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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "mozilla/dom/CustomElementRegistry.h"

#include "mozilla/CycleCollectedJSContext.h"
#include "mozilla/dom/CustomElementRegistryBinding.h"
#include "mozilla/dom/HTMLElementBinding.h"
#include "mozilla/dom/Promise.h"
#include "mozilla/dom/WebComponentsBinding.h"
#include "mozilla/dom/DocGroup.h"
#include "nsHTMLTags.h"
#include "jsapi.h"

namespace mozilla {
namespace dom {

//-----------------------------------------------------
// CustomElementUpgradeReaction

class CustomElementUpgradeReaction final : public CustomElementReaction {
 public:
  explicit CustomElementUpgradeReaction(CustomElementDefinition* aDefinition)
      : mDefinition(aDefinition) {
#if DEBUG
    mIsUpgradeReaction = true;
#endif
  }

 private:
  virtual void Invoke(Element* aElement, ErrorResult& aRv) override {
    CustomElementRegistry::Upgrade(aElement, mDefinition, aRv);
  }

  CustomElementDefinition* mDefinition;
};

//-----------------------------------------------------
// CustomElementCallbackReaction

class CustomElementCallbackReaction final : public CustomElementReaction {
 public:
  explicit CustomElementCallbackReaction(
      UniquePtr<CustomElementCallback> aCustomElementCallback)
      : mCustomElementCallback(Move(aCustomElementCallback)) {}

  virtual void Traverse(
      nsCycleCollectionTraversalCallback& aCb) const override {
    mCustomElementCallback->Traverse(aCb);
  }

 private:
  virtual void Invoke(Element* aElement, ErrorResult& aRv) override {
    mCustomElementCallback->Call();
  }

  UniquePtr<CustomElementCallback> mCustomElementCallback;
};

//-----------------------------------------------------
// CustomElementCallback

void CustomElementCallback::Call() {
  switch (mType) {
    case nsIDocument::eConnected:
      static_cast<LifecycleConnectedCallback*>(mCallback.get())
          ->Call(mThisObject);
      break;
    case nsIDocument::eDisconnected:
      static_cast<LifecycleDisconnectedCallback*>(mCallback.get())
          ->Call(mThisObject);
      break;
    case nsIDocument::eAdopted:
      static_cast<LifecycleAdoptedCallback*>(mCallback.get())
          ->Call(mThisObject, mAdoptedCallbackArgs.mOldDocument,
                 mAdoptedCallbackArgs.mNewDocument);
      break;
    case nsIDocument::eAttributeChanged:
      static_cast<LifecycleAttributeChangedCallback*>(mCallback.get())
          ->Call(mThisObject, mArgs.name, mArgs.oldValue, mArgs.newValue,
                 mArgs.namespaceURI);
      break;
  }
}

void CustomElementCallback::Traverse(
    nsCycleCollectionTraversalCallback& aCb) const {
  NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(aCb, "mThisObject");
  aCb.NoteXPCOMChild(mThisObject);

  NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(aCb, "mCallback");
  aCb.NoteXPCOMChild(mCallback);
}

CustomElementCallback::CustomElementCallback(
    Element* aThisObject, nsIDocument::ElementCallbackType aCallbackType,
    mozilla::dom::CallbackFunction* aCallback)
    : mThisObject(aThisObject), mCallback(aCallback), mType(aCallbackType) {}
//-----------------------------------------------------
// CustomElementConstructor

already_AddRefed<Element> CustomElementConstructor::Construct(
    const char* aExecutionReason, ErrorResult& aRv) {
  CallSetup s(this, aRv, aExecutionReason,
              CallbackFunction::eRethrowExceptions);

  JSContext* cx = s.GetContext();
  if (!cx) {
    MOZ_ASSERT(aRv.Failed());
    return nullptr;
  }

  JS::Rooted<JSObject*> result(cx);
  JS::Rooted<JS::Value> constructor(cx, JS::ObjectValue(*mCallback));
  if (!JS::Construct(cx, constructor, JS::HandleValueArray::empty(), &result)) {
    aRv.NoteJSContextException(cx);
    return nullptr;
  }

  RefPtr<Element> element;
  if (NS_FAILED(UNWRAP_OBJECT(Element, &result, element))) {
    return nullptr;
  }

  return element.forget();
}

//-----------------------------------------------------
// CustomElementData

CustomElementData::CustomElementData(nsAtom* aType)
    : CustomElementData(aType, CustomElementData::State::eUndefined) {}

CustomElementData::CustomElementData(nsAtom* aType, State aState)
    : mState(aState), mType(aType) {}

void CustomElementData::SetCustomElementDefinition(
    CustomElementDefinition* aDefinition) {
  MOZ_ASSERT(mState == State::eCustom);
  MOZ_ASSERT(!mCustomElementDefinition);
  MOZ_ASSERT(aDefinition->mType == mType);

  mCustomElementDefinition = aDefinition;
}

CustomElementDefinition* CustomElementData::GetCustomElementDefinition() {
  MOZ_ASSERT(mCustomElementDefinition ? mState == State::eCustom
                                      : mState != State::eCustom);

  return mCustomElementDefinition;
}

nsAtom* CustomElementData::GetCustomElementType() { return mType; }

void CustomElementData::Traverse(
    nsCycleCollectionTraversalCallback& aCb) const {
  for (uint32_t i = 0; i < mReactionQueue.Length(); i++) {
    if (mReactionQueue[i]) {
      mReactionQueue[i]->Traverse(aCb);
    }
  }

  if (mCustomElementDefinition) {
    NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(aCb, "mCustomElementDefinition");
    aCb.NoteNativeChild(
        mCustomElementDefinition,
        NS_CYCLE_COLLECTION_PARTICIPANT(CustomElementDefinition));
  }
}

void CustomElementData::Unlink() {
  mReactionQueue.Clear();
  mCustomElementDefinition = nullptr;
}

