/* -*- 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/. */

#include "nsBindingManager.h"

#include "nsAutoPtr.h"
#include "nsCOMPtr.h"
#include "nsXBLService.h"
#include "nsIInputStream.h"
#include "nsIURI.h"
#include "nsIURL.h"
#include "nsIChannel.h"
#include "nsXPIDLString.h"
#include "plstr.h"
#include "nsIContent.h"
#include "nsIDOMElement.h"
#include "nsIDocument.h"
#include "nsContentUtils.h"
#include "nsIPresShell.h"
#include "nsIXMLContentSink.h"
#include "nsContentCID.h"
#include "mozilla/dom/XMLDocument.h"
#include "nsIStreamListener.h"
#include "ChildIterator.h"
#include "nsITimer.h"

#include "nsXBLBinding.h"
#include "nsXBLPrototypeBinding.h"
#include "nsXBLDocumentInfo.h"
#include "mozilla/dom/XBLChildrenElement.h"
#include "mozilla/dom/ShadowRoot.h"

#include "nsIStyleRuleProcessor.h"
#include "nsRuleProcessorData.h"
#include "nsIWeakReference.h"

#include "nsWrapperCacheInlines.h"
#include "nsIXPConnect.h"
#include "nsDOMCID.h"
#include "nsIScriptGlobalObject.h"
#include "nsTHashtable.h"

#include "nsIScriptContext.h"
#include "xpcpublic.h"
#include "jswrapper.h"

#include "nsThreadUtils.h"
#include "mozilla/dom/NodeListBinding.h"
#include "mozilla/dom/ScriptSettings.h"
#include "mozilla/Unused.h"

using namespace mozilla;
using namespace mozilla::dom;

// Implement our nsISupports methods

NS_IMPL_CYCLE_COLLECTION_CLASS(nsBindingManager)

NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsBindingManager)
  tmp->mDestroyed = true;

  if (tmp->mBoundContentSet)
    tmp->mBoundContentSet->Clear();

  if (tmp->mDocumentTable)
    tmp->mDocumentTable->Clear();

  if (tmp->mLoadingDocTable)
    tmp->mLoadingDocTable->Clear();

  if (tmp->mWrapperTable) {
    tmp->mWrapperTable->Clear();
    tmp->mWrapperTable = nullptr;
  }

  NS_IMPL_CYCLE_COLLECTION_UNLINK(mAttachedStack)

  if (tmp->mProcessAttachedQueueEvent) {
    tmp->mProcessAttachedQueueEvent->Revoke();
  }
NS_IMPL_CYCLE_COLLECTION_UNLINK_END


NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsBindingManager)
  // The hashes keyed on nsIContent are traversed from the nsIContent itself.
  if (tmp->mDocumentTable) {
    for (auto iter = tmp->mDocumentTable->Iter(); !iter.Done(); iter.Next()) {
      NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mDocumentTable value");
      cb.NoteXPCOMChild(iter.UserData());
    }
  }
  if (tmp->mLoadingDocTable) {
    for (auto iter = tmp->mLoadingDocTable->Iter(); !iter.Done(); iter.Next()) {
      NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mLoadingDocTable value");
      cb.NoteXPCOMChild(iter.UserData());
    }
  }
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mAttachedStack)
  // No need to traverse mProcessAttachedQueueEvent, since it'll just
  // fire at some point or become revoke and drop its ref to us.
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsBindingManager)
  NS_INTERFACE_MAP_ENTRY(nsIMutationObserver)
  NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_END

NS_IMPL_CYCLE_COLLECTING_ADDREF(nsBindingManager)
NS_IMPL_CYCLE_COLLECTING_RELEASE(nsBindingManager)

// Constructors/Destructors
nsBindingManager::nsBindingManager(nsIDocument* aDocument)
  : mProcessingAttachedStack(false),
    mDestroyed(false),
    mAttachedStackSizeOnOutermost(0),
    mDocument(aDocument)
{
}

nsBindingManager::~nsBindingManager(void)
{
  mDestroyed = true;
}

nsXBLBinding*
nsBindingManager::GetBindingWithContent(const nsIContent* aContent)
{
  nsXBLBinding* binding = aContent ? aContent->GetXBLBinding() : nullptr;
  return binding ? binding->GetBindingWithContent() : nullptr;
}

void
nsBindingManager::AddBoundContent(nsIContent* aContent)
{
  if (!mBoundContentSet) {
    mBoundContentSet = new nsTHashtable<nsRefPtrHashKey<nsIContent> >;
  }
  mBoundContentSet->PutEntry(aContent);
}

void
nsBindingManager::RemoveBoundContent(nsIContent* aContent)
{
  if (mBoundContentSet) {
    mBoundContentSet->RemoveEntry(aContent);
  }

