/*
    *
    * 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.filter;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.hbase.exceptions.DeserializationException;
  import org.apache.hadoop.hbase.protobuf.generated.ComparatorProtos;
  
  import com.google.protobuf.InvalidProtocolBufferException;
  
  /**
   * A binary comparator which lexicographically compares against the specified
   * byte array using {@link org.apache.hadoop.hbase.util.Bytes#compareTo(byte[], byte[])}.
   */
  @InterfaceAudience.Public
  @InterfaceStability.Stable
  public class NullComparator extends ByteArrayComparable {
  
    public NullComparator() {
      super(new byte[0]);
    }
  
    @Override
    public int compareTo(byte[] value) {
      return value != null ? 1 : 0;
    }
  
    @Override
    @edu.umd.cs.findbugs.annotations.SuppressWarnings (value="EQ_UNUSUAL", justification="")
    public boolean equals(Object obj) {
      return obj == null;
    }
  
    @Override
    public int hashCode() {
      return 0;
    }
  
    @Override
    public int compareTo(byte[] value, int offset, int length) {
      return compareTo(value);
    }
  
    /**
     * @return The comparator serialized using pb
     */
    public byte [] toByteArray() {
      ComparatorProtos.NullComparator.Builder builder =
        ComparatorProtos.NullComparator.newBuilder();
      return builder.build().toByteArray();
    }
  
    /**
     * @param pbBytes A pb serialized {@link NullComparator} instance
     * @return An instance of {@link NullComparator} made from <code>bytes</code>
     * @throws DeserializationException
     * @see #toByteArray
     */
    public static NullComparator parseFrom(final byte [] pbBytes)
    throws DeserializationException {
      try {
        // Just parse.  Don't use what we parse since on end we are returning new NullComparator.
        ComparatorProtos.NullComparator.parseFrom(pbBytes);
      } catch (InvalidProtocolBufferException e) {
        throw new DeserializationException(e);
      }
      return new NullComparator();
    }
  
    /**
     * @param other
     * @return true if and only if the fields of the comparator that are serialized
     * are equal to the corresponding fields in other.  Used for testing.
     */
    boolean areSerializedFieldsEqual(ByteArrayComparable other) {
      if (other == this) return true;
      if (!(other instanceof NullComparator)) return false;
  
      return super.areSerializedFieldsEqual(other);
    }
  }