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/**
 * 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 com.datatorrent.lib.algo;

import java.util.HashMap;
import java.util.Map;

import com.datatorrent.api.DefaultInputPort;
import com.datatorrent.api.DefaultOutputPort;
import com.datatorrent.api.annotation.OperatorAnnotation;

import com.datatorrent.lib.util.BaseMatchOperator;

/**
 * This operator filters the incoming stream of key value pairs by obtaining the values corresponding to a specified key,
 * and comparing those values to a specified value. The last key value pair, in each window, to satisfy the comparison is emitted.
 * 
 * A compare function is  operated on a tuple value sub-classed from Number based on the property "key", "value", and "cmp". Every tuple
 * is checked and the last one that passes the condition is send during end of window on port "last". The comparison is done by getting double
 * value from the Number.
 * 
 * 
 * This module is an end of window module

 * 

 * StateFull : Yes,  tuple are compare across application window(s). 

 * Partitions : No,  will yield wrong result. 

 * 

 * Ports:

 * data: expects Map<K,V extends Number>

 * last: emits Map<K,V> in end of window for the last tuple on which the compare function is true

 * 

 * Properties:

 * key: The key on which compare is done

 * value: The value to compare with

 * cmp: The compare function. Supported values are "lte", "lt", "eq", "neq", "gt", "gte". Default is "eq"

 * 

 * Specific compile time checks:

 * Key must be non empty

 * Value must be able to convert to a "double"

 * Compare string, if specified, must be one of "lte", "lt", "eq", "neq", "gt", "gte"

 * 

 * 
 *
 * @displayName Emit Last Match (Number)
 * @category Rules and Alerts
 * @tags filter, key value, numeric
 *
 * @since 0.3.2
 */
@OperatorAnnotation(partitionable = false)
public class LastMatchMap extends BaseMatchOperator
{
  /**
   * Last tuple.
   */
  protected HashMap ltuple = null;

  /**
   * The input port on which key value pairs are received.
   */
  public final transient DefaultInputPort> data = new DefaultInputPort>()
  {
    /**
     * Processes tuples and keeps a copy of last matched tuple
     */
    @Override
    public void process(Map tuple)
    {
      V val = tuple.get(getKey());
      if (val == null) {
        return;
      }
      if (compareValue(val.doubleValue())) {
        ltuple = cloneTuple(tuple);
      }
    }
  };

  /**
   * The output port on which the last key value pair to satisfy the comparison function is emitted.
   */
  public final transient DefaultOutputPort> last = new DefaultOutputPort>();

  /**
   * Emits last matching tuple
   */
  @Override
  public void endWindow()
  {
    if (ltuple != null) {
      last.emit(ltuple);
    }
    ltuple = null;
  }
}