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/***********************************************************************************************************************
 *
 * blueMarine Semantic - open source media workflow
 * Copyright (C) 2008-2011 by Tidalwave s.a.s. (http://www.tidalwave.it)
 *
 ***********************************************************************************************************************
 *
 * Licensed 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.
 *
 ***********************************************************************************************************************
 *
 * WWW: http://bluemarine.tidalwave.it
 * SCM: https://kenai.com/hg/bluemarine~semantic-src
 *
 **********************************************************************************************************************/
package it.tidalwave.openrdf.elmo.impl;

import javax.annotation.CheckForNull;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.ThreadSafe;
import java.lang.reflect.Proxy;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.TreeSet;
import java.util.logging.Level;
import org.openrdf.elmo.Entity;
import it.tidalwave.util.logging.Logger;
import it.tidalwave.openrdf.elmo.ElmoUtils;
import it.tidalwave.semantic.Wrapper.WrapperSpi;

/*******************************************************************************
 *
 * @author  Fabrizio Giudici
 * @version $Id: ElmoWrapper.java,v 4fbb06e9364c 2011/03/06 21:25:16 fabrizio $
 *
 ******************************************************************************/
@ThreadSafe
public class ElmoWrapper implements WrapperSpi
  {
    private static final String CLASS = ElmoWrapper.class.getName();
    private static final Logger logger = Logger.getLogger(CLASS);

    private final Set> interfaces = new HashSet>();
    private final Map, Class> implementationMap = new HashMap, Class>();

//    // FIXME: there should be one per transaction
//    private final static IdentityWeakHashMap FLYWEIGHT_CACHE =
//            new IdentityWeakHashMap();

    /*******************************************************************************************************************
     *
     *
     ******************************************************************************************************************/
    @Override
    public void register (final @Nonnull Class interfaceClass,
                          final @Nonnull Class implementationClass)
      {
        interfaces.add(interfaceClass);
        implementationMap.put(interfaceClass, implementationClass);
      }

    /*******************************************************************************************************************
     *
     *
     ******************************************************************************************************************/
    @Override
    public boolean isRegistered (final @Nonnull Class clazz)
      {
        for (final Class interfaceClass : interfaces)
          {
            logger.finer(">>>> probing %s", interfaceClass);

            if (interfaceClass.isAssignableFrom(clazz))
              {
                return true;
              }
          }

        return false;
      }

    /*******************************************************************************************************************
     *
     *
     ******************************************************************************************************************/
    @Override
    @CheckForNull
    public  Class findImplementation (final @Nonnull Class clazz)
      {
        for (final Entry, Class> entrySet : implementationMap.entrySet())
          {
            final Class interfaceClass = entrySet.getKey();

            if (clazz.isAssignableFrom(interfaceClass))
              {
                return (Class)entrySet.getValue();
              }
          }

        return null;
//        return implementationMap.get(clazz);
      }

    /*******************************************************************************************************************
     *
     *
     ******************************************************************************************************************/
    @Override
    @CheckForNull
    public  X wrap (final @Nullable X object)
      {
        if (logger.isLoggable(Level.FINEST)) // safeToString() is expensive
          {
            logger.finest("wrap(%s)", ElmoUtils.safeToString(object));
          }

        X result = object;

        if ((object != null) && !(object instanceof ProxyMarker))
          {
//            logger.finest(">>>> FLYWEIGHT_CACHE is: %s", FLYWEIGHT_CACHE);
//
//            if (FLYWEIGHT_CACHE.containsKey(object))
//              {
//                result = (X)FLYWEIGHT_CACHE.get(object);
//                logger.finest(">>>> wrapper already in flyweight cache: %s", result);
//              }
//            else
//              {
                result = (object instanceof Collection) ? (X)wrapCollection((Collection)object)
                                                           : (X)wrapSingle(object);
//
//                if (object != result)
//                  {
//                    FLYWEIGHT_CACHE.put(object, (ProxyMarker)result);
//                  }
//              }
          }

        if (logger.isLoggable(Level.FINEST)) // safeToString() is expensive
          {
            logger.finest(">>>> returning %s", ElmoUtils.safeToString(result));
//            logger.finest(">>>> on exit FLYWEIGHT_CACHE is: %s", FLYWEIGHT_CACHE);
          }

        return result;
      }

    /*******************************************************************************************************************
     *
     *
     ******************************************************************************************************************/
    @Override
    @CheckForNull
    public  X unwrap (@CheckForNull final X object)
      {
        if (logger.isLoggable(Level.FINEST))
          {
            logger.finest("unwrap(%s)", ElmoUtils.safeToString(object));
          }

        X result = object;

        if (object != null)
          {
            if (object instanceof Collection) // this test FIRST since Collections aren't instanceof ProxyMarker
              {
                result = (X)unwrapCollection((Collection)object);
              }

            if (object.getClass().isArray())
              {
                result = (X)unwrapArray((Object[])object);
              }

            if (object instanceof ProxyMarker)
              {
                result = (X)((ProxyMarker)object).getDelegate();
              }
          }

        if (logger.isLoggable(Level.FINEST))
          {
            logger.finest(">>>> returning %s", ElmoUtils.safeToString(result));
          }

        return result;
      }

    /*******************************************************************************************************************
     *
     *
     ******************************************************************************************************************/
    @Override
    public boolean isWrapped (final @Nullable Object object)
      {
        return object instanceof ProxyMarker;
      }

