/*
    * Copyright 2002-2012 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.springframework.mock.web.test;
  
  import javax.servlet.RequestDispatcher;
  import javax.servlet.ServletRequest;
  import javax.servlet.ServletResponse;
  import javax.servlet.http.HttpServletResponseWrapper;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  import org.springframework.util.Assert;
  
  /**
   * Mock implementation of the {@link javax.servlet.RequestDispatcher} interface.
   *
   * <p>Used for testing the web framework; typically not necessary for
   * testing application controllers.
   *
   * @author Rod Johnson
   * @author Juergen Hoeller
   * @author Sam Brannen
   * @since 1.0.2
   */
  public class MockRequestDispatcher implements RequestDispatcher {
  
  	private final Log logger = LogFactory.getLog(getClass());
  
  	private final String resource;
  
  
  	/**
  	 * Create a new MockRequestDispatcher for the given resource.
  	 * @param resource the server resource to dispatch to, located at a
  	 * particular path or given by a particular name
  	 */
  	public MockRequestDispatcher(String resource) {
  		Assert.notNull(resource, "resource must not be null");
  		this.resource = resource;
  	}
  
  
  	@Override
  	public void forward(ServletRequest request, ServletResponse response) {
  		Assert.notNull(request, "Request must not be null");
  		Assert.notNull(response, "Response must not be null");
  		if (response.isCommitted()) {
  			throw new IllegalStateException("Cannot perform forward - response is already committed");
  		}
  		getMockHttpServletResponse(response).setForwardedUrl(this.resource);
  		if (logger.isDebugEnabled()) {
  			logger.debug("MockRequestDispatcher: forwarding to [" + this.resource + "]");
  		}
  	}
  
  	@Override
  	public void include(ServletRequest request, ServletResponse response) {
  		Assert.notNull(request, "Request must not be null");
  		Assert.notNull(response, "Response must not be null");
  		getMockHttpServletResponse(response).addIncludedUrl(this.resource);
  		if (logger.isDebugEnabled()) {
  			logger.debug("MockRequestDispatcher: including [" + this.resource + "]");
  		}
  	}
  
  	/**
  	 * Obtain the underlying {@link MockHttpServletResponse}, unwrapping
  	 * {@link HttpServletResponseWrapper} decorators if necessary.
  	 */
  	protected MockHttpServletResponse getMockHttpServletResponse(ServletResponse response) {
  		if (response instanceof MockHttpServletResponse) {
  			return (MockHttpServletResponse) response;
  		}
  		if (response instanceof HttpServletResponseWrapper) {
  			return getMockHttpServletResponse(((HttpServletResponseWrapper) response).getResponse());
  		}
  		throw new IllegalArgumentException("MockRequestDispatcher requires MockHttpServletResponse");
  	}
  
  }