/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */

// Microsoft's API Name hackery sucks
#undef CreateEvent

#include "mozilla/AddonPathService.h"
#include "mozilla/BasicEvents.h"
#include "mozilla/CycleCollectedJSContext.h"
#include "mozilla/DOMEventTargetHelper.h"
#include "mozilla/EventDispatcher.h"
#include "mozilla/EventListenerManager.h"
#include "mozilla/HalSensor.h"
#include "mozilla/InternalMutationEvent.h"
#include "mozilla/JSEventHandler.h"
#include "mozilla/Maybe.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/Preferences.h"
#include "mozilla/dom/BindingUtils.h"
#include "mozilla/dom/Element.h"
#include "mozilla/dom/Event.h"
#include "mozilla/dom/EventTargetBinding.h"
#include "mozilla/dom/ModuleScript.h"
#include "mozilla/dom/ScriptLoader.h"
#include "mozilla/dom/TouchEvent.h"
#include "mozilla/TimelineConsumers.h"
#include "mozilla/EventTimelineMarker.h"

#include "EventListenerService.h"
#include "nsCOMArray.h"
#include "nsCOMPtr.h"
#include "nsContentUtils.h"
#include "nsDOMCID.h"
#include "nsError.h"
#include "nsGkAtoms.h"
#include "nsHtml5Atoms.h"
#include "nsIContent.h"
#include "nsIContentSecurityPolicy.h"
#include "nsIDocument.h"
#include "nsIDOMEventListener.h"
#include "nsIScriptGlobalObject.h"
#include "nsISupports.h"
#include "nsIXPConnect.h"
#include "nsJSUtils.h"
#include "nsNameSpaceManager.h"
#include "nsPIDOMWindow.h"
#include "nsSandboxFlags.h"
#include "xpcpublic.h"
#include "nsIFrame.h"
#include "nsDisplayList.h"

namespace mozilla {

using namespace dom;
using namespace hal;

#define EVENT_TYPE_EQUALS(ls, message, userType, typeString, allEvents) \
  ((ls->mEventMessage == message &&                                     \
    (ls->mEventMessage != eUnidentifiedEvent ||                         \
    (mIsMainThreadELM && ls->mTypeAtom == userType) ||                  \
    (!mIsMainThreadELM && ls->mTypeString.Equals(typeString)))) ||      \
   (allEvents && ls->mAllEvents))

static const uint32_t kAllMutationBits =
  NS_EVENT_BITS_MUTATION_SUBTREEMODIFIED |
  NS_EVENT_BITS_MUTATION_NODEINSERTED |
  NS_EVENT_BITS_MUTATION_NODEREMOVED |
  NS_EVENT_BITS_MUTATION_NODEREMOVEDFROMDOCUMENT |
  NS_EVENT_BITS_MUTATION_NODEINSERTEDINTODOCUMENT |
  NS_EVENT_BITS_MUTATION_ATTRMODIFIED |
  NS_EVENT_BITS_MUTATION_CHARACTERDATAMODIFIED;

static uint32_t
MutationBitForEventType(EventMessage aEventType)
{
  switch (aEventType) {
    case eLegacySubtreeModified:
      return NS_EVENT_BITS_MUTATION_SUBTREEMODIFIED;
    case eLegacyNodeInserted:
      return NS_EVENT_BITS_MUTATION_NODEINSERTED;
    case eLegacyNodeRemoved:
      return NS_EVENT_BITS_MUTATION_NODEREMOVED;
    case eLegacyNodeRemovedFromDocument:
      return NS_EVENT_BITS_MUTATION_NODEREMOVEDFROMDOCUMENT;
    case eLegacyNodeInsertedIntoDocument:
      return NS_EVENT_BITS_MUTATION_NODEINSERTEDINTODOCUMENT;
    case eLegacyAttrModified:
      return NS_EVENT_BITS_MUTATION_ATTRMODIFIED;
    case eLegacyCharacterDataModified:
      return NS_EVENT_BITS_MUTATION_CHARACTERDATAMODIFIED;
    default:
      break;
  }
  return 0;
}

uint32_t EventListenerManager::sMainThreadCreatedCount = 0;

static bool
IsWebkitPrefixSupportEnabled()
{
  static bool sIsWebkitPrefixSupportEnabled;
  static bool sIsPrefCached = false;

  if (!sIsPrefCached) {
    sIsPrefCached = true;
    Preferences::AddBoolVarCache(&sIsWebkitPrefixSupportEnabled,
                                 "layout.css.prefixes.webkit");
  }

  return sIsWebkitPrefixSupportEnabled;
}

static bool
IsPrefixedPointerLockEnabled()
{
  static bool sIsPrefixedPointerLockEnabled;
  static bool sIsPrefCached = false;
  if (!sIsPrefCached) {
    sIsPrefCached = true;
    Preferences::AddBoolVarCache(&sIsPrefixedPointerLockEnabled,
                                 "pointer-lock-api.prefixed.enabled");
  }
  return sIsPrefixedPointerLockEnabled;
}

EventListenerManagerBase::EventListenerManagerBase()
  : mNoListenerForEvent(eVoidEvent)
  , mMayHavePaintEventListener(false)
  , mMayHaveMutationListeners(false)
  , mMayHaveCapturingListeners(false)
  , mMayHaveSystemGroupListeners(false)
  , mMayHaveTouchEventListener(false)
  , mMayHaveMouseEnterLeaveEventListener(false)
  , mMayHavePointerEnterLeaveEventListener(false)
  , mMayHaveKeyEventListener(false)
  , mMayHaveInputOrCompositionEventListener(false)
  , mClearingListeners(false)
  , mIsMainThreadELM(NS_IsMainThread())
{
  static_assert(sizeof(EventListenerManagerBase) == sizeof(uint32_t),
                "Keep the size of EventListenerManagerBase size compact!");
}

EventListenerManager::EventListenerManager(EventTarget* aTarget)
  : EventListenerManagerBase()
  , mTarget(aTarget)
{
  NS_ASSERTION(aTarget, "unexpected null pointer");

  if (mIsMainThreadELM) {
    ++sMainThreadCreatedCount;
  }
}

EventListenerManager::~EventListenerManager()
{
  // If your code fails this assertion, a possible reason is that
  // a class did not call our Disconnect() manually. Note that
  // this class can have Disconnect called in one of two ways:
  // if it is part of a cycle, then in Unlink() (such a cycle
  // would be with one of the listeners, not mTarget which is weak).
  // If not part of a cycle, then Disconnect must be called manually,
  // typically from the destructor of the owner class (mTarget).
  // XXX azakai: Is there any reason to not just call Disconnect
  //             from right here, if not previously called?
  NS_ASSERTION(!mTarget, "didn't call Disconnect");
  RemoveAllListenersSilently();
}

void
EventListenerManager::RemoveAllListenersSilently()
{
  if (mClearingListeners) {
    return;
  }
  mClearingListeners = true;
  mListeners.Clear();
  mClearingListeners = false;
}

void
EventListenerManager::Shutdown()
{
  Event::Shutdown();
}

NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(EventListenerManager, AddRef)
NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(EventListenerManager, Release)

inline void
ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
                            EventListenerManager::Listener& aField,
                            const char* aName,
                            unsigned aFlags)
{
  if (MOZ_UNLIKELY(aCallback.WantDebugInfo())) {
    nsAutoCString name;
    name.AppendASCII(aName);
    if (aField.mTypeAtom) {
      name.AppendASCII(" event=");
      name.Append(nsAtomCString(aField.mTypeAtom));
      name.AppendASCII(" listenerType=");
      name.AppendInt(aField.mListenerType);
      name.AppendASCII(" ");
    }
    CycleCollectionNoteChild(aCallback, aField.mListener.GetISupports(), name.get(),
                             aFlags);
  } else {
    CycleCollectionNoteChild(aCallback, aField.mListener.GetISupports(), aName,
                             aFlags);
  }
}

NS_IMPL_CYCLE_COLLECTION_CLASS(EventListenerManager)

NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(EventListenerManager)
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mListeners)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(EventListenerManager)
  tmp->Disconnect();
NS_IMPL_CYCLE_COLLECTION_UNLINK_END


nsPIDOMWindowInner*
EventListenerManager::GetInnerWindowForTarget()
{
  nsCOMPtr<nsINode> node = do_QueryInterface(mTarget);
  if (node) {
    // XXX sXBL/XBL2 issue -- do we really want the owner here?  What
    // if that's the XBL document?
    return node->OwnerDoc()->GetInnerWindow();
  }

  nsCOMPtr<nsPIDOMWindowInner> window = GetTargetAsInnerWindow();
  return window;
}

already_AddRefed<nsPIDOMWindowInner>
EventListenerManager::GetTargetAsInnerWindow() const
{
  nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(mTarget);
  return window.forget();
}

void
EventListenerManager::AddEventListenerInternal(
                        EventListenerHolder aListenerHolder,
                        EventMessage aEventMessage,
                        nsIAtom* aTypeAtom,
                        const nsAString& aTypeString,
                        const EventListenerFlags& aFlags,
                        bool aHandler,
                        bool aAllEvents)
{
  MOZ_ASSERT(// Main thread
             (NS_IsMainThread() && aEventMessage && aTypeAtom) ||
             // non-main-thread
             (!NS_IsMainThread() && aEventMessage) ||
             aAllEvents, "Missing type"); // all-events listener

  if (!aListenerHolder || mClearingListeners) {
    return;
  }

  // Since there is no public API to call us with an EventListenerHolder, we
  // know that there's an EventListenerHolder on the stack holding a strong ref
  // to the listener.