    /*******************************************************************************************************************
     *
     *
     ******************************************************************************************************************/
    @Nonnull
    private Object wrapSingle (final @Nonnull Object object)
      {
        if (logger.isLoggable(Level.FINEST)) // safeToString() is expensive
          {
            logger.finest("wrapSingle(%s)", ElmoUtils.safeToString(object));
          }

        if (object instanceof ProxyMarker)
          {
            Thread.dumpStack();
            throw new AssertionError("trying to wrap a wrapped object");
          }

        Object result = object;
        
        final List> proxiedInterfaces = new ArrayList>();

        // FIXME: can we just put the list of object.getClass().getInterfaces()?
        // Or is there any interface we don't want to expose?
        // The test is still important since we only wrap registered entities,
        // not all objects.
        for (final Class interfaceClass : interfaces)
          {
//                if (logger.isLoggable(Level.FINEST))
//                  {
//                    logger.finest(">>>> probing %s", interfaceClass);
//                  }
//
            if (interfaceClass.isAssignableFrom(object.getClass()))
              {
                proxiedInterfaces.add(interfaceClass);
              }
          }

        if (!proxiedInterfaces.isEmpty())
          {
            proxiedInterfaces.add(Entity.class); // FIXME: why expose it? Can be dropped?
            proxiedInterfaces.add(ProxyMarker.class);

            logger.finer(">>>> wrapping, proxied interfaces: %s", proxiedInterfaces);

//            final Class implementationClass =
//                    (proxiedInterfaces.size() == 1) ? implementationMap.get(proxiedInterfaces.get(0)) : Object.class;
            final ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
            result = Proxy.newProxyInstance(classLoader, proxiedInterfaces.toArray(new Class[0]),
                                            new DelegateInvocationHandler((Entity)object));
          }

        if (logger.isLoggable(Level.FINEST)) // safeToString() is expensive
          {
            logger.finest(">>>> returning %s", ElmoUtils.safeToString(result));
          }

        return result;
      }

    /*******************************************************************************************************************
     *
     *
     ******************************************************************************************************************/
    @Nonnull
    private Collection wrapCollection (final @Nonnull Collection collection)
      {
        // We could use the trick of copying collection into a temp, clearing
        // collection and putting results into it. In this way we would be sure
        // that the result if of the same type of the argument. Unfortunately,
        // we would get some decorated collections from Elmo that would create
        // performance issues when manipulated.

        Collection result = null;

        if (collection instanceof ArrayList)
          {
            result = new ArrayList();
          }
        else if (collection instanceof HashSet)
          {
            result = new HashSet();
          }
        else if (collection instanceof TreeSet)
          {
            result = new TreeSet();
          }
        // FIXME: e.g. a java.util.Collections$UnmodifiableRandomAccessList
        // But in this case you should wrap the result with an UnmodifiableXXX
        else if (collection instanceof Collection)
          {
            result = new ArrayList();
          }
        else
          {
            logger.warning("Cannot handle: " + collection.getClass());
            return collection;
          }

        for (final Object entity : collection)
          {
            result.add(wrap(entity));
          }

        return result;
      }

    /*******************************************************************************************************************
     *
     *
     ******************************************************************************************************************/
    @Nonnull
    private Collection unwrapCollection (final @Nonnull Collection collection)
      {
        // We could use the trick of copying collection into a temp, clearing
        // collection and putting results into it. In this way we would be sure
        // that the result if of the same type of the argument. Unfortunately,
        // we would get some decorated collections from Elmo that would create
        // performance issues when manipulated.

        Collection result = null;

        if (collection instanceof ArrayList)
          {
            result = new ArrayList();
          }
        else if (collection instanceof HashSet)
          {
            result = new HashSet();
          }
        else if (collection instanceof TreeSet)
          {
            result = new TreeSet();
          }
        else
          {
            logger.warning("Cannot handle: " + collection.getClass());
            return collection;
          }

        for (final Object entity : collection)
          {
            result.add(unwrap(entity));
          }

        return result;
      }

    /*******************************************************************************************************************
     *
     *
     ******************************************************************************************************************/
    @Nonnull
    private Object[] unwrapArray (final @Nonnull Object[] array)
      {
        if (array == null)
          {
            return null;
          }

        final Object[] result = new Object[array.length];

        if (array != null)
          {
            System.arraycopy(array, 0, result, 0, array.length);

            for (int i = 0; i < array.length; i++)
              {
                if (array[i] instanceof ProxyMarker)
                  {
                    result[i] = unwrap(array[i]);
                  }
              }
          }

        return result;
      }
  }
    

    

    

            

    

            



    
    






    
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