  // The death of the bindings means the death of the JS wrapper.
  SetWrappedJS(aContent, nullptr);
}

nsIXPConnectWrappedJS*
nsBindingManager::GetWrappedJS(nsIContent* aContent)
{
  if (!mWrapperTable) {
    return nullptr;
  }

  if (!aContent || !aContent->HasFlag(NODE_MAY_BE_IN_BINDING_MNGR)) {
    return nullptr;
  }

  return mWrapperTable->GetWeak(aContent);
}

nsresult
nsBindingManager::SetWrappedJS(nsIContent* aContent, nsIXPConnectWrappedJS* aWrappedJS)
{
  if (mDestroyed) {
    return NS_OK;
  }

  if (aWrappedJS) {
    // lazily create the table, but only when adding elements
    if (!mWrapperTable) {
      mWrapperTable = new WrapperHashtable();
    }
    aContent->SetFlags(NODE_MAY_BE_IN_BINDING_MNGR);

    NS_ASSERTION(aContent, "key must be non-null");
    if (!aContent) return NS_ERROR_INVALID_ARG;

    mWrapperTable->Put(aContent, aWrappedJS);

    return NS_OK;
  }

  // no value, so remove the key from the table
  if (mWrapperTable) {
    mWrapperTable->Remove(aContent);
  }

  return NS_OK;
}

void
nsBindingManager::RemovedFromDocumentInternal(nsIContent* aContent,
                                              nsIDocument* aOldDocument,
                                              DestructorHandling aDestructorHandling)
{
  NS_PRECONDITION(aOldDocument != nullptr, "no old document");

  RefPtr<nsXBLBinding> binding = aContent->GetXBLBinding();
  if (binding) {
    // The binding manager may have been destroyed before a runnable
    // has had a chance to reach this point. If so, we bail out on calling
    // BindingDetached (which may invoke a XBL destructor) and
    // ChangeDocument, but we still want to clear out the binding
    // and insertion parent that may hold references.
    if (!mDestroyed && aDestructorHandling == eRunDtor) {
      binding->PrototypeBinding()->BindingDetached(binding->GetBoundElement());
      binding->ChangeDocument(aOldDocument, nullptr);
    }

    aContent->SetXBLBinding(nullptr, this);
  }

  // Clear out insertion parent and content lists.
  aContent->SetXBLInsertionParent(nullptr);
}

nsIAtom*
nsBindingManager::ResolveTag(nsIContent* aContent, int32_t* aNameSpaceID)
{
  nsXBLBinding *binding = aContent->GetXBLBinding();

  if (binding) {
    nsIAtom* base = binding->GetBaseTag(aNameSpaceID);

    if (base) {
      return base;
    }
  }

  *aNameSpaceID = aContent->GetNameSpaceID();
  return aContent->NodeInfo()->NameAtom();
}

nsresult
nsBindingManager::GetAnonymousNodesFor(nsIContent* aContent,
                                       nsIDOMNodeList** aResult)
{
  NS_IF_ADDREF(*aResult = GetAnonymousNodesFor(aContent));
  return NS_OK;
}

nsINodeList*
nsBindingManager::GetAnonymousNodesFor(nsIContent* aContent)
{
  nsXBLBinding* binding = GetBindingWithContent(aContent);
  return binding ? binding->GetAnonymousNodeList() : nullptr;
}

nsresult
nsBindingManager::ClearBinding(nsIContent* aContent)
{
  // Hold a ref to the binding so it won't die when we remove it from our table
  RefPtr<nsXBLBinding> binding =
    aContent ? aContent->GetXBLBinding() : nullptr;

  if (!binding) {
    return NS_OK;
  }

  // For now we can only handle removing a binding if it's the only one
  NS_ENSURE_FALSE(binding->GetBaseBinding(), NS_ERROR_FAILURE);

  // Hold strong ref in case removing the binding tries to close the
  // window or something.
  // XXXbz should that be ownerdoc?  Wouldn't we need a ref to the
  // currentdoc too?  What's the one that should be passed to
  // ChangeDocument?
  nsCOMPtr<nsIDocument> doc = aContent->OwnerDoc();

  // Finally remove the binding...
  // XXXbz this doesn't remove the implementation!  Should fix!  Until
  // then we need the explicit UnhookEventHandlers here.
  binding->UnhookEventHandlers();
  binding->ChangeDocument(doc, nullptr);
  aContent->SetXBLBinding(nullptr, this);
  binding->MarkForDeath();

  // ...and recreate its frames. We need to do this since the frames may have
  // been removed and style may have changed due to the removal of the
  // anonymous children.
  // XXXbz this should be using the current doc (if any), not the owner doc.
  nsIPresShell *presShell = doc->GetShell();
  NS_ENSURE_TRUE(presShell, NS_ERROR_FAILURE);

  return presShell->RecreateFramesFor(aContent);;
}

nsresult
nsBindingManager::LoadBindingDocument(nsIDocument* aBoundDoc,
                                      nsIURI* aURL,
                                      nsIPrincipal* aOriginPrincipal)
{
  NS_PRECONDITION(aURL, "Must have a URI to load!");