  Listener* listener;
  uint32_t count = mListeners.Length();
  for (uint32_t i = 0; i < count; i++) {
    listener = &mListeners.ElementAt(i);
    // mListener == aListenerHolder is the last one, since it can be a bit slow.
    if (listener->mListenerIsHandler == aHandler &&
        listener->mFlags.EqualsForAddition(aFlags) &&
        EVENT_TYPE_EQUALS(listener, aEventMessage, aTypeAtom, aTypeString,
                          aAllEvents) &&
        listener->mListener == aListenerHolder) {
      return;
    }
  }

  mNoListenerForEvent = eVoidEvent;
  mNoListenerForEventAtom = nullptr;

  listener = aAllEvents ? mListeners.InsertElementAt(0) :
                          mListeners.AppendElement();
  listener->mEventMessage = aEventMessage;
  listener->mTypeString = aTypeString;
  listener->mTypeAtom = aTypeAtom;
  listener->mFlags = aFlags;
  listener->mListenerIsHandler = aHandler;
  listener->mHandlerIsString = false;
  listener->mAllEvents = aAllEvents;
  listener->mIsChrome = mIsMainThreadELM &&
    nsContentUtils::LegacyIsCallerChromeOrNativeCode();

  // Detect the type of event listener.
  nsCOMPtr<nsIXPConnectWrappedJS> wjs;
  if (aFlags.mListenerIsJSListener) {
    MOZ_ASSERT(!aListenerHolder.HasWebIDLCallback());
    listener->mListenerType = Listener::eJSEventListener;
  } else if (aListenerHolder.HasWebIDLCallback()) {
    listener->mListenerType = Listener::eWebIDLListener;
  } else if ((wjs = do_QueryInterface(aListenerHolder.GetXPCOMCallback()))) {
    listener->mListenerType = Listener::eWrappedJSListener;
  } else {
    listener->mListenerType = Listener::eNativeListener;
  }
  listener->mListener = Move(aListenerHolder);


  if (aFlags.mInSystemGroup) {
    mMayHaveSystemGroupListeners = true;
  }
  if (aFlags.mCapture) {
    mMayHaveCapturingListeners = true;
  }

  if (aEventMessage == eAfterPaint) {
    mMayHavePaintEventListener = true;
    if (nsPIDOMWindowInner* window = GetInnerWindowForTarget()) {
      window->SetHasPaintEventListeners();
    }
  } else if (aEventMessage >= eLegacyMutationEventFirst &&
             aEventMessage <= eLegacyMutationEventLast) {
    // For mutation listeners, we need to update the global bit on the DOM window.
    // Otherwise we won't actually fire the mutation event.
    mMayHaveMutationListeners = true;
    // Go from our target to the nearest enclosing DOM window.
    if (nsPIDOMWindowInner* window = GetInnerWindowForTarget()) {
      nsCOMPtr<nsIDocument> doc = window->GetExtantDoc();
      if (doc) {
        doc->WarnOnceAbout(nsIDocument::eMutationEvent);
      }
      // If aEventMessage is eLegacySubtreeModified, we need to listen all
      // mutations. nsContentUtils::HasMutationListeners relies on this.
      window->SetMutationListeners(
        (aEventMessage == eLegacySubtreeModified) ?
          kAllMutationBits : MutationBitForEventType(aEventMessage));
    }
  } else if (aTypeAtom == nsGkAtoms::ondeviceorientation) {
    EnableDevice(eDeviceOrientation);
  } else if (aTypeAtom == nsGkAtoms::onabsolutedeviceorientation) {
    EnableDevice(eAbsoluteDeviceOrientation);
  } else if (aTypeAtom == nsGkAtoms::ondeviceproximity || aTypeAtom == nsGkAtoms::onuserproximity) {
    EnableDevice(eDeviceProximity);
  } else if (aTypeAtom == nsGkAtoms::ondevicelight) {
    EnableDevice(eDeviceLight);
  } else if (aTypeAtom == nsGkAtoms::ondevicemotion) {
    EnableDevice(eDeviceMotion);
  } else if (aTypeAtom == nsGkAtoms::ontouchstart ||
             aTypeAtom == nsGkAtoms::ontouchend ||
             aTypeAtom == nsGkAtoms::ontouchmove ||
             aTypeAtom == nsGkAtoms::ontouchcancel) {
    mMayHaveTouchEventListener = true;
    nsPIDOMWindowInner* window = GetInnerWindowForTarget();
    // we don't want touchevent listeners added by scrollbars to flip this flag
    // so we ignore listeners created with system event flag
    if (window && !aFlags.mInSystemGroup) {
      window->SetHasTouchEventListeners();
    }
  } else if (aEventMessage >= ePointerEventFirst &&
             aEventMessage <= ePointerEventLast) {
    nsPIDOMWindowInner* window = GetInnerWindowForTarget();
    if (aTypeAtom == nsGkAtoms::onpointerenter ||
        aTypeAtom == nsGkAtoms::onpointerleave) {
      mMayHavePointerEnterLeaveEventListener = true;
      if (window) {
#ifdef DEBUG
        nsCOMPtr<nsIDocument> d = window->GetExtantDoc();
        NS_WARNING_ASSERTION(
          !nsContentUtils::IsChromeDoc(d),
          "Please do not use pointerenter/leave events in chrome. "
          "They are slower than pointerover/out!");
#endif
        window->SetHasPointerEnterLeaveEventListeners();
      }
    }
  } else if (aTypeAtom == nsGkAtoms::onmouseenter ||
             aTypeAtom == nsGkAtoms::onmouseleave) {
    mMayHaveMouseEnterLeaveEventListener = true;
    if (nsPIDOMWindowInner* window = GetInnerWindowForTarget()) {
#ifdef DEBUG
      nsCOMPtr<nsIDocument> d = window->GetExtantDoc();
      NS_WARNING_ASSERTION(
        !nsContentUtils::IsChromeDoc(d),
        "Please do not use mouseenter/leave events in chrome. "
        "They are slower than mouseover/out!");
#endif
      window->SetHasMouseEnterLeaveEventListeners();
    }
#ifdef MOZ_GAMEPAD
  } else if (aEventMessage >= eGamepadEventFirst &&
             aEventMessage <= eGamepadEventLast) {
    if (nsPIDOMWindowInner* window = GetInnerWindowForTarget()) {
      window->SetHasGamepadEventListener();
    }
#endif
  } else if (aTypeAtom == nsGkAtoms::onkeydown ||
             aTypeAtom == nsGkAtoms::onkeypress ||
             aTypeAtom == nsGkAtoms::onkeyup) {
    if (!aFlags.mInSystemGroup) {
      mMayHaveKeyEventListener = true;
    }
  } else if (aTypeAtom == nsGkAtoms::oncompositionend ||
             aTypeAtom == nsGkAtoms::oncompositionstart ||
             aTypeAtom == nsGkAtoms::oncompositionupdate ||
             aTypeAtom == nsGkAtoms::oninput) {
    if (!aFlags.mInSystemGroup) {
      mMayHaveInputOrCompositionEventListener = true;
    }
  }

  if (IsApzAwareListener(listener)) {
    ProcessApzAwareEventListenerAdd();
  }

  if (aTypeAtom && mTarget) {
    mTarget->EventListenerAdded(aTypeAtom);
  }

  if (mIsMainThreadELM && mTarget) {
    EventListenerService::NotifyAboutMainThreadListenerChange(mTarget,
                                                              aTypeAtom);
  }
}

void
EventListenerManager::ProcessApzAwareEventListenerAdd()
{
  // Mark the node as having apz aware listeners
  nsCOMPtr<nsINode> node = do_QueryInterface(mTarget);
  if (node) {
    node->SetMayBeApzAware();
  }

