/*
 * 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.flink.table.runtime.window.internal;

import org.apache.flink.table.api.window.Window;
import org.apache.flink.table.dataformat.BaseRow;
import org.apache.flink.table.runtime.functions.SubKeyedAggsHandleFunction;
import org.apache.flink.table.runtime.window.assigners.WindowAssigner;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

/**
 * The general implementation of {@link InternalWindowProcessFunction}. The {@link WindowAssigner}
 * should be a regular assigner without implement {@code PanedWindowAssigner} or {@code MergingWindowAssigner}.
 * @param <W> The type of {@code Window} that assigner assigns.
 */
public class GeneralWindowProcessFunction<K, W extends Window>
	extends InternalWindowProcessFunction<K, W> {

	private static final long serialVersionUID = 5992545519395844485L;

	private List<W> reuseAffectedWindows;

	public GeneralWindowProcessFunction(
		WindowAssigner<W> windowAssigner,
		SubKeyedAggsHandleFunction<W> windowAggregator,
		long allowedLateness) {

		super(windowAssigner, windowAggregator, allowedLateness);
	}

	@Override
	public Collection<W> assignStateNamespace(BaseRow inputRow, long timestamp) throws Exception {
		Collection<W> elementWindows = windowAssigner.assignWindows(inputRow, timestamp);
		reuseAffectedWindows = new ArrayList<>(elementWindows.size());
		for (W window : elementWindows) {
			if (!isWindowLate(window)) {
				reuseAffectedWindows.add(window);
			}
		}
		return reuseAffectedWindows;
	}

	@Override
	public Collection<W> assignActualWindows(BaseRow inputRow, long timestamp) throws Exception {
		// actual windows is equal to affected window, reuse it
		return reuseAffectedWindows;
	}

	@Override
	public BaseRow getWindowAggregationResult(W window) throws Exception {
		BaseRow acc = ctx.getWindowAccumulators(window);
		if (acc == null) {
			acc = windowAggregator.createAccumulators();
		}
		windowAggregator.setAccumulators(window, acc);
		return windowAggregator.getValue(window);
	}

	@Override
	public void cleanWindowIfNeeded(W window, long time) throws Exception {
		if (isCleanupTime(window, time)) {
			ctx.clearWindowState(window);
			ctx.clearPreviousState(window);
			ctx.clearTrigger(window);
		}
	}
}