  // First we need to load our binding.
  nsXBLService* xblService = nsXBLService::GetInstance();
  if (!xblService)
    return NS_ERROR_FAILURE;

  // Load the binding doc.
  RefPtr<nsXBLDocumentInfo> info;
  xblService->LoadBindingDocumentInfo(nullptr, aBoundDoc, aURL,
                                      aOriginPrincipal, true,
                                      getter_AddRefs(info));
  if (!info)
    return NS_ERROR_FAILURE;

  return NS_OK;
}

void
nsBindingManager::RemoveFromAttachedQueue(nsXBLBinding* aBinding)
{
  // Don't remove items here as that could mess up an executing
  // ProcessAttachedQueue. Instead, null the entry in the queue.
  size_t index = mAttachedStack.IndexOf(aBinding);
  if (index != mAttachedStack.NoIndex) {
    mAttachedStack[index] = nullptr;
  }
}

nsresult
nsBindingManager::AddToAttachedQueue(nsXBLBinding* aBinding)
{
  mAttachedStack.AppendElement(aBinding);

  // If we're in the middle of processing our queue already, don't
  // bother posting the event.
  if (!mProcessingAttachedStack && !mProcessAttachedQueueEvent) {
    PostProcessAttachedQueueEvent();
  }

  // Make sure that flushes will flush out the new items as needed.
  mDocument->SetNeedStyleFlush();

  return NS_OK;

}

void
nsBindingManager::PostProcessAttachedQueueEvent()
{
  mProcessAttachedQueueEvent =
    NewRunnableMethod(this, &nsBindingManager::DoProcessAttachedQueue);
  nsresult rv = NS_DispatchToCurrentThread(mProcessAttachedQueueEvent);
  if (NS_SUCCEEDED(rv) && mDocument) {
    mDocument->BlockOnload();
  }
}

// static
void
nsBindingManager::PostPAQEventCallback(nsITimer* aTimer, void* aClosure)
{
  RefPtr<nsBindingManager> mgr = 
    already_AddRefed<nsBindingManager>(static_cast<nsBindingManager*>(aClosure));
  mgr->PostProcessAttachedQueueEvent();
  NS_RELEASE(aTimer);
}

void
nsBindingManager::DoProcessAttachedQueue()
{
  if (!mProcessingAttachedStack) {
    ProcessAttachedQueue();

    NS_ASSERTION(mAttachedStack.Length() == 0,
               "Shouldn't have pending bindings!");

    mProcessAttachedQueueEvent = nullptr;
  } else {
    // Someone's doing event processing from inside a constructor.
    // They're evil, but we'll fight back!  Just poll on them being
    // done and repost the attached queue event.
    //
    // But don't poll in a tight loop -- otherwise we keep the Gecko
    // event loop non-empty and trigger bug 1021240 on OS X.
    nsresult rv = NS_ERROR_FAILURE;
    nsCOMPtr<nsITimer> timer = do_CreateInstance(NS_TIMER_CONTRACTID);
    if (timer) {
      rv = timer->InitWithFuncCallback(PostPAQEventCallback, this,
                                       100, nsITimer::TYPE_ONE_SHOT);
    }
    if (NS_SUCCEEDED(rv)) {
      NS_ADDREF_THIS();
      // We drop our reference to the timer here, since the timer callback is
      // responsible for releasing the object.
      Unused << timer.forget().take();
    }
  }

  // No matter what, unblock onload for the event that's fired.
  if (mDocument) {
    // Hold a strong reference while calling UnblockOnload since that might
    // run script.
    nsCOMPtr<nsIDocument> doc = mDocument;
    doc->UnblockOnload(true);
  }
}

void
nsBindingManager::ProcessAttachedQueueInternal(uint32_t aSkipSize)
{
  mProcessingAttachedStack = true;

  // Excute constructors. Do this from high index to low
  while (mAttachedStack.Length() > aSkipSize) {
    uint32_t lastItem = mAttachedStack.Length() - 1;
    RefPtr<nsXBLBinding> binding = mAttachedStack.ElementAt(lastItem);
    mAttachedStack.RemoveElementAt(lastItem);
    if (binding) {
      binding->ExecuteAttachedHandler();
    }
  }

  // If NodeWillBeDestroyed has run we don't want to clobber
  // mProcessingAttachedStack set there.
  if (mDocument) {
    mProcessingAttachedStack = false;
  }

