// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/metrics/histogram_base.h"

#include <limits>
#include <string_view>
#include <vector>

#include "base/metrics/histogram.h"
#include "base/metrics/sample_vector.h"
#include "base/metrics/sparse_histogram.h"
#include "base/metrics/statistics_recorder.h"
#include "base/pickle.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace base {

class HistogramBaseTest : public testing::Test {
 public:
  HistogramBaseTest() {
    // Each test will have a clean state (no Histogram / BucketRanges
    // registered).
    ResetStatisticsRecorder();
  }

  HistogramBaseTest(const HistogramBaseTest&) = delete;
  HistogramBaseTest& operator=(const HistogramBaseTest&) = delete;
  ~HistogramBaseTest() override = default;

 protected:
  void ResetStatisticsRecorder() {
    // It is necessary to fully destruct any existing StatisticsRecorder
    // before creating a new one.
    statistics_recorder_.reset();
    statistics_recorder_ = StatisticsRecorder::CreateTemporaryForTesting();
  }

 private:
  std::unique_ptr<StatisticsRecorder> statistics_recorder_;
};

TEST_F(HistogramBaseTest, DeserializeHistogram) {
  HistogramBase* histogram =
      Histogram::FactoryGet("TestHistogram", 1, 1000, 10,
                            (HistogramBase::kUmaTargetedHistogramFlag |
                             HistogramBase::kIPCSerializationSourceFlag));

  Pickle pickle;
  histogram->SerializeInfo(&pickle);

  PickleIterator iter(pickle);
  HistogramBase* deserialized = DeserializeHistogramInfo(&iter);
  EXPECT_EQ(histogram, deserialized);

  ResetStatisticsRecorder();

  PickleIterator iter2(pickle);
  deserialized = DeserializeHistogramInfo(&iter2);
  EXPECT_TRUE(deserialized);
  EXPECT_NE(histogram, deserialized);
  EXPECT_EQ("TestHistogram", deserialized->histogram_name());
  EXPECT_TRUE(deserialized->HasConstructionArguments(1, 1000, 10));

  // kIPCSerializationSourceFlag will be cleared.
  EXPECT_EQ(HistogramBase::kUmaTargetedHistogramFlag, deserialized->flags());
}

TEST_F(HistogramBaseTest, DeserializeLinearHistogram) {
  HistogramBase* histogram = LinearHistogram::FactoryGet(
      "TestHistogram", 1, 1000, 10, HistogramBase::kIPCSerializationSourceFlag);

  Pickle pickle;
  histogram->SerializeInfo(&pickle);

  PickleIterator iter(pickle);
  HistogramBase* deserialized = DeserializeHistogramInfo(&iter);
  EXPECT_EQ(histogram, deserialized);

  ResetStatisticsRecorder();

  PickleIterator iter2(pickle);
  deserialized = DeserializeHistogramInfo(&iter2);
  EXPECT_TRUE(deserialized);
  EXPECT_NE(histogram, deserialized);
  EXPECT_EQ("TestHistogram", deserialized->histogram_name());
  EXPECT_TRUE(deserialized->HasConstructionArguments(1, 1000, 10));
  EXPECT_EQ(0, deserialized->flags());
}

TEST_F(HistogramBaseTest, DeserializeBooleanHistogram) {
  HistogramBase* histogram = BooleanHistogram::FactoryGet(
      "TestHistogram", HistogramBase::kIPCSerializationSourceFlag);

  Pickle pickle;
  histogram->SerializeInfo(&pickle);

  PickleIterator iter(pickle);
  HistogramBase* deserialized = DeserializeHistogramInfo(&iter);
  EXPECT_EQ(histogram, deserialized);

  ResetStatisticsRecorder();

  PickleIterator iter2(pickle);
  deserialized = DeserializeHistogramInfo(&iter2);
  EXPECT_TRUE(deserialized);
  EXPECT_NE(histogram, deserialized);
  EXPECT_EQ("TestHistogram", deserialized->histogram_name());
  EXPECT_TRUE(deserialized->HasConstructionArguments(1, 2, 3));
  EXPECT_EQ(0, deserialized->flags());
}

TEST_F(HistogramBaseTest, DeserializeCustomHistogram) {
  std::vector<HistogramBase::Sample32> ranges;
  ranges.push_back(13);
  ranges.push_back(5);
  ranges.push_back(9);

  HistogramBase* histogram = CustomHistogram::FactoryGet(
      "TestHistogram", ranges, HistogramBase::kIPCSerializationSourceFlag);

  Pickle pickle;
  histogram->SerializeInfo(&pickle);

  PickleIterator iter(pickle);
  HistogramBase* deserialized = DeserializeHistogramInfo(&iter);
  EXPECT_EQ(histogram, deserialized);

  ResetStatisticsRecorder();

  PickleIterator iter2(pickle);
  deserialized = DeserializeHistogramInfo(&iter2);
  EXPECT_TRUE(deserialized);
  EXPECT_NE(histogram, deserialized);
  EXPECT_EQ("TestHistogram", deserialized->histogram_name());
  EXPECT_TRUE(deserialized->HasConstructionArguments(5, 13, 4));
  EXPECT_EQ(0, deserialized->flags());
}

TEST_F(HistogramBaseTest, DeserializeSparseHistogram) {
  HistogramBase* histogram = SparseHistogram::FactoryGet(
      "TestHistogram", HistogramBase::kIPCSerializationSourceFlag);

  Pickle pickle;
  histogram->SerializeInfo(&pickle);

  PickleIterator iter(pickle);
  HistogramBase* deserialized = DeserializeHistogramInfo(&iter);
  EXPECT_EQ(histogram, deserialized);

  ResetStatisticsRecorder();