//-----------------------------------------------------
// CustomElementRegistry

namespace {

class MOZ_RAII AutoConstructionStackEntry final {
 public:
  AutoConstructionStackEntry(nsTArray<RefPtr<Element>>& aStack,
                             Element* aElement)
      : mStack(aStack) {
    MOZ_ASSERT(aElement->IsHTMLElement() || aElement->IsXULElement());

    mIndex = mStack.Length();
    mStack.AppendElement(aElement);
  }

  ~AutoConstructionStackEntry() {
    MOZ_ASSERT(mIndex == mStack.Length() - 1,
               "Removed element should be the last element");
    mStack.RemoveElementAt(mIndex);
  }

 private:
  nsTArray<RefPtr<Element>>& mStack;
  uint32_t mIndex;
};

}  // namespace

// Only needed for refcounted objects.
NS_IMPL_CYCLE_COLLECTION_CLASS(CustomElementRegistry)

NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(CustomElementRegistry)
  tmp->mConstructors.clear();
  NS_IMPL_CYCLE_COLLECTION_UNLINK(mCustomDefinitions)
  NS_IMPL_CYCLE_COLLECTION_UNLINK(mWhenDefinedPromiseMap)
  NS_IMPL_CYCLE_COLLECTION_UNLINK(mWindow)
  NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
NS_IMPL_CYCLE_COLLECTION_UNLINK_END

NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(CustomElementRegistry)
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mCustomDefinitions)
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mWhenDefinedPromiseMap)
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mWindow)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(CustomElementRegistry)
  for (ConstructorMap::Enum iter(tmp->mConstructors); !iter.empty();
       iter.popFront()) {
    aCallbacks.Trace(&iter.front().mutableKey(), "mConstructors key", aClosure);
  }
  NS_IMPL_CYCLE_COLLECTION_TRACE_PRESERVED_WRAPPER
NS_IMPL_CYCLE_COLLECTION_TRACE_END

NS_IMPL_CYCLE_COLLECTING_ADDREF(CustomElementRegistry)
NS_IMPL_CYCLE_COLLECTING_RELEASE(CustomElementRegistry)

NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(CustomElementRegistry)
  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
  NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_END

CustomElementRegistry::CustomElementRegistry(nsPIDOMWindowInner* aWindow)
    : mWindow(aWindow), mIsCustomDefinitionRunning(false) {
  MOZ_ASSERT(aWindow);
  MOZ_ALWAYS_TRUE(mConstructors.init());

  mozilla::HoldJSObjects(this);
}

CustomElementRegistry::~CustomElementRegistry() {
  mozilla::DropJSObjects(this);
}

CustomElementDefinition* CustomElementRegistry::LookupCustomElementDefinition(
    nsAtom* aNameAtom, nsAtom* aTypeAtom) const {
  CustomElementDefinition* data = mCustomDefinitions.GetWeak(aTypeAtom);
  if (data && data->mLocalName == aNameAtom) {
    return data;
  }

  return nullptr;
}

CustomElementDefinition* CustomElementRegistry::LookupCustomElementDefinition(
    JSContext* aCx, JSObject* aConstructor) const {
  JS::Rooted<JSObject*> constructor(aCx, js::CheckedUnwrap(aConstructor));

  const auto& ptr = mConstructors.lookup(constructor);
  if (!ptr) {
    return nullptr;
  }

  CustomElementDefinition* definition =
      mCustomDefinitions.GetWeak(ptr->value());
  MOZ_ASSERT(definition, "Definition must be found in mCustomDefinitions");

  return definition;
}

void CustomElementRegistry::RegisterUnresolvedElement(Element* aElement,
                                                      nsAtom* aTypeName) {
  mozilla::dom::NodeInfo* info = aElement->NodeInfo();

  // Candidate may be a custom element through extension,
  // in which case the custom element type name will not
  // match the element tag name. e.g. <button is="x-button">.
  RefPtr<nsAtom> typeName = aTypeName;
  if (!typeName) {
    typeName = info->NameAtom();
  }

  if (mCustomDefinitions.GetWeak(typeName)) {
    return;
  }

  nsTArray<nsWeakPtr>* unresolved = mCandidatesMap.LookupOrAdd(typeName);
  nsWeakPtr* elem = unresolved->AppendElement();
  *elem = do_GetWeakReference(aElement);
}

void CustomElementRegistry::UnregisterUnresolvedElement(Element* aElement,
                                                        nsAtom* aTypeName) {
  nsTArray<nsWeakPtr>* candidates;
  if (mCandidatesMap.Get(aTypeName, &candidates)) {
    MOZ_ASSERT(candidates);
    // We don't need to iterate the candidates array and remove the element from
    // the array for performance reason. It'll be handled by bug 1396620.
    for (size_t i = 0; i < candidates->Length(); ++i) {
      nsCOMPtr<Element> elem = do_QueryReferent(candidates->ElementAt(i));
      if (elem && elem.get() == aElement) {
        candidates->RemoveElementAt(i);
      }
    }
  }
}

