// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef THIRD_PARTY_BLINK_RENDERER_MODULES_MEDIASTREAM_WEBAUDIO_MEDIA_STREAM_AUDIO_SINK_H_
#define THIRD_PARTY_BLINK_RENDERER_MODULES_MEDIASTREAM_WEBAUDIO_MEDIA_STREAM_AUDIO_SINK_H_

#include <stddef.h>

#include <memory>

#include "base/containers/span.h"
#include "base/gtest_prod_util.h"
#include "base/synchronization/lock.h"
#include "base/time/time.h"
#include "media/base/audio_converter.h"
#include "media/base/reentrancy_checker.h"
#include "third_party/blink/public/platform/modules/mediastream/web_media_stream_audio_sink.h"
#include "third_party/blink/public/platform/web_audio_source_provider.h"
#include "third_party/blink/renderer/modules/modules_export.h"
#include "third_party/blink/renderer/platform/mediastream/media_stream_component.h"

namespace media {
class AudioBus;
class AudioConverter;
class AudioFifo;
class AudioParameters;
}  // namespace media

namespace blink {

class WebAudioSourceProviderClient;

// WebAudioMediaStreamAudioSink provides a bridge between classes:
//     MediaStreamAudioTrack ---> WebAudioSourceProvider
//
// WebAudioMediaStreamAudioSink works as a sink to the MediaStreamAudioTrack
// and stores the capture data to a FIFO. When the media stream is connected to
// WebAudio MediaStreamAudioSourceNode as a source provider,
// MediaStreamAudioSourceNode will periodically call provideInput() to get the
// data from the FIFO.
//
// Most calls are protected by a lock.
class MODULES_EXPORT WebAudioMediaStreamAudioSink
    : public WebAudioSourceProvider,
      public media::AudioConverter::InputCallback,
      public WebMediaStreamAudioSink {
 public:
  WebAudioMediaStreamAudioSink(MediaStreamComponent* component,
                               int context_sample_rate,
                               base::TimeDelta platform_buffer_duration,
                               uint32_t render_quantum_frames);

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

  ~WebAudioMediaStreamAudioSink() override;

  // WebMediaStreamAudioSink implementation.
  void OnData(const media::AudioBus& audio_bus,
              base::TimeTicks estimated_capture_time) override;
  void OnSetFormat(const media::AudioParameters& params) override;
  void OnReadyStateChanged(WebMediaStreamSource::ReadyState state) override;

  // WebAudioSourceProvider implementation.
  void SetClient(WebAudioSourceProviderClient* client) override;
  void ProvideInput(base::span<const base::span<float>> audio_data,
                    int number_of_frames) override;

 private:
  FRIEND_TEST_ALL_PREFIXES(WebAudioMediaStreamAudioSinkFifoTest, VerifyFifo);

  struct FifoStats {
    int overruns = 0;
    int underruns = 0;
  };

  void ResetFifoStatsForTesting();
  const FifoStats& GetFifoStatsForTesting();

  // media::AudioConverter::InputCallback implementation.
  // This function is triggered by the above ProvideInput() on the WebAudio
  // audio thread, so it has be called under the protection of |lock_|.
  double ProvideInput(media::AudioBus* audio_bus,
                      uint32_t frames_delayed,
                      const media::AudioGlitchInfo& glitch_info) override;

  std::unique_ptr<media::AudioConverter> audio_converter_ GUARDED_BY(lock_);
  std::unique_ptr<media::AudioFifo> fifo_ GUARDED_BY(lock_);
  bool is_enabled_ GUARDED_BY(lock_);
  media::AudioParameters source_params_ GUARDED_BY(lock_);

  // Protects the above variables.
  base::Lock lock_;

  // No lock protection needed since only accessed in span version of
  // ProvideInput().
  std::unique_ptr<media::AudioBus> output_wrapper_;

  // The audio track that this source provider is connected to.
  // No lock protection needed since only accessed in constructor and
  // destructor.
  Persistent<MediaStreamComponent> component_;

  // Flag to tell if the track has been stopped or not.
  // No lock protection needed since only accessed in constructor, destructor
  // and OnReadyStateChanged().
  bool track_stopped_;

  // Buffer duration of the output backing up the audio context the sink
  // delivers audio to. Affects how many public ProvideInput() calls can be
  // received in one batch, and thus needs to be taken into account when
  // configuring `fifo_`.
  const base::TimeDelta platform_buffer_duration_;

  // Parameters at which audio is delivered to the WebAudio graph, i.e. of the
  // public ProvideInput() call.
  const media::AudioParameters sink_params_;

  // For testing. Instantiated only if ResetFifoStatsForTesting() is called.
  std::unique_ptr<FifoStats> fifo_stats_;

  // Used to assert that OnData() is only accessed by one thread at a time. We
  // can't use a thread checker since thread may change.
  REENTRANCY_CHECKER(capture_reentrancy_checker_);

  // Used to assert that ProvideInput() is not accessed concurrently.
  REENTRANCY_CHECKER(provide_input_reentrancy_checker_);

  // Used to assert that OnReadyStateChanged() is not accessed concurrently.
  REENTRANCY_CHECKER(ready_state_reentrancy_checker_);
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_MODULES_MEDIASTREAM_WEBAUDIO_MEDIA_STREAM_AUDIO_SINK_H_