  // Schedule a paint so event regions on the layer tree gets updated
  nsIDocument* doc = nullptr;
  if (node) {
    doc = node->OwnerDoc();
  }
  if (!doc) {
    if (nsCOMPtr<nsPIDOMWindowInner> window = GetTargetAsInnerWindow()) {
      doc = window->GetExtantDoc();
    }
  }
  if (!doc) {
    if (nsCOMPtr<DOMEventTargetHelper> helper = do_QueryInterface(mTarget)) {
      if (nsPIDOMWindowInner* window = helper->GetOwner()) {
        doc = window->GetExtantDoc();
      }
    }
  }

  if (doc && nsDisplayListBuilder::LayerEventRegionsEnabled()) {
    nsIPresShell* ps = doc->GetShell();
    if (ps) {
      nsIFrame* f = ps->GetRootFrame();
      if (f) {
        f->SchedulePaint();
      }
    }
  }
}

bool
EventListenerManager::IsDeviceType(EventMessage aEventMessage)
{
  switch (aEventMessage) {
    case eDeviceOrientation:
    case eAbsoluteDeviceOrientation:
    case eDeviceMotion:
    case eDeviceLight:
    case eDeviceProximity:
    case eUserProximity:
      return true;
    default:
      break;
  }
  return false;
}

void
EventListenerManager::EnableDevice(EventMessage aEventMessage)
{
  nsCOMPtr<nsPIDOMWindowInner> window = GetTargetAsInnerWindow();
  if (!window) {
    return;
  }

  switch (aEventMessage) {
    case eDeviceOrientation:
      window->EnableDeviceSensor(SENSOR_ORIENTATION);
      break;
    case eAbsoluteDeviceOrientation:
      window->EnableDeviceSensor(SENSOR_ORIENTATION);
      break;
    case eDeviceProximity:
    case eUserProximity:
      window->EnableDeviceSensor(SENSOR_PROXIMITY);
      break;
    case eDeviceLight:
      window->EnableDeviceSensor(SENSOR_LIGHT);
      break;
    case eDeviceMotion:
      window->EnableDeviceSensor(SENSOR_ACCELERATION);
      window->EnableDeviceSensor(SENSOR_LINEAR_ACCELERATION);
      window->EnableDeviceSensor(SENSOR_GYROSCOPE);
      break;
    default:
      NS_WARNING("Enabling an unknown device sensor.");
      break;
  }
}

void
EventListenerManager::DisableDevice(EventMessage aEventMessage)
{
  nsCOMPtr<nsPIDOMWindowInner> window = GetTargetAsInnerWindow();
  if (!window) {
    return;
  }

  switch (aEventMessage) {
    case eDeviceOrientation:
      window->DisableDeviceSensor(SENSOR_ORIENTATION);
      break;
    case eAbsoluteDeviceOrientation:
      window->DisableDeviceSensor(SENSOR_ORIENTATION);
      break;
    case eDeviceMotion:
      window->DisableDeviceSensor(SENSOR_ACCELERATION);
      window->DisableDeviceSensor(SENSOR_LINEAR_ACCELERATION);
      window->DisableDeviceSensor(SENSOR_GYROSCOPE);
      break;
    case eDeviceProximity:
    case eUserProximity:
      window->DisableDeviceSensor(SENSOR_PROXIMITY);
      break;
    case eDeviceLight:
      window->DisableDeviceSensor(SENSOR_LIGHT);
      break;
    default:
      NS_WARNING("Disabling an unknown device sensor.");
      break;
  }
}

void
EventListenerManager::NotifyEventListenerRemoved(nsIAtom* aUserType)
{
  // If the following code is changed, other callsites of EventListenerRemoved
  // and NotifyAboutMainThreadListenerChange should be changed too.
  mNoListenerForEvent = eVoidEvent;
  mNoListenerForEventAtom = nullptr;
  if (mTarget && aUserType) {
    mTarget->EventListenerRemoved(aUserType);
  }
  if (mIsMainThreadELM && mTarget) {
    EventListenerService::NotifyAboutMainThreadListenerChange(mTarget,
                                                              aUserType);
  }
}

void
EventListenerManager::RemoveEventListenerInternal(
                        EventListenerHolder aListenerHolder,
                        EventMessage aEventMessage,
                        nsIAtom* aUserType,
                        const nsAString& aTypeString,
                        const EventListenerFlags& aFlags,
                        bool aAllEvents)
{
  if (!aListenerHolder || !aEventMessage || mClearingListeners) {
    return;
  }

  Listener* listener;

  uint32_t count = mListeners.Length();
  bool deviceType = IsDeviceType(aEventMessage);

  RefPtr<EventListenerManager> kungFuDeathGrip(this);

  for (uint32_t i = 0; i < count; ++i) {
    listener = &mListeners.ElementAt(i);
    if (EVENT_TYPE_EQUALS(listener, aEventMessage, aUserType, aTypeString,
                          aAllEvents)) {
      if (listener->mListener == aListenerHolder &&
          listener->mFlags.EqualsForRemoval(aFlags)) {
        mListeners.RemoveElementAt(i);
        NotifyEventListenerRemoved(aUserType);
        if (!aAllEvents && deviceType) {
          DisableDevice(aEventMessage);
        }
        return;
      }
    }
  }

}

bool
EventListenerManager::ListenerCanHandle(const Listener* aListener,
                                        const WidgetEvent* aEvent,
                                        EventMessage aEventMessage) const

{
  MOZ_ASSERT(aEventMessage == aEvent->mMessage ||
             aEventMessage == GetLegacyEventMessage(aEvent->mMessage),
             "aEvent and aEventMessage should agree, modulo legacyness");

  // The listener has been removed, it cannot handle anything.
  if (aListener->mListenerType == Listener::eNoListener) {
    return false;
  }
  // This is slightly different from EVENT_TYPE_EQUALS in that it returns
  // true even when aEvent->mMessage == eUnidentifiedEvent and
  // aListener=>mEventMessage != eUnidentifiedEvent as long as the atoms are
  // the same
  if (aListener->mAllEvents) {
    return true;
  }
  if (aEvent->mMessage == eUnidentifiedEvent) {
    if (mIsMainThreadELM) {
      return aListener->mTypeAtom == aEvent->mSpecifiedEventType;
    }
    return aListener->mTypeString.Equals(aEvent->mSpecifiedEventTypeString);
  }
  if (!nsContentUtils::IsUnprefixedFullscreenApiEnabled() &&
      aEvent->IsTrusted() && (aEventMessage == eFullscreenChange ||
                              aEventMessage == eFullscreenError)) {
    // If unprefixed Fullscreen API is not enabled, don't dispatch it
    // to the content.
    if (!aEvent->mFlags.mInSystemGroup && !aListener->mIsChrome) {
      return false;
    }
  }
  MOZ_ASSERT(mIsMainThreadELM);
  return aListener->mEventMessage == aEventMessage;
}

void
EventListenerManager::AddEventListenerByType(
                        EventListenerHolder aListenerHolder,
                        const nsAString& aType,
                        const EventListenerFlags& aFlags)
{
  nsCOMPtr<nsIAtom> atom;
  EventMessage message = mIsMainThreadELM ?
    nsContentUtils::GetEventMessageAndAtomForListener(aType,
                                                      getter_AddRefs(atom)) :
    eUnidentifiedEvent;
  AddEventListenerInternal(Move(aListenerHolder),
                           message, atom, aType, aFlags);
}

void
EventListenerManager::RemoveEventListenerByType(
                        EventListenerHolder aListenerHolder,
                        const nsAString& aType,
                        const EventListenerFlags& aFlags)
{
  nsCOMPtr<nsIAtom> atom;
  EventMessage message = mIsMainThreadELM ?
    nsContentUtils::GetEventMessageAndAtomForListener(aType,
                                                      getter_AddRefs(atom)) :
    eUnidentifiedEvent;
  RemoveEventListenerInternal(Move(aListenerHolder),
                              message, atom, aType, aFlags);
}

