/*
 * 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.dataflow.worker.counters;

import static org.junit.Assert.assertEquals;

import java.util.List;
import org.apache.beam.runners.dataflow.worker.counters.CounterFactory.CounterDistribution;
import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.collect.ImmutableList;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/** Unit tests for {@link CounterFactory} and nested classes. */
@RunWith(JUnit4.class)
public class CounterFactoryTest {
  /**
   * Validate boundary values in the full range of positive long integers that they are placed in
   * the correct CounterDistribution histogram bucket. The naive bucketing implementation of using
   * Math.log10 introduces error for large values due to precision loss in converting large integers
   * to and from floating point.
   */
  @Test
  public void testCounterDistributionCalculateBucket() {
    assertEquals(0, CounterDistribution.calculateBucket(0));

    int bucket = 1;
    long powerOfTen = 1;
    while (powerOfTen > 0 /* break on overflow */) {
      for (int multiplier : new int[] {1, 2, 5}) {
        long value = powerOfTen * multiplier;
        verifyDistributionBucket(value - 1, bucket - 1);
        verifyDistributionBucket(value, bucket);
        bucket++;
      }
      powerOfTen *= 10;
    }
  }

  private void verifyDistributionBucket(long value, int expectedBucket) {
    int actualBucket = CounterDistribution.calculateBucket(value);
    assertEquals(String.format("Bucket value for %d", value), expectedBucket, actualBucket);
  }

  @Test
  public void testCounterDistributionAddValue() {
    CounterDistribution counter = CounterDistribution.empty();
    List<Long> expectedBuckets = ImmutableList.of(1L, 3L, 0L, 0L, 0L, 0L, 0L, 0L, 1L, 1L);
    for (long value : new long[] {1, 500, 2, 3, 1000, 4}) {
      counter = counter.addValue(value);
    }
    assertEquals(expectedBuckets, counter.getBuckets());
    assertEquals(1250030.0, counter.getSumOfSquares(), 0);
    assertEquals(1510, counter.getSum());
    assertEquals(1, counter.getFirstBucketOffset());
    assertEquals(6, counter.getCount());
    assertEquals(1, counter.getMin());
    assertEquals(1000, counter.getMax());
  }
}
