/*
 * 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.sdk.util.construction;

import static org.apache.beam.sdk.transforms.DoFn.ProcessContinuation.stop;
import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.instanceOf;
import static org.hamcrest.Matchers.not;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

import java.io.IOException;
import java.io.Serializable;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.Pipeline.PipelineVisitor.Defaults;
import org.apache.beam.sdk.coders.Coder;
import org.apache.beam.sdk.coders.StringUtf8Coder;
import org.apache.beam.sdk.io.BoundedSource;
import org.apache.beam.sdk.io.Read;
import org.apache.beam.sdk.options.ExperimentalOptions;
import org.apache.beam.sdk.options.PipelineOptions;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.sdk.runners.AppliedPTransform;
import org.apache.beam.sdk.runners.TransformHierarchy.Node;
import org.apache.beam.sdk.testing.CrashingRunner;
import org.apache.beam.sdk.testing.TestPipeline;
import org.apache.beam.sdk.transforms.Create;
import org.apache.beam.sdk.transforms.DoFn;
import org.apache.beam.sdk.transforms.ParDo;
import org.apache.beam.sdk.transforms.resourcehints.ResourceHints;
import org.apache.beam.sdk.transforms.splittabledofn.HasDefaultTracker;
import org.apache.beam.sdk.transforms.splittabledofn.RestrictionTracker;
import org.apache.beam.sdk.transforms.splittabledofn.SplitResult;
import org.apache.beam.sdk.util.construction.UnboundedReadFromBoundedSource.BoundedToUnboundedSourceAdapter;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.sdk.values.PCollectionTuple;
import org.apache.beam.sdk.values.PValues;
import org.apache.beam.sdk.values.TupleTag;
import org.apache.beam.sdk.values.TupleTagList;
import org.junit.Rule;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/** Tests for {@link SplittableParDo}. */
@RunWith(JUnit4.class)
public class SplittableParDoTest {
  // ----------------- Tests for whether the transform sets boundedness correctly --------------
  private static class SomeRestriction
      implements Serializable, HasDefaultTracker<SomeRestriction, SomeRestrictionTracker> {
    @Override
    public SomeRestrictionTracker newTracker() {
      return new SomeRestrictionTracker(this);
    }
  }

  private static class SomeRestrictionTracker extends RestrictionTracker<SomeRestriction, Void> {
    private final SomeRestriction someRestriction;

    public SomeRestrictionTracker(SomeRestriction someRestriction) {
      this.someRestriction = someRestriction;
    }

    @Override
    public boolean tryClaim(Void position) {
      return false;
    }

    @Override
    public SomeRestriction currentRestriction() {
      return someRestriction;
    }

    @Override
    public SplitResult<SomeRestriction> trySplit(double fractionOfRemainder) {
      return SplitResult.of(null, someRestriction);
    }

    @Override
    public void checkDone() {}

    @Override
    public IsBounded isBounded() {
      return IsBounded.BOUNDED;
    }
  }

  private static class BoundedFakeFn extends DoFn<Integer, String> {
    @ProcessElement
    public void processElement(
        @SuppressWarnings("unused") ProcessContext context,
        @SuppressWarnings("unused") RestrictionTracker<SomeRestriction, Void> tracker) {}

    @GetInitialRestriction
    public SomeRestriction getInitialRestriction(
        @SuppressWarnings("unused") @Element Integer element) {
      return null;
    }
  }

  private static class UnboundedFakeFn extends DoFn<Integer, String> {
    @ProcessElement
    public ProcessContinuation processElement(
        @SuppressWarnings("unused") ProcessContext context,
        @SuppressWarnings("unused") RestrictionTracker<SomeRestriction, Void> tracker) {
      return stop();
    }

