/**
    * 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.mapreduce;
  
  import java.io.DataInput;
  import java.io.DataInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.conf.Configured;
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.KeyValue;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.hbase.client.Result;
  import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.io.serializer.Deserializer;
  import org.apache.hadoop.io.serializer.Serialization;
  import org.apache.hadoop.io.serializer.Serializer;
  
  @InterfaceAudience.Public
  @InterfaceStability.Evolving
  public class ResultSerialization extends Configured implements Serialization<Result> {
    private static final Log LOG = LogFactory.getLog(ResultSerialization.class);
    // The following configuration property indicates import file format version.
    public static final String IMPORT_FORMAT_VER = "hbase.import.version";
  
    @Override
    public boolean accept(Class<?> c) {
      return Result.class.isAssignableFrom(c);
    }
  
    @Override
    public Deserializer<Result> getDeserializer(Class<Result> c) {
      // check input format version
      Configuration conf = getConf();
      if (conf != null) {
        String inputVersion = conf.get(IMPORT_FORMAT_VER);
        if (inputVersion != null && inputVersion.equals("0.94")) {
          LOG.info("Load exported file using deserializer for HBase 0.94 format");
          return new Result94Deserializer();
        }
      }
  
      return new ResultDeserializer();
    }
  
    @Override
    public Serializer<Result> getSerializer(Class<Result> c) {
      return new ResultSerializer();
    }
  
    /**
     * The following deserializer class is used to load exported file of 0.94
     */
    private static class Result94Deserializer implements Deserializer<Result> {
      private DataInputStream in;
  
      @Override
      public void close() throws IOException {
        in.close();
      }
  
      @Override
      public Result deserialize(Result mutation) throws IOException {
        int totalBuffer = in.readInt();
        if (totalBuffer == 0) {
          return Result.EMPTY_RESULT;
        }
        byte[] buf = new byte[totalBuffer];
        readChunked(in, buf, 0, totalBuffer);
        List<Cell> kvs = new ArrayList<Cell>();
        int offset = 0;
        while (offset < totalBuffer) {
          int keyLength = Bytes.toInt(buf, offset);
          offset += Bytes.SIZEOF_INT;
         kvs.add(new KeyValue(buf, offset, keyLength));
         offset += keyLength;
       }
       return Result.create(kvs);
     }
 
     @Override
     public void open(InputStream in) throws IOException {
       if (!(in instanceof DataInputStream)) {
         throw new IOException("Wrong input stream instance passed in");
       }
       this.in = (DataInputStream) in;
     }
 
     private void readChunked(final DataInput in, byte[] dest, int ofs, int len) throws IOException {
       int maxRead = 8192;
 
       for (; ofs < len; ofs += maxRead)
         in.readFully(dest, ofs, Math.min(len - ofs, maxRead));
     }
   }
 
   private static class ResultDeserializer implements Deserializer<Result> {
     private InputStream in;
 
     @Override
     public void close() throws IOException {
       in.close();
     }
 
     @Override
     public Result deserialize(Result mutation) throws IOException {
       ClientProtos.Result.Builder builder = ClientProtos.Result.newBuilder();
       ProtobufUtil.mergeDelimitedFrom(builder, in);
       ClientProtos.Result proto = builder.build();
       return ProtobufUtil.toResult(proto, true);
     }
 
     @Override
     public void open(InputStream in) throws IOException {
       this.in = in;
     }
   }
 
   private static class ResultSerializer implements Serializer<Result> {
     private OutputStream out;
 
     @Override
     public void close() throws IOException {
       out.close();
     }
 
     @Override
     public void open(OutputStream out) throws IOException {
       this.out = out;
     }
 
     @Override
     public void serialize(Result result) throws IOException {
       ProtobufUtil.toResult(result, true).writeDelimitedTo(out);
     }
   }
 }