/* static */ UniquePtr<CustomElementCallback>
CustomElementRegistry::CreateCustomElementCallback(
    nsIDocument::ElementCallbackType aType, Element* aCustomElement,
    LifecycleCallbackArgs* aArgs,
    LifecycleAdoptedCallbackArgs* aAdoptedCallbackArgs,
    CustomElementDefinition* aDefinition) {
  MOZ_ASSERT(aDefinition, "CustomElementDefinition should not be null");
  MOZ_ASSERT(aCustomElement->GetCustomElementData(),
             "CustomElementData should exist");

  // Let CALLBACK be the callback associated with the key NAME in CALLBACKS.
  CallbackFunction* func = nullptr;
  switch (aType) {
    case nsIDocument::eConnected:
      if (aDefinition->mCallbacks->mConnectedCallback.WasPassed()) {
        func = aDefinition->mCallbacks->mConnectedCallback.Value();
      }
      break;

    case nsIDocument::eDisconnected:
      if (aDefinition->mCallbacks->mDisconnectedCallback.WasPassed()) {
        func = aDefinition->mCallbacks->mDisconnectedCallback.Value();
      }
      break;

    case nsIDocument::eAdopted:
      if (aDefinition->mCallbacks->mAdoptedCallback.WasPassed()) {
        func = aDefinition->mCallbacks->mAdoptedCallback.Value();
      }
      break;

    case nsIDocument::eAttributeChanged:
      if (aDefinition->mCallbacks->mAttributeChangedCallback.WasPassed()) {
        func = aDefinition->mCallbacks->mAttributeChangedCallback.Value();
      }
      break;
  }

  // If there is no such callback, stop.
  if (!func) {
    return nullptr;
  }

  // Add CALLBACK to ELEMENT's callback queue.
  auto callback =
      MakeUnique<CustomElementCallback>(aCustomElement, aType, func);

  if (aArgs) {
    callback->SetArgs(*aArgs);
  }

  if (aAdoptedCallbackArgs) {
    callback->SetAdoptedCallbackArgs(*aAdoptedCallbackArgs);
  }
  return Move(callback);
}

/* static */ void CustomElementRegistry::EnqueueLifecycleCallback(
    nsIDocument::ElementCallbackType aType, Element* aCustomElement,
    LifecycleCallbackArgs* aArgs,
    LifecycleAdoptedCallbackArgs* aAdoptedCallbackArgs,
    CustomElementDefinition* aDefinition) {
  CustomElementDefinition* definition = aDefinition;
  if (!definition) {
    definition = aCustomElement->GetCustomElementDefinition();
    if (!definition ||
        definition->mLocalName != aCustomElement->NodeInfo()->NameAtom()) {
      return;
    }

    if (!definition->mCallbacks) {
      // definition has been unlinked.  Don't try to mess with it.
      return;
    }
  }

  auto callback = CreateCustomElementCallback(aType, aCustomElement, aArgs,
                                              aAdoptedCallbackArgs, definition);
  if (!callback) {
    return;
  }

  DocGroup* docGroup = aCustomElement->OwnerDoc()->GetDocGroup();
  if (!docGroup) {
    return;
  }

  if (aType == nsIDocument::eAttributeChanged) {
    RefPtr<nsAtom> attrName = NS_Atomize(aArgs->name);
    if (definition->mObservedAttributes.IsEmpty() ||
        !definition->mObservedAttributes.Contains(attrName)) {
      return;
    }
  }

  CustomElementReactionsStack* reactionsStack =
      docGroup->CustomElementReactionsStack();
  reactionsStack->EnqueueCallbackReaction(aCustomElement, Move(callback));
}

void CustomElementRegistry::UpgradeCandidates(
    nsAtom* aKey, CustomElementDefinition* aDefinition, ErrorResult& aRv) {
  DocGroup* docGroup = mWindow->GetDocGroup();
  if (!docGroup) {
    aRv.Throw(NS_ERROR_UNEXPECTED);
    return;
  }

