/*

  * $Id: PublisherRenderer.java 1306435 2012-03-28 15:39:11Z nlebas $

  *

  * 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.

  */

 package org.apache.tiles.request.render;

 import java.io.IOException;

 import java.util.ArrayList;

 import java.util.Collections;

 import java.util.List;

 import org.apache.tiles.request.Request;

 /**

  * Provides a Publisher-Subscriber implementation around the provided renderer to delegate to.

  *

  * @version $Rev: 1035784 $ $Date: 2010-11-16 20:24:12 +0000 (Tue, 16 Nov 2010) $

  */

 public class PublisherRenderer implements Renderer {

     public interface RendererListener{

         /** Called before the delegate's render method is called. */

         void start(String template, Request request) throws IOException;

         /** Called after the delegate's render method is called. */

         void end(String template, Request request) throws IOException;

         /** If the delegate render method throws an IOException it is passed through this. */

         void handleIOException(IOException ex, Request request) throws IOException;

     }

     private final Renderer renderer;

     private final List<RendererListener> listeners = new ArrayList<RendererListener>();

     private final List<RendererListener> listenersReversed = new ArrayList<RendererListener>();

     public PublisherRenderer(Renderer renderer){

         this.renderer = renderer;

     }

     @Override

     public void render(String path, Request request) throws IOException {

         if (path == null) {

             throw new CannotRenderException("Cannot dispatch a null path");

         }

         try{

             for(RendererListener listener : listeners){

                 listener.start(path, request);

             }

             renderer.render(path, request);

         }catch(IOException ex){

             handleIOException(ex, request);

         }finally{

             for(RendererListener wrapper : listenersReversed){

                 wrapper.end(path, request);

             }

         }

     }

     @Override

     public boolean isRenderable(String path, Request request) {

         return renderer.isRenderable(path, request);

     }

     public void addListener(RendererListener listener){

         listeners.add(listener);

         listenersReversed.clear();

         listenersReversed.addAll(listeners);

         Collections.reverse(listenersReversed);

     }

     private void handleIOException(IOException exception, Request request) throws IOException{

         IOException ex = exception;

         boolean throwIt = listeners.isEmpty();

         for(RendererListener listener : listenersReversed){

             try{

                 listener.handleIOException(ex, request);

                 throwIt = false;

             }catch(IOException newEx){

                 ex = newEx;

                 throwIt = true;

             }

         }

         if(throwIt){

             throw ex;

         }

     }

 }