/*
 * 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.core.triggers;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;

import org.apache.beam.runners.core.triggers.TriggerStateMachineTester.SimpleTriggerStateMachineTester;
import org.apache.beam.sdk.transforms.windowing.FixedWindows;
import org.apache.beam.sdk.transforms.windowing.IntervalWindow;
import org.apache.beam.sdk.transforms.windowing.Sessions;
import org.joda.time.Duration;
import org.joda.time.Instant;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/**
 * Tests for {@link AfterAllStateMachine}.
 */
@RunWith(JUnit4.class)
public class AfterAllStateMachineTest {

  private SimpleTriggerStateMachineTester<IntervalWindow> tester;

  @Test
  public void testT1FiresFirst() throws Exception {
    tester = TriggerStateMachineTester.forTrigger(
        AfterAllStateMachine.of(
            AfterPaneStateMachine.elementCountAtLeast(1),
            AfterPaneStateMachine.elementCountAtLeast(2)),
        FixedWindows.of(Duration.millis(100)));

    IntervalWindow window = new IntervalWindow(new Instant(0), new Instant(100));

    tester.injectElements(1);
    assertFalse(tester.shouldFire(window));

    tester.injectElements(2);
    assertTrue(tester.shouldFire(window));
    tester.fireIfShouldFire(window);
    assertTrue(tester.isMarkedFinished(window));
  }

  @Test
  public void testT2FiresFirst() throws Exception {
    tester = TriggerStateMachineTester.forTrigger(
        AfterAllStateMachine.of(
            AfterPaneStateMachine.elementCountAtLeast(2),
            AfterPaneStateMachine.elementCountAtLeast(1)),
        FixedWindows.of(Duration.millis(100)));

    IntervalWindow window = new IntervalWindow(new Instant(0), new Instant(100));

    tester.injectElements(1);
    assertFalse(tester.shouldFire(window));

    tester.injectElements(2);
    assertTrue(tester.shouldFire(window));
    tester.fireIfShouldFire(window);
    assertTrue(tester.isMarkedFinished(window));
  }

  /**
   * Tests that the AfterAll properly unsets finished bits when a merge causing it to become
   * unfinished.
   */
  @Test
  public void testOnMergeRewinds() throws Exception {
    tester = TriggerStateMachineTester.forTrigger(
        AfterEachStateMachine.inOrder(
            AfterAllStateMachine.of(
                AfterWatermarkStateMachine.pastEndOfWindow(),
                AfterPaneStateMachine.elementCountAtLeast(1)),
            RepeatedlyStateMachine.forever(AfterPaneStateMachine.elementCountAtLeast(1))),
        Sessions.withGapDuration(Duration.millis(10)));

    tester.injectElements(1);
    IntervalWindow firstWindow = new IntervalWindow(new Instant(1), new Instant(11));

    tester.injectElements(5);
    IntervalWindow secondWindow = new IntervalWindow(new Instant(5), new Instant(15));

    // Finish the AfterAll in the first window
    tester.advanceInputWatermark(new Instant(11));
    assertTrue(tester.shouldFire(firstWindow));
    assertFalse(tester.shouldFire(secondWindow));
    tester.fireIfShouldFire(firstWindow);

    // Merge them; the AfterAll should not be finished
    tester.mergeWindows();
    IntervalWindow mergedWindow = new IntervalWindow(new Instant(1), new Instant(15));
    assertFalse(tester.isMarkedFinished(mergedWindow));

    // Confirm that we are back on the first trigger by probing that it is not ready to fire
    // after an element (with merging)
    tester.injectElements(3);
    tester.mergeWindows();
    assertFalse(tester.shouldFire(mergedWindow));

    // Fire the AfterAll in the merged window
    tester.advanceInputWatermark(new Instant(15));
    assertTrue(tester.shouldFire(mergedWindow));
    tester.fireIfShouldFire(mergedWindow);

    // Confirm that we are on the second trigger by probing
    tester.injectElements(2);
    tester.mergeWindows();
    assertTrue(tester.shouldFire(mergedWindow));
    tester.fireIfShouldFire(mergedWindow);
    tester.injectElements(2);
    tester.mergeWindows();
    assertTrue(tester.shouldFire(mergedWindow));
    tester.fireIfShouldFire(mergedWindow);
  }

  @Test
  public void testToString() {
    TriggerStateMachine trigger =
        AfterAllStateMachine.of(
            StubTriggerStateMachine.named("t1"), StubTriggerStateMachine.named("t2"));
    assertEquals("AfterAll.of(t1, t2)", trigger.toString());
  }
}