/*
 *  Copyright (c) 2018 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_REVERB_MODEL_H_
#define MODULES_AUDIO_PROCESSING_AEC3_REVERB_MODEL_H_

#include <array>
#include <span>

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

namespace webrtc {

// The ReverbModel class describes an exponential reverberant model
// that can be applied over power spectrums.
class ReverbModel {
 public:
  ReverbModel();
  ~ReverbModel();

  // Resets the state.
  void Reset();

  // Returns the reverb.
  std::span<const float, kFftLengthBy2Plus1> reverb() const { return reverb_; }

  // The methods UpdateReverbNoFreqShaping and UpdateReverb update the
  // estimate of the reverberation contribution to an input/output power
  // spectrum. Before applying the exponential reverberant model, the input
  // power spectrum is pre-scaled. Use the method UpdateReverb when a different
  // scaling should be applied per frequency and UpdateReverb_no_freq_shape if
  // the same scaling should be used for all the frequencies.
  void UpdateReverbNoFreqShaping(std::span<const float> power_spectrum,
                                 float power_spectrum_scaling,
                                 float reverb_decay);

  // Update the reverb based on new data.
  void UpdateReverb(std::span<const float> power_spectrum,
                    std::span<const float> power_spectrum_scaling,
                    float reverb_decay);

 private:
  std::array<float, kFftLengthBy2Plus1> reverb_;
};

}  // namespace webrtc

#endif  // MODULES_AUDIO_PROCESSING_AEC3_REVERB_MODEL_H_