/*
 * 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.test.classloading.jar;

import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.common.restartstrategy.RestartStrategies;
import org.apache.flink.runtime.state.CheckpointListener;
import org.apache.flink.streaming.api.checkpoint.ListCheckpointed;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.sink.SinkFunction;
import org.apache.flink.streaming.api.functions.source.SourceFunction;

import java.lang.RuntimeException;
import java.util.Collections;
import java.util.List;

/**
 * A simple streaming program, which is using the state checkpointing of Flink.
 * It is using a user defined class as the state.
 */
@SuppressWarnings("serial")
public class CheckpointedStreamingProgram {

	private static final int CHECKPOINT_INTERVALL = 100;
	
	public static void main(String[] args) throws Exception {
		StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

		env.getConfig().disableSysoutLogging();
		env.enableCheckpointing(CHECKPOINT_INTERVALL);
		env.setRestartStrategy(RestartStrategies.fixedDelayRestart(1, 100L));
		env.disableOperatorChaining();
		
		DataStream<String> text = env.addSource(new SimpleStringGenerator());
		text.map(new StatefulMapper()).addSink(new NoOpSink());
		env.setParallelism(1);
		env.execute("Checkpointed Streaming Program");
	}


	// with Checkpoining
	public static class SimpleStringGenerator implements SourceFunction<String>, ListCheckpointed<Integer> {
		public boolean running = true;

		@Override
		public void run(SourceContext<String> ctx) throws Exception {
			while(running) {
				Thread.sleep(1);
				ctx.collect("someString");
			}
		}

		@Override
		public void cancel() {
			running = false;
		}

		@Override
		public List<Integer> snapshotState(long checkpointId, long timestamp) throws Exception {
			return Collections.emptyList();
		}

		@Override
		public void restoreState(List<Integer> state) throws Exception {

		}
	}

	public static class StatefulMapper implements MapFunction<String, String>, ListCheckpointed<StatefulMapper>, CheckpointListener {

		private String someState;
		private boolean atLeastOneSnapshotComplete = false;
		private boolean restored = false;

		@Override
		public List<StatefulMapper> snapshotState(long checkpointId, long timestamp) throws Exception {
			return Collections.singletonList(this);
		}

		@Override
		public void restoreState(List<StatefulMapper> state) throws Exception {
			if (state.isEmpty() || state.size() > 1) {
				throw new RuntimeException("Test failed due to unexpected recovered state size " + state.size());
			}
			restored = true;
			StatefulMapper s = state.get(0);
			this.someState = s.someState;
			this.atLeastOneSnapshotComplete = s.atLeastOneSnapshotComplete;
		}

		@Override
		public String map(String value) throws Exception {
			if(!atLeastOneSnapshotComplete) {
				// throttle consumption by the checkpoint interval until we have one snapshot.
				Thread.sleep(CHECKPOINT_INTERVALL);
			}
			if(atLeastOneSnapshotComplete && !restored) {
				throw new RuntimeException("Intended failure, to trigger restore");
			}
			if(restored) {
				throw new SuccessException();
				//throw new RuntimeException("All good");
			}
			someState = value; // update our state
			return value;
		}

		@Override
		public void notifyCheckpointComplete(long checkpointId) throws Exception {
			atLeastOneSnapshotComplete = true;
		}
	}
	// --------------------------------------------------------------------------------------------

	/**
	 * We intentionally use a user specified failure exception
	 */
	public static class SuccessException extends Exception {

	}

	public static class NoOpSink implements SinkFunction<String>{
		@Override
		public void invoke(String value) throws Exception {
		}
	}
}