/*
    * 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.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.io.encoding.DataBlockEncoder;
  import org.apache.hadoop.hbase.io.encoding.DataBlockEncoding;
  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.hfile.HFile.FileInfo;
  import org.apache.hadoop.hbase.util.Bytes;
  
  /**
   * Do different kinds of data block encoding according to column family
   * options.
   */
  @InterfaceAudience.Private
  public class HFileDataBlockEncoderImpl implements HFileDataBlockEncoder {
    private final DataBlockEncoding encoding;
  
    /**
     * Do data block encoding with specified options.
     * @param encoding What kind of data block encoding will be used.
     */
    public HFileDataBlockEncoderImpl(DataBlockEncoding encoding) {
      this.encoding = encoding != null ? encoding : DataBlockEncoding.NONE;
    }
  
    public static HFileDataBlockEncoder createFromFileInfo(
        FileInfo fileInfo) throws IOException {
      DataBlockEncoding encoding = DataBlockEncoding.NONE;
      byte[] dataBlockEncodingType = fileInfo.get(DATA_BLOCK_ENCODING);
      if (dataBlockEncodingType != null) {
        String dataBlockEncodingStr = Bytes.toString(dataBlockEncodingType);
        try {
          encoding = DataBlockEncoding.valueOf(dataBlockEncodingStr);
        } catch (IllegalArgumentException ex) {
          throw new IOException("Invalid data block encoding type in file info: "
            + dataBlockEncodingStr, ex);
        }
      }
  
      if (encoding == DataBlockEncoding.NONE) {
        return NoOpDataBlockEncoder.INSTANCE;
      }
      return new HFileDataBlockEncoderImpl(encoding);
    }
  
    @Override
    public void saveMetadata(HFile.Writer writer) throws IOException {
      writer.appendFileInfo(DATA_BLOCK_ENCODING, encoding.getNameInBytes());
    }
  
    @Override
    public DataBlockEncoding getDataBlockEncoding() {
      return encoding;
    }
  
    public boolean useEncodedScanner(boolean isCompaction) {
      if (isCompaction && encoding == DataBlockEncoding.NONE) {
        return false;
      }
      return encoding != DataBlockEncoding.NONE;
    }
  
    @Override
    public DataBlockEncoding getEffectiveEncodingInCache(boolean isCompaction) {
      if (!useEncodedScanner(isCompaction)) {
        return DataBlockEncoding.NONE;
      }
      return encoding;
    }
  
    @Override
    public int encode(Cell cell, HFileBlockEncodingContext encodingCtx, DataOutputStream out)
        throws IOException {
      return this.encoding.getEncoder().encode(cell, encodingCtx, out);
    }
  
   @Override
   public boolean useEncodedScanner() {
     return encoding != DataBlockEncoding.NONE;
   }
 
 
   @Override
   public String toString() {
     return getClass().getSimpleName() + "(encoding=" + encoding + ")";
   }
 
   @Override
   public HFileBlockEncodingContext newDataBlockEncodingContext(
       byte[] dummyHeader, HFileContext fileContext) {
     DataBlockEncoder encoder = encoding.getEncoder();
     if (encoder != null) {
       return encoder.newDataBlockEncodingContext(encoding, dummyHeader, fileContext);
     }
     return new HFileBlockDefaultEncodingContext(null, dummyHeader, fileContext);
   }
 
   @Override
   public HFileBlockDecodingContext newDataBlockDecodingContext(HFileContext fileContext) {
     DataBlockEncoder encoder = encoding.getEncoder();
     if (encoder != null) {
       return encoder.newDataBlockDecodingContext(fileContext);
     }
     return new HFileBlockDefaultDecodingContext(fileContext);
   }
 
   @Override
   public void startBlockEncoding(HFileBlockEncodingContext encodingCtx, DataOutputStream out)
       throws IOException {
     if (this.encoding != null && this.encoding != DataBlockEncoding.NONE) {
       this.encoding.getEncoder().startBlockEncoding(encodingCtx, out);
     }
   }
 
   @Override
   public void endBlockEncoding(HFileBlockEncodingContext encodingCtx, DataOutputStream out,
       byte[] uncompressedBytesWithHeader, BlockType blockType) throws IOException {
     this.encoding.getEncoder().endBlockEncoding(encodingCtx, out, uncompressedBytesWithHeader);
   }
 }