// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_MEDIA_SYSTEM_MEDIA_CONTROLS_SYSTEM_MEDIA_CONTROLS_NOTIFIER_H_
#define CONTENT_BROWSER_MEDIA_SYSTEM_MEDIA_CONTROLS_SYSTEM_MEDIA_CONTROLS_NOTIFIER_H_

#include <memory>
#include <vector>

#include "base/memory/raw_ptr.h"
#include "base/sequence_checker.h"
#include "base/timer/timer.h"
#include "build/build_config.h"
#include "components/system_media_controls/system_media_controls.h"
#include "content/common/content_export.h"
#include "mojo/public/cpp/bindings/receiver.h"
#include "mojo/public/cpp/bindings/remote.h"
#include "services/media_session/public/mojom/media_controller.mojom.h"

namespace base {
class UnguessableToken;
}
namespace content {

// The SystemMediaControlsNotifier connects to the SystemMediaControls API and
// keeps it informed of the current media playback state and metadata. It
// observes changes to the active Media Session and updates the
// SystemMediaControls accordingly.
class CONTENT_EXPORT SystemMediaControlsNotifier
    : public media_session::mojom::MediaControllerObserver,
      public media_session::mojom::MediaControllerImageObserver {
 public:
  SystemMediaControlsNotifier(
      system_media_controls::SystemMediaControls* system_media_controls,
      base::UnguessableToken request_id);

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

  ~SystemMediaControlsNotifier() override;

  // media_session::mojom::MediaControllerObserver implementation.
  void MediaSessionInfoChanged(
      media_session::mojom::MediaSessionInfoPtr session_info) override;
  void MediaSessionMetadataChanged(
      const std::optional<media_session::MediaMetadata>& metadata) override;
  void MediaSessionActionsChanged(
      const std::vector<media_session::mojom::MediaSessionAction>& actions)
      override;
  void MediaSessionChanged(
      const std::optional<base::UnguessableToken>& request_id) override;
  void MediaSessionPositionChanged(
      const std::optional<media_session::MediaPosition>& position) override;

  // media_session::mojom::MediaControllerImageObserver implementation.
  void MediaControllerImageChanged(
      ::media_session::mojom::MediaSessionImageType type,
      const SkBitmap& bitmap) override;
  // There's no chapter images in the system media tray view, so we don't need
  // to implement this method.
  void MediaControllerChapterImageChanged(int chapter_index,
                                          const SkBitmap& bitmap) override {}

 private:
  friend class SystemMediaControlsNotifierTest;

  // Updates the system media controls' metadata after a brief delay. If
  // multiple calls are received during the delay, only the last one is applied.
  // This prevents overloading the OS with system calls.
  void DebouncePositionUpdate(media_session::MediaPosition position);
  void DebounceMetadataUpdate(media_session::MediaMetadata metadata);
  void DebouncePlaybackStatusUpdate(
      system_media_controls::SystemMediaControls::PlaybackStatus
          playback_status);
  void DebounceIconUpdate(const SkBitmap& bitmap);
  void DebounceSetIsSeekToEnabled(bool is_seek_to_enabled);

  void MaybeScheduleMetadataUpdate();
  void UpdateMetadata();
  void UpdateIcon();

  // Clear the system's media controls' metadata, and any pending position or
  // metadata updates.
  void ClearAllMetadata();

  // We want to hide the controls on the lock screen on Windows in certain
  // cases. We don't want this functionality on other OSes.
#if BUILDFLAG(IS_WIN)
  // Polls the current idle state of the system.
  void CheckLockState();

  // Called when the idle state changes from unlocked to locked.
  void OnScreenLocked();

  // Called when the idle state changes from locked to unlocked.
  void OnScreenUnlocked();

  // Helper functions for dealing with the timer that hides the System Media
  // Transport Controls on the lock screen 5 seconds after the user pauses.
  void StartHideSmtcTimer();
  void StopHideSmtcTimer();
  void HideSmtcTimerFired();

  bool screen_locked_ = false;
  base::RepeatingTimer lock_polling_timer_;
  base::OneShotTimer hide_smtc_timer_;
#endif  // BUILDFLAG(IS_WIN)

  // Our connection to the System Media Controls instance we should notify.
  // Owned by WebAppSystemMediaControls.
  const raw_ptr<system_media_controls::SystemMediaControls>
      system_media_controls_;

  // Timer to debounce updates.
  base::OneShotTimer metadata_update_timer_;
  base::OneShotTimer icon_update_timer_;
  base::OneShotTimer actions_update_timer_;

  // Pending metadata to be set once `metadata_update_timer_` fires.
  std::optional<media_session::MediaPosition> delayed_position_update_;
  std::optional<media_session::MediaMetadata> delayed_metadata_update_;
  std::optional<system_media_controls::SystemMediaControls::PlaybackStatus>
      delayed_playback_status_;

  // Icon to use once `icon_update_timer_` fires.
  std::optional<SkBitmap> delayed_icon_update_;

  // Pending action to set once `actions_update_timer_` fires.
  std::optional<bool> delayed_is_seek_to_enabled_;

  // Tracks current media session state/metadata.
  mojo::Remote<media_session::mojom::MediaController> media_controller_remote_;
  media_session::mojom::MediaSessionInfoPtr session_info_ptr_;

  // Used to receive updates to the active media controller.
  mojo::Receiver<media_session::mojom::MediaControllerObserver>
      media_controller_observer_receiver_{this};
  mojo::Receiver<media_session::mojom::MediaControllerImageObserver>
      media_controller_image_observer_receiver_{this};

  SEQUENCE_CHECKER(sequence_checker_);
};

}  // namespace content

#endif  // CONTENT_BROWSER_MEDIA_SYSTEM_MEDIA_CONTROLS_SYSTEM_MEDIA_CONTROLS_NOTIFIER_H_