EventListenerManager::Listener*
EventListenerManager::FindEventHandler(EventMessage aEventMessage,
                                       nsIAtom* aTypeAtom,
                                       const nsAString& aTypeString)
{
  // Run through the listeners for this type and see if a script
  // listener is registered
  Listener* listener;
  uint32_t count = mListeners.Length();
  for (uint32_t i = 0; i < count; ++i) {
    listener = &mListeners.ElementAt(i);
    if (listener->mListenerIsHandler &&
        EVENT_TYPE_EQUALS(listener, aEventMessage, aTypeAtom, aTypeString,
                          false)) {
      return listener;
    }
  }
  return nullptr;
}

EventListenerManager::Listener*
EventListenerManager::SetEventHandlerInternal(
                        nsIAtom* aName,
                        const nsAString& aTypeString,
                        const TypedEventHandler& aTypedHandler,
                        bool aPermitUntrustedEvents)
{
  MOZ_ASSERT(aName || !aTypeString.IsEmpty());

  EventMessage eventMessage = nsContentUtils::GetEventMessage(aName);
  Listener* listener = FindEventHandler(eventMessage, aName, aTypeString);

  if (!listener) {
    // If we didn't find a script listener or no listeners existed
    // create and add a new one.
    EventListenerFlags flags;
    flags.mListenerIsJSListener = true;

    nsCOMPtr<JSEventHandler> jsEventHandler;
    NS_NewJSEventHandler(mTarget, aName,
                         aTypedHandler, getter_AddRefs(jsEventHandler));
    AddEventListenerInternal(EventListenerHolder(jsEventHandler),
                             eventMessage, aName, aTypeString, flags, true);

    listener = FindEventHandler(eventMessage, aName, aTypeString);
  } else {
    JSEventHandler* jsEventHandler = listener->GetJSEventHandler();
    MOZ_ASSERT(jsEventHandler,
               "How can we have an event handler with no JSEventHandler?");

    bool same = jsEventHandler->GetTypedEventHandler() == aTypedHandler;
    // Possibly the same listener, but update still the context and scope.
    jsEventHandler->SetHandler(aTypedHandler);
    if (mTarget && !same && aName) {
      mTarget->EventListenerRemoved(aName);
      mTarget->EventListenerAdded(aName);
    }
    if (mIsMainThreadELM && mTarget) {
      EventListenerService::NotifyAboutMainThreadListenerChange(mTarget, aName);
    }
  }

  // Set flag to indicate possible need for compilation later
  listener->mHandlerIsString = !aTypedHandler.HasEventHandler();
  if (aPermitUntrustedEvents) {
    listener->mFlags.mAllowUntrustedEvents = true;
  }

  return listener;
}

nsresult
EventListenerManager::SetEventHandler(nsIAtom* aName,
                                      const nsAString& aBody,
                                      bool aDeferCompilation,
                                      bool aPermitUntrustedEvents,
                                      Element* aElement)
{
  auto removeEventHandler = MakeScopeExit([&] { RemoveEventHandler(aName, EmptyString()); });

  nsCOMPtr<nsIDocument> doc;
  nsCOMPtr<nsIScriptGlobalObject> global =
    GetScriptGlobalAndDocument(getter_AddRefs(doc));

  if (!global) {
    // This can happen; for example this document might have been
    // loaded as data.
    return NS_OK;
  }

#ifdef DEBUG
  if (nsCOMPtr<nsPIDOMWindowInner> win = do_QueryInterface(global)) {
    MOZ_ASSERT(win->IsInnerWindow(), "We should not have an outer window here!");
  }
#endif

  nsresult rv = NS_OK;
  // return early preventing the event listener from being added
  // 'doc' is fetched above
  if (doc) {
    // Don't allow adding an event listener if the document is sandboxed
    // without 'allow-scripts'.
    if (doc->HasScriptsBlockedBySandbox()) {
      return NS_ERROR_DOM_SECURITY_ERR;
    }

    // Perform CSP check
    nsCOMPtr<nsIContentSecurityPolicy> csp;
    rv = doc->NodePrincipal()->GetCsp(getter_AddRefs(csp));
    NS_ENSURE_SUCCESS(rv, rv);

    unsigned lineNum = 0;
    unsigned columnNum = 0;

    JSContext* cx = nsContentUtils::GetCurrentJSContext();
    if (cx && !JS::DescribeScriptedCaller(cx, nullptr, &lineNum, &columnNum)) {
      JS_ClearPendingException(cx);
    }

    if (csp) {
      bool allowsInlineScript = true;
      rv = csp->GetAllowsInline(nsIContentSecurityPolicy::SCRIPT_SRC_ATTR_DIRECTIVE,
                                EmptyString(), // aNonce
                                true, // aParserCreated (true because attribute event handler)
                                aBody,
                                lineNum,             // aLineNumber
                                columnNum,           // aColumnNumber
                                &allowsInlineScript);
      NS_ENSURE_SUCCESS(rv, rv);

      // return early if CSP wants us to block inline scripts
      if (!allowsInlineScript) {
        return NS_OK;
      }
    }
  }

  // This might be the first reference to this language in the global
  // We must init the language before we attempt to fetch its context.
  if (NS_FAILED(global->EnsureScriptEnvironment())) {
    NS_WARNING("Failed to setup script environment for this language");
    // but fall through and let the inevitable failure below handle it.
  }

  nsIScriptContext* context = global->GetScriptContext();
  NS_ENSURE_TRUE(context, NS_ERROR_FAILURE);
  NS_ENSURE_STATE(global->GetGlobalJSObject());

  removeEventHandler.release();

  Listener* listener = SetEventHandlerInternal(aName,
                                               EmptyString(),
                                               TypedEventHandler(),
                                               aPermitUntrustedEvents);

  if (!aDeferCompilation) {
    return CompileEventHandlerInternal(listener, &aBody, aElement);
  }

  return NS_OK;
}

void
EventListenerManager::RemoveEventHandler(nsIAtom* aName,
                                         const nsAString& aTypeString)
{
  if (mClearingListeners) {
    return;
  }

  EventMessage eventMessage = nsContentUtils::GetEventMessage(aName);
  Listener* listener = FindEventHandler(eventMessage, aName, aTypeString);

  if (listener) {
    mListeners.RemoveElementAt(uint32_t(listener - &mListeners.ElementAt(0)));
    NotifyEventListenerRemoved(aName);
    if (IsDeviceType(eventMessage)) {
      DisableDevice(eventMessage);
    }
  }
}

nsresult
EventListenerManager::CompileEventHandlerInternal(Listener* aListener,
                                                  const nsAString* aBody,
                                                  Element* aElement)
{
  MOZ_ASSERT(aListener->GetJSEventHandler());
  MOZ_ASSERT(aListener->mHandlerIsString, "Why are we compiling a non-string JS listener?");
  JSEventHandler* jsEventHandler = aListener->GetJSEventHandler();
  MOZ_ASSERT(!jsEventHandler->GetTypedEventHandler().HasEventHandler(),
             "What is there to compile?");

  nsresult result = NS_OK;
  nsCOMPtr<nsIDocument> doc;
  nsCOMPtr<nsIScriptGlobalObject> global =
    GetScriptGlobalAndDocument(getter_AddRefs(doc));
  NS_ENSURE_STATE(global);

  // Activate JSAPI, and make sure that exceptions are reported on the right
  // Window.
  AutoJSAPI jsapi;
  if (NS_WARN_IF(!jsapi.Init(global))) {
    return NS_ERROR_UNEXPECTED;
  }
  JSContext* cx = jsapi.cx();

  nsCOMPtr<nsIAtom> typeAtom = aListener->mTypeAtom;
  nsIAtom* attrName = typeAtom;

  // Flag us as not a string so we don't keep trying to compile strings which
  // can't be compiled.
  aListener->mHandlerIsString = false;

