/*
    * Copyright 2007-2012 the original author or authors.
    *
    * 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.springbyexample.web.servlet.view.tiles2;
  
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.Locale;
  import java.util.Map;
  
  import javax.servlet.ServletContext;
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.apache.tiles.Attribute;
  import org.apache.tiles.AttributeContext;
  import org.apache.tiles.Definition;
  import org.apache.tiles.TilesContainer;
  import org.apache.tiles.access.TilesAccess;
  import org.apache.tiles.context.TilesRequestContext;
  import org.apache.tiles.impl.BasicTilesContainer;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.js.ajax.AjaxHandler;
  import org.springframework.js.ajax.SpringJavascriptAjaxHandler;
  import org.springframework.js.ajax.tiles2.AjaxTilesView;
  import org.springframework.web.servlet.support.JstlUtils;
  import org.springframework.web.servlet.support.RequestContext;
  
  /**
   * <p>If the request isn't an AJAX request, <code>DynamicTilesView</code> 
   * will handle the request.  Otherwise it is expected that an AJAX 
   * view render will be next in the chain and can handle the request.</p>
   *
   * <p><strong>Note</strong>: Most code is copied from <code>AjaxTilesView</code> (giving author credit to original author).  
   * If the method <code>flattenedAttributeMap</code> also processed temporary 
   * Tiles context attributes, no changes to this class only <code>renderMergedOutputModel</code> 
   * would need to be overridden.</p>
   *
   * @author Jeremy Grelle
   * @author David Winterfeldt
   */
  public class AjaxDynamicTilesView extends AjaxTilesView {
  
      final Logger logger = LoggerFactory.getLogger(AjaxDynamicTilesView.class);
          
      final DynamicTilesViewProcessor dynamicTilesViewProcessor = new DynamicTilesViewProcessor();
  	final AjaxHandler ajaxHandler = new SpringJavascriptAjaxHandler();
  
  	/**
  	 * Renders output using Tiles.
  	 */
      protected void renderMergedOutputModel(Map model,
  	                                       HttpServletRequest request, HttpServletResponse response)
  	       throws Exception {
  	    String beanName = getBeanName();
  	    String url = getUrl();
  
          ServletContext servletContext = getServletContext();
          TilesContainer container = TilesAccess.getContainer(servletContext);
          if (container == null) {
              throw new ServletException("Tiles container is not initialized. " + 
                                         "Have you added a TilesConfigurer to your web application context?");
          }
  
  	    if (ajaxHandler.isAjaxRequest(request, response)) {
  	        // change URL used to lookup tiles template to correct definition
  	        String definitionName = dynamicTilesViewProcessor.startDynamicDefinition(beanName, url, request, response, container);
  	        
  	        super.renderMergedOutputModel(model, request, response);
  	        
  	        dynamicTilesViewProcessor.endDynamicDefinition(definitionName, beanName, request, response, container);
          } else {
              exposeModelAsRequestAttributes(model, request);
  
              dynamicTilesViewProcessor.renderMergedOutputModel(beanName, url, 
                                                                servletContext, request, response, container);
          }
      }
  	
      /**
       * Check whether the underlying resource that the configured URL points to
       * actually exists.
       * @param locale the desired Locale that we're looking for
       * @return <code>true</code> if the resource exists (or is assumed to exist);
      * <code>false</code> if we know that it does not exist
      * @throws Exception if the resource exists but is invalid (e.g. could not be parsed)
      */
 	@Override
     public boolean checkResource(Locale locale) throws Exception {
 	    // possibly could check if the Tiles template exists or 
 	    // the file that will be the body of the dynamic context exists
 	    
         return true;
     }
     
 }