/*
 * 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.beam.io.debezium;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.coders.MapCoder;
import org.apache.beam.sdk.coders.StringUtf8Coder;
import org.apache.beam.sdk.coders.VarIntCoder;
import org.apache.beam.sdk.testing.PAssert;
import org.apache.beam.sdk.transforms.Create;
import org.apache.beam.sdk.transforms.ParDo;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.collect.ImmutableMap;
import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.collect.Lists;
import org.apache.kafka.common.config.AbstractConfig;
import org.apache.kafka.common.config.ConfigDef;
import org.apache.kafka.connect.connector.Task;
import org.apache.kafka.connect.data.Schema;
import org.apache.kafka.connect.source.SourceConnector;
import org.apache.kafka.connect.source.SourceRecord;
import org.apache.kafka.connect.source.SourceTask;
import org.apache.kafka.connect.source.SourceTaskContext;
import org.checkerframework.checker.nullness.qual.Nullable;
import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

@RunWith(JUnit4.class)
public class KafkaSourceConsumerFnTest implements Serializable {
  @Test
  public void testKafkaSourceConsumerFn() {
    Map<String, String> config =
        ImmutableMap.of(
            "from", "1",
            "to", "10",
            "delay", "0.4",
            "topic", "any");

    Pipeline pipeline = Pipeline.create();

    PCollection<Integer> counts =
        pipeline
            .apply(
                Create.of(Lists.newArrayList(config))
                    .withCoder(MapCoder.of(StringUtf8Coder.of(), StringUtf8Coder.of())))
            .apply(
                ParDo.of(
                    new KafkaSourceConsumerFn<>(
                        CounterSourceConnector.class,
                        sourceRecord -> (Integer) sourceRecord.value(),
                        10)))
            .setCoder(VarIntCoder.of());

    PAssert.that(counts).containsInAnyOrder(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
    pipeline.run().waitUntilFinish();
  }

  @Test
  public void testStoppableKafkaSourceConsumerFn() {
    Map<String, String> config =
        ImmutableMap.of(
            "from", "1",
            "to", "3",
            "delay", "0.2",
            "topic", "any");

    Pipeline pipeline = Pipeline.create();

    pipeline
        .apply(
            Create.of(Lists.newArrayList(config))
                .withCoder(MapCoder.of(StringUtf8Coder.of(), StringUtf8Coder.of())))
        .apply(
            ParDo.of(
                new KafkaSourceConsumerFn<>(
                    CounterSourceConnector.class,
                    sourceRecord -> (Integer) sourceRecord.value(),
                    1)))
        .setCoder(VarIntCoder.of());

    pipeline.run().waitUntilFinish();
    Assert.assertEquals(3, CounterTask.getCountTasks());
  }
}

class CounterSourceConnector extends SourceConnector {
  public static class CounterSourceConnectorConfig extends AbstractConfig {
    final Map<String, String> props;

    CounterSourceConnectorConfig(Map<String, String> props) {
      super(configDef(), props);
      this.props = props;
    }

    protected static ConfigDef configDef() {
      return new ConfigDef()
          .define("from", ConfigDef.Type.INT, ConfigDef.Importance.HIGH, "Number to start from")
          .define("to", ConfigDef.Type.INT, ConfigDef.Importance.HIGH, "Number to go to")
          .define(
              "delay", ConfigDef.Type.DOUBLE, ConfigDef.Importance.HIGH, "Time between each event")
          .define(
              "topic",
              ConfigDef.Type.STRING,
              ConfigDef.Importance.HIGH,
              "Name of Kafka topic to produce to");
    }
  }

  @Nullable private CounterSourceConnectorConfig connectorConfig;

  @Override
  public void start(Map<String, String> props) {
    this.connectorConfig = new CounterSourceConnectorConfig(props);
  }

  @Override
  public Class<? extends Task> taskClass() {
    return CounterTask.class;
  }

  @Override
  public List<Map<String, String>> taskConfigs(int maxTasks) {
    if (this.connectorConfig == null || this.connectorConfig.props == null) {
      return Collections.emptyList();
    }

    return Collections.singletonList(
        ImmutableMap.of(
            "from", this.connectorConfig.props.get("from"),
            "to", this.connectorConfig.props.get("to"),
            "delay", this.connectorConfig.props.get("delay"),
            "topic", this.connectorConfig.props.get("topic")));
  }

  @Override
  public void stop() {}

  @Override
  public ConfigDef config() {
    return CounterSourceConnectorConfig.configDef();
  }

  @Override
  public String version() {
    return "ONE";
  }
}

class CounterTask extends SourceTask {
  private static int countStopTasks = 0;
  private String topic = "";
  private Integer from = 0;
  private Integer to = 0;
  private Double delay = 0.0;

  private Long start = System.currentTimeMillis();
  private Integer last = 0;
  private Object lastOffset = null;

  private static final String PARTITION_FIELD = "mod";
  private static final Integer PARTITION_NAME = 1;

  @Override
  public String version() {
    return "ONE";
  }

  @Override
  public void initialize(SourceTaskContext context) {
    super.initialize(context);

    Map<String, Object> offset =
        context
            .offsetStorageReader()
            .offset(Collections.singletonMap(PARTITION_FIELD, PARTITION_NAME));

    if (offset == null) {
      this.start = System.currentTimeMillis();
      this.last = 0;
    } else {
      this.start = (Long) offset.get("start");
      this.last = ((Long) offset.getOrDefault("last", 0)).intValue();
    }
    this.lastOffset = offset;
  }

  @Override
  public void start(Map<String, String> props) {
    this.topic = props.getOrDefault("topic", "");
    this.from = Integer.parseInt(props.getOrDefault("from", "0"));
    this.to = Integer.parseInt(props.getOrDefault("to", "0"));
    this.delay = Double.parseDouble(props.getOrDefault("delay", "0"));

    if (this.lastOffset != null) {
      return;
    }

    this.start =
        props.containsKey("start")
            ? Long.parseLong(props.get("start"))
            : System.currentTimeMillis();
    this.last = this.from - 1;
  }

  @Override
  public List<SourceRecord> poll() throws InterruptedException {
    if (this.last.equals(to)) {
      return null;
    }

    List<SourceRecord> records = new ArrayList<>();
    Long callTime = System.currentTimeMillis();
    Long secondsSinceStart = (callTime - this.start) / 1000;
    Long recordsToOutput = Math.round(Math.floor(secondsSinceStart / this.delay));

    while (this.last < this.to) {
      this.last = this.last + 1;
      Map<String, Integer> sourcePartition = Collections.singletonMap(PARTITION_FIELD, 1);
      Map<String, Long> sourceOffset =
          ImmutableMap.of("last", this.last.longValue(), "start", this.start);

      records.add(
          new SourceRecord(
              sourcePartition, sourceOffset, this.topic, Schema.INT64_SCHEMA, this.last));

      if (records.size() >= recordsToOutput) {
        break;
      }
    }

    return records;
  }

  @Override
  public void stop() {
    CounterTask.countStopTasks++;
  }

  public static int getCountTasks() {
    return CounterTask.countStopTasks;
  }
}
