/*
    * 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 io.netty.handler.codec.http.websocketx;
  
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelFutureListener;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelInboundHandlerAdapter;
  import io.netty.channel.ChannelPipeline;
  import io.netty.handler.codec.http.DefaultFullHttpResponse;
  import io.netty.handler.codec.http.FullHttpRequest;
  import io.netty.handler.codec.http.HttpHeaderNames;
  import io.netty.handler.codec.http.HttpRequest;
  import io.netty.handler.codec.http.HttpResponse;
  import io.netty.handler.ssl.SslHandler;
  
  import static io.netty.handler.codec.http.HttpUtil.*;
  import static io.netty.handler.codec.http.HttpMethod.*;
  import static io.netty.handler.codec.http.HttpResponseStatus.*;
  import static io.netty.handler.codec.http.HttpVersion.*;
  
  /**
   * Handles the HTTP handshake (the HTTP Upgrade request) for {@link WebSocketServerProtocolHandler}.
   */
  class WebSocketServerProtocolHandshakeHandler extends ChannelInboundHandlerAdapter {
  
      private final String websocketPath;
      private final String subprotocols;
      private final boolean allowExtensions;
      private final int maxFramePayloadSize;
      private final boolean allowMaskMismatch;
      private final boolean checkStartsWith;
  
      WebSocketServerProtocolHandshakeHandler(String websocketPath, String subprotocols,
              boolean allowExtensions, int maxFrameSize, boolean allowMaskMismatch) {
          this(websocketPath, subprotocols, allowExtensions, maxFrameSize, allowMaskMismatch, false);
      }
  
      WebSocketServerProtocolHandshakeHandler(String websocketPath, String subprotocols,
              boolean allowExtensions, int maxFrameSize, boolean allowMaskMismatch, boolean checkStartsWith) {
          this.websocketPath = websocketPath;
          this.subprotocols = subprotocols;
          this.allowExtensions = allowExtensions;
          maxFramePayloadSize = maxFrameSize;
          this.allowMaskMismatch = allowMaskMismatch;
          this.checkStartsWith = checkStartsWith;
      }
  
      @Override
      public void channelRead(final ChannelHandlerContext ctx, Object msg) throws Exception {
          final FullHttpRequest req = (FullHttpRequest) msg;
          if (isNotWebSocketPath(req)) {
              ctx.fireChannelRead(msg);
              return;
          }
  
          try {
              if (req.method() != GET) {
                  sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, FORBIDDEN));
                  return;
              }
  
              final WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(
                      getWebSocketLocation(ctx.pipeline(), req, websocketPath), subprotocols,
                              allowExtensions, maxFramePayloadSize, allowMaskMismatch);
              final WebSocketServerHandshaker handshaker = wsFactory.newHandshaker(req);
              if (handshaker == null) {
                  WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse(ctx.channel());
              } else {
                  final ChannelFuture handshakeFuture = handshaker.handshake(ctx.channel(), req);
                  handshakeFuture.addListener(new ChannelFutureListener() {
                      @Override
                      public void operationComplete(ChannelFuture future) throws Exception {
                          if (!future.isSuccess()) {
                              ctx.fireExceptionCaught(future.cause());
                          } else {
                              // Kept for compatibility
                              ctx.fireUserEventTriggered(
                                      WebSocketServerProtocolHandler.ServerHandshakeStateEvent.HANDSHAKE_COMPLETE);
                              ctx.fireUserEventTriggered(
                                      new WebSocketServerProtocolHandler.HandshakeComplete(
                                              req.uri(), req.headers(), handshaker.selectedSubprotocol()));
                          }
                      }
                  });
                  WebSocketServerProtocolHandler.setHandshaker(ctx.channel(), handshaker);
                 ctx.pipeline().replace(this, "WS403Responder",
                         WebSocketServerProtocolHandler.forbiddenHttpRequestResponder());
             }
         } finally {
             req.release();
         }
     }
 
     private boolean isNotWebSocketPath(FullHttpRequest req) {
         return checkStartsWith ? !req.uri().startsWith(websocketPath) : !req.uri().equals(websocketPath);
     }
 
     private static void sendHttpResponse(ChannelHandlerContext ctx, HttpRequest req, HttpResponse res) {
         ChannelFuture f = ctx.channel().writeAndFlush(res);
         if (!isKeepAlive(req) || res.status().code() != 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";
         }
         String host = req.headers().get(HttpHeaderNames.HOST);
         return protocol + "://" + host + path;
     }
 }