  // TODO: Bug 1326028 - Upgrade custom element in shadow-including tree order
  nsAutoPtr<nsTArray<nsWeakPtr>> candidates;
  if (mCandidatesMap.Remove(aKey, &candidates)) {
    MOZ_ASSERT(candidates);
    CustomElementReactionsStack* reactionsStack =
        docGroup->CustomElementReactionsStack();
    for (size_t i = 0; i < candidates->Length(); ++i) {
      nsCOMPtr<Element> elem = do_QueryReferent(candidates->ElementAt(i));
      if (!elem) {
        continue;
      }

      reactionsStack->EnqueueUpgradeReaction(elem, aDefinition);
    }
  }
}

JSObject* CustomElementRegistry::WrapObject(JSContext* aCx,
                                            JS::Handle<JSObject*> aGivenProto) {
  return CustomElementRegistryBinding::Wrap(aCx, this, aGivenProto);
}

nsISupports* CustomElementRegistry::GetParentObject() const { return mWindow; }

DocGroup* CustomElementRegistry::GetDocGroup() const {
  return mWindow ? mWindow->GetDocGroup() : nullptr;
}

static const char* kLifeCycleCallbackNames[] = {
    "connectedCallback", "disconnectedCallback", "adoptedCallback",
    "attributeChangedCallback"};

static void CheckLifeCycleCallbacks(JSContext* aCx,
                                    JS::Handle<JSObject*> aConstructor,
                                    ErrorResult& aRv) {
  for (size_t i = 0; i < ArrayLength(kLifeCycleCallbackNames); ++i) {
    const char* callbackName = kLifeCycleCallbackNames[i];
    JS::Rooted<JS::Value> callbackValue(aCx);
    if (!JS_GetProperty(aCx, aConstructor, callbackName, &callbackValue)) {
      aRv.StealExceptionFromJSContext(aCx);
      return;
    }
    if (!callbackValue.isUndefined()) {
      if (!callbackValue.isObject()) {
        aRv.ThrowTypeError<MSG_NOT_OBJECT>(
            NS_ConvertASCIItoUTF16(callbackName));
        return;
      }
      JS::Rooted<JSObject*> callback(aCx, &callbackValue.toObject());
      if (!JS::IsCallable(callback)) {
        aRv.ThrowTypeError<MSG_NOT_CALLABLE>(
            NS_ConvertASCIItoUTF16(callbackName));
        return;
      }
    }
  }
}

// https://html.spec.whatwg.org/multipage/scripting.html#element-definition
void CustomElementRegistry::Define(const nsAString& aName,
                                   Function& aFunctionConstructor,
                                   const ElementDefinitionOptions& aOptions,
                                   ErrorResult& aRv) {
  aRv.MightThrowJSException();

  AutoJSAPI jsapi;
  if (NS_WARN_IF(!jsapi.Init(mWindow))) {
    aRv.Throw(NS_ERROR_FAILURE);
    return;
  }

  JSContext* cx = jsapi.cx();
  // Note: No calls that might run JS or trigger CC before this point, or
  // there's a (vanishingly small) chance of our constructor being nulled
  // before we access it.
  JS::Rooted<JSObject*> constructor(cx, aFunctionConstructor.CallableOrNull());

  /**
   * 1. If IsConstructor(constructor) is false, then throw a TypeError and abort
   *    these steps.
   */
  // For now, all wrappers are constructable if they are callable. So we need to
  // unwrap constructor to check it is really constructable.
  JS::Rooted<JSObject*> constructorUnwrapped(cx,
                                             js::CheckedUnwrap(constructor));
  if (!constructorUnwrapped) {
    // If the caller's compartment does not have permission to access the
    // unwrapped constructor then throw.
    aRv.Throw(NS_ERROR_DOM_SECURITY_ERR);
    return;
  }

  if (!JS::IsConstructor(constructorUnwrapped)) {
    aRv.ThrowTypeError<MSG_NOT_CONSTRUCTOR>(
        NS_LITERAL_STRING("Argument 2 of CustomElementRegistry.define"));
    return;
  }

  /**
   * 2. If name is not a valid custom element name, then throw a "SyntaxError"
   *    DOMException and abort these steps.
   */
  RefPtr<nsAtom> nameAtom(NS_Atomize(aName));
  if (!nsContentUtils::IsCustomElementName(nameAtom)) {
    aRv.Throw(NS_ERROR_DOM_SYNTAX_ERR);
    return;
  }

  /**
   * 3. If this CustomElementRegistry contains an entry with name name, then
   *    throw a "NotSupportedError" DOMException and abort these steps.
   */
  if (mCustomDefinitions.GetWeak(nameAtom)) {
    aRv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
    return;
  }

  /**
   * 4. If this CustomElementRegistry contains an entry with constructor
   * constructor, then throw a "NotSupportedError" DOMException and abort these
   * steps.
   */
  const auto& ptr = mConstructors.lookup(constructorUnwrapped);
  if (ptr) {
    MOZ_ASSERT(mCustomDefinitions.GetWeak(ptr->value()),
               "Definition must be found in mCustomDefinitions");
    aRv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
    return;
  }

  /**
   * 5. Let localName be name.
   * 6. Let extends be the value of the extends member of options, or null if
   *    no such member exists.
   * 7. If extends is not null, then:
   *    1. If extends is a valid custom element name, then throw a
   *       "NotSupportedError" DOMException.
   *    2. If the element interface for extends and the HTML namespace is
   *       HTMLUnknownElement (e.g., if extends does not indicate an element
   *       definition in this specification), then throw a "NotSupportedError"
   *       DOMException.
   *    3. Set localName to extends.
   */
  nsAutoString localName(aName);
  if (aOptions.mExtends.WasPassed()) {
    RefPtr<nsAtom> extendsAtom(NS_Atomize(aOptions.mExtends.Value()));
    if (nsContentUtils::IsCustomElementName(extendsAtom)) {
      aRv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
      return;
    }