  // mTarget may not be an Element if it's a window and we're
  // getting an inline event listener forwarded from <html:body> or
  // <html:frameset> or <xul:window> or the like.
  // XXX I don't like that we have to reference content from
  // here. The alternative is to store the event handler string on
  // the JSEventHandler itself, and that still doesn't address
  // the arg names issue.
  nsCOMPtr<Element> element = do_QueryInterface(mTarget);
  MOZ_ASSERT(element || aBody, "Where will we get our body?");
  nsAutoString handlerBody;
  const nsAString* body = aBody;
  if (!aBody) {
    if (aListener->mTypeAtom == nsGkAtoms::onSVGLoad) {
      attrName = nsGkAtoms::onload;
    } else if (aListener->mTypeAtom == nsGkAtoms::onSVGUnload) {
      attrName = nsGkAtoms::onunload;
    } else if (aListener->mTypeAtom == nsGkAtoms::onSVGResize) {
      attrName = nsGkAtoms::onresize;
    } else if (aListener->mTypeAtom == nsGkAtoms::onSVGScroll) {
      attrName = nsGkAtoms::onscroll;
    } else if (aListener->mTypeAtom == nsGkAtoms::onSVGZoom) {
      attrName = nsGkAtoms::onzoom;
    } else if (aListener->mTypeAtom == nsGkAtoms::onbeginEvent) {
      attrName = nsGkAtoms::onbegin;
    } else if (aListener->mTypeAtom == nsGkAtoms::onrepeatEvent) {
      attrName = nsGkAtoms::onrepeat;
    } else if (aListener->mTypeAtom == nsGkAtoms::onendEvent) {
      attrName = nsGkAtoms::onend;
    }

    element->GetAttr(kNameSpaceID_None, attrName, handlerBody);
    body = &handlerBody;
    aElement = element;
  }
  aListener = nullptr;

  nsAutoCString url (NS_LITERAL_CSTRING("-moz-evil:lying-event-listener"));
  MOZ_ASSERT(body);
  MOZ_ASSERT(aElement);
  nsIURI *uri = aElement->OwnerDoc()->GetDocumentURI();
  if (uri) {
    uri->GetSpec(url);
  }

  nsCOMPtr<nsPIDOMWindowInner> win = do_QueryInterface(mTarget);
  uint32_t argCount;
  const char **argNames;
  nsContentUtils::GetEventArgNames(aElement->GetNameSpaceID(),
                                   typeAtom, win,
                                   &argCount, &argNames);

  JSAddonId *addonId = MapURIToAddonID(uri);

  // Wrap the event target, so that we can use it as the scope for the event
  // handler. Note that mTarget is different from aElement in the <body> case,
  // where mTarget is a Window.
  //
  // The wrapScope doesn't really matter here, because the target will create
  // its reflector in the proper scope, and then we'll enter that compartment.
  JS::Rooted<JSObject*> wrapScope(cx, global->GetGlobalJSObject());
  JS::Rooted<JS::Value> v(cx);
  {
    JSAutoCompartment ac(cx, wrapScope);
    nsresult rv = nsContentUtils::WrapNative(cx, mTarget, &v,
                                             /* aAllowWrapping = */ false);
    if (NS_WARN_IF(NS_FAILED(rv))) {
      return rv;
    }
  }

  if (addonId) {
    JS::Rooted<JSObject*> vObj(cx, &v.toObject());
    JS::Rooted<JSObject*> addonScope(cx, xpc::GetAddonScope(cx, vObj, addonId));
    if (!addonScope) {
      return NS_ERROR_FAILURE;
    }
    JSAutoCompartment ac(cx, addonScope);

    // Wrap our event target into the addon scope, since that's where we want to
    // do all our work.
    if (!JS_WrapValue(cx, &v)) {
      return NS_ERROR_FAILURE;
    }
  }
  JS::Rooted<JSObject*> target(cx, &v.toObject());
  JSAutoCompartment ac(cx, target);

  // Now that we've entered the compartment we actually care about, create our
  // scope chain.  Note that we start with |element|, not aElement, because
  // mTarget is different from aElement in the <body> case, where mTarget is a
  // Window, and in that case we do not want the scope chain to include the body
  // or the document.
  JS::AutoObjectVector scopeChain(cx);
  if (!nsJSUtils::GetScopeChainForElement(cx, element, scopeChain)) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  nsDependentAtomString str(attrName);
  // Most of our names are short enough that we don't even have to malloc
  // the JS string stuff, so don't worry about playing games with
  // refcounting XPCOM stringbuffers.
  JS::Rooted<JSString*> jsStr(cx, JS_NewUCStringCopyN(cx,
                                                      str.BeginReading(),
                                                      str.Length()));
  NS_ENSURE_TRUE(jsStr, NS_ERROR_OUT_OF_MEMORY);

  // Get the reflector for |aElement|, so that we can pass to setElement.
  if (NS_WARN_IF(!GetOrCreateDOMReflector(cx, aElement, &v))) {
    return NS_ERROR_FAILURE;
  }
  JS::CompileOptions options(cx);
  // Use line 0 to make the function body starts from line 1.
  options.setIntroductionType("eventHandler")
         .setFileAndLine(url.get(), 0)
         .setVersion(JSVERSION_DEFAULT)
         .setElement(&v.toObject())
         .setElementAttributeName(jsStr);

  JS::Rooted<JSObject*> handler(cx);
  result = nsJSUtils::CompileFunction(jsapi, scopeChain, options,
                                      nsAtomCString(typeAtom),
                                      argCount, argNames, *body, handler.address());
  NS_ENSURE_SUCCESS(result, result);
  NS_ENSURE_TRUE(handler, NS_ERROR_FAILURE);

  JS::Rooted<JSFunction*> func(cx, JS_GetObjectFunction(handler));
  MOZ_ASSERT(func);
  JS::Rooted<JSScript*> jsScript(cx, JS_GetFunctionScript(cx, func));
  MOZ_ASSERT(jsScript);
  RefPtr<LoadedScript> loaderScript = ScriptLoader::GetActiveScript(cx);
  if (loaderScript) {
    loaderScript->AssociateWithScript(jsScript);
  }

  if (jsEventHandler->EventName() == nsGkAtoms::onerror && win) {
    RefPtr<OnErrorEventHandlerNonNull> handlerCallback =
      new OnErrorEventHandlerNonNull(nullptr, handler, /* aIncumbentGlobal = */ nullptr);
    jsEventHandler->SetHandler(handlerCallback);
  } else if (jsEventHandler->EventName() == nsGkAtoms::onbeforeunload && win) {
    RefPtr<OnBeforeUnloadEventHandlerNonNull> handlerCallback =
      new OnBeforeUnloadEventHandlerNonNull(nullptr, handler, /* aIncumbentGlobal = */ nullptr);
    jsEventHandler->SetHandler(handlerCallback);
  } else {
    RefPtr<EventHandlerNonNull> handlerCallback =
      new EventHandlerNonNull(nullptr, handler, /* aIncumbentGlobal = */ nullptr);
    jsEventHandler->SetHandler(handlerCallback);
  }

  return result;
}

nsresult
EventListenerManager::HandleEventSubType(Listener* aListener,
                                         nsIDOMEvent* aDOMEvent,
                                         EventTarget* aCurrentTarget)
{
  nsresult result = NS_OK;
  // strong ref
  EventListenerHolder listenerHolder(aListener->mListener.Clone());

  // If this is a script handler and we haven't yet
  // compiled the event handler itself
  if ((aListener->mListenerType == Listener::eJSEventListener) &&
      aListener->mHandlerIsString) {
    result = CompileEventHandlerInternal(aListener, nullptr, nullptr);
    aListener = nullptr;
  }

  if (NS_SUCCEEDED(result)) {
    nsAutoMicroTask mt;