  PickleIterator iter2(pickle);
  deserialized = DeserializeHistogramInfo(&iter2);
  EXPECT_TRUE(deserialized);
  EXPECT_NE(histogram, deserialized);
  EXPECT_EQ("TestHistogram", deserialized->histogram_name());
  EXPECT_EQ(0, deserialized->flags());
}

TEST_F(HistogramBaseTest, AddKilo) {
  HistogramBase* histogram =
      LinearHistogram::FactoryGet("TestAddKiloHistogram", 1, 1000, 100, 0);

  histogram->AddKilo(100, 1000);
  histogram->AddKilo(200, 2000);
  histogram->AddKilo(300, 1500);

  std::unique_ptr<HistogramSamples> samples = histogram->SnapshotSamples();
  EXPECT_EQ(1, samples->GetCount(100));
  EXPECT_EQ(2, samples->GetCount(200));
  EXPECT_LE(1, samples->GetCount(300));
  EXPECT_GE(2, samples->GetCount(300));
}

TEST_F(HistogramBaseTest, AddKiB) {
  HistogramBase* histogram =
      LinearHistogram::FactoryGet("TestAddKiBHistogram", 1, 1000, 100, 0);

  histogram->AddKiB(100, 1024);
  histogram->AddKiB(200, 2048);
  histogram->AddKiB(300, 1536);

  std::unique_ptr<HistogramSamples> samples = histogram->SnapshotSamples();
  EXPECT_EQ(1, samples->GetCount(100));
  EXPECT_EQ(2, samples->GetCount(200));
  EXPECT_LE(1, samples->GetCount(300));
  EXPECT_GE(2, samples->GetCount(300));
}

TEST_F(HistogramBaseTest, AddTimeMillisecondsGranularityOverflow) {
  const HistogramBase::Sample32 sample_max =
      std::numeric_limits<HistogramBase::Sample32>::max() / 2;
  HistogramBase* histogram = LinearHistogram::FactoryGet(
      "TestAddTimeMillisecondsGranularity1", 1, sample_max, 100, 0);
  int64_t large_positive = std::numeric_limits<int64_t>::max();
  // |add_count| is the number of large values that have been added to the
  // histogram. We consider a number to be 'large' if it cannot be represented
  // in a HistogramBase::Sample32.
  int add_count = 0;
  while (large_positive > std::numeric_limits<HistogramBase::Sample32>::max()) {
    // Add the TimeDelta corresponding to |large_positive| milliseconds to the
    // histogram.
    histogram->AddTimeMillisecondsGranularity(Milliseconds(large_positive));
    ++add_count;
    // Reduce the value of |large_positive|. The choice of 7 here is
    // arbitrary.
    large_positive /= 7;
  }
  std::unique_ptr<HistogramSamples> samples = histogram->SnapshotSamples();
  // All of the reported values must have gone into the max overflow bucket.
  EXPECT_EQ(add_count, samples->GetCount(sample_max));

  // We now perform the analoguous operations, now with negative values with a
  // large absolute value.
  histogram = LinearHistogram::FactoryGet("TestAddTimeMillisecondsGranularity2",
                                          1, sample_max, 100, 0);
  int64_t large_negative = std::numeric_limits<int64_t>::min();
  add_count = 0;
  while (large_negative < std::numeric_limits<HistogramBase::Sample32>::min()) {
    histogram->AddTimeMillisecondsGranularity(Milliseconds(large_negative));
    ++add_count;
    large_negative /= 7;
  }
  samples = histogram->SnapshotSamples();
  // All of the reported values must have gone into the min overflow bucket.
  EXPECT_EQ(add_count, samples->GetCount(0));
}

TEST_F(HistogramBaseTest, AddTimeMicrosecondsGranularityOverflow) {
  // Nothing to test if we don't have a high resolution clock.
  if (!TimeTicks::IsHighResolution()) {
    return;
  }

  const HistogramBase::Sample32 sample_max =
      std::numeric_limits<HistogramBase::Sample32>::max() / 2;
  HistogramBase* histogram = LinearHistogram::FactoryGet(
      "TestAddTimeMicrosecondsGranularity1", 1, sample_max, 100, 0);
  int64_t large_positive = std::numeric_limits<int64_t>::max();
  // |add_count| is the number of large values that have been added to the
  // histogram. We consider a number to be 'large' if it cannot be represented
  // in a HistogramBase::Sample32.
  int add_count = 0;
  while (large_positive > std::numeric_limits<HistogramBase::Sample32>::max()) {
    // Add the TimeDelta corresponding to |large_positive| microseconds to the
    // histogram.
    histogram->AddTimeMicrosecondsGranularity(Microseconds(large_positive));
    ++add_count;
    // Reduce the value of |large_positive|. The choice of 7 here is
    // arbitrary.
    large_positive /= 7;
  }
  std::unique_ptr<HistogramSamples> samples = histogram->SnapshotSamples();
  // All of the reported values must have gone into the max overflow bucket.
  EXPECT_EQ(add_count, samples->GetCount(sample_max));

  // We now perform the analoguous operations, now with negative values with a
  // large absolute value.
  histogram = LinearHistogram::FactoryGet("TestAddTimeMicrosecondsGranularity2",
                                          1, sample_max, 100, 0);
  int64_t large_negative = std::numeric_limits<int64_t>::min();
  add_count = 0;
  while (large_negative < std::numeric_limits<HistogramBase::Sample32>::min()) {
    histogram->AddTimeMicrosecondsGranularity(Microseconds(large_negative));
    ++add_count;
    large_negative /= 7;
  }
  samples = histogram->SnapshotSamples();
  // All of the reported values must have gone into the min overflow bucket.
  EXPECT_EQ(add_count, samples->GetCount(0));
}

}  // namespace base