/*
    * 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.io.encoding;
  
  import java.io.DataInputStream;
  import java.io.DataOutputStream;
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.KeyValue;
  import org.apache.hadoop.hbase.KeyValue.KVComparator;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.util.ByteBufferUtils;
  import org.apache.hadoop.hbase.util.Bytes;
  
  /**
   * Store cells following every row's start offset, so we can binary search to a row's cells.
   *
   * Format:
   * flat cells
   * integer: number of rows
   * integer: row0's offset
   * integer: row1's offset
   * ....
   * integer: dataSize
   *
  */
  @InterfaceAudience.Private
  public class RowIndexCodecV1 extends AbstractDataBlockEncoder {
  
    private static class RowIndexEncodingState extends EncodingState {
      RowIndexEncoderV1 encoder = null;
    }
  
    @Override
    public void startBlockEncoding(HFileBlockEncodingContext blkEncodingCtx,
        DataOutputStream out) throws IOException {
      if (blkEncodingCtx.getClass() != HFileBlockDefaultEncodingContext.class) {
        throw new IOException(this.getClass().getName() + " only accepts "
            + HFileBlockDefaultEncodingContext.class.getName() + " as the "
            + "encoding context.");
      }
  
      HFileBlockDefaultEncodingContext encodingCtx = (HFileBlockDefaultEncodingContext) blkEncodingCtx;
      encodingCtx.prepareEncoding(out);
  
      RowIndexEncoderV1 encoder = new RowIndexEncoderV1(out, encodingCtx);
      RowIndexEncodingState state = new RowIndexEncodingState();
      state.encoder = encoder;
      blkEncodingCtx.setEncodingState(state);
    }
  
    @Override
    public int encode(Cell cell, HFileBlockEncodingContext encodingCtx,
        DataOutputStream out) throws IOException {
      RowIndexEncodingState state = (RowIndexEncodingState) encodingCtx
          .getEncodingState();
      RowIndexEncoderV1 encoder = state.encoder;
      return encoder.write(cell);
    }
  
    @Override
    public void endBlockEncoding(HFileBlockEncodingContext encodingCtx,
        DataOutputStream out, byte[] uncompressedBytesWithHeader)
        throws IOException {
      RowIndexEncodingState state = (RowIndexEncodingState) encodingCtx
          .getEncodingState();
      RowIndexEncoderV1 encoder = state.encoder;
      encoder.flush();
      postEncoding(encodingCtx);
    }
  
    @Override
    public ByteBuffer decodeKeyValues(DataInputStream source,
        HFileBlockDecodingContext decodingCtx) throws IOException {
      if (!decodingCtx.getHFileContext().isIncludesTags()) {
        ByteBuffer sourceAsBuffer = ByteBufferUtils
            .drainInputStreamToBuffer(source);// waste
        sourceAsBuffer.mark();
        sourceAsBuffer.position(sourceAsBuffer.limit() - Bytes.SIZEOF_INT);
        int onDiskSize = sourceAsBuffer.getInt();
        sourceAsBuffer.reset();
       ByteBuffer dup = sourceAsBuffer.duplicate();
       dup.position(sourceAsBuffer.position());
       dup.limit(sourceAsBuffer.position() + onDiskSize);
       return dup.slice();
     } else {
       ByteBuffer sourceAsBuffer = ByteBufferUtils
           .drainInputStreamToBuffer(source);// waste
       sourceAsBuffer.mark();
       RowIndexSeekerV1 seeker = new RowIndexSeekerV1(KeyValue.COMPARATOR,
           decodingCtx);
       seeker.setCurrentBuffer(sourceAsBuffer);
       List<ByteBuffer> kvs = new ArrayList<ByteBuffer>();
       kvs.add(seeker.getKeyValueBuffer());
       while (seeker.next()) {
         kvs.add(seeker.getKeyValueBuffer());
       }
       int totalLength = 0;
       for (ByteBuffer buf : kvs) {
         totalLength += buf.remaining();
       }
       byte[] keyValueBytes = new byte[totalLength];
       ByteBuffer result = ByteBuffer.wrap(keyValueBytes);
       for (ByteBuffer buf : kvs) {
         result.put(buf);
       }
       return result;
     }
   }
 
   @Override
   public ByteBuffer getFirstKeyInBlock(ByteBuffer block) {
     block.mark();
     int keyLength = block.getInt();
     block.getInt();
     int pos = block.position();
     block.reset();
     ByteBuffer dup = block.duplicate();
     dup.position(pos);
     dup.limit(pos + keyLength);
     return dup.slice();
   }
 
   @Override
   public EncodedSeeker createSeeker(KVComparator comparator,
       HFileBlockDecodingContext decodingCtx) {
     return new RowIndexSeekerV1(comparator, decodingCtx);
   }
 
 }