/*
 * Copyright (c) 2013 DataTorrent, Inc. ALL Rights Reserved.
 *
 * Licensed 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.multiwindow;

import com.datatorrent.api.annotation.OperatorAnnotation;
import com.datatorrent.lib.math.SumKeyVal;
import com.datatorrent.lib.util.KeyValPair;

import java.util.Map;
import javax.validation.constraints.Min;

/**
 * A sum operator of KeyValPair schema which accumulates sum across multiple
 * streaming windows.
 * <p>
 * This is an end window operator which emits only at Nth window. <br>
 * <br>
 * <b>StateFull : Yes, </b> sum is computed across streaming windows.  <br>
 * <b>Partitions : No, </b> sum is not unified at output port. <br>
 * <br>
 * <b>Ports</b>:<br>
 * <b>data</b>: expects KeyValPair&lt;K,V extends Number&gt;<br>
 * <b>sum</b>: emits KeyValPair&lt;K,V&gt;<br>
 * <b>count</b>: emits KeyValPair&lt;K,Integer&gt;</b><br>
 * <br>
 * <b>Properties</b>:<br>
 * <b>inverse</b>: If set to true the key in the filter will block tuple.<br>
 * <b>filterBy</b>: List of keys to filter on.<br>
 * <b>windowSize i.e. N</b>: Number of streaming windows that define application
 * window.<br>
 * <br>
 * @displayName Multi Window Sum Key Value
 * @category Multi-Window
 * @tags key value, sum, numeric
 * @since 0.3.3
 */
@OperatorAnnotation(partitionable = false)
public class MultiWindowSumKeyVal<K, V extends Number> extends SumKeyVal<K, V>
{
	/**
	 * Number of streaming window after which tuple got emitted.
	 */
	@Min(2)
	private int windowSize = 2;
	private long windowCount = 0;

	public void setWindowSize(int windowSize)
	{
		this.windowSize = windowSize;
	}

	/**
	 * Emit only at the end of windowSize window boundary.
	 */
	@SuppressWarnings({ "unchecked", "rawtypes" })
	@Override
	public void endWindow()
	{
		boolean emit = (++windowCount) % windowSize == 0;

		if (!emit) {
			return;
		}

		// Emit only at the end of application window boundary.
		boolean dosum = sum.isConnected();

		if (dosum) {
			for (Map.Entry<K, SumEntry> e : sums.entrySet()) {
				K key = e.getKey();
				if (dosum) {
					sum.emit(new KeyValPair(key, getValue(e.getValue().sum.doubleValue())));
				}
			}
		}

		// Clear cumulative sum at the end of application window boundary.
		sums.clear();
	}
}