/*
    * 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:
    *
    *   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.netty5.testsuite.autobahn;
  
  import io.netty5.channel.ChannelFutureListeners;
  import io.netty5.channel.ChannelHandler;
  import io.netty5.channel.ChannelHandlerContext;
  import io.netty5.handler.codec.http.DefaultFullHttpResponse;
  import io.netty5.handler.codec.http.FullHttpResponse;
  import io.netty5.handler.codec.http.HttpHeaderNames;
  import io.netty5.handler.codec.http.HttpRequest;
  import io.netty5.handler.codec.http.websocketx.BinaryWebSocketFrame;
  import io.netty5.handler.codec.http.websocketx.CloseWebSocketFrame;
  import io.netty5.handler.codec.http.websocketx.ContinuationWebSocketFrame;
  import io.netty5.handler.codec.http.websocketx.PingWebSocketFrame;
  import io.netty5.handler.codec.http.websocketx.PongWebSocketFrame;
  import io.netty5.handler.codec.http.websocketx.TextWebSocketFrame;
  import io.netty5.handler.codec.http.websocketx.WebSocketFrame;
  import io.netty5.handler.codec.http.websocketx.WebSocketServerHandshaker;
  import io.netty5.handler.codec.http.websocketx.WebSocketServerHandshakerFactory;
  import io.netty5.util.CharsetUtil;
  import io.netty5.util.concurrent.Future;
  import io.netty5.util.internal.StringUtil;
  
  import java.util.logging.Level;
  import java.util.logging.Logger;
  
  import static io.netty5.handler.codec.http.HttpMethod.GET;
  import static io.netty5.handler.codec.http.HttpResponseStatus.BAD_REQUEST;
  import static io.netty5.handler.codec.http.HttpResponseStatus.FORBIDDEN;
  import static io.netty5.handler.codec.http.HttpUtil.isKeepAlive;
  import static io.netty5.handler.codec.http.HttpUtil.setContentLength;
  import static io.netty5.handler.codec.http.HttpVersion.HTTP_1_1;
  
  /**
   * Handles handshakes and messages
   */
  public class AutobahnServerHandler implements ChannelHandler {
      private static final Logger logger = Logger.getLogger(AutobahnServerHandler.class.getName());
  
      private WebSocketServerHandshaker handshaker;
  
      @Override
      public void channelRead(ChannelHandlerContext ctx, Object msg) {
          if (msg instanceof HttpRequest) {
              handleHttpRequest(ctx, (HttpRequest) msg);
          } else if (msg instanceof WebSocketFrame) {
              handleWebSocketFrame(ctx, (WebSocketFrame) msg);
          } else {
              throw new IllegalStateException("unknown message: " + msg);
          }
      }
  
      @Override
      public void channelReadComplete(ChannelHandlerContext ctx) {
          ctx.flush();
      }
  
      private void handleHttpRequest(ChannelHandlerContext ctx, HttpRequest req) {
          // Handle a bad request.
          if (!req.decoderResult().isSuccess()) {
              sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, BAD_REQUEST,
                      ctx.bufferAllocator().allocate(0)));
              return;
          }
  
          // Allow only GET methods.
          if (!GET.equals(req.method())) {
              sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, FORBIDDEN,
                      ctx.bufferAllocator().allocate(0)));
              return;
          }
  
          // Handshake
          WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(
                  getWebSocketLocation(req), null, false, Integer.MAX_VALUE);
          handshaker = wsFactory.newHandshaker(req);
          if (handshaker == null) {
              WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse(ctx.channel());
          } else {
              handshaker.handshake(ctx.channel(), req);
          }
      }
  
      private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame) {
          if (logger.isLoggable(Level.FINE)) {
             logger.fine(String.format(
                     "Channel %s received %s", ctx.channel().hashCode(), StringUtil.simpleClassName(frame)));
         }
 
         if (frame instanceof CloseWebSocketFrame) {
             handshaker.close(ctx, (CloseWebSocketFrame) frame);
         } else if (frame instanceof PingWebSocketFrame) {
             ctx.write(new PongWebSocketFrame(frame.isFinalFragment(), frame.rsv(), frame.binaryData()));
         } else if (frame instanceof TextWebSocketFrame ||
                 frame instanceof BinaryWebSocketFrame ||
                 frame instanceof ContinuationWebSocketFrame) {
             ctx.write(frame);
         } else if (frame instanceof PongWebSocketFrame) {
             frame.close();
             // Ignore
         } else {
             throw new UnsupportedOperationException(String.format("%s frame types not supported", frame.getClass()
                     .getName()));
         }
     }
 
     private static void sendHttpResponse(
             ChannelHandlerContext ctx, HttpRequest req, FullHttpResponse res) {
         // Generate an error page if response status code is not OK (200).
         if (res.status().code() != 200) {
             res.payload().writeCharSequence(res.status().toString(), CharsetUtil.UTF_8);
             setContentLength(res, res.payload().readableBytes());
         }
 
         // Send the response and close the connection if necessary.
         Future<Void> f = ctx.writeAndFlush(res);
         if (!isKeepAlive(req) || res.status().code() != 200) {
             f.addListener(ctx, ChannelFutureListeners.CLOSE);
         }
     }
 
     @Override
     public void channelExceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
         ctx.close();
     }
 
     private static String getWebSocketLocation(HttpRequest req) {
         return "ws://" + req.headers().get(HttpHeaderNames.HOST);
     }
 }