/*
    * Copyright 2014 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:
    *
    *   https://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 io.netty.example.http.websocketx.benchmarkserver;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.ByteBufUtil;
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelFutureListener;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.SimpleChannelInboundHandler;
  import io.netty.handler.codec.http.DefaultFullHttpResponse;
  import io.netty.handler.codec.http.FullHttpRequest;
  import io.netty.handler.codec.http.FullHttpResponse;
  import io.netty.handler.codec.http.HttpHeaderNames;
  import io.netty.handler.codec.http.HttpResponseStatus;
  import io.netty.handler.codec.http.HttpUtil;
  import io.netty.handler.codec.http.websocketx.BinaryWebSocketFrame;
  import io.netty.handler.codec.http.websocketx.CloseWebSocketFrame;
  import io.netty.handler.codec.http.websocketx.PingWebSocketFrame;
  import io.netty.handler.codec.http.websocketx.PongWebSocketFrame;
  import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
  import io.netty.handler.codec.http.websocketx.WebSocketFrame;
  import io.netty.handler.codec.http.websocketx.WebSocketServerHandshaker;
  import io.netty.handler.codec.http.websocketx.WebSocketServerHandshakerFactory;
  
  import static io.netty.handler.codec.http.HttpMethod.*;
  import static io.netty.handler.codec.http.HttpResponseStatus.*;
  
  /**
   * Handles handshakes and messages
   */
  public class WebSocketServerHandler extends SimpleChannelInboundHandler<Object> {
  
      private static final String WEBSOCKET_PATH = "/websocket";
  
      private WebSocketServerHandshaker handshaker;
  
      @Override
      public void channelRead0(ChannelHandlerContext ctx, Object msg) {
          if (msg instanceof FullHttpRequest) {
              handleHttpRequest(ctx, (FullHttpRequest) msg);
          } else if (msg instanceof WebSocketFrame) {
              handleWebSocketFrame(ctx, (WebSocketFrame) msg);
          }
      }
  
      @Override
      public void channelReadComplete(ChannelHandlerContext ctx) {
          ctx.flush();
      }
  
      private void handleHttpRequest(ChannelHandlerContext ctx, FullHttpRequest req) {
          // Handle a bad request.
          if (!req.decoderResult().isSuccess()) {
              sendHttpResponse(ctx, req, new DefaultFullHttpResponse(req.protocolVersion(), BAD_REQUEST,
                                                                     ctx.alloc().buffer(0)));
              return;
          }
  
          // Allow only GET methods.
          if (!GET.equals(req.method())) {
              sendHttpResponse(ctx, req, new DefaultFullHttpResponse(req.protocolVersion(), FORBIDDEN,
                                                                     ctx.alloc().buffer(0)));
              return;
          }
  
          // Send the demo page and favicon.ico
          if ("/".equals(req.uri())) {
              ByteBuf content = WebSocketServerBenchmarkPage.getContent(getWebSocketLocation(req));
              FullHttpResponse res = new DefaultFullHttpResponse(req.protocolVersion(), OK, content);
  
              res.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/html; charset=UTF-8");
              HttpUtil.setContentLength(res, content.readableBytes());
  
              sendHttpResponse(ctx, req, res);
              return;
          }
  
          if ("/favicon.ico".equals(req.uri())) {
              FullHttpResponse res = new DefaultFullHttpResponse(req.protocolVersion(), NOT_FOUND,
                                                                 ctx.alloc().buffer(0));
              sendHttpResponse(ctx, req, res);
              return;
          }
  
          // Handshake
         WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(
                 getWebSocketLocation(req), null, true, 5 * 1024 * 1024);
         handshaker = wsFactory.newHandshaker(req);
         if (handshaker == null) {
             WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse(ctx.channel());
         } else {
             handshaker.handshake(ctx.channel(), req);
         }
     }
 
     private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame) {
 
         // Check for closing frame
         if (frame instanceof CloseWebSocketFrame) {
             handshaker.close(ctx, (CloseWebSocketFrame) frame.retain());
             return;
         }
         if (frame instanceof PingWebSocketFrame) {
             ctx.write(new PongWebSocketFrame(frame.content().retain()));
             return;
         }
         if (frame instanceof TextWebSocketFrame) {
             // Echo the frame
             ctx.write(frame.retain());
             return;
         }
         if (frame instanceof BinaryWebSocketFrame) {
             // Echo the frame
             ctx.write(frame.retain());
         }
     }
 
     private static void sendHttpResponse(ChannelHandlerContext ctx, FullHttpRequest req, FullHttpResponse res) {
         // Generate an error page if response getStatus code is not OK (200).
         HttpResponseStatus responseStatus = res.status();
         if (responseStatus.code() != 200) {
             ByteBufUtil.writeUtf8(res.content(), responseStatus.toString());
             HttpUtil.setContentLength(res, res.content().readableBytes());
         }
         // Send the response and close the connection if necessary.
         boolean keepAlive = HttpUtil.isKeepAlive(req) && responseStatus.code() == 200;
         HttpUtil.setKeepAlive(res, keepAlive);
         ChannelFuture future = ctx.write(res); // Flushed in channelReadComplete()
         if (!keepAlive) {
             future.addListener(ChannelFutureListener.CLOSE);
         }
     }
 
     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
         cause.printStackTrace();
         ctx.close();
     }
 
     private static String getWebSocketLocation(FullHttpRequest req) {
         String location =  req.headers().get(HttpHeaderNames.HOST) + WEBSOCKET_PATH;
         if (WebSocketServer.SSL) {
             return "wss://" + location;
         } else {
             return "ws://" + location;
         }
     }
 }