// ========================================================================
   // Copyright (c) 2006-2009 Mort Bay Consulting Pty. Ltd.
   // ------------------------------------------------------------------------
   // All rights reserved. This program and the accompanying materials
   // are made available under the terms of the Eclipse Public License v1.0
   // and Apache License v2.0 which accompanies this distribution.
   // The Eclipse Public License is available at 
   // http://www.eclipse.org/legal/epl-v10.html
   // The Apache License v2.0 is available at
  // http://www.opensource.org/licenses/apache2.0.php
  // You may elect to redistribute this code under either of these licenses. 
  // ========================================================================
  
  package org.eclipse.jetty.embedded;
  
  import java.io.File;
  import java.io.IOException;
  import java.util.Map;
  
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.eclipse.jetty.server.Handler;
  import org.eclipse.jetty.server.NCSARequestLog;
  import org.eclipse.jetty.server.Request;
  import org.eclipse.jetty.server.Server;
  import org.eclipse.jetty.server.handler.AbstractHandler;
  import org.eclipse.jetty.server.handler.DefaultHandler;
  import org.eclipse.jetty.server.handler.HandlerCollection;
  import org.eclipse.jetty.server.handler.HandlerList;
  import org.eclipse.jetty.server.handler.HandlerWrapper;
  import org.eclipse.jetty.server.handler.RequestLogHandler;
  import org.eclipse.jetty.util.ajax.JSON;
  
  
  /* ------------------------------------------------------------ */
  /**
   * Frequently many handlers are combined together to handle
   * different aspects of a request.  A handler may:<ul>
   * <li>handle the request and completely generate the response
   * <li>partially handle the request, but defer response generation
   * to another handler.
   * <li>select another handler to pass the request to.
   * <li>use business logic to decide to do one of the above.
   * </ul>
   * 
   * Multiple handlers may be combined with:<ul>
   * <li>{@link HandlerWrapper} which will nest one handler inside another. 
   * In this example, the HelloHandler is nested inside a HandlerWrapper
   * that sets the greeting as a request attribute.
   * <li>{@link ListHandler} which will call a collection of handlers
   * until the request is marked as handled.  In this example, a list
   * is used to combine the param handler (which only handles the 
   * request if there are parameters) and the wrapper handler. 
   * Frequently handler lists are terminated with the {@link DefaultHandler},
   * which will generate a suitable 404 response if the request has
   * not been handled.
   * <li>{@link HandlerCollection} which will call each handler
   * regardless if the request has been handled or not. Typically
   * this is used to always pass a request to the logging handler.
   * </ul>
   */
  public class ManyHandlers
  {
      public static void main(String[] args)
          throws Exception
      {
          Server server = new Server(8080);
          
          // create the handlers
          Handler param=new ParamHandler();
          HandlerWrapper wrapper = new HandlerWrapper()
          {
              public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
              {
                  request.setAttribute("welcome","Hello");
                  super.handle(target,baseRequest,request, response);
              }
          };
          Handler hello=new HelloHandler();
          Handler dft=new DefaultHandler();
          RequestLogHandler log=new RequestLogHandler();
          
          // configure logs
          log.setRequestLog(new NCSARequestLog(File.createTempFile("demo","log").getAbsolutePath()));
          
          // create the handler collections
          HandlerCollection handlers = new HandlerCollection();
          HandlerList list = new HandlerList();
          
          // link them all together
          wrapper.setHandler(hello);
          list.setHandlers(new Handler[]{param,wrapper,dft});
          handlers.setHandlers(new Handler[]{list,log});
          
          server.setHandler(handlers);
          
          server.start();
         server.join();
     }
 
     
     public static class ParamHandler extends AbstractHandler
     {
         public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
         {
             Map params = request.getParameterMap();
             if (params.size()>0)
             {
                 response.setContentType("text/plain");
                 response.getWriter().println(JSON.toString(params));
                 ((Request)request).setHandled(true);
             }
         }
     }
     
     public static class HelloHandler extends AbstractHandler
     {
         public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
         {
             response.setContentType("text/html");
             response.setStatus(HttpServletResponse.SC_OK);
             response.getWriter().println("<h1>"+request.getAttribute("welcome") +" ManyHandler</h1>");
             ((Request)request).setHandled(true);
         }
     }
 }