/*
    * 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.example.http.websocketx.server;
  
  import org.jboss.netty.buffer.ChannelBuffer;
  import org.jboss.netty.buffer.ChannelBuffers;
  import org.jboss.netty.channel.ChannelFuture;
  import org.jboss.netty.channel.ChannelFutureListener;
  import org.jboss.netty.channel.ChannelHandlerContext;
  import org.jboss.netty.channel.ExceptionEvent;
  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.HttpRequest;
  import org.jboss.netty.handler.codec.http.HttpResponse;
  import org.jboss.netty.handler.codec.http.websocketx.CloseWebSocketFrame;
  import org.jboss.netty.handler.codec.http.websocketx.PingWebSocketFrame;
  import org.jboss.netty.handler.codec.http.websocketx.PongWebSocketFrame;
  import org.jboss.netty.handler.codec.http.websocketx.TextWebSocketFrame;
  import org.jboss.netty.handler.codec.http.websocketx.WebSocketFrame;
  import org.jboss.netty.handler.codec.http.websocketx.WebSocketServerHandshaker;
  import org.jboss.netty.handler.codec.http.websocketx.WebSocketServerHandshakerFactory;
  import org.jboss.netty.logging.InternalLogger;
  import org.jboss.netty.logging.InternalLoggerFactory;
  import org.jboss.netty.util.CharsetUtil;
  
  import static org.jboss.netty.handler.codec.http.HttpHeaders.Names.*;
  import static org.jboss.netty.handler.codec.http.HttpHeaders.*;
  import static org.jboss.netty.handler.codec.http.HttpMethod.*;
  import static org.jboss.netty.handler.codec.http.HttpResponseStatus.*;
  import static org.jboss.netty.handler.codec.http.HttpVersion.*;
  
  /**
   * Handles handshakes and messages
   */
  public class WebSocketServerHandler extends SimpleChannelUpstreamHandler {
      private static final InternalLogger logger = InternalLoggerFactory.getInstance(WebSocketServerHandler.class);
  
      private static final String WEBSOCKET_PATH = "/websocket";
  
      private WebSocketServerHandshaker handshaker;
  
      @Override
      public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
          Object msg = e.getMessage();
          if (msg instanceof HttpRequest) {
              handleHttpRequest(ctx, (HttpRequest) msg);
          } else if (msg instanceof WebSocketFrame) {
              handleWebSocketFrame(ctx, (WebSocketFrame) msg);
          }
      }
  
      private void handleHttpRequest(ChannelHandlerContext ctx, HttpRequest req) throws Exception {
          // Allow only GET methods.
          if (req.getMethod() != GET) {
              sendHttpResponse(ctx, req, new DefaultHttpResponse(HTTP_1_1, FORBIDDEN));
              return;
          }
  
          // Send the demo page and favicon.ico
          if ("/".equals(req.getUri())) {
              HttpResponse res = new DefaultHttpResponse(HTTP_1_1, OK);
  
              ChannelBuffer content = WebSocketServerIndexPage.getContent(getWebSocketLocation(req));
  
              res.setHeader(CONTENT_TYPE, "text/html; charset=UTF-8");
              setContentLength(res, content.readableBytes());
  
              res.setContent(content);
              sendHttpResponse(ctx, req, res);
              return;
          }
          if ("/favicon.ico".equals(req.getUri())) {
              HttpResponse res = new DefaultHttpResponse(HTTP_1_1, NOT_FOUND);
              sendHttpResponse(ctx, req, res);
              return;
          }
  
          // Handshake
          WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(
                  getWebSocketLocation(req), null, false);
          handshaker = wsFactory.newHandshaker(req);
          if (handshaker == null) {
              wsFactory.sendUnsupportedWebSocketVersionResponse(ctx.getChannel());
          } else {
              handshaker.handshake(ctx.getChannel(), req).addListener(WebSocketServerHandshaker.HANDSHAKE_LISTENER);
         }
     }
 
     private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame) {
 
         // Check for closing frame
         if (frame instanceof CloseWebSocketFrame) {
             handshaker.close(ctx.getChannel(), (CloseWebSocketFrame) frame);
             return;
         }
         if (frame instanceof PingWebSocketFrame) {
             ctx.getChannel().write(new PongWebSocketFrame(frame.getBinaryData()));
             return;
         }
         if (!(frame instanceof TextWebSocketFrame)) {
             throw new UnsupportedOperationException(String.format("%s frame types not supported", frame.getClass()
                     .getName()));
         }
 
         // Send the uppercase string back.
         String request = ((TextWebSocketFrame) frame).getText();
         if (logger.isDebugEnabled()) {
             logger.debug(String.format("Channel %s received %s", ctx.getChannel().getId(), request));
         }
         ctx.getChannel().write(new TextWebSocketFrame(request.toUpperCase()));
     }
 
     private static void sendHttpResponse(ChannelHandlerContext ctx, HttpRequest req, HttpResponse res) {
         // Generate an error page if response status code is not OK (200).
         if (res.getStatus().getCode() != 200) {
             res.setContent(ChannelBuffers.copiedBuffer(res.getStatus().toString(), CharsetUtil.UTF_8));
             setContentLength(res, res.getContent().readableBytes());
         }
 
         // Send the response and close the connection if necessary.
         ChannelFuture f = ctx.getChannel().write(res);
         if (!isKeepAlive(req) || res.getStatus().getCode() != 200) {
             f.addListener(ChannelFutureListener.CLOSE);
         }
     }
 
     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
         e.getCause().printStackTrace();
         e.getChannel().close();
     }
 
     private static String getWebSocketLocation(HttpRequest req) {
         return "ws://" + req.getHeader(HOST) + WEBSOCKET_PATH;
     }
 }