code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC 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.openqa.selenium.netty.server;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.SimpleChannelInboundHandler;
  import io.netty.handler.codec.http.websocketx.BinaryWebSocketFrame;
  import io.netty.handler.codec.http.websocketx.CloseWebSocketFrame;
  import io.netty.handler.codec.http.websocketx.ContinuationWebSocketFrame;
  import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
  import io.netty.handler.codec.http.websocketx.WebSocketFrame;
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.UncheckedIOException;
  import java.nio.ByteBuffer;
  import java.util.logging.Logger;
  import org.openqa.selenium.remote.http.BinaryMessage;
  import org.openqa.selenium.remote.http.CloseMessage;
  import org.openqa.selenium.remote.http.Message;
  import org.openqa.selenium.remote.http.TextMessage;
  
  class MessageInboundConverter extends SimpleChannelInboundHandler<WebSocketFrame> {
  
    private enum Continuation {
      Text,
      Binary,
      None
    }
  
    private static final Logger LOG = Logger.getLogger(MessageInboundConverter.class.getName());
  
    private Continuation next;
    private StringBuilder builder;
    private ByteArrayOutputStream buffer;
  
    public MessageInboundConverter() {
      next = Continuation.None;
      buffer = new ByteArrayOutputStream();
      builder = new StringBuilder();
    }
  
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, WebSocketFrame frame) {
      boolean finalFragment = frame.isFinalFragment();
      Message message;
  
      if (frame instanceof ContinuationWebSocketFrame) {
        switch (next) {
          case Binary:
            try {
              ByteBuf content = frame.content();
              content.readBytes(buffer, content.readableBytes());
            } catch (IOException e) {
              throw new UncheckedIOException("failed to transfer buffer", e);
            }
  
            if (finalFragment) {
              message = new BinaryMessage(buffer.toByteArray());
              buffer.reset();
              next = Continuation.None;
            } else {
              message = null;
            }
            break;
          case Text:
            builder.append(((ContinuationWebSocketFrame) frame).text());
  
            if (finalFragment) {
              message = new TextMessage(builder.toString());
              builder.setLength(0);
              next = Continuation.None;
            } else {
              message = null;
            }
            break;
          case None:
            ctx.write(frame);
            return;
          default:
            throw new IllegalStateException("unexpected enum: " + next);
        }
      } else if (next != Continuation.None) {
        throw new IllegalStateException("expected a continuation frame");
      } else if (frame instanceof TextWebSocketFrame) {
        if (finalFragment) {
          message = new TextMessage(((TextWebSocketFrame) frame).text());
        } else {
          next = Continuation.Text;
          message = null;
          builder.append(((TextWebSocketFrame) frame).text());
        }
      } else if (frame instanceof BinaryWebSocketFrame) {
        ByteBuf content = frame.content();
        if (finalFragment) {
          if (content.nioBufferCount() != -1) {
            message = new BinaryMessage(content.nioBuffer());
          } else if (content.hasArray()) {
            message = new BinaryMessage(ByteBuffer.wrap(content.array()));
          } else {
            throw new IllegalStateException("Unable to handle bytebuf: " + content);
          }
        } else {
          next = Continuation.Binary;
          message = null;
          try {
            content.readBytes(buffer, content.readableBytes());
          } catch (IOException e) {
            throw new UncheckedIOException("failed to transfer buffer", e);
          }
        }
      } else if (frame instanceof CloseWebSocketFrame) {
        CloseWebSocketFrame closeFrame = (CloseWebSocketFrame) frame;
        message = new CloseMessage(closeFrame.statusCode(), closeFrame.reasonText());
      } else {
        ctx.write(frame);
        return;
      }
  
      if (message != null) {
        ctx.fireChannelRead(message);
      }
    }
  }
  