/*
 *  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.
 */

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

#include <math.h>

#include <algorithm>
#include <functional>

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

namespace webrtc {

ReverbModel::ReverbModel() {
  Reset();
}

ReverbModel::~ReverbModel() = default;

void ReverbModel::Reset() {
  reverb_.fill(0.);
}

void ReverbModel::UpdateReverbContributions(
    rtc::ArrayView<const float> power_spectrum,
    float power_spectrum_scaling,
    float reverb_decay) {
  if (reverb_decay > 0) {
    // Update the estimate of the reverberant power.
    std::transform(power_spectrum.begin(), power_spectrum.end(),
                   reverb_.begin(), reverb_.begin(),
                   [reverb_decay, power_spectrum_scaling](float a, float b) {
                     return (b + a * power_spectrum_scaling) * reverb_decay;
                   });
  }
}

void ReverbModel::AddReverb(rtc::ArrayView<const float> power_spectrum,
                            float power_spectrum_scaling,
                            float reverb_decay,
                            rtc::ArrayView<float> reverb_power_spectrum) {
  UpdateReverbContributions(power_spectrum, power_spectrum_scaling,
                            reverb_decay);

  // Add the power of the echo reverb to the residual echo power.
  std::transform(reverb_power_spectrum.begin(), reverb_power_spectrum.end(),
                 reverb_.begin(), reverb_power_spectrum.begin(),
                 std::plus<float>());
}

}  // namespace webrtc