/*
    * Copyright 2019 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.handler.codec.http.websocketx;
  
  import io.netty.buffer.Unpooled;
  import io.netty.channel.Channel;
  import io.netty.channel.ChannelFutureListener;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelInboundHandler;
  import io.netty.channel.ChannelPipeline;
  import io.netty.channel.ChannelPromise;
  import io.netty.handler.codec.http.DefaultFullHttpResponse;
  import io.netty.handler.codec.http.FullHttpResponse;
  import io.netty.handler.codec.http.HttpHeaders;
  import io.netty.handler.codec.http.HttpResponseStatus;
  import io.netty.util.AttributeKey;
  
  import java.util.List;
  
  import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;
  import static io.netty.handler.codec.http.websocketx.WebSocketServerProtocolConfig.DEFAULT_HANDSHAKE_TIMEOUT_MILLIS;
  import static io.netty.util.internal.ObjectUtil.checkNotNull;
  
  /**
   * This handler does all the heavy lifting for you to run a websocket server.
   *
   * It takes care of websocket handshaking as well as processing of control frames (Close, Ping, Pong). Text and Binary
   * data frames are passed to the next handler in the pipeline (implemented by you) for processing.
   *
   * See <tt>io.netty.example.http.websocketx.html5.WebSocketServer</tt> for usage.
   *
   * The implementation of this handler assumes that you just want to run  a websocket server and not process other types
   * HTTP requests (like GET and POST). If you wish to support both HTTP requests and websockets in the one server, refer
   * to the <tt>io.netty.example.http.websocketx.server.WebSocketServer</tt> example.
   *
   * To know once a handshake was done you can intercept the
   * {@link ChannelInboundHandler#userEventTriggered(ChannelHandlerContext, Object)} and check if the event was instance
   * of {@link HandshakeComplete}, the event will contain extra information about the handshake such as the request and
   * selected subprotocol.
   */
  public class WebSocketServerProtocolHandler extends WebSocketProtocolHandler {
  
      /**
       * Events that are fired to notify about handshake status
       */
      public enum ServerHandshakeStateEvent {
          /**
           * The Handshake was completed successfully and the channel was upgraded to websockets.
           *
           * @deprecated in favor of {@link HandshakeComplete} class,
           * it provides extra information about the handshake
           */
          @Deprecated
          HANDSHAKE_COMPLETE,
  
          /**
           * The Handshake was timed out
           */
          HANDSHAKE_TIMEOUT
      }
  
      /**
       * The Handshake was completed successfully and the channel was upgraded to websockets.
       */
      public static final class HandshakeComplete {
          private final String requestUri;
          private final HttpHeaders requestHeaders;
          private final String selectedSubprotocol;
  
          public HandshakeComplete(String requestUri, HttpHeaders requestHeaders, String selectedSubprotocol) {
              this.requestUri = requestUri;
              this.requestHeaders = requestHeaders;
              this.selectedSubprotocol = selectedSubprotocol;
          }
  
          public String requestUri() {
              return requestUri;
          }
  
          public HttpHeaders requestHeaders() {
              return requestHeaders;
          }
  
          public String selectedSubprotocol() {
              return selectedSubprotocol;
          }
     }
 
     private static final AttributeKey<WebSocketServerHandshaker> HANDSHAKER_ATTR_KEY =
             AttributeKey.valueOf(WebSocketServerHandshaker.class, "HANDSHAKER");
 
     private final WebSocketServerProtocolConfig serverConfig;
 
     /**
      * Base constructor
      *
      * @param serverConfig
      *            Server protocol configuration.
      */
     public WebSocketServerProtocolHandler(WebSocketServerProtocolConfig serverConfig) {
         super(checkNotNull(serverConfig, "serverConfig").dropPongFrames(),
               serverConfig.sendCloseFrame(),
               serverConfig.forceCloseTimeoutMillis()
         );
         this.serverConfig = serverConfig;
     }
 