    // bgsound and multicol are unknown html element.
    int32_t tag = nsHTMLTags::CaseSensitiveAtomTagToId(extendsAtom);
    if (tag == eHTMLTag_userdefined || tag == eHTMLTag_bgsound ||
        tag == eHTMLTag_multicol) {
      aRv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
      return;
    }

    localName.Assign(aOptions.mExtends.Value());
  }

  /**
   * 8. If this CustomElementRegistry's element definition is running flag is
   * set, then throw a "NotSupportedError" DOMException and abort these steps.
   */
  if (mIsCustomDefinitionRunning) {
    aRv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
    return;
  }

  JS::Rooted<JS::Value> constructorPrototype(cx);
  nsAutoPtr<LifecycleCallbacks> callbacksHolder(new LifecycleCallbacks());
  nsTArray<RefPtr<nsAtom>> observedAttributes;
  {  // Set mIsCustomDefinitionRunning.
    /**
     * 9. Set this CustomElementRegistry's element definition is running flag.
     */
    AutoSetRunningFlag as(this);

    {  // Enter constructor's compartment.
      /**
       * 10.1. Let prototype be Get(constructor, "prototype"). Rethrow any
       * exceptions.
       */
      JSAutoCompartment ac(cx, constructor);
      // The .prototype on the constructor passed could be an "expando" of a
      // wrapper. So we should get it from wrapper instead of the underlying
      // object.
      if (!JS_GetProperty(cx, constructor, "prototype",
                          &constructorPrototype)) {
        aRv.StealExceptionFromJSContext(cx);
        return;
      }

      /**
       * 10.2. If Type(prototype) is not Object, then throw a TypeError
       * exception.
       */
      if (!constructorPrototype.isObject()) {
        aRv.ThrowTypeError<MSG_NOT_OBJECT>(
            NS_LITERAL_STRING("constructor.prototype"));
        return;
      }
    }  // Leave constructor's compartment.

    JS::Rooted<JSObject*> constructorProtoUnwrapped(
        cx, js::CheckedUnwrap(&constructorPrototype.toObject()));
    if (!constructorProtoUnwrapped) {
      // If the caller's compartment does not have permission to access the
      // unwrapped prototype then throw.
      aRv.Throw(NS_ERROR_DOM_SECURITY_ERR);
      return;
    }

    {  // Enter constructorProtoUnwrapped's compartment
      JSAutoCompartment ac(cx, constructorProtoUnwrapped);

      /**
       * 10.3. Let lifecycleCallbacks be a map with the four keys
       *       "connectedCallback", "disconnectedCallback", "adoptedCallback",
       * and "attributeChangedCallback", each of which belongs to an entry whose
       *       value is null.
       * 10.4. For each of the four keys callbackName in lifecycleCallbacks:
       *       1. Let callbackValue be Get(prototype, callbackName). Rethrow any
       *          exceptions.
       *       2. If callbackValue is not undefined, then set the value of the
       *          entry in lifecycleCallbacks with key callbackName to the
       * result of converting callbackValue to the Web IDL Function callback
       * type. Rethrow any exceptions from the conversion.
       */
      // Will do the same checking for the life cycle callbacks from v0 spec.
      CheckLifeCycleCallbacks(cx, constructorProtoUnwrapped, aRv);
      if (aRv.Failed()) {
        return;
      }

      // Note: We call the init from the constructorProtoUnwrapped's compartment
      //       here.
      JS::RootedValue rootedv(cx, JS::ObjectValue(*constructorProtoUnwrapped));
      if (!JS_WrapValue(cx, &rootedv) || !callbacksHolder->Init(cx, rootedv)) {
        aRv.StealExceptionFromJSContext(cx);
        return;
      }

      /**
       * 10.5. Let observedAttributes be an empty sequence<DOMString>.
       * 10.6. If the value of the entry in lifecycleCallbacks with key
       *       "attributeChangedCallback" is not null, then:
       *       1. Let observedAttributesIterable be Get(constructor,
       *          "observedAttributes"). Rethrow any exceptions.
       *       2. If observedAttributesIterable is not undefined, then set
       *          observedAttributes to the result of converting
       *          observedAttributesIterable to a sequence<DOMString>. Rethrow
       *          any exceptions from the conversion.
       */
      if (callbacksHolder->mAttributeChangedCallback.WasPassed()) {
        // Enter constructor's compartment.
        JSAutoCompartment ac(cx, constructor);
        JS::Rooted<JS::Value> observedAttributesIterable(cx);

        if (!JS_GetProperty(cx, constructor, "observedAttributes",
                            &observedAttributesIterable)) {
          aRv.StealExceptionFromJSContext(cx);
          return;
        }

        if (!observedAttributesIterable.isUndefined()) {
          if (!observedAttributesIterable.isObject()) {
            aRv.ThrowTypeError<MSG_NOT_SEQUENCE>(
                NS_LITERAL_STRING("observedAttributes"));
            return;
          }

          JS::ForOfIterator iter(cx);
          if (!iter.init(observedAttributesIterable,
                         JS::ForOfIterator::AllowNonIterable)) {
            aRv.StealExceptionFromJSContext(cx);
            return;
          }

          if (!iter.valueIsIterable()) {
            aRv.ThrowTypeError<MSG_NOT_SEQUENCE>(
                NS_LITERAL_STRING("observedAttributes"));
            return;
          }