    @GetInitialRestriction
    public SomeRestriction getInitialRestriction(
        @SuppressWarnings("unused") @Element Integer element) {
      return null;
    }
  }

  private static PCollection<Integer> makeUnboundedCollection(Pipeline pipeline) {
    return pipeline
        .apply("unbounded", Create.of(1, 2, 3))
        .setIsBoundedInternal(PCollection.IsBounded.UNBOUNDED);
  }

  private static PCollection<Integer> makeBoundedCollection(Pipeline pipeline) {
    return pipeline
        .apply("bounded", Create.of(1, 2, 3))
        .setIsBoundedInternal(PCollection.IsBounded.BOUNDED);
  }

  private static final TupleTag<String> MAIN_OUTPUT_TAG = new TupleTag<String>() {};

  private PCollection<String> applySplittableParDo(
      String name, PCollection<Integer> input, DoFn<Integer, String> fn) {
    ParDo.MultiOutput<Integer, String> multiOutput =
        ParDo.of(fn).withOutputTags(MAIN_OUTPUT_TAG, TupleTagList.empty());
    PCollectionTuple output = multiOutput.expand(input);
    output.get(MAIN_OUTPUT_TAG).setName("main");
    AppliedPTransform<PCollection<Integer>, PCollectionTuple, ?> transform =
        AppliedPTransform.of(
            "ParDo",
            PValues.expandInput(input),
            PValues.expandOutput(output),
            multiOutput,
            ResourceHints.create(),
            pipeline);
    return input.apply(name, SplittableParDo.forAppliedParDo(transform)).get(MAIN_OUTPUT_TAG);
  }

  @Rule public TestPipeline pipeline = TestPipeline.create();

  @Test
  public void testBoundednessForBoundedFn() {
    pipeline.enableAbandonedNodeEnforcement(false);

    DoFn<Integer, String> boundedFn = new BoundedFakeFn();
    assertEquals(
        "Applying a bounded SDF to a bounded collection produces a bounded collection",
        PCollection.IsBounded.BOUNDED,
        applySplittableParDo("bounded to bounded", makeBoundedCollection(pipeline), boundedFn)
            .isBounded());
    assertEquals(
        "Applying a bounded SDF to an unbounded collection produces an unbounded collection",
        PCollection.IsBounded.UNBOUNDED,
        applySplittableParDo("bounded to unbounded", makeUnboundedCollection(pipeline), boundedFn)
            .isBounded());
  }

  @Test
  public void testBoundednessForUnboundedFn() {
    pipeline.enableAbandonedNodeEnforcement(false);

    DoFn<Integer, String> unboundedFn = new UnboundedFakeFn();
    assertEquals(
        "Applying an unbounded SDF to a bounded collection produces a bounded collection",
        PCollection.IsBounded.UNBOUNDED,
        applySplittableParDo("unbounded to bounded", makeBoundedCollection(pipeline), unboundedFn)
            .isBounded());
    assertEquals(
        "Applying an unbounded SDF to an unbounded collection produces an unbounded collection",
        PCollection.IsBounded.UNBOUNDED,
        applySplittableParDo(
                "unbounded to unbounded", makeUnboundedCollection(pipeline), unboundedFn)
            .isBounded());
  }

  private static class FakeBoundedSource extends BoundedSource<String> {
    @Override
    public List<? extends BoundedSource<String>> split(
        long desiredBundleSizeBytes, PipelineOptions options) throws Exception {
      return Collections.singletonList(this);
    }

    @Override
    public long getEstimatedSizeBytes(PipelineOptions options) throws Exception {
      return 0;
    }

    @Override
    public BoundedReader<String> createReader(PipelineOptions options) throws IOException {
      throw new UnsupportedOperationException();
    }

    @Override
    public Coder<String> getOutputCoder() {
      return StringUtf8Coder.of();
    }
  }

