/*
 * Copyright 2018, OpenCensus Authors
 *
 * Licensed 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 io.opencensus.metrics.export;

import static com.google.common.truth.Truth.assertThat;

import com.google.common.testing.EqualsTester;
import io.opencensus.common.Function;
import io.opencensus.common.Functions;
import io.opencensus.common.Timestamp;
import io.opencensus.metrics.data.AttachmentValue;
import io.opencensus.metrics.data.AttachmentValue.AttachmentValueString;
import io.opencensus.metrics.data.Exemplar;
import io.opencensus.metrics.export.Distribution.Bucket;
import io.opencensus.metrics.export.Distribution.BucketOptions;
import io.opencensus.metrics.export.Distribution.BucketOptions.ExplicitOptions;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/** Unit tests for {@link Distribution}. */
@RunWith(JUnit4.class)
public class DistributionTest {

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

  private static final Timestamp TIMESTAMP = Timestamp.create(1, 0);
  private static final AttachmentValue VALUE = AttachmentValueString.create("value");
  private static final Map<String, AttachmentValue> ATTACHMENTS =
      Collections.<String, AttachmentValue>singletonMap("key", VALUE);
  private static final double TOLERANCE = 1e-6;

  @Test
  public void createAndGet_Bucket() {
    Bucket bucket = Bucket.create(98);
    assertThat(bucket.getCount()).isEqualTo(98);
    assertThat(bucket.getExemplar()).isNull();
  }

  @Test
  public void createAndGet_BucketWithExemplar() {
    Exemplar exemplar = Exemplar.create(12.2, TIMESTAMP, ATTACHMENTS);
    Bucket bucket = Bucket.create(7, exemplar);
    assertThat(bucket.getCount()).isEqualTo(7);
    assertThat(bucket.getExemplar()).isEqualTo(exemplar);
  }

  @Test
  public void createBucket_preventNullExemplar() {
    thrown.expect(NullPointerException.class);
    thrown.expectMessage("exemplar");
    Bucket.create(1, null);
  }

  @Test
  public void createAndGet_Exemplar() {
    Exemplar exemplar = Exemplar.create(-9.9, TIMESTAMP, ATTACHMENTS);
    assertThat(exemplar.getValue()).isWithin(TOLERANCE).of(-9.9);
    assertThat(exemplar.getTimestamp()).isEqualTo(TIMESTAMP);
    assertThat(exemplar.getAttachments()).isEqualTo(ATTACHMENTS);
  }

  @Test
  public void createAndGet_ExplicitBuckets() {
    List<Double> bucketBounds = Arrays.asList(1.0, 2.0, 3.0);

    BucketOptions bucketOptions = BucketOptions.explicitOptions(bucketBounds);
    final List<Double> actual = new ArrayList<Double>();
    bucketOptions.match(
        new Function<ExplicitOptions, Object>() {
          @Override
          public Object apply(ExplicitOptions arg) {
            actual.addAll(arg.getBucketBoundaries());
            return null;
          }
        },
        Functions.throwAssertionError());

    assertThat(actual).containsExactlyElementsIn(bucketBounds).inOrder();
  }

  @Test
  public void createAndGet_ExplicitBucketsNegativeBounds() {
    List<Double> bucketBounds = Collections.singletonList(-1.0);
    thrown.expect(IllegalArgumentException.class);
    thrown.expectMessage("bucket boundary should be > 0");
    BucketOptions.explicitOptions(bucketBounds);
  }

  @Test
  public void createAndGet_PreventNullExplicitBuckets() {
    thrown.expect(NullPointerException.class);
    BucketOptions.explicitOptions(Arrays.asList(1.0, null, 3.0));
  }

  @Test
  public void createAndGet_ExplicitBucketsEmptyBounds() {
    List<Double> bucketBounds = new ArrayList<Double>();
    BucketOptions bucketOptions = BucketOptions.explicitOptions(bucketBounds);

    final List<Double> actual = new ArrayList<Double>();
    bucketOptions.match(
        new Function<ExplicitOptions, Object>() {
          @Override
          public Object apply(ExplicitOptions arg) {
            actual.addAll(arg.getBucketBoundaries());
            return null;
          }
        },
        Functions.throwAssertionError());

    assertThat(actual).isEmpty();
  }

  @Test
  public void createBucketOptions_UnorderedBucketBounds() {
    List<Double> bucketBounds = Arrays.asList(1.0, 5.0, 2.0);
    thrown.expect(IllegalArgumentException.class);
    thrown.expectMessage("bucket boundaries not sorted.");
    BucketOptions.explicitOptions(bucketBounds);
  }

