package org.apache.ojb.broker.util.interceptor;

 /* Copyright 2002-2005 The Apache Software Foundation

  *

  * 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.

  */

 //#ifdef JDK13

 import java.lang.reflect.Proxy;

 import java.lang.reflect.InvocationHandler;

 //#else

 /*

 import net.sf.cglib.proxy.Proxy;

 import net.sf.cglib.proxy.InvocationHandler;

 */

 //#endif

 import java.util.HashMap;

 import org.apache.ojb.broker.util.configuration.Configurable;

 import org.apache.ojb.broker.util.configuration.Configuration;

 import org.apache.ojb.broker.util.configuration.ConfigurationException;

 import org.apache.ojb.broker.util.configuration.impl.OjbConfigurator;

 import org.apache.ojb.broker.util.logging.LoggerFactory;

 import org.apache.ojb.broker.util.ClassHelper;

 /**

  * @author <a href="mailto:thma@apache.org">Thomas Mahler<a>

  * @version $Id: InterceptorFactory.java,v 1.1 2007-08-24 22:17:39 ewestfal Exp $

  */

 public class InterceptorFactory implements Configurable

 {

         private static InterceptorFactory instance = null;

         private Class interceptorClassToBeUsed = null;

         /**

          * Returns the instance.

          * @return InterceptorFactory

          */

         public static InterceptorFactory getInstance()

         {

                 if (instance == null)

                 {

                         instance = new InterceptorFactory();

                         OjbConfigurator.getInstance().configure(instance);

                 }

                 return instance;

         }

         /**

          * @see org.apache.ojb.broker.util.configuration.Configurable#configure(Configuration)

          */

         public void configure(Configuration pConfig) throws ConfigurationException

         {

                 Class clazz = pConfig.getClass("InterceptorClass", Object.class);

                 if(!clazz.equals(Object.class)) setInterceptorClassToBeUsed(clazz);

         }

         public Object createInterceptorFor(Object instanceToIntercept)

         {

                 if (getInterceptorClassToBeUsed() != null)

                 {

                         try

                         {

 //                                Class[] parameterTypes = {Object.class};

 //                                Object[] parameters = {instanceToIntercept};

 //              Constructor constructor = getInterceptorClassToBeUsed().getConstructor(parameterTypes);

 //                                InvocationHandler handler = (InvocationHandler) constructor.newInstance(parameters);

                 // use helper class to instantiate

                 InvocationHandler handler = (InvocationHandler) ClassHelper.newInstance(

                                             getInterceptorClassToBeUsed(), Object.class, instanceToIntercept);

                                 Class[] interfaces = computeInterfaceArrayFor(instanceToIntercept.getClass());

                                 Object result =

                                         Proxy.newProxyInstance(

                                                 ClassHelper.getClassLoader(),

                                                 interfaces,

                                                 handler);

                                 return result;

                         }

                         catch (Throwable t)

                         {

                                 LoggerFactory.getDefaultLogger().error("can't use Interceptor " + getInterceptorClassToBeUsed().getName() +

                                         "for " + instanceToIntercept.getClass().getName(), t);

                                 return instanceToIntercept;

                         }

                 }

                 else

                 {

                         return instanceToIntercept;

                 }

         }

         public Class[] computeInterfaceArrayFor(Class clazz)

         {

                 Class superClass = clazz;

                 Class[] interfaces = clazz.getInterfaces();

                 // clazz can be an interface itself and when getInterfaces()

                 // is called on an interface it returns only the extending

                 // interfaces, not the interface itself.

                 if (clazz.isInterface())

                 {

                         Class[] tempInterfaces = new Class[interfaces.length + 1];

                         tempInterfaces[0] = clazz;

                         System.arraycopy(interfaces, 0, tempInterfaces, 1, interfaces.length);

                         interfaces = tempInterfaces;

                 }

                 // add all interfaces implemented by superclasses to the interfaces array

                 while ((superClass = superClass.getSuperclass()) != null)

                 {

                         Class[] superInterfaces = superClass.getInterfaces();

                         Class[] combInterfaces = new Class[interfaces.length + superInterfaces.length];

                         System.arraycopy(interfaces, 0, combInterfaces, 0, interfaces.length);

                         System.arraycopy(

                                 superInterfaces,

                                 0,

                                 combInterfaces,

                                 interfaces.length,

                                 superInterfaces.length);

                         interfaces = combInterfaces;

                 }

                 /**

                  * Must remove duplicate interfaces before calling Proxy.getProxyClass().

                  * Duplicates can occur if a subclass re-declares that it implements

                  * the same interface as one of its ancestor classes.

                 **/

                 HashMap unique = new HashMap();

                 for (int i = 0; i < interfaces.length; i++)

                 {

                         unique.put(interfaces[i].getName(), interfaces[i]);

                 }

                 interfaces = (Class[]) unique.values().toArray(new Class[unique.size()]);

                 return interfaces;

         }

         /**

          * Returns the interceptorClassToBeUsed.

          * @return Class

          */

         public Class getInterceptorClassToBeUsed()

         {

                 return interceptorClassToBeUsed;

         }

         /**

          * Sets the interceptorClassToBeUsed.

          * @param interceptorClassToBeUsed The interceptorClassToBeUsed to set

          */

         public void setInterceptorClassToBeUsed(Class interceptorClassToBeUsed)

         {

                 this.interceptorClassToBeUsed = interceptorClassToBeUsed;

         }

 }