/*
    * 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.Cell;
  import org.apache.hadoop.hbase.CellUtil;
  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.FilterProtos;
  import org.apache.hadoop.hbase.util.ByteStringer;
  import org.apache.hadoop.hbase.util.Bytes;
  
  import com.google.protobuf.ByteString;
  import com.google.protobuf.InvalidProtocolBufferException;
  
  import java.util.Objects;
  import java.util.Set;
  import java.util.TreeSet;
  
  /**
   * The filter looks for the given columns in KeyValue. Once there is a match for
   * any one of the columns, it returns ReturnCode.NEXT_ROW for remaining
   * KeyValues in the row.
   * <p>
   * Note : It may emit KVs which do not have the given columns in them, if
   * these KVs happen to occur before a KV which does have a match. Given this
   * caveat, this filter is only useful for special cases
   * like {@link org.apache.hadoop.hbase.mapreduce.RowCounter}.
   * <p>
   */
  @InterfaceAudience.Public
  @InterfaceStability.Stable
  public class FirstKeyValueMatchingQualifiersFilter extends FirstKeyOnlyFilter {
  
    private Set<byte []> qualifiers;
  
    /**
     * Constructor which takes a set of columns. As soon as first KeyValue
     * matching any of these columns is found, filter moves to next row.
     * 
     * @param qualifiers the set of columns to me matched.
     */
    public FirstKeyValueMatchingQualifiersFilter(Set<byte []> qualifiers) {
      this.qualifiers = qualifiers;
    }
  
    @Override
    public ReturnCode filterKeyValue(Cell v) {
      if (hasFoundKV()) {
        return ReturnCode.NEXT_ROW;
      } else if (hasOneMatchingQualifier(v)) {
        setFoundKV(true);
      }
      return ReturnCode.INCLUDE;
    }
  
    private boolean hasOneMatchingQualifier(Cell v) {
      for (byte[] q : qualifiers) {
        if (CellUtil.matchingQualifier(v, q)) {
          return true;
        }
      }
      return false;
    }
  
    /**
     * @return The filter serialized using pb
     */
    @Override
    public byte [] toByteArray() {
      FilterProtos.FirstKeyValueMatchingQualifiersFilter.Builder builder =
        FilterProtos.FirstKeyValueMatchingQualifiersFilter.newBuilder();
      for (byte[] qualifier : qualifiers) {
        if (qualifier != null) builder.addQualifiers(ByteStringer.wrap(qualifier));
      }
      return builder.build().toByteArray();
    }
  
    /**
     * @param pbBytes A pb serialized {@link FirstKeyValueMatchingQualifiersFilter} instance
     * @return An instance of {@link FirstKeyValueMatchingQualifiersFilter} made from <code>bytes</code>
     * @throws DeserializationException
    * @see #toByteArray
    */
   public static FirstKeyValueMatchingQualifiersFilter parseFrom(final byte [] pbBytes)
   throws DeserializationException {
     FilterProtos.FirstKeyValueMatchingQualifiersFilter proto;
     try {
       proto = FilterProtos.FirstKeyValueMatchingQualifiersFilter.parseFrom(pbBytes);
     } catch (InvalidProtocolBufferException e) {
       throw new DeserializationException(e);
     }
 
     TreeSet<byte []> qualifiers = new TreeSet<byte []>(Bytes.BYTES_COMPARATOR);
     for (ByteString qualifier : proto.getQualifiersList()) {
       qualifiers.add(qualifier.toByteArray());
     }
     return new FirstKeyValueMatchingQualifiersFilter(qualifiers);
   }
 
   /**
    * @param other
    * @return true if and only if the fields of the filter that are serialized
    * are equal to the corresponding fields in other.  Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
     if (o == this) return true;
     if (!(o instanceof FirstKeyValueMatchingQualifiersFilter)) return false;
 
     FirstKeyValueMatchingQualifiersFilter other = (FirstKeyValueMatchingQualifiersFilter)o;
     return this.qualifiers.equals(other.qualifiers);
   }
 
   @Override
   public boolean equals(Object obj) {
     return obj instanceof Filter && areSerializedFieldsEqual((Filter) obj);
   }
 
   @Override
   public int hashCode() {
     return Objects.hash(this.qualifiers);
   }
 }