  @Test
  public void testConvertIsSkippedWhenUsingUseSDFRead() {
    PipelineOptions pipelineOptions = PipelineOptionsFactory.create();
    pipelineOptions.setRunner(CrashingRunner.class);
    ExperimentalOptions.addExperiment(
        pipelineOptions.as(ExperimentalOptions.class), "use_sdf_read");
    Pipeline sdfRead = Pipeline.create(pipelineOptions);
    sdfRead.apply(Read.from(new FakeBoundedSource()));
    sdfRead.apply(Read.from(new BoundedToUnboundedSourceAdapter<>(new FakeBoundedSource())));
    SplittableParDo.convertReadBasedSplittableDoFnsToPrimitiveReadsIfNecessary(sdfRead);
    sdfRead.traverseTopologically(
        new Defaults() {
          @Override
          public void visitPrimitiveTransform(Node node) {
            assertThat(
                node.getTransform(), not(instanceOf(SplittableParDo.PrimitiveBoundedRead.class)));
            assertThat(
                node.getTransform(), not(instanceOf(SplittableParDo.PrimitiveUnboundedRead.class)));
          }
        });
  }

  @Test
  public void testConvertIsSkippedWhenUsingUseUnboundedSDFWrapper() {
    PipelineOptions pipelineOptions = PipelineOptionsFactory.create();
    pipelineOptions.setRunner(CrashingRunner.class);
    ExperimentalOptions.addExperiment(
        pipelineOptions.as(ExperimentalOptions.class), "use_unbounded_sdf_wrapper");
    Pipeline sdfRead = Pipeline.create(pipelineOptions);
    sdfRead.apply(Read.from(new FakeBoundedSource()));
    sdfRead.apply(Read.from(new BoundedToUnboundedSourceAdapter<>(new FakeBoundedSource())));
    SplittableParDo.convertReadBasedSplittableDoFnsToPrimitiveReadsIfNecessary(sdfRead);
    sdfRead.traverseTopologically(
        new Defaults() {
          @Override
          public void visitPrimitiveTransform(Node node) {
            assertThat(
                node.getTransform(), not(instanceOf(SplittableParDo.PrimitiveBoundedRead.class)));
            assertThat(
                node.getTransform(), not(instanceOf(SplittableParDo.PrimitiveUnboundedRead.class)));
          }
        });
  }

  @Test
  public void testConvertToPrimitiveReadsHappen() {
    PipelineOptions deprecatedReadOptions = PipelineOptionsFactory.create();
    deprecatedReadOptions.setRunner(CrashingRunner.class);
    ExperimentalOptions.addExperiment(
        deprecatedReadOptions.as(ExperimentalOptions.class), "use_deprecated_read");

    Pipeline pipeline = Pipeline.create(deprecatedReadOptions);
    pipeline.apply(Read.from(new FakeBoundedSource()));
    pipeline.apply(Read.from(new BoundedToUnboundedSourceAdapter<>(new FakeBoundedSource())));
    SplittableParDo.convertReadBasedSplittableDoFnsToPrimitiveReadsIfNecessary(pipeline);
    AtomicBoolean sawPrimitiveBoundedRead = new AtomicBoolean();
    AtomicBoolean sawPrimitiveUnboundedRead = new AtomicBoolean();
    pipeline.traverseTopologically(
        new Defaults() {
          @Override
          public CompositeBehavior enterCompositeTransform(Node node) {
            assertThat(node.getTransform(), not(instanceOf(Read.Bounded.class)));
            assertThat(node.getTransform(), not(instanceOf(Read.Unbounded.class)));
            return super.enterCompositeTransform(node);
          }

          @Override
          public void visitPrimitiveTransform(Node node) {
            if (node.getTransform() instanceof SplittableParDo.PrimitiveBoundedRead) {
              sawPrimitiveBoundedRead.set(true);
            } else if (node.getTransform() instanceof SplittableParDo.PrimitiveUnboundedRead) {
              sawPrimitiveUnboundedRead.set(true);
            }
          }
        });
    assertTrue(sawPrimitiveBoundedRead.get());
    assertTrue(sawPrimitiveUnboundedRead.get());
  }
}