    // nsIDOMEvent::currentTarget is set in EventDispatcher.
    if (listenerHolder.HasWebIDLCallback()) {
      ErrorResult rv;
      listenerHolder.GetWebIDLCallback()->
        HandleEvent(aCurrentTarget, *(aDOMEvent->InternalDOMEvent()), rv);
      result = rv.StealNSResult();
    } else {
      result = listenerHolder.GetXPCOMCallback()->HandleEvent(aDOMEvent);
    }
  }

  return result;
}

EventMessage
EventListenerManager::GetLegacyEventMessage(EventMessage aEventMessage) const
{
  // (If we're off-main-thread, we can't check the pref; so we just behave as
  // if it's disabled.)
  if (mIsMainThreadELM) {
    if (IsWebkitPrefixSupportEnabled()) {
      // webkit-prefixed legacy events:
      if (aEventMessage == eTransitionEnd) {
        return eWebkitTransitionEnd;
      }
      if (aEventMessage == eAnimationStart) {
        return eWebkitAnimationStart;
      }
      if (aEventMessage == eAnimationEnd) {
        return eWebkitAnimationEnd;
      }
      if (aEventMessage == eAnimationIteration) {
        return eWebkitAnimationIteration;
      }
    }
    if (IsPrefixedPointerLockEnabled()) {
      if (aEventMessage == ePointerLockChange) {
        return eMozPointerLockChange;
      }
      if (aEventMessage == ePointerLockError) {
        return eMozPointerLockError;
      }
    }
  }

  switch (aEventMessage) {
    case eFullscreenChange:
      return eMozFullscreenChange;
    case eFullscreenError:
      return eMozFullscreenError;
    default:
      return aEventMessage;
  }
}

already_AddRefed<nsPIDOMWindowInner>
EventListenerManager::WindowFromListener(Listener* aListener,
                                         bool aItemInShadowTree)
{
  nsCOMPtr<nsPIDOMWindowInner> innerWindow;
  if (!aItemInShadowTree) {
    if (aListener->mListener.HasWebIDLCallback()) {
      CallbackObject* callback = aListener->mListener.GetWebIDLCallback();
      nsGlobalWindow* win;
      if (callback) {
        // Find the real underlying callback.
        JSObject* realCallback =
          js::UncheckedUnwrap(callback->CallbackPreserveColor());
        // Get the global for this callback.
        win = mIsMainThreadELM ?
              xpc::WindowGlobalOrNull(realCallback) :
              nullptr;
      }
      if (win && win->IsInnerWindow()) {
        innerWindow = win->AsInner(); // Can be nullptr
      }
    } else {
      // Can't get the global from
      // listener->mListener.GetXPCOMCallback().
      // In most cases, it would be the same as for
      // the target, so let's do that.
      innerWindow = GetInnerWindowForTarget(); // Can be nullptr
    }
  }
  return innerWindow.forget();
}

/**
* Causes a check for event listeners and processing by them if they exist.
* @param an event listener
*/

void
EventListenerManager::HandleEventInternal(nsPresContext* aPresContext,
                                          WidgetEvent* aEvent,
                                          nsIDOMEvent** aDOMEvent,
                                          EventTarget* aCurrentTarget,
                                          nsEventStatus* aEventStatus,
                                          bool aItemInShadowTree)
{
  //Set the value of the internal PreventDefault flag properly based on aEventStatus
  if (!aEvent->DefaultPrevented() &&
      *aEventStatus == nsEventStatus_eConsumeNoDefault) {
    // Assume that if only aEventStatus claims that the event has already been
    // consumed, the consumer is default event handler.
    aEvent->PreventDefault();
  }

  Maybe<nsAutoPopupStatePusher> popupStatePusher;
  if (mIsMainThreadELM) {
    popupStatePusher.emplace(Event::GetEventPopupControlState(aEvent, *aDOMEvent));
  }

  bool hasListener = false;
  bool hasListenerForCurrentGroup = false;
  bool usingLegacyMessage = false;
  bool hasRemovedListener = false;
  EventMessage eventMessage = aEvent->mMessage;

  while (true) {
    nsAutoTObserverArray<Listener, 2>::EndLimitedIterator iter(mListeners);
    Maybe<EventMessageAutoOverride> legacyAutoOverride;
    while (iter.HasMore()) {
      if (aEvent->mFlags.mImmediatePropagationStopped) {
        break;
      }
      Listener* listener = &iter.GetNext();
      // Check that the phase is same in event and event listener.
      // Handle only trusted events, except when listener permits untrusted events.
      if (ListenerCanHandle(listener, aEvent, eventMessage)) {
        hasListener = true;
        hasListenerForCurrentGroup = hasListenerForCurrentGroup ||
          listener->mFlags.mInSystemGroup == aEvent->mFlags.mInSystemGroup;
        if (listener->IsListening(aEvent) &&
            (aEvent->IsTrusted() || listener->mFlags.mAllowUntrustedEvents)) {
          if (!*aDOMEvent) {
            // This is tiny bit slow, but happens only once per event.
            nsCOMPtr<EventTarget> et =
              do_QueryInterface(aEvent->mOriginalTarget);
            RefPtr<Event> event = EventDispatcher::CreateEvent(et, aPresContext,
                                                               aEvent,
                                                               EmptyString());
            event.forget(aDOMEvent);
          }
          if (*aDOMEvent) {
            if (!aEvent->mCurrentTarget) {
              aEvent->mCurrentTarget = aCurrentTarget->GetTargetForDOMEvent();
              if (!aEvent->mCurrentTarget) {
                break;
              }
            }
            if (usingLegacyMessage && !legacyAutoOverride) {
              // Override the aDOMEvent's event-message (its .type) until we
              // finish traversing listeners (when legacyAutoOverride destructs)
              legacyAutoOverride.emplace(*aDOMEvent, eventMessage);
            }

            // Maybe add a marker to the docshell's timeline, but only
            // bother with all the logic if some docshell is recording.
            nsCOMPtr<nsIDocShell> docShell;
            RefPtr<TimelineConsumers> timelines = TimelineConsumers::Get();
            bool needsEndEventMarker = false;

            if (mIsMainThreadELM &&
                listener->mListenerType != Listener::eNativeListener) {
              docShell = nsContentUtils::GetDocShellForEventTarget(mTarget);
              if (docShell) {
                if (timelines && timelines->HasConsumer(docShell)) {
                  needsEndEventMarker = true;
                  nsAutoString typeStr;
                  (*aDOMEvent)->GetType(typeStr);
                  uint16_t phase;
                  (*aDOMEvent)->GetEventPhase(&phase);
                  timelines->AddMarkerForDocShell(docShell, Move(
                    MakeUnique<EventTimelineMarker>(
                      typeStr, phase, MarkerTracingType::START)));
                }
              }
            }

            aEvent->mFlags.mInPassiveListener = listener->mFlags.mPassive;
            Maybe<Listener> listenerHolder;
            if (listener->mFlags.mOnce) {
              // Move the listener to the stack before handling the event.
              // The order is important, otherwise the listener could be
              // called again inside the listener.
              listenerHolder.emplace(Move(*listener));
              listener = listenerHolder.ptr();
              hasRemovedListener = true;
            }
            nsCOMPtr<nsPIDOMWindowInner> innerWindow =
              WindowFromListener(listener, aItemInShadowTree);
            nsIDOMEvent* oldWindowEvent = nullptr;
            if (innerWindow) {
              oldWindowEvent = innerWindow->SetEvent(*aDOMEvent);
            }
            if (NS_FAILED(HandleEventSubType(listener, *aDOMEvent, aCurrentTarget))) {
              aEvent->mFlags.mExceptionWasRaised = true;
            }
            if (innerWindow) {
              Unused << innerWindow->SetEvent(oldWindowEvent);
            }
            aEvent->mFlags.mInPassiveListener = false;

            if (needsEndEventMarker) {
              timelines->AddMarkerForDocShell(
                docShell, "DOMEvent", MarkerTracingType::END);
            }
          }
        }
      }
    }

    // If we didn't find any matching listeners, and our event has a legacy
    // version, we'll now switch to looking for that legacy version and we'll
    // recheck our listeners.
    if (hasListenerForCurrentGroup || usingLegacyMessage) {
      // (No need to recheck listeners, because we already found a match, or we
      // already rechecked them.)
      break;
    }
    EventMessage legacyEventMessage = GetLegacyEventMessage(eventMessage);
    if (legacyEventMessage == eventMessage) {
      break; // There's no legacy version of our event; no need to recheck.
    }
    MOZ_ASSERT(GetLegacyEventMessage(legacyEventMessage) == legacyEventMessage,
               "Legacy event messages should not themselves have legacy versions");

