/*
 * 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.junit.Assert.assertFalse;
import static org.junit.Assert.fail;

import org.apache.beam.runners.spark.examples.WordCount;
import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.PipelineResult;
import org.apache.beam.sdk.coders.StringUtf8Coder;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.sdk.testing.PAssert;
import org.apache.beam.sdk.testing.TestPipeline;
import org.apache.beam.sdk.transforms.Create;
import org.apache.beam.sdk.transforms.MapElements;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.vendor.guava.v20_0.com.google.common.collect.ImmutableList;
import org.apache.beam.vendor.guava.v20_0.com.google.common.collect.ImmutableSet;
import org.apache.spark.api.java.JavaSparkContext;
import org.junit.Test;

/** Provided Spark Context tests. */
public class ProvidedSparkContextTest {
  private static final String[] WORDS_ARRAY = {
    "hi there", "hi", "hi sue bob",
    "hi sue", "", "bob hi"
  };
  private static final ImmutableList<String> WORDS = ImmutableList.copyOf(WORDS_ARRAY);
  private static final ImmutableSet<String> EXPECTED_COUNT_SET =
      ImmutableSet.of("hi: 5", "there: 1", "sue: 2", "bob: 2");
  private static final String PROVIDED_CONTEXT_EXCEPTION =
      "The provided Spark context was not created or was stopped";

  /** Provide a context and call pipeline run. */
  @Test
  public void testWithProvidedContext() throws Exception {
    JavaSparkContext jsc = new JavaSparkContext("local[*]", "Existing_Context");
    testWithValidProvidedContext(jsc);
    // A provided context must not be stopped after execution
    assertFalse(jsc.sc().isStopped());
    jsc.stop();
  }

  /** Provide a context and call pipeline run. */
  @Test
  public void testWithNullContext() throws Exception {
    testWithInvalidContext(null);
  }

  /** A SparkRunner with a stopped provided Spark context cannot run pipelines. */
  @Test
  public void testWithStoppedProvidedContext() throws Exception {
    JavaSparkContext jsc = new JavaSparkContext("local[*]", "Existing_Context");
    // Stop the provided Spark context directly
    jsc.stop();
    testWithInvalidContext(jsc);
  }

  private void testWithValidProvidedContext(JavaSparkContext jsc) throws Exception {
    SparkContextOptions options = getSparkContextOptions(jsc);

    Pipeline p = Pipeline.create(options);
    PCollection<String> inputWords = p.apply(Create.of(WORDS).withCoder(StringUtf8Coder.of()));
    PCollection<String> output =
        inputWords
            .apply(new WordCount.CountWords())
            .apply(MapElements.via(new WordCount.FormatAsTextFn()));

    PAssert.that(output).containsInAnyOrder(EXPECTED_COUNT_SET);

    // Run test from pipeline
    PipelineResult result = p.run();

    TestPipeline.verifyPAssertsSucceeded(p, result);
  }

  private void testWithInvalidContext(JavaSparkContext jsc) {
    SparkContextOptions options = getSparkContextOptions(jsc);

    Pipeline p = Pipeline.create(options);
    PCollection<String> inputWords = p.apply(Create.of(WORDS).withCoder(StringUtf8Coder.of()));
    inputWords
        .apply(new WordCount.CountWords())
        .apply(MapElements.via(new WordCount.FormatAsTextFn()));

    try {
      p.run().waitUntilFinish();
      fail("Should throw an exception when The provided Spark context is null or stopped");
    } catch (RuntimeException e) {
      assert e.getMessage().contains(PROVIDED_CONTEXT_EXCEPTION);
    }
  }

  private static SparkContextOptions getSparkContextOptions(JavaSparkContext jsc) {
    final SparkContextOptions options = PipelineOptionsFactory.as(SparkContextOptions.class);
    options.setRunner(TestSparkRunner.class);
    options.setUsesProvidedSparkContext(true);
    options.setProvidedSparkContext(jsc);
    options.setEnableSparkMetricSinks(false);
    return options;
  }
}