          JS::Rooted<JS::Value> attribute(cx);
          while (true) {
            bool done;
            if (!iter.next(&attribute, &done)) {
              aRv.StealExceptionFromJSContext(cx);
              return;
            }
            if (done) {
              break;
            }

            nsAutoString attrStr;
            if (!ConvertJSValueToString(cx, attribute, eStringify, eStringify,
                                        attrStr)) {
              aRv.StealExceptionFromJSContext(cx);
              return;
            }

            if (!observedAttributes.AppendElement(NS_Atomize(attrStr))) {
              aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
              return;
            }
          }
        }
      }  // Leave constructor's compartment.
    }    // Leave constructorProtoUnwrapped's compartment.
  }      // Unset mIsCustomDefinitionRunning

  /**
   * 11. Let definition be a new custom element definition with name name,
   *     local name localName, constructor constructor, prototype prototype,
   *     observed attributes observedAttributes, and lifecycle callbacks
   *     lifecycleCallbacks.
   */
  // Associate the definition with the custom element.
  RefPtr<nsAtom> localNameAtom(NS_Atomize(localName));
  LifecycleCallbacks* callbacks = callbacksHolder.forget();

  /**
   * 12. Add definition to this CustomElementRegistry.
   */
  if (!mConstructors.put(constructorUnwrapped, nameAtom)) {
    aRv.Throw(NS_ERROR_FAILURE);
    return;
  }

  RefPtr<CustomElementDefinition> definition = new CustomElementDefinition(
      nameAtom, localNameAtom, &aFunctionConstructor, Move(observedAttributes),
      callbacks);

  CustomElementDefinition* def = definition.get();
  mCustomDefinitions.Put(nameAtom, definition.forget());

  MOZ_ASSERT(mCustomDefinitions.Count() == mConstructors.count(),
             "Number of entries should be the same");

  /**
   * 13. 14. 15. Upgrade candidates
   */
  UpgradeCandidates(nameAtom, def, aRv);

  /**
   * 16. If this CustomElementRegistry's when-defined promise map contains an
   *     entry with key name:
   *     1. Let promise be the value of that entry.
   *     2. Resolve promise with undefined.
   *     3. Delete the entry with key name from this CustomElementRegistry's
   *        when-defined promise map.
   */
  RefPtr<Promise> promise;
  mWhenDefinedPromiseMap.Remove(nameAtom, getter_AddRefs(promise));
  if (promise) {
    promise->MaybeResolveWithUndefined();
  }
}

void CustomElementRegistry::Get(JSContext* aCx, const nsAString& aName,
                                JS::MutableHandle<JS::Value> aRetVal) {
  RefPtr<nsAtom> nameAtom(NS_Atomize(aName));
  CustomElementDefinition* data = mCustomDefinitions.GetWeak(nameAtom);

  if (!data) {
    aRetVal.setUndefined();
    return;
  }

  aRetVal.setObject(*data->mConstructor->Callback(aCx));
}

already_AddRefed<Promise> CustomElementRegistry::WhenDefined(
    const nsAString& aName, ErrorResult& aRv) {
  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(mWindow);
  RefPtr<Promise> promise = Promise::Create(global, aRv);

  if (aRv.Failed()) {
    return nullptr;
  }

  RefPtr<nsAtom> nameAtom(NS_Atomize(aName));
  if (!nsContentUtils::IsCustomElementName(nameAtom)) {
    promise->MaybeReject(NS_ERROR_DOM_SYNTAX_ERR);
    return promise.forget();
  }

  if (mCustomDefinitions.GetWeak(nameAtom)) {
    promise->MaybeResolve(JS::UndefinedHandleValue);
    return promise.forget();
  }

  auto entry = mWhenDefinedPromiseMap.LookupForAdd(nameAtom);
  if (entry) {
    promise = entry.Data();
  } else {
    entry.OrInsert([&promise]() { return promise; });
  }

  return promise.forget();
}

namespace {

static void DoUpgrade(Element* aElement, CustomElementConstructor* aConstructor,
                      ErrorResult& aRv) {
  // Rethrow the exception since it might actually throw the exception from the
  // upgrade steps back out to the caller of document.createElement.
  RefPtr<Element> constructResult =
      aConstructor->Construct("Custom Element Upgrade", aRv);
  if (aRv.Failed()) {
    return;
  }

  if (!constructResult || constructResult.get() != aElement) {
    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
    return;
  }
}

}  // anonymous namespace

// https://html.spec.whatwg.org/multipage/scripting.html#upgrades
/* static */ void CustomElementRegistry::Upgrade(
    Element* aElement, CustomElementDefinition* aDefinition, ErrorResult& aRv) {
  RefPtr<CustomElementData> data = aElement->GetCustomElementData();
  MOZ_ASSERT(data, "CustomElementData should exist");

  // Step 1 and step 2.
  if (data->mState == CustomElementData::State::eCustom ||
      data->mState == CustomElementData::State::eFailed) {
    return;
  }