    // Recheck our listeners, using the legacy event message we just looked up:
    eventMessage = legacyEventMessage;
    usingLegacyMessage = true;
  }

  aEvent->mCurrentTarget = nullptr;

  if (hasRemovedListener) {
    // If there are any once listeners replaced with a placeholder in
    // the loop above, we need to clean up them here. Note that, this
    // could clear once listeners handled in some outer level as well,
    // but that should not affect the result.
    mListeners.RemoveElementsBy([](const Listener& aListener) {
      return aListener.mListenerType == Listener::eNoListener;
    });
    NotifyEventListenerRemoved(aEvent->mSpecifiedEventType);
    if (IsDeviceType(aEvent->mMessage)) {
      // This is a device-type event, we need to check whether we can
      // disable device after removing the once listeners.
      bool hasAnyListener = false;
      nsAutoTObserverArray<Listener, 2>::ForwardIterator iter(mListeners);
      while (iter.HasMore()) {
        Listener* listener = &iter.GetNext();
        if (EVENT_TYPE_EQUALS(listener, aEvent->mMessage,
                              aEvent->mSpecifiedEventType,
                              aEvent->mSpecifiedEventTypeString,
                              /* all events */ false)) {
          hasAnyListener = true;
          break;
        }
      }
      if (!hasAnyListener) {
        DisableDevice(aEvent->mMessage);
      }
    }
  }

  if (mIsMainThreadELM && !hasListener) {
    mNoListenerForEvent = aEvent->mMessage;
    mNoListenerForEventAtom = aEvent->mSpecifiedEventType;
  }

  if (aEvent->DefaultPrevented()) {
    *aEventStatus = nsEventStatus_eConsumeNoDefault;
  }
}

void
EventListenerManager::Disconnect()
{
  mTarget = nullptr;
  RemoveAllListenersSilently();
}

void
EventListenerManager::AddEventListener(
                        const nsAString& aType,
                        EventListenerHolder aListenerHolder,
                        bool aUseCapture,
                        bool aWantsUntrusted)
{
  EventListenerFlags flags;
  flags.mCapture = aUseCapture;
  flags.mAllowUntrustedEvents = aWantsUntrusted;
  return AddEventListenerByType(Move(aListenerHolder), aType, flags);
}

void
EventListenerManager::AddEventListener(
                        const nsAString& aType,
                        EventListenerHolder aListenerHolder,
                        const dom::AddEventListenerOptionsOrBoolean& aOptions,
                        bool aWantsUntrusted)
{
  EventListenerFlags flags;
  if (aOptions.IsBoolean()) {
    flags.mCapture = aOptions.GetAsBoolean();
  } else {
    const auto& options = aOptions.GetAsAddEventListenerOptions();
    flags.mCapture = options.mCapture;
    flags.mInSystemGroup = options.mMozSystemGroup;
    flags.mPassive = options.mPassive;
    flags.mOnce = options.mOnce;
  }
  flags.mAllowUntrustedEvents = aWantsUntrusted;
  return AddEventListenerByType(Move(aListenerHolder), aType, flags);
}

void
EventListenerManager::RemoveEventListener(
                        const nsAString& aType,
                        EventListenerHolder aListenerHolder,
                        bool aUseCapture)
{
  EventListenerFlags flags;
  flags.mCapture = aUseCapture;
  RemoveEventListenerByType(Move(aListenerHolder), aType, flags);
}

void
EventListenerManager::RemoveEventListener(
                        const nsAString& aType,
                        EventListenerHolder aListenerHolder,
                        const dom::EventListenerOptionsOrBoolean& aOptions)
{
  EventListenerFlags flags;
  if (aOptions.IsBoolean()) {
    flags.mCapture = aOptions.GetAsBoolean();
  } else {
    const auto& options = aOptions.GetAsEventListenerOptions();
    flags.mCapture = options.mCapture;
    flags.mInSystemGroup = options.mMozSystemGroup;
  }
  RemoveEventListenerByType(Move(aListenerHolder), aType, flags);
}

void
EventListenerManager::AddListenerForAllEvents(nsIDOMEventListener* aDOMListener,
                                              bool aUseCapture,
                                              bool aWantsUntrusted,
                                              bool aSystemEventGroup)
{
  EventListenerFlags flags;
  flags.mCapture = aUseCapture;
  flags.mAllowUntrustedEvents = aWantsUntrusted;
  flags.mInSystemGroup = aSystemEventGroup;
  AddEventListenerInternal(EventListenerHolder(aDOMListener), eAllEvents,
                           nullptr, EmptyString(), flags, false, true);
}

void
EventListenerManager::RemoveListenerForAllEvents(
                        nsIDOMEventListener* aDOMListener,
                        bool aUseCapture,
                        bool aSystemEventGroup)
{
  EventListenerFlags flags;
  flags.mCapture = aUseCapture;
  flags.mInSystemGroup = aSystemEventGroup;
  RemoveEventListenerInternal(EventListenerHolder(aDOMListener), eAllEvents,
                              nullptr, EmptyString(), flags, true);
}

bool
EventListenerManager::HasMutationListeners()
{
  if (mMayHaveMutationListeners) {
    uint32_t count = mListeners.Length();
    for (uint32_t i = 0; i < count; ++i) {
      Listener* listener = &mListeners.ElementAt(i);
      if (listener->mEventMessage >= eLegacyMutationEventFirst &&
          listener->mEventMessage <= eLegacyMutationEventLast) {
        return true;
      }
    }
  }

  return false;
}

uint32_t
EventListenerManager::MutationListenerBits()
{
  uint32_t bits = 0;
  if (mMayHaveMutationListeners) {
    uint32_t count = mListeners.Length();
    for (uint32_t i = 0; i < count; ++i) {
      Listener* listener = &mListeners.ElementAt(i);
      if (listener->mEventMessage >= eLegacyMutationEventFirst &&
          listener->mEventMessage <= eLegacyMutationEventLast) {
        if (listener->mEventMessage == eLegacySubtreeModified) {
          return kAllMutationBits;
        }
        bits |= MutationBitForEventType(listener->mEventMessage);
      }
    }
  }
  return bits;
}

bool
EventListenerManager::HasListenersFor(const nsAString& aEventName)
{
  if (mIsMainThreadELM) {
    nsCOMPtr<nsIAtom> atom = NS_Atomize(NS_LITERAL_STRING("on") + aEventName);
    return HasListenersFor(atom);
  }

  uint32_t count = mListeners.Length();
  for (uint32_t i = 0; i < count; ++i) {
    Listener* listener = &mListeners.ElementAt(i);
    if (listener->mTypeString == aEventName) {
      return true;
    }
  }
  return false;
}

bool
EventListenerManager::HasListenersFor(nsIAtom* aEventNameWithOn)
{
#ifdef DEBUG
  nsAutoString name;
  aEventNameWithOn->ToString(name);
#endif
  NS_ASSERTION(StringBeginsWith(name, NS_LITERAL_STRING("on")),
               "Event name does not start with 'on'");
  uint32_t count = mListeners.Length();
  for (uint32_t i = 0; i < count; ++i) {
    Listener* listener = &mListeners.ElementAt(i);
    if (listener->mTypeAtom == aEventNameWithOn) {
      return true;
    }
  }
  return false;
}

bool
EventListenerManager::HasListeners()
{
  return !mListeners.IsEmpty();
}

nsresult
EventListenerManager::GetListenerInfo(nsCOMArray<nsIEventListenerInfo>* aList)
{
  nsCOMPtr<EventTarget> target = do_QueryInterface(mTarget);
  NS_ENSURE_STATE(target);
  aList->Clear();
  nsAutoTObserverArray<Listener, 2>::ForwardIterator iter(mListeners);
  while (iter.HasMore()) {
    const Listener& listener = iter.GetNext();
    // If this is a script handler and we haven't yet
    // compiled the event handler itself go ahead and compile it
    if (listener.mListenerType == Listener::eJSEventListener &&
        listener.mHandlerIsString) {
      CompileEventHandlerInternal(const_cast<Listener*>(&listener), nullptr,
                                  nullptr);
    }
    nsAutoString eventType;
    if (listener.mAllEvents) {
      eventType.SetIsVoid(true);
    } else {
      eventType.Assign(Substring(nsDependentAtomString(listener.mTypeAtom), 2));
    }
    // EventListenerInfo is defined in XPCOM, so we have to go ahead
    // and convert to an XPCOM callback here...
    RefPtr<EventListenerInfo> info =
      new EventListenerInfo(eventType, listener.mListener.ToXPCOMCallback(),
                            listener.mFlags.mCapture,
                            listener.mFlags.mAllowUntrustedEvents,
                            listener.mFlags.mInSystemGroup);
    aList->AppendElement(info.forget());
  }
  return NS_OK;
}

bool
EventListenerManager::HasUnloadListeners()
{
  uint32_t count = mListeners.Length();
  for (uint32_t i = 0; i < count; ++i) {
    Listener* listener = &mListeners.ElementAt(i);
    if (listener->mEventMessage == eUnload ||
        listener->mEventMessage == eBeforeUnload) {
      return true;
    }
  }
  return false;
}

void
EventListenerManager::SetEventHandler(nsIAtom* aEventName,
                                      const nsAString& aTypeString,
                                      EventHandlerNonNull* aHandler)
{
  if (!aHandler) {
    RemoveEventHandler(aEventName, aTypeString);
    return;
  }

