/* 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/. */

#include "BackgroundVideoDecodingPermissionObserver.h"

#include "mozilla/AsyncEventDispatcher.h"

#include "mozilla/StaticPrefs.h"

#include "MediaDecoder.h"

#include "nsContentUtils.h"

#include "nsIDocument.h"

namespace mozilla {

BackgroundVideoDecodingPermissionObserver::

  BackgroundVideoDecodingPermissionObserver(MediaDecoder* aDecoder)

  : mDecoder(aDecoder)

  , mIsRegisteredForEvent(false)

{

  MOZ_ASSERT(mDecoder);

}

NS_IMETHODIMP

BackgroundVideoDecodingPermissionObserver::Observe(nsISupports* aSubject,

                                                   const char* aTopic,

                                                   const char16_t* aData)

{

  if (!StaticPrefs::MediaResumeBkgndVideoOnTabhover()) {

    return NS_OK;

  }

  if (!IsValidEventSender(aSubject)) {

    return NS_OK;

  }

  if (strcmp(aTopic, "unselected-tab-hover") == 0) {

    bool allowed = !NS_strcmp(aData, u"true");

    mDecoder->SetIsBackgroundVideoDecodingAllowed(allowed);

  }

  return NS_OK;

}

void

BackgroundVideoDecodingPermissionObserver::RegisterEvent()

{

  MOZ_ASSERT(!mIsRegisteredForEvent);

  nsCOMPtr<nsIObserverService> observerService = services::GetObserverService();

  if (observerService) {

    observerService->AddObserver(this, "unselected-tab-hover", false);

    mIsRegisteredForEvent = true;

    if (nsContentUtils::IsInStableOrMetaStableState()) {

      // Events shall not be fired synchronously to prevent anything visible

      // from the scripts while we are in stable state.

      if (nsCOMPtr<nsIDocument> doc = GetOwnerDoc()) {

        doc->Dispatch(

          TaskCategory::Other,

          NewRunnableMethod(

            "BackgroundVideoDecodingPermissionObserver::"

            "EnableEvent",

            this,

            &BackgroundVideoDecodingPermissionObserver::

              EnableEvent));

      }

    } else {

      EnableEvent();

    }

  }

}

void

BackgroundVideoDecodingPermissionObserver::UnregisterEvent()

{

  MOZ_ASSERT(mIsRegisteredForEvent);

  nsCOMPtr<nsIObserverService> observerService = services::GetObserverService();

  if (observerService) {

    observerService->RemoveObserver(this, "unselected-tab-hover");

    mIsRegisteredForEvent = false;

    mDecoder->SetIsBackgroundVideoDecodingAllowed(false);

    if (nsContentUtils::IsInStableOrMetaStableState()) {

      // Events shall not be fired synchronously to prevent anything visible

      // from the scripts while we are in stable state.

      if (nsCOMPtr<nsIDocument> doc = GetOwnerDoc()) {

        doc->Dispatch(

          TaskCategory::Other,

          NewRunnableMethod(

            "BackgroundVideoDecodingPermissionObserver::"

            "DisableEvent",

            this,

            &BackgroundVideoDecodingPermissionObserver::

              DisableEvent));

      }

    } else {

      DisableEvent();

    }

  }

}

BackgroundVideoDecodingPermissionObserver::

  ~BackgroundVideoDecodingPermissionObserver()

{

  MOZ_ASSERT(!mIsRegisteredForEvent);

}

void

BackgroundVideoDecodingPermissionObserver::EnableEvent() const

{

  nsIDocument* doc = GetOwnerDoc();

  if (!doc) {

    return;

  }

  nsCOMPtr<nsPIDOMWindowOuter> ownerTop = GetOwnerWindow();

  if (!ownerTop) {

    return;

  }

  RefPtr<AsyncEventDispatcher> asyncDispatcher =

    new AsyncEventDispatcher(doc,

                             NS_LITERAL_STRING("UnselectedTabHover:Enable"),

                             CanBubble::eYes,

                             ChromeOnlyDispatch::eYes);

  asyncDispatcher->PostDOMEvent();

}

void

BackgroundVideoDecodingPermissionObserver::DisableEvent() const

{

  nsIDocument* doc = GetOwnerDoc();

  if (!doc) {

    return;

  }

  nsCOMPtr<nsPIDOMWindowOuter> ownerTop = GetOwnerWindow();

  if (!ownerTop) {

    return;

  }

  RefPtr<AsyncEventDispatcher> asyncDispatcher =

    new AsyncEventDispatcher(doc,

                             NS_LITERAL_STRING("UnselectedTabHover:Disable"),

                             CanBubble::eYes,

                             ChromeOnlyDispatch::eYes);

  asyncDispatcher->PostDOMEvent();

}

already_AddRefed<nsPIDOMWindowOuter>

BackgroundVideoDecodingPermissionObserver::GetOwnerWindow() const

{

  nsIDocument* doc = GetOwnerDoc();

  if (!doc) {

    return nullptr;

  }

  nsCOMPtr<nsPIDOMWindowInner> innerWin = doc->GetInnerWindow();

  if (!innerWin) {

    return nullptr;

  }

  nsCOMPtr<nsPIDOMWindowOuter> outerWin = innerWin->GetOuterWindow();

  if (!outerWin) {

    return nullptr;

  }

  nsCOMPtr<nsPIDOMWindowOuter> topWin = outerWin->GetTop();

  return topWin.forget();

}

nsIDocument*

BackgroundVideoDecodingPermissionObserver::GetOwnerDoc() const

{

  if (!mDecoder->GetOwner()) {

    return nullptr;

  }

  return mDecoder->GetOwner()->GetDocument();

}

bool

BackgroundVideoDecodingPermissionObserver::IsValidEventSender(

  nsISupports* aSubject) const

{

  nsCOMPtr<nsPIDOMWindowInner> senderInner(do_QueryInterface(aSubject));

  if (!senderInner) {

    return false;

  }

  nsCOMPtr<nsPIDOMWindowOuter> senderOuter = senderInner->GetOuterWindow();

  if (!senderOuter) {

    return false;

  }

  nsCOMPtr<nsPIDOMWindowOuter> senderTop = senderOuter->GetTop();

  if (!senderTop) {

    return false;

  }

  nsCOMPtr<nsPIDOMWindowOuter> ownerTop = GetOwnerWindow();

  if (!ownerTop) {

    return false;

  }

  return ownerTop == senderTop;

}

NS_IMPL_ISUPPORTS(BackgroundVideoDecodingPermissionObserver, nsIObserver)

} // namespace mozilla