/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#if !defined(AutoplayPolicy_h_)
#  define AutoplayPolicy_h_

#  include "mozilla/NotNull.h"

namespace mozilla {
namespace dom {

class HTMLMediaElement;
class AudioContext;
class Document;

/**
 * AutoplayPolicy is used to manage autoplay logic for all kinds of media,
 * including MediaElement, Web Audio and Web Speech.
 *
 * Autoplay could be disable by setting the pref "media.autoplay.default"
 * to anything but nsIAutoplay::Allowed. Once user disables autoplay, media
 * could only be played if one of following conditions is true.
 * 1) Owner document is activated by user gestures
 *    We restrict user gestures to "mouse click", "keyboard press" and "touch".
 * 2) Muted media content or video without audio content.
 * 3) Document's origin has the "autoplay-media" permission.
 */
class AutoplayPolicy {
 public:
  // Returns a DocumentAutoplayPolicy for given document.
  static DocumentAutoplayPolicy IsAllowedToPlay(const Document& aDocument);

  // Returns whether a given media element is allowed to play.
  static bool IsAllowedToPlay(const HTMLMediaElement& aElement);

  // Returns whether a given AudioContext is allowed to play.
  static bool IsAllowedToPlay(const AudioContext& aContext);
};

/**
 * This class contains helper funtions which could be used in AutoplayPolicy
 * for determing Telemetry use-only result. They shouldn't represent the final
 * result of blocking autoplay.
 */
class AutoplayPolicyTelemetryUtils {
 public:
  // Returns true if a given media element would be allowed to play
  // if block autoplay was enabled. If this returns false, it means we would
  // either block or ask for permission.
  // Note: this is for telemetry purposes, and doesn't check the prefs
  // which enable/disable block autoplay. Do not use for blocking logic!
  static bool WouldBeAllowedToPlayIfAutoplayDisabled(
      const HTMLMediaElement& aElement);

  // Returns true if a given AudioContext would be allowed to play
  // if block autoplay was enabled. If this returns false, it means we would
  // either block or ask for permission.
  // Note: this is for telemetry purposes, and doesn't check the prefs
  // which enable/disable block autoplay. Do not use for blocking logic!
  static bool WouldBeAllowedToPlayIfAutoplayDisabled(
      const AudioContext& aContext);
};

}  // namespace dom
}  // namespace mozilla

#endif