  // Untrusted events are always permitted for non-chrome script
  // handlers.
  SetEventHandlerInternal(aEventName, aTypeString, TypedEventHandler(aHandler),
                          !mIsMainThreadELM ||
                          !nsContentUtils::IsCallerChrome());
}

void
EventListenerManager::SetEventHandler(OnErrorEventHandlerNonNull* aHandler)
{
  if (mIsMainThreadELM) {
    if (!aHandler) {
      RemoveEventHandler(nsGkAtoms::onerror, EmptyString());
      return;
    }

    // Untrusted events are always permitted for non-chrome script
    // handlers.
    SetEventHandlerInternal(nsGkAtoms::onerror, EmptyString(),
                            TypedEventHandler(aHandler),
                            !nsContentUtils::IsCallerChrome());
  } else {
    if (!aHandler) {
      RemoveEventHandler(nullptr, NS_LITERAL_STRING("error"));
      return;
    }

    // Untrusted events are always permitted.
    SetEventHandlerInternal(nullptr, NS_LITERAL_STRING("error"),
                            TypedEventHandler(aHandler), true);
  }
}

void
EventListenerManager::SetEventHandler(
                        OnBeforeUnloadEventHandlerNonNull* aHandler)
{
  if (!aHandler) {
    RemoveEventHandler(nsGkAtoms::onbeforeunload, EmptyString());
    return;
  }

  // Untrusted events are always permitted for non-chrome script
  // handlers.
  SetEventHandlerInternal(nsGkAtoms::onbeforeunload, EmptyString(),
                          TypedEventHandler(aHandler),
                          !mIsMainThreadELM ||
                          !nsContentUtils::IsCallerChrome());
}

const TypedEventHandler*
EventListenerManager::GetTypedEventHandler(nsIAtom* aEventName,
                                           const nsAString& aTypeString)
{
  EventMessage eventMessage = nsContentUtils::GetEventMessage(aEventName);
  Listener* listener = FindEventHandler(eventMessage, aEventName, aTypeString);

  if (!listener) {
    return nullptr;
  }

  JSEventHandler* jsEventHandler = listener->GetJSEventHandler();

  if (listener->mHandlerIsString) {
    CompileEventHandlerInternal(listener, nullptr, nullptr);
  }

  const TypedEventHandler& typedHandler =
    jsEventHandler->GetTypedEventHandler();
  return typedHandler.HasEventHandler() ? &typedHandler : nullptr;
}

size_t
EventListenerManager::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
{
  size_t n = aMallocSizeOf(this);
  n += mListeners.ShallowSizeOfExcludingThis(aMallocSizeOf);
  uint32_t count = mListeners.Length();
  for (uint32_t i = 0; i < count; ++i) {
    JSEventHandler* jsEventHandler =
      mListeners.ElementAt(i).GetJSEventHandler();
    if (jsEventHandler) {
      n += jsEventHandler->SizeOfIncludingThis(aMallocSizeOf);
    }
  }
  return n;
}

void
EventListenerManager::MarkForCC()
{
  uint32_t count = mListeners.Length();
  for (uint32_t i = 0; i < count; ++i) {
    const Listener& listener = mListeners.ElementAt(i);
    JSEventHandler* jsEventHandler = listener.GetJSEventHandler();
    if (jsEventHandler) {
      const TypedEventHandler& typedHandler =
        jsEventHandler->GetTypedEventHandler();
      if (typedHandler.HasEventHandler()) {
        typedHandler.Ptr()->MarkForCC();
      }
    } else if (listener.mListenerType == Listener::eWrappedJSListener) {
      xpc_TryUnmarkWrappedGrayObject(listener.mListener.GetXPCOMCallback());
    } else if (listener.mListenerType == Listener::eWebIDLListener) {
      listener.mListener.GetWebIDLCallback()->MarkForCC();
    }
  }
  if (mRefCnt.IsPurple()) {
    mRefCnt.RemovePurple();
  }
}

void
EventListenerManager::TraceListeners(JSTracer* aTrc)
{
  uint32_t count = mListeners.Length();
  for (uint32_t i = 0; i < count; ++i) {
    const Listener& listener = mListeners.ElementAt(i);
    JSEventHandler* jsEventHandler = listener.GetJSEventHandler();
    if (jsEventHandler) {
      const TypedEventHandler& typedHandler =
        jsEventHandler->GetTypedEventHandler();
      if (typedHandler.HasEventHandler()) {
        mozilla::TraceScriptHolder(typedHandler.Ptr(), aTrc);
      }
    } else if (listener.mListenerType == Listener::eWebIDLListener) {
      mozilla::TraceScriptHolder(listener.mListener.GetWebIDLCallback(), aTrc);
    }
    // We might have eWrappedJSListener, but that is the legacy type for
    // JS implemented event listeners, and trickier to handle here.
  }
}

bool
EventListenerManager::HasApzAwareListeners()
{
  uint32_t count = mListeners.Length();
  for (uint32_t i = 0; i < count; ++i) {
    Listener* listener = &mListeners.ElementAt(i);
    if (IsApzAwareListener(listener)) {
      return true;
    }
  }
  return false;
}

bool
EventListenerManager::IsApzAwareListener(Listener* aListener)
{
  return !aListener->mFlags.mPassive && IsApzAwareEvent(aListener->mTypeAtom);
}

bool
EventListenerManager::IsApzAwareEvent(nsIAtom* aEvent)
{
  if (aEvent == nsGkAtoms::onwheel ||
      aEvent == nsGkAtoms::onDOMMouseScroll ||
      aEvent == nsHtml5Atoms::onmousewheel ||
      aEvent == nsGkAtoms::onMozMousePixelScroll) {
    return true;
  }
  // In theory we should schedule a repaint if the touch event pref changes,
  // because the event regions might be out of date. In practice that seems like
  // overkill because users generally shouldn't be flipping this pref, much
  // less expecting touch listeners on the page to immediately start preventing
  // scrolling without so much as a repaint. Tests that we write can work
  // around this constraint easily enough.
  if (aEvent == nsGkAtoms::ontouchstart ||
      aEvent == nsGkAtoms::ontouchmove) {
    return TouchEvent::PrefEnabled(
        nsContentUtils::GetDocShellForEventTarget(mTarget));
  }
  return false;
}

void
EventListenerManager::RemoveAllListeners()
{
  while (!mListeners.IsEmpty()) {
    size_t idx = mListeners.Length() - 1;
    nsCOMPtr<nsIAtom> type = mListeners.ElementAt(idx).mTypeAtom;
    EventMessage message = mListeners.ElementAt(idx).mEventMessage;
    mListeners.RemoveElementAt(idx);
    NotifyEventListenerRemoved(type);
    if (IsDeviceType(message)) {
      DisableDevice(message);
    }
  }
}

already_AddRefed<nsIScriptGlobalObject>
EventListenerManager::GetScriptGlobalAndDocument(nsIDocument** aDoc)
{
  nsCOMPtr<nsINode> node(do_QueryInterface(mTarget));
  nsCOMPtr<nsIDocument> doc;
  nsCOMPtr<nsIScriptGlobalObject> global;
  if (node) {
    // Try to get context from doc
    // XXX sXBL/XBL2 issue -- do we really want the owner here?  What
    // if that's the XBL document?
    doc = node->OwnerDoc();
    if (doc->IsLoadedAsData()) {
      return nullptr;
    }

    // We want to allow compiling an event handler even in an unloaded
    // document, so use GetScopeObject here, not GetScriptHandlingObject.
    global = do_QueryInterface(doc->GetScopeObject());
  } else {
    if (nsCOMPtr<nsPIDOMWindowInner> win = GetTargetAsInnerWindow()) {
      doc = win->GetExtantDoc();
      global = do_QueryInterface(win);
    } else {
      global = do_QueryInterface(mTarget);
    }
  }

  doc.forget(aDoc);
  return global.forget();
}

} // namespace mozilla
