/*
    * $Id: VelocityRequest.java 1332186 2012-04-30 13:20:15Z 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.velocity;
  
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.io.Writer;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  
  import javax.servlet.RequestDispatcher;
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.apache.tiles.request.AbstractViewRequest;
  import org.apache.tiles.request.ApplicationContext;
  import org.apache.tiles.request.DispatchRequest;
  import org.apache.tiles.request.servlet.ExternalWriterHttpServletResponse;
  import org.apache.tiles.request.servlet.ServletRequest;
  import org.apache.tiles.request.servlet.ServletUtil;
  import org.apache.velocity.context.Context;
  
  /**
   * The implementation of the Tiles request context specific for Velocity.
   *
   * @version $Rev: 1332186 $ $Date: 2012-04-30 23:20:15 +1000 (Mon, 30 Apr 2012) $
   */
  public class VelocityRequest extends AbstractViewRequest {
  
      /**
       * The native available scopes, in fact only "page".
       */
      private final List<String> scopes;
  
      /**
       * The Velocity current context.
       */
      private final Context ctx;
  
      /**
       * The writer to use to render the response. It may be null, if not necessary.
       */
      private Writer writer;
  
      /**
       * The map of the page scope.
       */
      private Map<String, Object> pageScope;
  
      /**
       * Factory method to create a Velocity request.
       *
       * @param applicationContext The application context.
       * @param request The request.
       * @param response The response.
       * @param velocityContext The Velocity context.
       * @param writer The writer to write into.
       * @return The request.
       */
      public static VelocityRequest createVelocityRequest(
              ApplicationContext applicationContext, HttpServletRequest request,
              HttpServletResponse response, Context velocityContext, Writer writer) {
          DispatchRequest servletRequest = new ServletRequest(
                  applicationContext, request, response);
          VelocityRequest velocityRequest = new VelocityRequest(
                  servletRequest, velocityContext, writer);
          return velocityRequest;
      }
  
      /**
       * Constructor.
       *
       * @param enclosedRequest The request that exposes non-Velocity specific properties
       * @param ctx The Velocity current context.
       * @param writer The writer to use to render the response. It may be null, if not necessary.
       */
      public VelocityRequest(
             DispatchRequest enclosedRequest, Context ctx, Writer writer) {
         super(enclosedRequest);
         List<String> scopes = new ArrayList<String>();
         scopes.addAll(enclosedRequest.getAvailableScopes());
         scopes.add("page");
         this.scopes = Collections.unmodifiableList(scopes);
         this.ctx = ctx;
         this.writer = writer;
     }
 
     @Override
     public List<String> getAvailableScopes() {
         return scopes;
     }
 
     /** {@inheritDoc} */
     @Override
     protected void doInclude(String path) throws IOException {
         ServletRequest servletRequest = org.apache.tiles.request.servlet.ServletUtil.getServletRequest(this);
         HttpServletRequest request = servletRequest.getRequest();
         HttpServletResponse response = servletRequest.getResponse();
         RequestDispatcher rd = request.getRequestDispatcher(path);
 
         if (rd == null) {
             throw new IOException("No request dispatcher returned for path '"
                     + path + "'");
         }
 
         PrintWriter printWriter = getPrintWriter();
         try {
             rd.include(request, new ExternalWriterHttpServletResponse(response,
                     printWriter));
         } catch (ServletException ex) {
             throw ServletUtil.wrapServletException(ex, "ServletException including path '"
                     + path + "'.");
         }
     }
 
     /** {@inheritDoc} */
     @Override
     public PrintWriter getPrintWriter() {
         if (writer == null) {
             throw new IllegalStateException(
                     "A writer-less Tiles request has been created, cannot return a PrintWriter");
         }
         if (writer instanceof PrintWriter) {
             return (PrintWriter) writer;
         }
         return new PrintWriter(writer);
     }
 
     /** {@inheritDoc} */
     @Override
     public Writer getWriter() {
         if (writer == null) {
             throw new IllegalStateException(
                     "A writer-less Tiles request has been created, cannot return a PrintWriter");
         }
         return writer;
     }
 
     /**
      * Returns the page scope.
      *
      * @return The page scope.
      */
     public Map<String, Object> getPageScope() {
         if (pageScope == null) {
             pageScope = new VelocityScopeMap(ctx);
         }
         return pageScope;
     }
 
     @Override
     public Map<String, Object> getContext(String scope) {
         return "page".equals(scope) ? getPageScope() : super.getContext(scope);
     }
 
 }