/**
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF 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.apache.hadoop.hbase.ipc;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.ByteBufInputStream;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelInboundHandlerAdapter;
  
  import java.io.IOException;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.CellScanner;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
  import org.apache.hadoop.hbase.protobuf.generated.RPCProtos;
  import org.apache.hadoop.ipc.RemoteException;
  
  import com.google.protobuf.Message;
  
  /**
   * Handles Hbase responses
   */
  @InterfaceAudience.Private
  public class AsyncServerResponseHandler extends ChannelInboundHandlerAdapter {
    public static final Log LOG = LogFactory.getLog(AsyncServerResponseHandler.class.getName());
  
    private final AsyncRpcChannel channel;
  
    /**
     * Constructor
     *
     * @param channel on which this response handler operates
     */
    public AsyncServerResponseHandler(AsyncRpcChannel channel) {
      this.channel = channel;
    }
  
    @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
      ByteBuf inBuffer = (ByteBuf) msg;
      ByteBufInputStream in = new ByteBufInputStream(inBuffer);
      int totalSize = inBuffer.readableBytes();
      try {
        // Read the header
        RPCProtos.ResponseHeader responseHeader = RPCProtos.ResponseHeader.parseDelimitedFrom(in);
        int id = responseHeader.getCallId();
        AsyncCall call = channel.removePendingCall(id);
        if (call == null) {
          // So we got a response for which we have no corresponding 'call' here on the client-side.
          // We probably timed out waiting, cleaned up all references, and now the server decides
          // to return a response.  There is nothing we can do w/ the response at this stage. Clean
          // out the wire of the response so its out of the way and we can get other responses on
          // this connection.
          int readSoFar = IPCUtil.getTotalSizeWhenWrittenDelimited(responseHeader);
          int whatIsLeftToRead = totalSize - readSoFar;
  
          // This is done through a Netty ByteBuf which has different behavior than InputStream.
          // It does not return number of bytes read but will update pointer internally and throws an
          // exception when too many bytes are to be skipped.
          inBuffer.skipBytes(whatIsLeftToRead);
          return;
        }
  
        if (responseHeader.hasException()) {
          RPCProtos.ExceptionResponse exceptionResponse = responseHeader.getException();
          RemoteException re = createRemoteException(exceptionResponse);
          if (exceptionResponse.getExceptionClassName().
              equals(FatalConnectionException.class.getName())) {
            channel.close(re);
          } else {
            call.setFailed(re);
          }
        } else {
          Message value = null;
          // Call may be null because it may have timedout and been cleaned up on this side already
          if (call.responseDefaultType != null) {
            Message.Builder builder = call.responseDefaultType.newBuilderForType();
            ProtobufUtil.mergeDelimitedFrom(builder, in);
            value = builder.build();
          }
          CellScanner cellBlockScanner = null;
          if (responseHeader.hasCellBlockMeta()) {
            int size = responseHeader.getCellBlockMeta().getLength();
           byte[] cellBlock = new byte[size];
           inBuffer.readBytes(cellBlock, 0, cellBlock.length);
           cellBlockScanner = channel.client.createCellScanner(cellBlock);
         }
         call.setSuccess(value, cellBlockScanner);
       }
     } catch (IOException e) {
       // Treat this as a fatal condition and close this connection
       channel.close(e);
     } finally {
       inBuffer.release();
     }
   }
 
   /**
    * @param e Proto exception
    * @return RemoteException made from passed <code>e</code>
    */
   private RemoteException createRemoteException(final RPCProtos.ExceptionResponse e) {
     String innerExceptionClassName = e.getExceptionClassName();
     boolean doNotRetry = e.getDoNotRetry();
     return e.hasHostname() ?
         // If a hostname then add it to the RemoteWithExtrasException
         new RemoteWithExtrasException(innerExceptionClassName, e.getStackTrace(), e.getHostname(),
             e.getPort(), doNotRetry) :
         new RemoteWithExtrasException(innerExceptionClassName, e.getStackTrace(), doNotRetry);
   }
 }