/*
 * 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.runners.spark;

import static org.hamcrest.core.IsEqual.equalTo;
import static org.junit.Assert.assertThat;

import org.apache.beam.runners.spark.translation.SparkContextFactory;
import org.apache.beam.runners.spark.util.GlobalWatermarkHolder;
import org.apache.beam.runners.spark.util.GlobalWatermarkHolder.SparkWatermarks;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.sdk.testing.RegexMatcher;
import org.apache.spark.api.java.JavaSparkContext;
import org.joda.time.Duration;
import org.joda.time.Instant;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;


/**
 * A test suite for the propagation of watermarks in the Spark runner.
 */
public class GlobalWatermarkHolderTest {

  @Rule
  public ClearWatermarksRule clearWatermarksRule = new ClearWatermarksRule();

  @Rule
  public ExpectedException thrown = ExpectedException.none();

  @Rule
  public ReuseSparkContextRule reuseContext = ReuseSparkContextRule.yes();

  // only needed in-order to get context from the SparkContextFactory.
  private static final SparkPipelineOptions options =
      PipelineOptionsFactory.create().as(SparkPipelineOptions.class);

  private static final String INSTANT_PATTERN =
      "[0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9]{2}:[0-9]{2}:[0-9]{2}.[0-9]{3}Z";

  @Test
  public void testLowHighWatermarksAdvance() {
    JavaSparkContext jsc = SparkContextFactory.getSparkContext(options);

    Instant instant = new Instant(0);
    // low == high.
    GlobalWatermarkHolder.add(1,
        new SparkWatermarks(
            instant.plus(Duration.millis(5)),
            instant.plus(Duration.millis(5)),
            instant));
    GlobalWatermarkHolder.advance(jsc);
    // low < high.
    GlobalWatermarkHolder.add(1,
        new SparkWatermarks(
            instant.plus(Duration.millis(10)),
            instant.plus(Duration.millis(15)),
            instant.plus(Duration.millis(100))));
    GlobalWatermarkHolder.advance(jsc);

    // assert watermarks in Broadcast.
    SparkWatermarks currentWatermarks = GlobalWatermarkHolder.get().getValue().get(1);
    assertThat(currentWatermarks.getLowWatermark(), equalTo(instant.plus(Duration.millis(10))));
    assertThat(currentWatermarks.getHighWatermark(), equalTo(instant.plus(Duration.millis(15))));
    assertThat(currentWatermarks.getSynchronizedProcessingTime(),
        equalTo(instant.plus(Duration.millis(100))));

    // assert illegal watermark advance.
    thrown.expect(IllegalStateException.class);
    thrown.expectMessage(
        RegexMatcher.matches(
            "Low watermark " + INSTANT_PATTERN + " cannot be later then high watermark "
            + INSTANT_PATTERN));
    // low > high -> not allowed!
    GlobalWatermarkHolder.add(1,
        new SparkWatermarks(
            instant.plus(Duration.millis(25)),
            instant.plus(Duration.millis(20)),
            instant.plus(Duration.millis(200))));
    GlobalWatermarkHolder.advance(jsc);
  }

  @Test
  public void testSynchronizedTimeMonotonic() {
    JavaSparkContext jsc = SparkContextFactory.getSparkContext(options);

    Instant instant = new Instant(0);
    GlobalWatermarkHolder.add(1,
        new SparkWatermarks(
            instant.plus(Duration.millis(5)),
            instant.plus(Duration.millis(10)),
            instant));
    GlobalWatermarkHolder.advance(jsc);

    thrown.expect(IllegalStateException.class);
    thrown.expectMessage("Synchronized processing time must advance.");
    // no actual advancement of watermarks - fine by Watermarks
    // but not by synchronized processing time.
    GlobalWatermarkHolder.add(1,
        new SparkWatermarks(
            instant.plus(Duration.millis(5)),
            instant.plus(Duration.millis(10)),
            instant));
    GlobalWatermarkHolder.advance(jsc);
  }

  @Test
  public void testMultiSource() {
    JavaSparkContext jsc = SparkContextFactory.getSparkContext(options);

    Instant instant = new Instant(0);
    GlobalWatermarkHolder.add(1,
        new SparkWatermarks(
            instant.plus(Duration.millis(5)),
            instant.plus(Duration.millis(10)),
            instant));
    GlobalWatermarkHolder.add(2,
        new SparkWatermarks(
            instant.plus(Duration.millis(3)),
            instant.plus(Duration.millis(6)),
            instant));

    GlobalWatermarkHolder.advance(jsc);

    // assert watermarks for source 1.
    SparkWatermarks watermarksForSource1 = GlobalWatermarkHolder.get().getValue().get(1);
    assertThat(watermarksForSource1.getLowWatermark(), equalTo(instant.plus(Duration.millis(5))));
    assertThat(watermarksForSource1.getHighWatermark(), equalTo(instant.plus(Duration.millis(10))));

    // assert watermarks for source 2.
    SparkWatermarks watermarksForSource2 = GlobalWatermarkHolder.get().getValue().get(2);
    assertThat(watermarksForSource2.getLowWatermark(), equalTo(instant.plus(Duration.millis(3))));
    assertThat(watermarksForSource2.getHighWatermark(), equalTo(instant.plus(Duration.millis(6))));
  }
}