     public WebSocketServerProtocolHandler(String websocketPath) {
         this(websocketPath, DEFAULT_HANDSHAKE_TIMEOUT_MILLIS);
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, long handshakeTimeoutMillis) {
         this(websocketPath, false, handshakeTimeoutMillis);
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, boolean checkStartsWith) {
         this(websocketPath, checkStartsWith, DEFAULT_HANDSHAKE_TIMEOUT_MILLIS);
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, boolean checkStartsWith, long handshakeTimeoutMillis) {
         this(websocketPath, null, false, 65536, false, checkStartsWith, handshakeTimeoutMillis);
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, String subprotocols) {
         this(websocketPath, subprotocols, DEFAULT_HANDSHAKE_TIMEOUT_MILLIS);
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, String subprotocols, long handshakeTimeoutMillis) {
         this(websocketPath, subprotocols, false, handshakeTimeoutMillis);
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, String subprotocols, boolean allowExtensions) {
         this(websocketPath, subprotocols, allowExtensions, DEFAULT_HANDSHAKE_TIMEOUT_MILLIS);
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, String subprotocols, boolean allowExtensions,
                                           long handshakeTimeoutMillis) {
         this(websocketPath, subprotocols, allowExtensions, 65536, handshakeTimeoutMillis);
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, String subprotocols,
                                           boolean allowExtensions, int maxFrameSize) {
         this(websocketPath, subprotocols, allowExtensions, maxFrameSize, DEFAULT_HANDSHAKE_TIMEOUT_MILLIS);
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, String subprotocols,
                                           boolean allowExtensions, int maxFrameSize, long handshakeTimeoutMillis) {
         this(websocketPath, subprotocols, allowExtensions, maxFrameSize, false, handshakeTimeoutMillis);
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, String subprotocols,
             boolean allowExtensions, int maxFrameSize, boolean allowMaskMismatch) {
         this(websocketPath, subprotocols, allowExtensions, maxFrameSize, allowMaskMismatch,
              DEFAULT_HANDSHAKE_TIMEOUT_MILLIS);
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, String subprotocols, boolean allowExtensions,
                                           int maxFrameSize, boolean allowMaskMismatch, long handshakeTimeoutMillis) {
         this(websocketPath, subprotocols, allowExtensions, maxFrameSize, allowMaskMismatch, false,
              handshakeTimeoutMillis);
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, String subprotocols,
             boolean allowExtensions, int maxFrameSize, boolean allowMaskMismatch, boolean checkStartsWith) {
         this(websocketPath, subprotocols, allowExtensions, maxFrameSize, allowMaskMismatch, checkStartsWith,
              DEFAULT_HANDSHAKE_TIMEOUT_MILLIS);
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, String subprotocols,
                                           boolean allowExtensions, int maxFrameSize, boolean allowMaskMismatch,
                                           boolean checkStartsWith, long handshakeTimeoutMillis) {
         this(websocketPath, subprotocols, allowExtensions, maxFrameSize, allowMaskMismatch, checkStartsWith, true,
              handshakeTimeoutMillis);
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, String subprotocols,
                                           boolean allowExtensions, int maxFrameSize, boolean allowMaskMismatch,
                                           boolean checkStartsWith, boolean dropPongFrames) {
         this(websocketPath, subprotocols, allowExtensions, maxFrameSize, allowMaskMismatch, checkStartsWith,
              dropPongFrames, DEFAULT_HANDSHAKE_TIMEOUT_MILLIS);
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, String subprotocols, boolean allowExtensions,
                                           int maxFrameSize, boolean allowMaskMismatch, boolean checkStartsWith,
                                           boolean dropPongFrames, long handshakeTimeoutMillis) {
         this(websocketPath, subprotocols, checkStartsWith, dropPongFrames, handshakeTimeoutMillis,
             WebSocketDecoderConfig.newBuilder()
                 .maxFramePayloadLength(maxFrameSize)
                 .allowMaskMismatch(allowMaskMismatch)
                 .allowExtensions(allowExtensions)
                 .build());
     }
 
     public WebSocketServerProtocolHandler(String websocketPath, String subprotocols, boolean checkStartsWith,
                                           boolean dropPongFrames, long handshakeTimeoutMillis,
                                           WebSocketDecoderConfig decoderConfig) {
         this(WebSocketServerProtocolConfig.newBuilder()
             .websocketPath(websocketPath)
             .subprotocols(subprotocols)
             .checkStartsWith(checkStartsWith)
             .handshakeTimeoutMillis(handshakeTimeoutMillis)
             .dropPongFrames(dropPongFrames)
             .decoderConfig(decoderConfig)
             .build());
     }
 
     @Override
     public void handlerAdded(ChannelHandlerContext ctx) {
         ChannelPipeline cp = ctx.pipeline();
         if (cp.get(WebSocketServerProtocolHandshakeHandler.class) == null) {
             // Add the WebSocketHandshakeHandler before this one.
             cp.addBefore(ctx.name(), WebSocketServerProtocolHandshakeHandler.class.getName(),
                     new WebSocketServerProtocolHandshakeHandler(serverConfig));
         }
         if (serverConfig.decoderConfig().withUTF8Validator() && cp.get(Utf8FrameValidator.class) == null) {
             // Add the UFT8 checking before this one.
             cp.addBefore(ctx.name(), Utf8FrameValidator.class.getName(),
                     new Utf8FrameValidator(serverConfig.decoderConfig().closeOnProtocolViolation()));
         }
     }
 
     @Override
     protected void decode(ChannelHandlerContext ctx, WebSocketFrame frame, List<Object> out) throws Exception {
         if (serverConfig.handleCloseFrames() && frame instanceof CloseWebSocketFrame) {
             WebSocketServerHandshaker handshaker = getHandshaker(ctx.channel());
             if (handshaker != null) {
                 frame.retain();
                 ChannelPromise promise = ctx.newPromise();
                 closeSent(promise);
                 handshaker.close(ctx, (CloseWebSocketFrame) frame, promise);
             } else {
                 ctx.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
             }
             return;
         }
         super.decode(ctx, frame, out);
     }
 
     @Override
     protected WebSocketServerHandshakeException buildHandshakeException(String message) {
         return new WebSocketServerHandshakeException(message);
     }
 
     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
         if (cause instanceof WebSocketHandshakeException) {
             FullHttpResponse response = new DefaultFullHttpResponse(
                     HTTP_1_1, HttpResponseStatus.BAD_REQUEST, Unpooled.wrappedBuffer(cause.getMessage().getBytes()));
             ctx.channel().writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
         } else {
             ctx.fireExceptionCaught(cause);
             ctx.close();
         }
     }
 
     static WebSocketServerHandshaker getHandshaker(Channel channel) {
         return channel.attr(HANDSHAKER_ATTR_KEY).get();
     }
 
     static void setHandshaker(Channel channel, WebSocketServerHandshaker handshaker) {
         channel.attr(HANDSHAKER_ATTR_KEY).set(handshaker);
     }
 }