// Copyright (c) 2012 The Chromium Authors. 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/browser/web_contents_delegate.h"
#include "content/public/common/media_stream_request.h"

class AudioStreamIndicator;
class MediaStreamCaptureIndicator;
class Profile;

namespace extensions {
class Extension;
}

namespace user_prefs {
class PrefRegistrySyncable;
}

// This singleton is used to receive updates about media events from the content
// layer.
class MediaCaptureDevicesDispatcher : public content::MediaObserver {
 public:
  class Observer {
   public:
    // Handle an information update consisting of a up-to-date audio capture
    // device lists. This happens when a microphone is plugged in or unplugged.
    virtual void OnUpdateAudioDevices(
        const content::MediaStreamDevices& devices) {}

    // Handle an information update consisting of a up-to-date video capture
    // device lists. This happens when a camera is plugged in or unplugged.
    virtual void OnUpdateVideoDevices(
        const content::MediaStreamDevices& devices) {}

    // Handle an information update related to a media stream request.
    virtual void OnRequestUpdate(
        int render_process_id,
        int render_view_id,
        const content::MediaStreamDevice& device,
        const content::MediaRequestState state) {}

    virtual ~Observer() {}
  };

  static MediaCaptureDevicesDispatcher* GetInstance();

  // Registers the preferences related to Media Stream default devices.
  static void RegisterUserPrefs(user_prefs::PrefRegistrySyncable* registry);

  // Methods for observers. Called on UI thread.
  // Observers should add themselves on construction and remove themselves
  // on destruction.
  void AddObserver(Observer* observer);
  void RemoveObserver(Observer* observer);
  const content::MediaStreamDevices& GetAudioCaptureDevices();
  const content::MediaStreamDevices& GetVideoCaptureDevices();

  // Method called from WebCapturerDelegate implementations to process access
  // requests. |extension| is set to NULL if request was made from a drive-by
  // page.
  void ProcessMediaAccessRequest(
      content::WebContents* web_contents,
      const content::MediaStreamRequest& request,
      const content::MediaResponseCallback& callback,
      const extensions::Extension* extension);

  // Helper to get the default devices which can be used by the media request,
  // if the return list is empty, it means there is no available device on the
  // OS.
  // Called on the UI thread.
  void GetDefaultDevicesForProfile(Profile* profile,
                                   bool audio,
                                   bool video,
                                   content::MediaStreamDevices* devices);

  // 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);

  // 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 is_playing_and_audible) OVERRIDE;

  scoped_refptr<MediaStreamCaptureIndicator> GetMediaStreamCaptureIndicator();

  scoped_refptr<AudioStreamIndicator> GetAudioStreamIndicator();

 private:
  friend struct DefaultSingletonTraits<MediaCaptureDevicesDispatcher>;

  MediaCaptureDevicesDispatcher();
  virtual ~MediaCaptureDevicesDispatcher();

  // Helpers for ProcessMediaAccessRequest().
  void ProcessScreenCaptureAccessRequest(
      content::WebContents* web_contents,
      const content::MediaStreamRequest& request,
      const content::MediaResponseCallback& callback);
  void ProcessMediaAccessRequestFromExtension(
      content::WebContents* web_contents,
      const content::MediaStreamRequest& request,
      const content::MediaResponseCallback& callback,
      const extensions::Extension* extension);

  // 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_;

  // A list of observers for the device update notifications.
  ObserverList<Observer> observers_;

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

  scoped_refptr<MediaStreamCaptureIndicator> media_stream_capture_indicator_;

  scoped_refptr<AudioStreamIndicator> audio_stream_indicator_;
};

#endif  // CHROME_BROWSER_MEDIA_MEDIA_CAPTURE_DEVICES_DISPATCHER_H_