  // Step 3.
  if (!aDefinition->mObservedAttributes.IsEmpty()) {
    uint32_t count = aElement->GetAttrCount();
    for (uint32_t i = 0; i < count; i++) {
      mozilla::dom::BorrowedAttrInfo info = aElement->GetAttrInfoAt(i);

      const nsAttrName* name = info.mName;
      nsAtom* attrName = name->LocalName();

      if (aDefinition->IsInObservedAttributeList(attrName)) {
        int32_t namespaceID = name->NamespaceID();
        nsAutoString attrValue, namespaceURI;
        info.mValue->ToString(attrValue);
        nsContentUtils::NameSpaceManager()->GetNameSpaceURI(namespaceID,
                                                            namespaceURI);

        LifecycleCallbackArgs args = {
            nsDependentAtomString(attrName), VoidString(), attrValue,
            (namespaceURI.IsEmpty() ? VoidString() : namespaceURI)};
        nsContentUtils::EnqueueLifecycleCallback(nsIDocument::eAttributeChanged,
                                                 aElement, &args, nullptr,
                                                 aDefinition);
      }
    }
  }

  // Step 4.
  if (aElement->IsInComposedDoc()) {
    nsContentUtils::EnqueueLifecycleCallback(nsIDocument::eConnected, aElement,
                                             nullptr, nullptr, aDefinition);
  }

  // Step 5.
  AutoConstructionStackEntry acs(aDefinition->mConstructionStack, aElement);

  // Step 6 and step 7.
  DoUpgrade(aElement, aDefinition->mConstructor, aRv);
  if (aRv.Failed()) {
    data->mState = CustomElementData::State::eFailed;
    // Empty element's custom element reaction queue.
    data->mReactionQueue.Clear();
    return;
  }

  // Step 8.
  data->mState = CustomElementData::State::eCustom;

  // Step 9.
  aElement->SetCustomElementDefinition(aDefinition);
}

//-----------------------------------------------------
// CustomElementReactionsStack

void CustomElementReactionsStack::CreateAndPushElementQueue() {
  MOZ_ASSERT(mRecursionDepth);
  MOZ_ASSERT(!mIsElementQueuePushedForCurrentRecursionDepth);

  // Push a new element queue onto the custom element reactions stack.
  mReactionsStack.AppendElement(MakeUnique<ElementQueue>());
  mIsElementQueuePushedForCurrentRecursionDepth = true;
}

void CustomElementReactionsStack::PopAndInvokeElementQueue() {
  MOZ_ASSERT(mRecursionDepth);
  MOZ_ASSERT(mIsElementQueuePushedForCurrentRecursionDepth);
  MOZ_ASSERT(!mReactionsStack.IsEmpty(), "Reaction stack shouldn't be empty");

  // Pop the element queue from the custom element reactions stack,
  // and invoke custom element reactions in that queue.
  const uint32_t lastIndex = mReactionsStack.Length() - 1;
  ElementQueue* elementQueue = mReactionsStack.ElementAt(lastIndex).get();
  // Check element queue size in order to reduce function call overhead.
  if (!elementQueue->IsEmpty()) {
    // It is still not clear what error reporting will look like in custom
    // element, see https://github.com/w3c/webcomponents/issues/635.
    // We usually report the error to entry global in gecko, so just follow the
    // same behavior here.
    // This may be null if it's called from parser, see the case of
    // attributeChangedCallback in
    // https://html.spec.whatwg.org/multipage/parsing.html#create-an-element-for-the-token
    // In that case, the exception of callback reactions will be automatically
    // reported in CallSetup.
    nsIGlobalObject* global = GetEntryGlobal();
    InvokeReactions(elementQueue, global);
  }

  // InvokeReactions() might create other custom element reactions, but those
  // new reactions should be already consumed and removed at this point.
  MOZ_ASSERT(
      lastIndex == mReactionsStack.Length() - 1,
      "reactions created by InvokeReactions() should be consumed and removed");

  mReactionsStack.RemoveElementAt(lastIndex);
  mIsElementQueuePushedForCurrentRecursionDepth = false;
}

void CustomElementReactionsStack::EnqueueUpgradeReaction(
    Element* aElement, CustomElementDefinition* aDefinition) {
  Enqueue(aElement, new CustomElementUpgradeReaction(aDefinition));
}

void CustomElementReactionsStack::EnqueueCallbackReaction(
    Element* aElement,
    UniquePtr<CustomElementCallback> aCustomElementCallback) {
  Enqueue(aElement,
          new CustomElementCallbackReaction(Move(aCustomElementCallback)));
}

void CustomElementReactionsStack::Enqueue(Element* aElement,
                                          CustomElementReaction* aReaction) {
  RefPtr<CustomElementData> elementData = aElement->GetCustomElementData();
  MOZ_ASSERT(elementData, "CustomElementData should exist");

  if (mRecursionDepth) {
    // If the element queue is not created for current recursion depth, create
    // and push an element queue to reactions stack first.
    if (!mIsElementQueuePushedForCurrentRecursionDepth) {
      CreateAndPushElementQueue();
    }

    MOZ_ASSERT(!mReactionsStack.IsEmpty());
    // Add element to the current element queue.
    mReactionsStack.LastElement()->AppendElement(aElement);
    elementData->mReactionQueue.AppendElement(aReaction);
    return;
  }

