/*
    * 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.hfile;
  
  import java.io.DataOutputStream;
  import java.io.IOException;
  
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.io.encoding.DataBlockEncoding;
  import org.apache.hadoop.hbase.io.encoding.EncodingState;
  import org.apache.hadoop.hbase.io.encoding.HFileBlockDecodingContext;
  import org.apache.hadoop.hbase.io.encoding.HFileBlockDefaultDecodingContext;
  import org.apache.hadoop.hbase.io.encoding.HFileBlockDefaultEncodingContext;
  import org.apache.hadoop.hbase.io.encoding.HFileBlockEncodingContext;
  import org.apache.hadoop.hbase.io.encoding.NoneEncoder;
  
  /**
   * Does not perform any kind of encoding/decoding.
   */
  @InterfaceAudience.Private
  public class NoOpDataBlockEncoder implements HFileDataBlockEncoder {
  
    public static final NoOpDataBlockEncoder INSTANCE =
        new NoOpDataBlockEncoder();
  
    private static class NoneEncodingState extends EncodingState {
      NoneEncoder encoder = null;
    }
  
    /** Cannot be instantiated. Use {@link #INSTANCE} instead. */
    private NoOpDataBlockEncoder() {
    }
  
    @Override
    public int encode(Cell cell, HFileBlockEncodingContext encodingCtx,
        DataOutputStream out) throws IOException {
      NoneEncodingState state = (NoneEncodingState) encodingCtx
          .getEncodingState();
      NoneEncoder encoder = state.encoder;
      return encoder.write(cell);
    }
  
    @Override
    public boolean useEncodedScanner() {
      return false;
    }
  
    @Override
    public void saveMetadata(HFile.Writer writer) {
    }
  
    @Override
    public DataBlockEncoding getDataBlockEncoding() {
      return DataBlockEncoding.NONE;
    }
  
    @Override
    public DataBlockEncoding getEffectiveEncodingInCache(boolean isCompaction) {
      return DataBlockEncoding.NONE;
    }
    
    @Override
    public String toString() {
      return getClass().getSimpleName();
    }
  
    @Override
    public HFileBlockEncodingContext newDataBlockEncodingContext(
        byte[] dummyHeader, HFileContext meta) {
      return new HFileBlockDefaultEncodingContext(null, dummyHeader, meta);
    }
  
    @Override
    public HFileBlockDecodingContext newDataBlockDecodingContext(HFileContext meta) {
      return new HFileBlockDefaultDecodingContext(meta);
    }
  
    @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);
 
     NoneEncoder encoder = new NoneEncoder(out, encodingCtx);
     NoneEncodingState state = new NoneEncodingState();
     state.encoder = encoder;
     blkEncodingCtx.setEncodingState(state);
   }
 
   @Override
   public void endBlockEncoding(HFileBlockEncodingContext encodingCtx, DataOutputStream out,
       byte[] uncompressedBytesWithHeader, BlockType blockType) throws IOException {
     encodingCtx.postEncoding(BlockType.DATA);
   }
 }