// Copyright 2017 The Cobalt Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef COBALT_MEDIA_SESSION_MEDIA_SESSION_CLIENT_H_
#define COBALT_MEDIA_SESSION_MEDIA_SESSION_CLIENT_H_

#include <bitset>
#include <memory>

#include "base/threading/thread_checker.h"
#include "cobalt/media/web_media_player_factory.h"
#include "cobalt/media_session/media_session.h"
#include "cobalt/media_session/media_session_action_details.h"
#include "cobalt/media_session/media_session_state.h"
#include "starboard/time.h"

namespace cobalt {
namespace media_session {

// Base class for a platform-level implementation of MediaSession.
// Platforms should subclass this to connect MediaSession to their platform.
class MediaSessionClient {
  friend class MediaSession;

 public:
  MediaSessionClient() : MediaSessionClient(new MediaSession(this)) {}

  // Injectable MediaSession for tests.
  explicit MediaSessionClient(scoped_refptr<MediaSession> media_session)
      : media_session_(media_session),
        platform_playback_state_(kMediaSessionPlaybackStateNone) {}

  virtual ~MediaSessionClient();

  // Creates platform-specific instance.
  static std::unique_ptr<MediaSessionClient> Create();

  // Retrieves the singleton MediaSession associated with this client.
  scoped_refptr<MediaSession>& GetMediaSession() { return media_session_; }

  // The web app should set the MediaPositionState of the MediaSession object.
  // However, if that is not done, then query the web media player factory to
  // guess which player is associated with the media session to get the media
  // position state. The player factory must outlive the media session client.
  void SetMediaPlayerFactory(const media::WebMediaPlayerFactory* factory);

  // Sets the platform's current playback state. This is used to compute
  // the "guessed playback state"
  // https://wicg.github.io/mediasession/#guessed-playback-state
  // Can be invoked from any thread.
  void UpdatePlatformPlaybackState(MediaSessionPlaybackState state);

  // Invokes a given media session action
  // https://wicg.github.io/mediasession/#actions-model
  // Can be invoked from any thread.
  void InvokeAction(MediaSessionAction action) {
    std::unique_ptr<MediaSessionActionDetails> details(
        new MediaSessionActionDetails());
    details->set_action(action);
    InvokeActionInternal(std::move(details));
  }

  // Invokes a given media session action that takes additional details.
  void InvokeAction(std::unique_ptr<MediaSessionActionDetails> details) {
    InvokeActionInternal(std::move(details));
  }

  // Invoked on the browser thread when any metadata, position state, playback
  // state, or supported session actions change.
  virtual void OnMediaSessionStateChanged(
      const MediaSessionState& session_state) = 0;

 private:
  THREAD_CHECKER(thread_checker_);
  scoped_refptr<MediaSession> media_session_;
  MediaSessionState session_state_;
  MediaSessionPlaybackState platform_playback_state_;
  const media::WebMediaPlayerFactory* media_player_factory_ = nullptr;

  void UpdateMediaSessionState();
  MediaSessionPlaybackState ComputeActualPlaybackState() const;
  MediaSessionState::AvailableActionsSet ComputeAvailableActions() const;

  void InvokeActionInternal(std::unique_ptr<MediaSessionActionDetails> details);

  DISALLOW_COPY_AND_ASSIGN(MediaSessionClient);
};

}  // namespace media_session
}  // namespace cobalt

#endif  // COBALT_MEDIA_SESSION_MEDIA_SESSION_CLIENT_H_