//
   //  ========================================================================
   //  Copyright (c) 1995-2013 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.websocket.servlet;
  
  import java.io.IOException;
  import java.util.Iterator;
  import java.util.ServiceLoader;
  
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.eclipse.jetty.websocket.api.WebSocketBehavior;
  import org.eclipse.jetty.websocket.api.WebSocketPolicy;
  import org.eclipse.jetty.websocket.api.annotations.WebSocket;
  
  /**
   * Abstract Servlet used to bridge the Servlet API to the WebSocket API.
   * <p>
   * To use this servlet, you will be required to register your websockets with the {@link WebSocketServerFactory} so that it can create your websockets under the
   * appropriate conditions.
   * <p>
   * The most basic implementation would be as follows.
   * 
   * <pre>
   * package my.example;
   * 
   * import javax.servlet.http.HttpServletRequest;
   * import org.eclipse.jetty.websocket.WebSocket;
   * import org.eclipse.jetty.websocket.server.WebSocketServlet;
   * 
   * public class MyEchoServlet extends WebSocketServlet
   * {
   *     &#064;Override
   *     public void registerWebSockets(WebSocketServerFactory factory)
   *     {
   *         factory.register(MyEchoSocket.class);
   *     }
   * }
   * </pre>
   * 
   * Note: that only request that conforms to a "WebSocket: Upgrade" handshake request will trigger the {@link WebSocketServerFactory} handling of creating
   * WebSockets.<br>
   * All other requests are treated as normal servlet requests.
   * 
   * <p>
   * <b>Configuration / Init-Parameters:</b><br>
   * Note: If you use the {@link WebSocket &#064;WebSocket} annotation, these configuration settings can be specified on a per WebSocket basis, vs a per Servlet
   * basis.
   * 
   * <dl>
   * <dt>maxIdleTime</dt>
   * <dd>set the time in ms that a websocket may be idle before closing<br>
   * 
   * <dt>maxMessagesSize</dt>
   * <dd>set the size in bytes that a websocket may be accept before closing<br>
   * 
   * <dt>inputBufferSize</dt>
   * <dd>set the size in bytes of the buffer used to read raw bytes from the network layer<br>
   * </dl>
   */
  @SuppressWarnings("serial")
  public abstract class WebSocketServlet extends HttpServlet
  {
      private WebSocketServletFactory factory;
  
      public abstract void configure(WebSocketServletFactory factory);
  
      @Override
      public void destroy()
      {
          factory.cleanup();
      }
  
      /**
       * @see javax.servlet.GenericServlet#init()
       */
      @Override
      public void init() throws ServletException
      {
          try
          {
             WebSocketPolicy policy = new WebSocketPolicy(WebSocketBehavior.SERVER);
 
             String max = getInitParameter("maxIdleTime");
             if (max != null)
             {
                 policy.setIdleTimeout(Long.parseLong(max));
             }
 
             max = getInitParameter("maxMessageSize");
             if (max != null)
             {
                 policy.setMaxMessageSize(Long.parseLong(max));
             }
 
             max = getInitParameter("inputBufferSize");
             if (max != null)
             {
                 policy.setInputBufferSize(Integer.parseInt(max));
             }
 
             WebSocketServletFactory baseFactory;
             Iterator<WebSocketServletFactory> factories = ServiceLoader.load(WebSocketServletFactory.class).iterator();
 
             if (factories.hasNext())
             {
                 baseFactory = factories.next();
             }
             else
             {
                 // Load the default class if ServiceLoader mechanism isn't valid in this environment. (such as OSGi)
                 ClassLoader loader = Thread.currentThread().getContextClassLoader();
                 @SuppressWarnings("unchecked")
                 Class<WebSocketServletFactory> wssf = (Class<WebSocketServletFactory>)loader
                         .loadClass("org.eclipse.jetty.websocket.server.WebSocketServerFactory");
                 baseFactory = wssf.newInstance();
             }
 
             factory = baseFactory.createFactory(policy);
 
             configure(factory);
 
             factory.init();
         }
         catch (Exception x)
         {
             throw new ServletException(x);
         }
     }
 
     /**
      * @see javax.servlet.http.HttpServlet#service(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
      */
     @Override
     protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
     {
         if (factory.isUpgradeRequest(request,response))
         {
             // We have an upgrade request
             if (factory.acceptWebSocket(request,response))
             {
                 // We have a socket instance created
                 return;
             }
             // If we reach this point, it means we had an incoming request to upgrade
             // but it was either not a proper websocket upgrade, or it was possibly rejected
             // due to incoming request constraints (controlled by WebSocketCreator)
             if (response.isCommitted())
             {
                 // not much we can do at this point.
                 return;
             }
         }
 
         // All other processing
         super.service(request,response);
     }
 }