/**
    *
    * 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;
  
  import java.nio.ByteBuffer;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.util.ByteBufferUtils;
  import org.apache.hadoop.hbase.util.Bytes;
  
  /**
   * This is a key only Cell implementation which is identical to {@link KeyValue.KeyOnlyKeyValue}
   * with respect to key serialization but have its data in the form of Byte buffer
   * (onheap and offheap).
   */
  @InterfaceAudience.Private
  public class ByteBufferedKeyOnlyKeyValue extends ByteBufferedCell {
  
    private ByteBuffer buf;
    private int offset = 0; // offset into buffer where key starts at
    private int length = 0; // length of this.
    private short rowLen;
  
    /**
     * Used in cases where we want to avoid lot of garbage by allocating new objects with different
     * keys. Use the emtpy construtor and set the keys using {@link #setKey(ByteBuffer, int, int)}
     */
    public ByteBufferedKeyOnlyKeyValue() {
    }
  
    public ByteBufferedKeyOnlyKeyValue(ByteBuffer buf, int offset, int length) {
      setKey(buf, offset, length);
    }
  
    /**
     * A setter that helps to avoid object creation every time and whenever
     * there is a need to create new OffheapKeyOnlyKeyValue.
     * @param key
     * @param offset
     * @param length
     */
    public void setKey(ByteBuffer key, int offset, int length) {
      this.buf = key;
      this.offset = offset;
      this.length = length;
      this.rowLen = ByteBufferUtils.toShort(this.buf, this.offset);
    }
  
    @Override
    public byte[] getRowArray() {
      if (this.buf.hasArray()) {
        return this.buf.array();
      }
      return CellUtil.cloneRow(this);
    }
  
    @Override
    public int getRowOffset() {
      if (this.buf.hasArray()) {
        return getRowPosition() + this.buf.arrayOffset();
      }
      return 0;
    }
  
    @Override
    public short getRowLength() {
      return this.rowLen;
    }
  
    @Override
    public byte[] getFamilyArray() {
      if (this.buf.hasArray()) {
        return this.buf.array();
      }
      return CellUtil.cloneFamily(this);
    }
  
    @Override
    public int getFamilyOffset() {
      if (this.buf.hasArray()) {
        return getFamilyPosition() + this.buf.arrayOffset();
      }
      return 0;
   }
 
   @Override
   public byte getFamilyLength() {
     return getFamilyLength(getFamilyLengthPosition());
   }
 
   private byte getFamilyLength(int famLenPos) {
     return ByteBufferUtils.toByte(this.buf, famLenPos);
   }
 
   @Override
   public byte[] getQualifierArray() {
     if (this.buf.hasArray()) {
       return this.buf.array();
     }
     return CellUtil.cloneQualifier(this);
   }
 
   @Override
   public int getQualifierOffset() {
     if (this.buf.hasArray()) {
       return getQualifierPosition() + this.buf.arrayOffset();
     }
     return 0;
   }
 
   @Override
   public int getQualifierLength() {
     return getQualifierLength(getRowLength(), getFamilyLength());
   }
 
   private int getQualifierLength(int rlength, int flength) {
     return this.length - (int) KeyValue.getKeyDataStructureSize(rlength, flength, 0);
   }
 
   @Override
   public long getTimestamp() {
     return ByteBufferUtils.toLong(this.buf, getTimestampOffset());
   }
 
   private int getTimestampOffset() {
     return this.offset + this.length - KeyValue.TIMESTAMP_TYPE_SIZE;
   }
 
   @Override
   public byte getTypeByte() {
     return ByteBufferUtils.toByte(this.buf, this.offset + this.length - 1);
   }
 
   @Override
   public long getSequenceId() {
     return 0;
   }
 
   @Override
   public byte[] getValueArray() {
     throw new IllegalArgumentException("This is a key only Cell");
   }
 
   @Override
   public int getValueOffset() {
     return 0;
   }
 
   @Override
   public int getValueLength() {
     return 0;
   }
 
   @Override
   public byte[] getTagsArray() {
     throw new IllegalArgumentException("This is a key only Cell");
   }
 
   @Override
   public int getTagsOffset() {
     return 0;
   }
 
   @Override
   public int getTagsLength() {
     return 0;
   }
 
   @Override
   public ByteBuffer getRowByteBuffer() {
     return this.buf;
   }
 
   @Override
   public int getRowPosition() {
     return this.offset + Bytes.SIZEOF_SHORT;
   }
 
   @Override
   public ByteBuffer getFamilyByteBuffer() {
     return this.buf;
   }
 
   @Override
   public int getFamilyPosition() {
     return getFamilyLengthPosition() + Bytes.SIZEOF_BYTE;
   }
 
   // The position in BB where the family length is added.
   private int getFamilyLengthPosition() {
     return this.offset + Bytes.SIZEOF_SHORT + getRowLength();
   }
 
   @Override
   public ByteBuffer getQualifierByteBuffer() {
     return this.buf;
   }
 
   @Override
   public int getQualifierPosition() {
     int famLenPos = getFamilyLengthPosition();
     return famLenPos + Bytes.SIZEOF_BYTE + getFamilyLength(famLenPos);
   }
 
   @Override
   public ByteBuffer getValueByteBuffer() {
     throw new IllegalArgumentException("This is a key only Cell");
   }
 
   @Override
   public int getValuePosition() {
     return 0;
   }
 
   @Override
   public ByteBuffer getTagsByteBuffer() {
     throw new IllegalArgumentException("This is a key only Cell");
   }
 
   @Override
   public int getTagsPosition() {
     return 0;
   }
 
   @Override
   public String toString() {
     return CellUtil.toString(this, false);
   }
 }