// Copyright (c) 2013 GitHub, Inc. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROME_BROWSER_MEDIA_MEDIA_CAPTURE_DEVICES_DISPATCHER_H_
#define CHROME_BROWSER_MEDIA_MEDIA_CAPTURE_DEVICES_DISPATCHER_H_

#include "base/callback.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/singleton.h"
#include "base/observer_list.h"
#include "content/public/browser/media_observer.h"
#include "content/public/common/media_stream_request.h"

// This singleton is used to receive updates about media events from the content
// layer.
class MediaCaptureDevicesDispatcher : public content::MediaObserver {
 public:
  static MediaCaptureDevicesDispatcher* GetInstance();

  // Helper for picking the device that was requested for an OpenDevice request.
  // If the device requested is not available it will revert to using the first
  // available one instead or will return an empty list if no devices of the
  // requested kind are present.
  void GetRequestedDevice(const std::string& requested_device_id,
                          bool audio,
                          bool video,
                          content::MediaStreamDevices* devices);
  void GetDefaultDevices(bool audio,
                         bool video,
                         content::MediaStreamDevices* devices);

  const content::MediaStreamDevices& GetAudioCaptureDevices();
  const content::MediaStreamDevices& GetVideoCaptureDevices();

  // Overridden from content::MediaObserver:
  virtual void OnAudioCaptureDevicesChanged(
      const content::MediaStreamDevices& devices) OVERRIDE;
  virtual void OnVideoCaptureDevicesChanged(
      const content::MediaStreamDevices& devices) OVERRIDE;
  virtual void OnMediaRequestStateChanged(
      int render_process_id,
      int render_view_id,
      const content::MediaStreamDevice& device,
      content::MediaRequestState state) OVERRIDE;
  virtual void OnAudioStreamPlayingChanged(
      int render_process_id,
      int render_view_id,
      int stream_id,
      bool playing) OVERRIDE {}

 private:
  friend struct DefaultSingletonTraits<MediaCaptureDevicesDispatcher>;

  MediaCaptureDevicesDispatcher();
  virtual ~MediaCaptureDevicesDispatcher();

  // Called by the MediaObserver() functions, executed on UI thread.
  void UpdateAudioDevicesOnUIThread(const content::MediaStreamDevices& devices);
  void UpdateVideoDevicesOnUIThread(const content::MediaStreamDevices& devices);
  void UpdateMediaRequestStateOnUIThread(
      int render_process_id,
      int render_view_id,
      const content::MediaStreamDevice& device,
      content::MediaRequestState state);

  // A list of cached audio capture devices.
  content::MediaStreamDevices audio_devices_;

  // A list of cached video capture devices.
  content::MediaStreamDevices video_devices_;

  // Flag to indicate if device enumeration has been done/doing.
  // Only accessed on UI thread.
  bool devices_enumerated_;
};

#endif  // CHROME_BROWSER_MEDIA_MEDIA_CAPTURE_DEVICES_DISPATCHER_H_