/*
 *  Copyright (c) 2017 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_AEC3_ERL_ESTIMATOR_H_
#define MODULES_AUDIO_PROCESSING_AEC3_ERL_ESTIMATOR_H_

#include <stddef.h>

#include <array>
#include <span>
#include <vector>

#include "modules/audio_processing/aec3/aec3_common.h"

namespace webrtc {

// Estimates the echo return loss based on the signal spectra.
class ErlEstimator {
 public:
  explicit ErlEstimator(size_t startup_phase_length_blocks_);
  ~ErlEstimator();

  ErlEstimator(const ErlEstimator&) = delete;
  ErlEstimator& operator=(const ErlEstimator&) = delete;

  // Resets the ERL estimation.
  void Reset();

  // Updates the ERL estimate.
  void Update(
      const std::vector<bool>& converged_filters,
      std::span<const std::array<float, kFftLengthBy2Plus1>> render_spectra,
      std::span<const std::array<float, kFftLengthBy2Plus1>> capture_spectra);

  // Returns the most recent ERL estimate.
  const std::array<float, kFftLengthBy2Plus1>& Erl() const { return erl_; }
  float ErlTimeDomain() const { return erl_time_domain_; }

 private:
  const size_t startup_phase_length_blocks__;
  std::array<float, kFftLengthBy2Plus1> erl_;
  std::array<int, kFftLengthBy2Minus1> hold_counters_;
  float erl_time_domain_;
  int hold_counter_time_domain_;
  size_t blocks_since_reset_ = 0;
};

}  // namespace webrtc

#endif  // MODULES_AUDIO_PROCESSING_AEC3_ERL_ESTIMATOR_H_