcache ehcache, Element element) throws net.sf.ehcache.CacheException
         {
             listenerSupport.notifyRemove((K) element.getObjectKey(), (V) element.getObjectValue());
         }
 
         @Override
         public void notifyElementPut(Ehcache ehcache, Element element) throws net.sf.ehcache.CacheException
         {
             listenerSupport.notifyAdd((K) element.getObjectKey(), (V) element.getObjectValue());
         }
 
         @Override
         public void notifyElementUpdated(Ehcache ehcache, Element element) throws net.sf.ehcache.CacheException
         {
             listenerSupport.notifyUpdate((K) element.getObjectKey(), (V) element.getObjectValue(), null);
         }
 
         @Override
         public void notifyElementExpired(Ehcache ehcache, Element element)
         {
             listenerSupport.notifyEvict((K) element.getObjectKey(), (V) element.getObjectValue());
         }
 
         @Override
         public void notifyElementEvicted(Ehcache ehcache, Element element)
         {
             listenerSupport.notifyEvict((K) element.getObjectKey(), (V) element.getObjectValue());
         }
 
         @Override
         public void notifyRemoveAll(Ehcache ehcache)
         {
             // There is no way to enumerate the keys that were in the cache, therefore we cannot
             // produce any meaningful event
         }
 
         @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();
         }
     }
 }