  // If the custom element reactions stack is empty, then:
  // Add element to the backup element queue.
  MOZ_ASSERT(mReactionsStack.IsEmpty(),
             "custom element reactions stack should be empty");
  MOZ_ASSERT(!aReaction->IsUpgradeReaction(),
             "Upgrade reaction should not be scheduled to backup queue");
  mBackupQueue.AppendElement(aElement);
  elementData->mReactionQueue.AppendElement(aReaction);

  if (mIsBackupQueueProcessing) {
    return;
  }

  CycleCollectedJSContext* context = CycleCollectedJSContext::Get();
  RefPtr<BackupQueueMicroTask> bqmt = new BackupQueueMicroTask(this);
  context->DispatchToMicroTask(bqmt.forget());
}

void CustomElementReactionsStack::InvokeBackupQueue() {
  // Check backup queue size in order to reduce function call overhead.
  if (!mBackupQueue.IsEmpty()) {
    // Upgrade reactions won't be scheduled in backup queue and the exception of
    // callback reactions will be automatically reported in CallSetup.
    // If the reactions are invoked from backup queue (in microtask check
    // point), we don't need to pass global object for error reporting.
    InvokeReactions(&mBackupQueue, nullptr);
  }
  MOZ_ASSERT(
      mBackupQueue.IsEmpty(),
      "There are still some reactions in BackupQueue not being consumed!?!");
}

void CustomElementReactionsStack::InvokeReactions(ElementQueue* aElementQueue,
                                                  nsIGlobalObject* aGlobal) {
  // This is used for error reporting.
  Maybe<AutoEntryScript> aes;
  if (aGlobal) {
    aes.emplace(aGlobal, "custom elements reaction invocation");
  }

  // Note: It's possible to re-enter this method.
  for (uint32_t i = 0; i < aElementQueue->Length(); ++i) {
    Element* element = aElementQueue->ElementAt(i);
    // ElementQueue hold a element's strong reference, it should not be a
    // nullptr.
    MOZ_ASSERT(element);

    RefPtr<CustomElementData> elementData = element->GetCustomElementData();
    if (!elementData) {
      // This happens when the document is destroyed and the element is already
      // unlinked, no need to fire the callbacks in this case.
      continue;
    }

    auto& reactions = elementData->mReactionQueue;
    for (uint32_t j = 0; j < reactions.Length(); ++j) {
      // Transfer the ownership of the entry due to reentrant invocation of
      // this funciton. The entry will be removed when bug 1379573 is landed.
      auto reaction(Move(reactions.ElementAt(j)));
      if (reaction) {
        ErrorResult rv;
        reaction->Invoke(element, rv);
        if (aes) {
          JSContext* cx = aes->cx();
          if (rv.MaybeSetPendingException(cx)) {
            aes->ReportException();
          }
          MOZ_ASSERT(!JS_IsExceptionPending(cx));
        }
        MOZ_ASSERT(!rv.Failed());
      }
    }
    reactions.Clear();
  }
  aElementQueue->Clear();
}

//-----------------------------------------------------
// CustomElementDefinition

NS_IMPL_CYCLE_COLLECTION_CLASS(CustomElementDefinition)

NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(CustomElementDefinition)
  NS_IMPL_CYCLE_COLLECTION_UNLINK(mConstructor)
  tmp->mCallbacks = nullptr;
NS_IMPL_CYCLE_COLLECTION_UNLINK_END

NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(CustomElementDefinition)
  mozilla::dom::LifecycleCallbacks* callbacks = tmp->mCallbacks.get();

  if (callbacks->mAttributeChangedCallback.WasPassed()) {
    NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb,
                                       "mCallbacks->mAttributeChangedCallback");
    cb.NoteXPCOMChild(callbacks->mAttributeChangedCallback.Value());
  }

  if (callbacks->mConnectedCallback.WasPassed()) {
    NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mCallbacks->mConnectedCallback");
    cb.NoteXPCOMChild(callbacks->mConnectedCallback.Value());
  }

  if (callbacks->mDisconnectedCallback.WasPassed()) {
    NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mCallbacks->mDisconnectedCallback");
    cb.NoteXPCOMChild(callbacks->mDisconnectedCallback.Value());
  }

  if (callbacks->mAdoptedCallback.WasPassed()) {
    NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mCallbacks->mAdoptedCallback");
    cb.NoteXPCOMChild(callbacks->mAdoptedCallback.Value());
  }

  NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mConstructor");
  cb.NoteXPCOMChild(tmp->mConstructor);
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(CustomElementDefinition)
NS_IMPL_CYCLE_COLLECTION_TRACE_END

NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(CustomElementDefinition, AddRef)
NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(CustomElementDefinition, Release)

CustomElementDefinition::CustomElementDefinition(
    nsAtom* aType, nsAtom* aLocalName, Function* aConstructor,
    nsTArray<RefPtr<nsAtom>>&& aObservedAttributes,
    LifecycleCallbacks* aCallbacks)
    : mType(aType),
      mLocalName(aLocalName),
      mConstructor(new CustomElementConstructor(aConstructor)),
      mObservedAttributes(Move(aObservedAttributes)),
      mCallbacks(aCallbacks) {}

}  // namespace dom
}  // namespace mozilla