/*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project 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.jboss.netty.handler.codec.http.websocketx;
  
  import static org.jboss.netty.handler.codec.http.HttpHeaders.isKeepAlive;
  import static org.jboss.netty.handler.codec.http.HttpMethod.GET;
  import static org.jboss.netty.handler.codec.http.HttpResponseStatus.FORBIDDEN;
  import static org.jboss.netty.handler.codec.http.HttpVersion.HTTP_1_1;
  
  import org.jboss.netty.channel.ChannelFuture;
  import org.jboss.netty.channel.ChannelFutureListener;
  import org.jboss.netty.channel.ChannelHandlerContext;
  import org.jboss.netty.channel.ChannelPipeline;
  import org.jboss.netty.channel.Channels;
  import org.jboss.netty.channel.MessageEvent;
  import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
  import org.jboss.netty.handler.codec.http.DefaultHttpResponse;
  import org.jboss.netty.handler.codec.http.HttpHeaders;
  import org.jboss.netty.handler.codec.http.HttpRequest;
  import org.jboss.netty.handler.codec.http.HttpResponse;
  import org.jboss.netty.handler.ssl.SslHandler;
  import org.jboss.netty.logging.InternalLogger;
  import org.jboss.netty.logging.InternalLoggerFactory;
  
  /**
   * Handles the HTTP handshake (the HTTP Upgrade request)
   */
  public class WebSocketServerProtocolHandshakeHandler extends SimpleChannelUpstreamHandler {
  
      private static final InternalLogger logger =
              InternalLoggerFactory.getInstance(WebSocketServerProtocolHandshakeHandler.class);
      private final String websocketPath;
      private final String subprotocols;
      private final boolean allowExtensions;
  
      public WebSocketServerProtocolHandshakeHandler(String websocketPath, String subprotocols,
              boolean allowExtensions) {
          this.websocketPath = websocketPath;
          this.subprotocols = subprotocols;
          this.allowExtensions = allowExtensions;
      }
  
      @Override
      public void messageReceived(final ChannelHandlerContext ctx, MessageEvent e) throws Exception {
          if (e.getMessage() instanceof HttpRequest) {
              HttpRequest req = (HttpRequest) e.getMessage();
              if (req.getMethod() != GET) {
                  sendHttpResponse(ctx, req, new DefaultHttpResponse(HTTP_1_1, FORBIDDEN));
                  return;
              }
  
              final WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(
                      getWebSocketLocation(ctx.getPipeline(), req, websocketPath), subprotocols, allowExtensions);
              final WebSocketServerHandshaker handshaker = wsFactory.newHandshaker(req);
              if (handshaker == null) {
                  wsFactory.sendUnsupportedWebSocketVersionResponse(ctx.getChannel());
              } else {
                  final ChannelFuture handshakeFuture = handshaker.handshake(ctx.getChannel(), req);
                  handshakeFuture.addListener(new ChannelFutureListener() {
                      public void operationComplete(ChannelFuture future) throws Exception {
                          if (!future.isSuccess()) {
                              Channels.fireExceptionCaught(ctx, future.getCause());
                          }
                      }
                  });
                  WebSocketServerProtocolHandler.setHandshaker(ctx, handshaker);
                  ctx.getPipeline().replace(this, "WS403Responder",
                  WebSocketServerProtocolHandler.forbiddenHttpRequestResponder());
              }
          }
      }
  
      public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
          logger.error("Exception Caught", cause);
          ctx.getChannel().close();
      }
  
      private static void sendHttpResponse(ChannelHandlerContext ctx, HttpRequest req, HttpResponse res) {
          ChannelFuture f = ctx.getChannel().write(res);
          if (!isKeepAlive(req) || res.getStatus().getCode() != 200) {
              f.addListener(ChannelFutureListener.CLOSE);
          }
      }
  
      private static String getWebSocketLocation(ChannelPipeline cp, HttpRequest req, String path) {
          String protocol = "ws";
         if (cp.get(SslHandler.class) != null) {
             // SSL in use so use Secure WebSockets
             protocol = "wss";
         }
         return protocol + "://" + req.getHeader(HttpHeaders.Names.HOST) + path;
     }
 
 }