/*
    * 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.util;
  
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  
  import com.google.common.annotations.VisibleForTesting;
  
  /**
   * Extends the basic {@link SimpleByteRange} implementation with position
   * support. {@code position} is considered transient, not fundamental to the
   * definition of the range, and does not participate in
   * {@link #compareTo(ByteRange)}, {@link #hashCode()}, or
   * {@link #equals(Object)}. {@code Position} is retained by copy operations.
   */
  @InterfaceAudience.Private
  @InterfaceStability.Evolving
  public abstract class AbstractPositionedByteRange extends AbstractByteRange implements
      PositionedByteRange {
    /**
     * The current index into the range. Like {@link java.nio.ByteBuffer} position, it
     * points to the next value that will be read/written in the array. It
     * provides the appearance of being 0-indexed, even though its value is
     * calculated according to offset.
     * <p>
     * Position is considered transient and does not participate in
     * {@link #equals(Object)} or {@link #hashCode()} comparisons.
     * </p>
     */
    protected int position = 0;
  
    protected int limit = 0;
  
    @Override
    public abstract PositionedByteRange unset();
  
    @Override
    public PositionedByteRange set(int capacity) {
      this.position = 0;
      super.set(capacity);
      this.limit = capacity;
      return this;
    }
  
    @Override
    public PositionedByteRange set(byte[] bytes) {
      this.position = 0;
      super.set(bytes);
      this.limit = bytes.length;
      return this;
    }
  
    @Override
    public PositionedByteRange set(byte[] bytes, int offset, int length) {
      this.position = 0;
      super.set(bytes, offset, length);
      limit = length;
      return this;
    }
  
    /**
     * Update the beginning of this range. {@code offset + length} may not be
     * greater than {@code bytes.length}. Resets {@code position} to 0.
     *
     * @param offset
     *          the new start of this range.
     * @return this.
     */
    @Override
    public PositionedByteRange setOffset(int offset) {
      this.position = 0;
      super.setOffset(offset);
      return this;
    }
  
    /**
     * Update the length of this range. {@code offset + length} should not be
     * greater than {@code bytes.length}. If {@code position} is greater than the
     * new {@code length}, sets {@code position} to {@code length}.
     *
     * @param length
     *          The new length of this range.
    * @return this.
    */
   @Override
   public PositionedByteRange setLength(int length) {
     this.position = Math.min(position, length);
     super.setLength(length);
     return this;
   }
 
   @Override
   public int getPosition() {
     return position;
   }
 
   @Override
   public PositionedByteRange setPosition(int position) {
     this.position = position;
     return this;
   }
 
   @Override
   public int getRemaining() {
     return length - position;
   }
 
   @Override
   public byte peek() {
     return bytes[offset + position];
   }
 
   @Override
   public byte get() {
     return get(position++);
   }
 
   @Override
   public PositionedByteRange get(byte[] dst) {
     if (0 == dst.length)
       return this;
     return this.get(dst, 0, dst.length); // be clear we're calling self, not
                                          // super
   }
 
   @Override
   public PositionedByteRange get(byte[] dst, int offset, int length) {
     if (0 == length)
       return this;
     super.get(this.position, dst, offset, length);
     this.position += length;
     return this;
   }
 
   @Override
   public abstract PositionedByteRange put(byte val);
 
   @Override
   public abstract PositionedByteRange put(byte[] val);
 
   @Override
   public abstract PositionedByteRange put(byte[] val, int offset, int length);
 
   @Override
   public abstract PositionedByteRange putInt(int index, int val);
 
   @Override
   public abstract PositionedByteRange putLong(int index, long val);
 
   @Override
   public abstract PositionedByteRange putShort(int index, short val);
 
   @Override
   public abstract PositionedByteRange putInt(int val);
 
   @Override
   public abstract PositionedByteRange putLong(long val);
 
   @Override
   public abstract PositionedByteRange putShort(short val);
 
   @Override
   public abstract int putVLong(int index, long val);
 
   @Override
   public abstract int putVLong(long val);
   /**
    * Similar to {@link java.nio.ByteBuffer#flip()}. Sets length to position, position to
    * offset.
    */
   @VisibleForTesting
   PositionedByteRange flip() {
     clearHashCache();
     length = position;
     position = offset;
     return this;
   }
 
   /**
    * Similar to {@link java.nio.ByteBuffer#clear()}. Sets position to 0, length to
    * capacity.
    */
   @VisibleForTesting
   PositionedByteRange clear() {
     clearHashCache();
     position = 0;
     length = bytes.length - offset;
     return this;
   }
 
   // java boilerplate
 
   @Override
   public PositionedByteRange get(int index, byte[] dst) {
     super.get(index, dst);
     return this;
   }
 
   @Override
   public PositionedByteRange get(int index, byte[] dst, int offset, int length) {
     super.get(index, dst, offset, length);
     return this;
   }
 
   @Override
   public short getShort() {
     short s = getShort(position);
     position += Bytes.SIZEOF_SHORT;
     return s;
   }
 
   @Override
   public int getInt() {
     int i = getInt(position);
     position += Bytes.SIZEOF_INT;
     return i;
   }
 
   @Override
   public long getLong() {
     long l = getLong(position);
     position += Bytes.SIZEOF_LONG;
     return l;
   }
 
   @Override
   public long getVLong() {
     long p = getVLong(position);
     position += getVLongSize(p);
     return p;
   }
 
   @Override
   public abstract PositionedByteRange put(int index, byte val);
 
   @Override
   public abstract PositionedByteRange put(int index, byte[] val);
 
   @Override
   public abstract PositionedByteRange put(int index, byte[] val, int offset, int length);
 
   @Override
   public abstract PositionedByteRange deepCopy();
 
   @Override
   public abstract PositionedByteRange shallowCopy();
 
   @Override
   public abstract PositionedByteRange shallowCopySubRange(int innerOffset, int copyLength);
 
   @Override
   public PositionedByteRange setLimit(int limit) {
     this.limit = limit;
     return this;
   }
 
   @Override
   public int getLimit() {
     return this.limit;
   }
 }