/*
 *  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 <array>

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

namespace webrtc {

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

  // Updates the ERL estimate.
  void Update(rtc::ArrayView<const float> render_spectrum,
              rtc::ArrayView<const float> capture_spectrum);

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

 private:
  std::array<float, kFftLengthBy2Plus1> erl_;
  std::array<int, kFftLengthBy2Minus1> hold_counters_;
  float erl_time_domain_;
  int hold_counter_time_domain_;

  RTC_DISALLOW_COPY_AND_ASSIGN(ErlEstimator);
};

}  // namespace webrtc

#endif  // MODULES_AUDIO_PROCESSING_AEC3_ERL_ESTIMATOR_H_