  @Test
  public void createAndGet_PreventNullBucketOptions() {
    thrown.expect(NullPointerException.class);
    BucketOptions.explicitOptions(null);
  }

  @Test
  public void createAndGet_Distribution() {
    Exemplar exemplar = Exemplar.create(15.0, TIMESTAMP, ATTACHMENTS);
    List<Double> bucketBounds = Arrays.asList(1.0, 2.0, 5.0);
    BucketOptions bucketOptions = BucketOptions.explicitOptions(bucketBounds);
    List<Bucket> buckets =
        Arrays.asList(
            Bucket.create(3), Bucket.create(1), Bucket.create(2), Bucket.create(4, exemplar));
    Distribution distribution = Distribution.create(10, 6.6, 678.54, bucketOptions, buckets);
    assertThat(distribution.getCount()).isEqualTo(10);
    assertThat(distribution.getSum()).isWithin(TOLERANCE).of(6.6);
    assertThat(distribution.getSumOfSquaredDeviations()).isWithin(TOLERANCE).of(678.54);

    final List<Double> actual = new ArrayList<Double>();
    distribution
        .getBucketOptions()
        .match(
            new Function<ExplicitOptions, Object>() {
              @Override
              public Object apply(ExplicitOptions arg) {
                actual.addAll(arg.getBucketBoundaries());
                return null;
              }
            },
            Functions.throwAssertionError());

    assertThat(actual).containsExactlyElementsIn(bucketBounds).inOrder();

    assertThat(distribution.getBuckets()).containsExactlyElementsIn(buckets).inOrder();
  }

  @Test
  public void createBucket_NegativeCount() {
    thrown.expect(IllegalArgumentException.class);
    thrown.expectMessage("bucket count should be non-negative.");
    Bucket.create(-5);
  }

  @Test
  public void createExemplar_PreventNullAttachments() {
    thrown.expect(NullPointerException.class);
    thrown.expectMessage("attachments");
    Exemplar.create(15, TIMESTAMP, null);
  }

  @Test
  public void createExemplar_PreventNullAttachmentKey() {
    Map<String, AttachmentValue> attachments = Collections.singletonMap(null, VALUE);
    thrown.expect(NullPointerException.class);
    thrown.expectMessage("key of attachment");
    Exemplar.create(15, TIMESTAMP, attachments);
  }

  @Test
  public void createExemplar_PreventNullAttachmentValue() {
    Map<String, AttachmentValue> attachments = Collections.singletonMap("key", null);
    thrown.expect(NullPointerException.class);
    thrown.expectMessage("value of attachment");
    Exemplar.create(15, TIMESTAMP, attachments);
  }

  @Test
  public void createDistribution_NegativeCount() {
    List<Double> bucketBounds = Arrays.asList(1.0, 2.0, 5.0);
    BucketOptions bucketOptions = BucketOptions.explicitOptions(bucketBounds);

    List<Bucket> buckets =
        Arrays.asList(Bucket.create(3), Bucket.create(1), Bucket.create(2), Bucket.create(4));
    thrown.expect(IllegalArgumentException.class);
    thrown.expectMessage("count should be non-negative.");
    Distribution.create(-10, 6.6, 678.54, bucketOptions, buckets);
  }

  @Test
  public void createDistribution_NegativeSumOfSquaredDeviations() {
    List<Double> bucketBounds = Arrays.asList(1.0, 2.0, 5.0);
    BucketOptions bucketOptions = BucketOptions.explicitOptions(bucketBounds);

    List<Bucket> buckets =
        Arrays.asList(Bucket.create(0), Bucket.create(0), Bucket.create(0), Bucket.create(0));
    thrown.expect(IllegalArgumentException.class);
    thrown.expectMessage("sum of squared deviations should be non-negative.");
    Distribution.create(0, 6.6, -678.54, bucketOptions, buckets);
  }

