/*
    * 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.myfaces.mc.test.core.mock;
  
  import java.beans.BeanInfo;
  import java.io.IOException;
  
  import javax.faces.FacesException;
  import javax.faces.FactoryFinder;
  import javax.faces.application.Application;
  import javax.faces.application.Resource;
  import javax.faces.application.ViewHandler;
  import javax.faces.component.UIViewRoot;
  import javax.faces.context.ExternalContext;
  import javax.faces.context.FacesContext;
  import javax.faces.context.ResponseWriter;
  import javax.faces.render.RenderKit;
  import javax.faces.render.RenderKitFactory;
  import javax.faces.view.StateManagementStrategy;
  import javax.faces.view.ViewDeclarationLanguage;
  import javax.faces.view.ViewMetadata;
  import javax.servlet.http.HttpServletResponse;
  
  import org.apache.myfaces.shared.application.InvalidViewIdException;
  
  /**
   * It is a vdl that is just provided as fallback, to ensure if
   * viewHandler.createView(context, null) is called, an instance
   * is retrieved just like with jsp vdl, and it provides some methods
   * to hook a view instance for createView() and restoreView() methods.
   * 
   * In this way, it is possible to create view instance programatically
   * and simulate that it is generated by the vdl. 
   * 
   * @author Leonardo Uribe
   *
   */
  public class MockDefaultViewDeclarationLanguage extends ViewDeclarationLanguage
  {
      public static final String DUMMY_VIEW_CREATE_HOOK = "oam.dummy.create.UIViewRoot";
      public static final String DUMMY_VIEW_RESTORE_HOOK = "oam.dummy.restore.UIViewRoot";
  
      @Override
      public void buildView(FacesContext context, UIViewRoot view)
              throws IOException
      {
      }
  
      @Override
      public UIViewRoot createView(FacesContext context, String viewId)
      {
          if (context.getAttributes().containsKey(DUMMY_VIEW_CREATE_HOOK))
          {
              UIViewRoot root = (UIViewRoot) context.getAttributes().remove(DUMMY_VIEW_CREATE_HOOK);
              Application application = context.getApplication();
              ViewHandler handler = application.getViewHandler();
              root.setLocale(handler.calculateLocale(context));
              root.setRenderKitId(handler.calculateRenderKitId(context));
              root.setViewId(viewId);
              return root;
          }
          else
          {
              try
              {
                  viewId = calculateViewId(context, viewId);
                  
                  Application application = context.getApplication();
                  // Create a new UIViewRoot object instance using Application.createComponent(UIViewRoot.COMPONENT_TYPE).
                  UIViewRoot newViewRoot = (UIViewRoot) application.createComponent(UIViewRoot.COMPONENT_TYPE);
                  UIViewRoot oldViewRoot = context.getViewRoot();
                  if (oldViewRoot == null)
                  {
                      // If not, this method must call calculateLocale() and calculateRenderKitId(), and store the results
                      // as the values of the locale and renderKitId, proeprties, respectively, of the newly created
                      // UIViewRoot.
                      ViewHandler handler = application.getViewHandler();
                      newViewRoot.setLocale(handler.calculateLocale(context));
                      newViewRoot.setRenderKitId(handler.calculateRenderKitId(context));
                  }
                  else
                  {
                      // If there is an existing UIViewRoot available on the FacesContext, 
                     //this method must copy its locale
                     // and renderKitId to this new view root
                     newViewRoot.setLocale(oldViewRoot.getLocale());
                     newViewRoot.setRenderKitId(oldViewRoot.getRenderKitId());
                 }
                 
                 // TODO: VALIDATE - The spec is silent on the following line, but I feel bad if I don't set it
                 newViewRoot.setViewId(viewId);
     
                 return newViewRoot;
             }
             catch (InvalidViewIdException e)
             {
                 // If no viewId could be identified, or the viewId is exactly equal to the servlet mapping, 
                 // send the response error code SC_NOT_FOUND with a suitable message to the client.
                 sendSourceNotFound(context, e.getMessage());
                 
                 // TODO: VALIDATE - Spec is silent on the return value when an error was sent
                 return null;
             }
         }
     }
     
