/*
 *  Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#ifndef MODULES_AUDIO_PROCESSING_AGC_ANALOG_GAIN_STATS_REPORTER_H_
#define MODULES_AUDIO_PROCESSING_AGC_ANALOG_GAIN_STATS_REPORTER_H_

#include "absl/types/optional.h"
#include "rtc_base/gtest_prod_util.h"

namespace webrtc {

// Analog gain statistics calculator. Computes aggregate stats based on the
// framewise mic levels processed in `UpdateStatistics()`. Periodically logs the
// statistics into a histogram.
class AnalogGainStatsReporter {
 public:
  AnalogGainStatsReporter();
  AnalogGainStatsReporter(const AnalogGainStatsReporter&) = delete;
  AnalogGainStatsReporter operator=(const AnalogGainStatsReporter&) = delete;
  ~AnalogGainStatsReporter();

  // Updates the stats based on the `analog_mic_level`. Periodically logs the
  // stats into a histogram.
  void UpdateStatistics(int analog_mic_level);

 private:
  FRIEND_TEST_ALL_PREFIXES(AnalogGainStatsReporterTest,
                           CheckLevelUpdateStatsForEmptyStats);
  FRIEND_TEST_ALL_PREFIXES(AnalogGainStatsReporterTest,
                           CheckLevelUpdateStatsAfterNoGainChange);
  FRIEND_TEST_ALL_PREFIXES(AnalogGainStatsReporterTest,
                           CheckLevelUpdateStatsAfterGainIncrease);
  FRIEND_TEST_ALL_PREFIXES(AnalogGainStatsReporterTest,
                           CheckLevelUpdateStatsAfterGainDecrease);
  FRIEND_TEST_ALL_PREFIXES(AnalogGainStatsReporterTest,
                           CheckLevelUpdateStatsAfterReset);

  // Stores analog gain update stats to enable calculation of update rate and
  // average update separately for gain increases and decreases.
  struct LevelUpdateStats {
    int num_decreases = 0;
    int num_increases = 0;
    int sum_decreases = 0;
    int sum_increases = 0;
  } level_update_stats_;

  // Returns a copy of the stored statistics. Use only for testing.
  const LevelUpdateStats level_update_stats() const {
    return level_update_stats_;
  }

  // Computes aggregate stat and logs them into a histogram.
  void LogLevelUpdateStats() const;

  int log_level_update_stats_counter_ = 0;
  absl::optional<int> previous_analog_mic_level_ = absl::nullopt;
};
}  // namespace webrtc

#endif  // MODULES_AUDIO_PROCESSING_AGC_ANALOG_GAIN_STATS_REPORTER_H_