/*
    *
    * 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.client.coprocessor;
  
  import java.io.IOException;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
  import org.apache.hadoop.hbase.coprocessor.ColumnInterpreter;
  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.EmptyMsg;
  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.LongMsg;
  import org.apache.hadoop.hbase.util.Bytes;
  
  /**
   * a concrete column interpreter implementation. The cell value is a Long value
   * and its promoted data type is also a Long value. For computing aggregation
   * function, this class is used to find the datatype of the cell value. Client
   * is supposed to instantiate it and passed along as a parameter. See
   * TestAggregateProtocol methods for its sample usage.
   * Its methods handle null arguments gracefully. 
   */
  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)
  @InterfaceStability.Evolving
  public class LongColumnInterpreter extends ColumnInterpreter<Long, Long,
                   EmptyMsg, LongMsg, LongMsg> {
  
    @Override
    public Long getValue(byte[] colFamily, byte[] colQualifier, Cell kv)
        throws IOException {
      if (kv == null || kv.getValueLength() != Bytes.SIZEOF_LONG)
        return null;
      return Bytes.toLong(kv.getValueArray(), kv.getValueOffset());
    }
  
    @Override
    public Long add(Long l1, Long l2) {
      if (l1 == null ^ l2 == null) {
        return (l1 == null) ? l2 : l1; // either of one is null.
      } else if (l1 == null) // both are null
        return null;
      return l1 + l2;
    }
  
    @Override
    public int compare(final Long l1, final Long l2) {
      if (l1 == null ^ l2 == null) {
        return l1 == null ? -1 : 1; // either of one is null.
      } else if (l1 == null)
        return 0; // both are null
      return l1.compareTo(l2); // natural ordering.
    }
  
    @Override
    public Long getMaxValue() {
      return Long.MAX_VALUE;
    }
  
    @Override
    public Long increment(Long o) {
      return o == null ? null : (o + 1l);
    }
  
    @Override
    public Long multiply(Long l1, Long l2) {
      return (l1 == null || l2 == null) ? null : l1 * l2;
    }
  
    @Override
    public Long getMinValue() {
      return Long.MIN_VALUE;
    }
  
    @Override
    public double divideForAvg(Long l1, Long l2) {
      return (l2 == null || l1 == null) ? Double.NaN : (l1.doubleValue() / l2
          .doubleValue());
    }
  
    @Override
    public Long castToReturnType(Long o) {
      return o;
   }
 
   @Override
   public Long castToCellType(Long l) {
     return l;
   }
 
   @Override
   public EmptyMsg getRequestData() {
     return EmptyMsg.getDefaultInstance();
   }
 
   @Override
   public void initialize(EmptyMsg msg) {
     //nothing 
   }
 
   @Override
   public LongMsg getProtoForCellType(Long t) {
     LongMsg.Builder builder = LongMsg.newBuilder();
     return builder.setLongMsg(t).build();
   }
 
   @Override
   public LongMsg getProtoForPromotedType(Long s) {
     LongMsg.Builder builder = LongMsg.newBuilder();
     return builder.setLongMsg(s).build();
   }
 
   @Override
   public Long getPromotedValueFromProto(LongMsg r) {
     return r.getLongMsg();
   }
 
   @Override
   public Long getCellValueFromProto(LongMsg q) {
     return q.getLongMsg();
   }
 }