/*
 * 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;

import org.apache.flink.streaming.api.TimerService;
import org.apache.flink.streaming.api.operators.AbstractStreamOperator;
import org.apache.flink.streaming.api.operators.ChainingStrategy;
import org.apache.flink.streaming.api.operators.InternalTimerService;
import org.apache.flink.streaming.api.watermark.Watermark;
import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
import org.apache.flink.streaming.runtime.tasks.ProcessingTimeService;

import static org.apache.flink.util.Preconditions.checkNotNull;
import static org.apache.flink.util.Preconditions.checkState;

/**
 * AbstractProcessStreamOperator is a base class for stream operators without key.
 *
 * @param <OUT> The output type of the operator.
 */
public abstract class AbstractProcessStreamOperator<OUT> extends AbstractStreamOperator<OUT> {

	/** We listen to this ourselves because we don't have an {@link InternalTimerService}. */
	protected long currentWatermark = Long.MIN_VALUE;

	protected transient ContextImpl ctx;

	protected boolean closed = false;

	public AbstractProcessStreamOperator() {
		setChainingStrategy(ChainingStrategy.ALWAYS);
	}

	@Override
	public void open() throws Exception {
		super.open();
		this.ctx = new ContextImpl(getProcessingTimeService());
	}

	@Override
	public void processWatermark(Watermark mark) throws Exception {
		super.processWatermark(mark);
		currentWatermark = mark.getTimestamp();
	}

	@Override
	public void close() throws Exception {
		super.close();
		closed = true;
	}

	@Override
	public void dispose() throws Exception {
		if (!closed) {
			close();
		}
		super.dispose();
	}

	/**
	 * Information available in an invocation of processElement.
	 */
	protected class ContextImpl implements TimerService {

		protected final ProcessingTimeService timerService;

		public StreamRecord<?> element;

		ContextImpl(ProcessingTimeService timerService) {
			this.timerService = checkNotNull(timerService);
		}

		public Long timestamp() {
			checkState(element != null);

			if (element.hasTimestamp()) {
				return element.getTimestamp();
			} else {
				return null;
			}
		}

		@Override
		public long currentProcessingTime() {
			return timerService.getCurrentProcessingTime();
		}

		@Override
		public long currentWatermark() {
			return currentWatermark;
		}

		@Override
		public void registerProcessingTimeTimer(long time) {
			throw new UnsupportedOperationException("Setting timers is only supported on a keyed streams.");
		}

		@Override
		public void registerEventTimeTimer(long time) {
			throw new UnsupportedOperationException("Setting timers is only supported on a keyed streams.");
		}

		public TimerService timerService() {
			return this;
		}
	}
}