/*
    * $Id: ServletRequest.java 1375743 2012-08-21 20:05:58Z 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.servlet;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.io.PrintWriter;
  import java.io.Writer;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.List;
  import java.util.Locale;
  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.AbstractClientRequest;
  import org.apache.tiles.request.ApplicationContext;
  import org.apache.tiles.request.attribute.Addable;
  import org.apache.tiles.request.collection.HeaderValuesMap;
  import org.apache.tiles.request.collection.ReadOnlyEnumerationMap;
  import org.apache.tiles.request.collection.ScopeMap;
  import org.apache.tiles.request.servlet.extractor.ParameterExtractor;
  import org.apache.tiles.request.servlet.extractor.RequestScopeExtractor;
  import org.apache.tiles.request.servlet.extractor.HeaderExtractor;
  import org.apache.tiles.request.servlet.extractor.SessionScopeExtractor;
  
  /**
   * Servlet-based implementation of the TilesApplicationContext interface.
   *
   * @version $Rev: 1375743 $ $Date: 2012-08-22 06:05:58 +1000 (Wed, 22 Aug 2012) $
   */
  public class ServletRequest extends AbstractClientRequest {
  
      /**
       * The native available scopes: request, session and application.
       */
      private static final List<String> SCOPES
              = Collections.unmodifiableList(Arrays.asList(REQUEST_SCOPE, "session", APPLICATION_SCOPE));
  
      /**
       * The request object to use.
       */
      private HttpServletRequest request;
  
      /**
       * The response object to use.
       */
      private HttpServletResponse response;
  
      /**
       * The response output stream, lazily initialized.
       */
      private OutputStream outputStream;
  
      /**
       * The response writer, lazily initialized.
       */
      private PrintWriter writer;
  
      /**
       * <p>The lazily instantiated <code>Map</code> of header name-value
       * combinations (immutable).</p>
       */
      private Map<String, String> header = null;
  
      /**
       * <p>The lazily instantiated <code>Map</code> of header name-value
       * combinations (write-only).</p>
       */
      private Addable<String> responseHeaders = null;
  
  
      /**
       * <p>The lazily instantitated <code>Map</code> of header name-values
       * combinations (immutable).</p>
       */
      private Map<String, String[]> headerValues = null;
 
 
     /**
      * <p>The lazily instantiated <code>Map</code> of request
      * parameter name-value.</p>
      */
     private Map<String, String> param = null;
 
 
     /**
      * <p>The lazily instantiated <code>Map</code> of request scope
      * attributes.</p>
      */
     private Map<String, Object> requestScope = null;
 
     /**
      * <p>The lazily instantiated <code>Map</code> of session scope
      * attributes.</p>
      */
     private Map<String, Object> sessionScope = null;
 
 
     /**
      * Creates a new instance of ServletTilesRequestContext.
      *
      * @param applicationContext The application context.
      * @param request The request object.
      * @param response The response object.
      */
     public ServletRequest(
             ApplicationContext applicationContext,
             HttpServletRequest request, HttpServletResponse response) {
         super(applicationContext);
         this.request = request;
         this.response = response;
     }
 
     /** {@inheritDoc} */
     public Map<String, String> getHeader() {
 
         if ((header == null) && (request != null)) {
             header = new ReadOnlyEnumerationMap<String>(new HeaderExtractor(request, null));
         }
         return (header);
 
     }
 
     /** {@inheritDoc} */
     public Addable<String> getResponseHeaders() {
 
         if ((responseHeaders == null) && (response != null)) {
             responseHeaders = new HeaderExtractor(null, response);
         }
         return (responseHeaders);
 
     }
 
     /** {@inheritDoc} */
     public Map<String, String[]> getHeaderValues() {
 
         if ((headerValues == null) && (request != null)) {
             headerValues = new HeaderValuesMap(new HeaderExtractor(request, response));
         }
         return (headerValues);
 
     }
 
 
     /** {@inheritDoc} */
     public Map<String, String> getParam() {
 
         if ((param == null) && (request != null)) {
             param = new ReadOnlyEnumerationMap<String>(new ParameterExtractor(request));
         }
         return (param);
 
     }
 
 
     /** {@inheritDoc} */
     @SuppressWarnings("unchecked")
     public Map<String, String[]> getParamValues() {
         return request.getParameterMap();
     }
 
     @Override
     public Map<String, Object> getContext(String scope) {
         if(REQUEST_SCOPE.equals(scope)){
             return getRequestScope();
         }else if("session".equals(scope)){
             return getSessionScope();
         }else if(APPLICATION_SCOPE.equals(scope)){
             return getApplicationScope();
         }
         throw new IllegalArgumentException(scope + " does not exist. Call getAvailableScopes() first to check.");
     }
 
     /** {@inheritDoc} */
     public Map<String, Object> getRequestScope() {
 
         if ((requestScope == null) && (request != null)) {
             requestScope = new ScopeMap(new RequestScopeExtractor(request));
         }
         return (requestScope);
 
     }
 
 
     /** {@inheritDoc} */
     public Map<String, Object> getSessionScope() {
 
         if ((sessionScope == null) && (request != null)) {
             sessionScope = new ScopeMap(new SessionScopeExtractor(request));
         }
         return (sessionScope);
 
     }
 
     @Override
     public List<String> getAvailableScopes() {
         return SCOPES;
     }
 
     /** {@inheritDoc} */
     public void doForward(String path) throws IOException {
         if (response.isCommitted()) {
             doInclude(path);
         } else {
             forward(path);
         }
     }
 
 
     /** {@inheritDoc} */
     public void doInclude(String path) throws IOException {
         RequestDispatcher rd = request.getRequestDispatcher(path);
 
         if (rd == null) {
             throw new IOException("No request dispatcher returned for path '"
                     + path + "'");
         }
 
         try {
             rd.include(request, response);
         } catch (ServletException ex) {
             throw ServletUtil.wrapServletException(ex, "ServletException including path '"
                     + path + "'.");
         }
     }
 
     /**
      * Forwards to a path.
      *
      * @param path The path to forward to.
      * @throws IOException If something goes wrong during the operation.
      */
     private void forward(String path) throws IOException {
         RequestDispatcher rd = request.getRequestDispatcher(path);
 
         if (rd == null) {
             throw new IOException("No request dispatcher returned for path '"
                     + path + "'");
         }
 
         try {
             rd.forward(request, response);
         } catch (ServletException ex) {
             throw ServletUtil.wrapServletException(ex, "ServletException including path '"
                     + path + "'.");
         }
     }
 
     /** {@inheritDoc} */
     public OutputStream getOutputStream() throws IOException {
         if (outputStream == null) {
             outputStream = response.getOutputStream();
         }
         return outputStream;
     }
 
     /** {@inheritDoc} */
     public Writer getWriter() throws IOException {
         return getPrintWriter();
     }
 
     /** {@inheritDoc} */
     public PrintWriter getPrintWriter() throws IOException {
         if (writer == null) {
             writer = response.getWriter();
         }
         return writer;
     }
 
     /** {@inheritDoc} */
     public boolean isResponseCommitted() {
         return response.isCommitted();
     }
 
     /** {@inheritDoc} */
     public void setContentType(String contentType) {
         response.setContentType(contentType);
     }
 
     /** {@inheritDoc} */
     public Locale getRequestLocale() {
         return request.getLocale();
     }
 
     public HttpServletRequest getRequest() {
         return request;
     }
 
     public HttpServletResponse getResponse() {
         return response;
     }
 
     /** {@inheritDoc} */
     public boolean isUserInRole(String role) {
         return request.isUserInRole(role);
     }
 }