     /**
      * Calculates the effective view identifier for the specified raw view identifier.
      * 
      * @param context le current FacesContext
      * @param viewId the raw view identifier
      * 
      * @return the effective view identifier
      */
     protected String calculateViewId(FacesContext context, String viewId)
     {
         if (viewId != null)
         {
             throw new InvalidViewIdException();
         }
         return null;
     }
     
     protected void sendSourceNotFound(FacesContext context, String message)
     {
         HttpServletResponse response = (HttpServletResponse) context.getExternalContext().getResponse();
         try
         {
             context.responseComplete();
             response.sendError(HttpServletResponse.SC_NOT_FOUND, message);
         }
         catch (IOException ioe)
         {
             throw new FacesException(ioe);
         }
     }
     
     /**
      * Hook the passed instance on UIViewRoot, storing into facesContext attribute map,
      * so the next call to createView() will return that value.
      * 
      * @param context
      * @param root
      */
     public static void hookCreateView(FacesContext context, UIViewRoot root)
     {
         context.getAttributes().put(DUMMY_VIEW_CREATE_HOOK, root);
     }
 
     /**
      * Hook the passed instance on UIViewRoot, storing into facesContext attribute map,
      * so the next call to createView() will return that value.
      * 
      * @param context
      * @param root
      */
     public static void hookRestoreView(FacesContext context, UIViewRoot root)
     {
         context.getAttributes().put(DUMMY_VIEW_RESTORE_HOOK, root);
     }
 
     @Override
     public BeanInfo getComponentMetadata(FacesContext context,
             Resource componentResource)
     {
         return null;
     }
 
     @Override
     public Resource getScriptComponentResource(FacesContext context,
             Resource componentResource)
     {
         return null;
     }
 
     @Override
     public StateManagementStrategy getStateManagementStrategy(
             FacesContext context, String viewId)
     {
         return null;
     }
 
     @Override
     public ViewMetadata getViewMetadata(FacesContext context, String viewId)
     {
         return null;
     }
 
     @Override
     public void renderView(FacesContext context, UIViewRoot view)
             throws IOException
     {
         checkNull(context, "context");
         checkNull(view, "view");
         
         ExternalContext externalContext = context.getExternalContext();
         ResponseWriter responseWriter = context.getResponseWriter();
         if (responseWriter == null)
         {
             RenderKitFactory renderFactory = (RenderKitFactory) 
                 FactoryFinder.getFactory(FactoryFinder.RENDER_KIT_FACTORY);
             RenderKit renderKit = renderFactory.getRenderKit(context, view.getRenderKitId());
 
             responseWriter = renderKit.createResponseWriter(externalContext.getResponseOutputWriter(), 
                     null, externalContext.getRequestCharacterEncoding());
             context.setResponseWriter(responseWriter);
         }
 
         // Now we actually render the document
         // Call startDocument() on the ResponseWriter.
         responseWriter.startDocument();
 
         view.encodeAll(context);
         
         // Call endDocument() on the ResponseWriter
         responseWriter.endDocument();
     
         responseWriter.flush();
     }
 
     @Override
     public UIViewRoot restoreView(FacesContext context, String viewId)
     {
         checkNull(context, "context");
         //checkNull(viewId, "viewId");
 
         if (context.getAttributes().containsKey(DUMMY_VIEW_RESTORE_HOOK))
         {
             UIViewRoot root = (UIViewRoot) context.getAttributes().remove(DUMMY_VIEW_RESTORE_HOOK);
             root.setViewId(viewId);
             return root;
         }
         else
         {
             Application application = context.getApplication();
             
             ViewHandler applicationViewHandler = application.getViewHandler();
             
             String renderKitId = applicationViewHandler.calculateRenderKitId(context);
     
             UIViewRoot viewRoot = application.getStateManager().restoreView(context, viewId, renderKitId);
     
             return viewRoot;
         }
     }
     
     protected void checkNull(final Object o, final String param)
     {
         if (o == null)
         {
             throw new NullPointerException(param + " can not be null.");
         }
     }
 }