  @Test
  public void createDistribution_ZeroCountAndPositiveMean() {
    List<Double> bucketBounds = Arrays.asList(1.0, 2.0, 5.0);
    BucketOptions bucketOptions = BucketOptions.explicitOptions(bucketBounds);

    List<Bucket> buckets =
        Arrays.asList(Bucket.create(0), Bucket.create(0), Bucket.create(0), Bucket.create(0));
    thrown.expect(IllegalArgumentException.class);
    thrown.expectMessage("sum should be 0 if count is 0.");
    Distribution.create(0, 6.6, 0, bucketOptions, buckets);
  }

  @Test
  public void createDistribution_ZeroCountAndSumOfSquaredDeviations() {
    List<Double> bucketBounds = Arrays.asList(1.0, 2.0, 5.0);
    BucketOptions bucketOptions = BucketOptions.explicitOptions(bucketBounds);
    List<Bucket> buckets =
        Arrays.asList(Bucket.create(0), Bucket.create(0), Bucket.create(0), Bucket.create(0));
    thrown.expect(IllegalArgumentException.class);
    thrown.expectMessage("sum of squared deviations should be 0 if count is 0.");
    Distribution.create(0, 0, 678.54, bucketOptions, buckets);
  }

  @Test
  public void createDistribution_NullBucketBoundaries() {
    List<Bucket> buckets =
        Arrays.asList(Bucket.create(3), Bucket.create(1), Bucket.create(2), Bucket.create(4));
    thrown.expect(NullPointerException.class);
    thrown.expectMessage("bucketBoundaries");
    Distribution.create(10, 6.6, 678.54, BucketOptions.explicitOptions(null), buckets);
  }

  @Test
  public void createDistribution_NullBucketBoundary() {
    List<Bucket> buckets =
        Arrays.asList(Bucket.create(3), Bucket.create(1), Bucket.create(2), Bucket.create(4));
    thrown.expect(NullPointerException.class);
    thrown.expectMessage("bucketBoundary");
    Distribution.create(
        10, 6.6, 678.54, BucketOptions.explicitOptions(Arrays.asList(2.5, null)), buckets);
  }

  @Test
  public void createDistribution_NullBucketOptions() {
    List<Bucket> buckets =
        Arrays.asList(Bucket.create(3), Bucket.create(1), Bucket.create(2), Bucket.create(4));
    thrown.expect(NullPointerException.class);
    thrown.expectMessage("bucketOptions");
    Distribution.create(10, 6.6, 678.54, null, buckets);
  }

  @Test
  public void createDistribution_NullBucketList() {
    List<Double> bucketBounds = Arrays.asList(1.0, 2.0, 5.0);
    BucketOptions bucketOptions = BucketOptions.explicitOptions(bucketBounds);
    thrown.expect(NullPointerException.class);
    thrown.expectMessage("buckets");
    Distribution.create(10, 6.6, 678.54, bucketOptions, null);
  }

  @Test
  public void createDistribution_NullBucket() {
    List<Double> bucketBounds = Arrays.asList(1.0, 2.0, 5.0);
    BucketOptions bucketOptions = BucketOptions.explicitOptions(bucketBounds);
    List<Bucket> buckets =
        Arrays.asList(Bucket.create(3), Bucket.create(1), null, Bucket.create(4));
    thrown.expect(NullPointerException.class);
    thrown.expectMessage("bucket");
    Distribution.create(10, 6.6, 678.54, bucketOptions, buckets);
  }

  @Test
  public void testEquals() {
    List<Double> bucketBounds = Arrays.asList(1.0, 2.0, 2.5);
    new EqualsTester()
        .addEqualityGroup(
            Distribution.create(
                10,
                10,
                1,
                BucketOptions.explicitOptions(bucketBounds),
                Arrays.asList(
                    Bucket.create(3), Bucket.create(1), Bucket.create(2), Bucket.create(4))),
            Distribution.create(
                10,
                10,
                1,
                BucketOptions.explicitOptions(bucketBounds),
                Arrays.asList(
                    Bucket.create(3), Bucket.create(1), Bucket.create(2), Bucket.create(4))))
        .addEqualityGroup(
            Distribution.create(
                7,
                10,
                23.456,
                BucketOptions.explicitOptions(bucketBounds),
                Arrays.asList(
                    Bucket.create(3), Bucket.create(1), Bucket.create(2), Bucket.create(4))))
        .testEquals();
  }
}