/*
 * 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.state.operator.restore.unkeyed;

import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.common.functions.RichMapFunction;
import org.apache.flink.configuration.CheckpointingOptions;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.core.execution.CheckpointingMode;
import org.apache.flink.streaming.api.checkpoint.ListCheckpointed;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.source.legacy.RichParallelSourceFunction;
import org.apache.flink.streaming.util.CheckpointStorageUtils;
import org.apache.flink.streaming.util.RestartStrategyUtils;
import org.apache.flink.streaming.util.StateBackendUtils;
import org.apache.flink.test.state.operator.restore.ExecutionMode;
import org.apache.flink.util.ParameterTool;

import org.junit.Assert;

import java.util.Arrays;
import java.util.List;

/**
 * Savepoint generator to create the savepoint used by the {@link
 * AbstractNonKeyedOperatorRestoreTestBase}. Switch to specific version branches and run this job to
 * create savepoints of different Flink versions.
 *
 * <p>The job should be cancelled manually through the REST API using the cancel-with-savepoint
 * operation.
 */
public class NonKeyedJob {

    public static void main(String[] args) throws Exception {
        ParameterTool pt = ParameterTool.fromArgs(args);

        String savepointsPath = pt.getRequired("savepoint-path");

        Configuration config = new Configuration();
        config.set(CheckpointingOptions.SAVEPOINT_DIRECTORY, savepointsPath);

        StreamExecutionEnvironment env =
                StreamExecutionEnvironment.createLocalEnvironmentWithWebUI(config);
        env.enableCheckpointing(500, CheckpointingMode.EXACTLY_ONCE);
        RestartStrategyUtils.configureNoRestartStrategy(env);

        StateBackendUtils.configureHashMapStateBackend(env);
        CheckpointStorageUtils.configureJobManagerCheckpointStorage(env);

        /** Source -> StatefulMap1 -> CHAIN(StatefulMap2 -> Map -> StatefulMap3) */
        DataStream<Integer> source = createSource(env, ExecutionMode.GENERATE);

        SingleOutputStreamOperator<Integer> first =
                createFirstStatefulMap(ExecutionMode.GENERATE, source);
        first.startNewChain();

        SingleOutputStreamOperator<Integer> second =
                createSecondStatefulMap(ExecutionMode.GENERATE, first);
        second.startNewChain();

        SingleOutputStreamOperator<Integer> stateless = createStatelessMap(second);

        SingleOutputStreamOperator<Integer> third =
                createThirdStatefulMap(ExecutionMode.GENERATE, stateless);

        env.execute("job");
    }

    public static SingleOutputStreamOperator<Integer> createSource(
            StreamExecutionEnvironment env, ExecutionMode mode) {
        return env.addSource(new IntegerSource(mode)).setParallelism(4);
    }

    public static SingleOutputStreamOperator<Integer> createFirstStatefulMap(
            ExecutionMode mode, DataStream<Integer> input) {
        return input.map(new StatefulStringStoringMap(mode, "first"))
                .setParallelism(4)
                .uid("first");
    }

    public static SingleOutputStreamOperator<Integer> createSecondStatefulMap(
            ExecutionMode mode, DataStream<Integer> input) {
        return input.map(new StatefulStringStoringMap(mode, "second"))
                .setParallelism(4)
                .uid("second");
    }

    public static SingleOutputStreamOperator<Integer> createThirdStatefulMap(
            ExecutionMode mode, DataStream<Integer> input) {
        SingleOutputStreamOperator<Integer> map =
                input.map(new StatefulStringStoringMap(mode, "third"))
                        .setParallelism(4)
                        .uid("third");

        return map;
    }

    public static SingleOutputStreamOperator<Integer> createStatelessMap(
            DataStream<Integer> input) {
        return input.map(new NoOpMapFunction()).setParallelism(4);
    }

    private static class StatefulStringStoringMap extends RichMapFunction<Integer, Integer>
            implements ListCheckpointed<String> {

        private static final long serialVersionUID = 6092985758425330235L;
        private final ExecutionMode mode;
        private final String valueToStore;

        private StatefulStringStoringMap(ExecutionMode mode, String valueToStore) {
            this.mode = mode;
            this.valueToStore = valueToStore;
        }

        @Override
        public Integer map(Integer value) throws Exception {
            return value;
        }

        @Override
        public List<String> snapshotState(long checkpointId, long timestamp) throws Exception {
            return Arrays.asList(
                    valueToStore + getRuntimeContext().getTaskInfo().getIndexOfThisSubtask());
        }

        @Override
        public void restoreState(List<String> state) throws Exception {
            switch (mode) {
                case GENERATE:
                    break;
                case MIGRATE:
                case RESTORE:
                    Assert.assertEquals(
                            "Failed for "
                                    + valueToStore
                                    + getRuntimeContext().getTaskInfo().getIndexOfThisSubtask(),
                            1,
                            state.size());
                    String value = state.get(0);
                    Assert.assertEquals(
                            valueToStore
                                    + getRuntimeContext().getTaskInfo().getIndexOfThisSubtask(),
                            value);
            }
        }
    }

    private static class NoOpMapFunction implements MapFunction<Integer, Integer> {

        private static final long serialVersionUID = 6584823409744624276L;

        @Override
        public Integer map(Integer value) throws Exception {
            return value;
        }
    }

    private static final class IntegerSource extends RichParallelSourceFunction<Integer> {

        private static final long serialVersionUID = 1912878510707871659L;
        private final ExecutionMode mode;

        private volatile boolean running = true;

        private IntegerSource(ExecutionMode mode) {
            this.mode = mode;
        }

        @Override
        public void run(SourceContext<Integer> ctx) throws Exception {
            ctx.collect(1);

            switch (mode) {
                case GENERATE:
                case MIGRATE:
                    // keep the job running until cancel-with-savepoint was done
                    synchronized (this) {
                        while (running) {
                            this.wait();
                        }
                    }
            }
        }

        @Override
        public void cancel() {
            synchronized (this) {
                running = false;
                this.notifyAll();
            }
        }
    }
}
