// Copyright 2007, 2008 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.

 package org.apache.tapestry5.internal.services;

 import org.apache.tapestry5.ContentType;

 import org.apache.tapestry5.EventConstants;

 import org.apache.tapestry5.internal.InternalConstants;

 import org.apache.tapestry5.internal.structure.ComponentPageElement;

 import org.apache.tapestry5.internal.structure.Page;

 import org.apache.tapestry5.internal.util.Holder;

 import org.apache.tapestry5.ioc.internal.util.TapestryException;

 import org.apache.tapestry5.json.JSONObject;

 import org.apache.tapestry5.services.*;

 import java.io.IOException;

 /**

  * Similar to {@link ComponentEventRequestHandlerImpl}, but built around the Ajax request cycle, where the action

  * request sends back an immediate JSON response containing the new content.

  */

 public class AjaxComponentEventRequestHandler implements ComponentEventRequestHandler

 {

     private final RequestPageCache cache;

     private final Request request;

     private final PageRenderQueue queue;

     private final ComponentEventResultProcessor resultProcessor;

     private final PageContentTypeAnalyzer pageContentTypeAnalyzer;

     private final Environment environment;

     private final AjaxPartialResponseRenderer partialRenderer;

     public AjaxComponentEventRequestHandler(RequestPageCache cache, Request request, PageRenderQueue queue,

                                             @Ajax ComponentEventResultProcessor resultProcessor,

                                             PageContentTypeAnalyzer pageContentTypeAnalyzer, Environment environment,

                                             AjaxPartialResponseRenderer partialRenderer)

     {

         this.cache = cache;

         this.queue = queue;

         this.resultProcessor = resultProcessor;

         this.pageContentTypeAnalyzer = pageContentTypeAnalyzer;

         this.request = request;

         this.environment = environment;

         this.partialRenderer = partialRenderer;

     }

     public void handle(ComponentEventRequestParameters parameters) throws IOException

     {

         Page activePage = cache.get(parameters.getActivePageName());

         final Holder<Boolean> resultProcessorInvoked = Holder.create();

         resultProcessorInvoked.put(false);

         ComponentEventResultProcessor interceptor = new ComponentEventResultProcessor()

         {

             public void processResultValue(Object value) throws IOException

             {

                 resultProcessorInvoked.put(true);

                 resultProcessor.processResultValue(value);

             }

         };

         ComponentResultProcessorWrapper callback = new ComponentResultProcessorWrapper(interceptor);

         activePage.getRootElement().triggerContextEvent(EventConstants.ACTIVATE,

                                                         parameters.getPageActivationContext(), callback);

         if (callback.isAborted()) return;

         // If we end up doing a partial render, the page render queue service needs to know the

         // page that will be rendered (for logging purposes, if nothing else).

         queue.setRenderingPage(activePage);

         ContentType contentType = pageContentTypeAnalyzer.findContentType(activePage);

         request.setAttribute(InternalConstants.CONTENT_TYPE_ATTRIBUTE_NAME, contentType);

         Page containerPage = cache.get(parameters.getContainingPageName());

         ComponentPageElement element = containerPage.getComponentElementByNestedId(parameters.getNestedComponentId());

         // In many cases, the triggered element is a Form that needs to be able to

         // pass its event handler return values to the correct result processor.

         // This is certainly the case for forms.

         environment.push(ComponentEventResultProcessor.class, interceptor);

         boolean handled = element.triggerContextEvent(parameters.getEventType(), parameters.getEventContext(),

                                                       callback);

         if (!handled)

             throw new TapestryException(ServicesMessages.eventNotHandled(element, parameters.getEventType()), element,

                                         null);

         environment.pop(ComponentEventResultProcessor.class);

         if (queue.isPartialRenderInitialized())

         {

             partialRenderer.renderPartialPageMarkup();

             return;

         }

         // If  some other form of return value that's not a partial page render was send through to the

         // Ajax ComponentEventResultProcessor, then there's nothing more to do.

         if (resultProcessorInvoked.get()) return;

         // Send an empty JSON reply if no value was returned from the component event handler method.

         JSONObject reply = new JSONObject();

         resultProcessor.processResultValue(reply);

     }

 }