  NS_ASSERTION(mAttachedStack.Length() == aSkipSize, "How did we get here?");

  mAttachedStack.Compact();
}

// Keep bindings and bound elements alive while executing detached handlers.
void
nsBindingManager::ExecuteDetachedHandlers()
{
  // Walk our hashtable of bindings.
  if (!mBoundContentSet) {
    return;
  }

  nsCOMArray<nsIContent> boundElements;
  nsBindingList bindings;

  for (auto iter = mBoundContentSet->Iter(); !iter.Done(); iter.Next()) {
    nsXBLBinding* binding = iter.Get()->GetKey()->GetXBLBinding();
    if (binding && bindings.AppendElement(binding)) {
      if (!boundElements.AppendObject(binding->GetBoundElement())) {
        bindings.RemoveElementAt(bindings.Length() - 1);
      }
    }
  }

  uint32_t i, count = bindings.Length();
  for (i = 0; i < count; ++i) {
    bindings[i]->ExecuteDetachedHandler();
  }
}

nsresult
nsBindingManager::PutXBLDocumentInfo(nsXBLDocumentInfo* aDocumentInfo)
{
  NS_PRECONDITION(aDocumentInfo, "Must have a non-null documentinfo!");

  if (!mDocumentTable) {
    mDocumentTable = new nsRefPtrHashtable<nsURIHashKey,nsXBLDocumentInfo>();
  }

  mDocumentTable->Put(aDocumentInfo->DocumentURI(), aDocumentInfo);

  return NS_OK;
}

void
nsBindingManager::RemoveXBLDocumentInfo(nsXBLDocumentInfo* aDocumentInfo)
{
  if (mDocumentTable) {
    mDocumentTable->Remove(aDocumentInfo->DocumentURI());
  }
}

nsXBLDocumentInfo*
nsBindingManager::GetXBLDocumentInfo(nsIURI* aURL)
{
  if (!mDocumentTable)
    return nullptr;

  return mDocumentTable->GetWeak(aURL);
}

nsresult
nsBindingManager::PutLoadingDocListener(nsIURI* aURL, nsIStreamListener* aListener)
{
  NS_PRECONDITION(aListener, "Must have a non-null listener!");

  if (!mLoadingDocTable) {
    mLoadingDocTable =
      new nsInterfaceHashtable<nsURIHashKey,nsIStreamListener>();
  }
  mLoadingDocTable->Put(aURL, aListener);

  return NS_OK;
}

nsIStreamListener*
nsBindingManager::GetLoadingDocListener(nsIURI* aURL)
{
  if (!mLoadingDocTable)
    return nullptr;

  return mLoadingDocTable->GetWeak(aURL);
}

void
nsBindingManager::RemoveLoadingDocListener(nsIURI* aURL)
{
  if (mLoadingDocTable) {
    mLoadingDocTable->Remove(aURL);
  }
}

void
nsBindingManager::FlushSkinBindings()
{
  if (!mBoundContentSet) {
    return;
  }

  for (auto iter = mBoundContentSet->Iter(); !iter.Done(); iter.Next()) {
    nsXBLBinding* binding = iter.Get()->GetKey()->GetXBLBinding();

    if (binding->MarkedForDeath()) {
      continue;
    }

    nsAutoCString path;
    binding->PrototypeBinding()->DocURI()->GetPath(path);

    if (!strncmp(path.get(), "/skin", 5)) {
      binding->MarkForDeath();
    }
  }
}

// Used below to protect from recurring in QI calls through XPConnect.
struct AntiRecursionData {
  nsIContent* element;
  REFNSIID iid;
  AntiRecursionData* next;

  AntiRecursionData(nsIContent* aElement,
                    REFNSIID aIID,
                    AntiRecursionData* aNext)
    : element(aElement), iid(aIID), next(aNext) {}
};

nsresult
nsBindingManager::GetBindingImplementation(nsIContent* aContent, REFNSIID aIID,
                                           void** aResult)
{
  *aResult = nullptr;
  nsXBLBinding *binding = aContent ? aContent->GetXBLBinding() : nullptr;
  if (binding) {
    // The binding should not be asked for nsISupports
    NS_ASSERTION(!aIID.Equals(NS_GET_IID(nsISupports)), "Asking a binding for nsISupports");
    if (binding->ImplementsInterface(aIID)) {
      nsCOMPtr<nsIXPConnectWrappedJS> wrappedJS = GetWrappedJS(aContent);

      if (wrappedJS) {
        // Protect from recurring in QI calls through XPConnect.
        // This can happen when a second binding is being resolved.
        // At that point a wrappedJS exists, but it doesn't yet know about
        // the iid we are asking for. So, without this protection,
        // AggregatedQueryInterface would end up recurring back into itself
        // through this code.
        //
        // With this protection, when we detect the recursion we return
        // NS_NOINTERFACE in the inner call. The outer call will then fall
        // through (see below) and build a new chained wrappedJS for the iid.
        //
        // We're careful to not assume that only one direct nesting can occur
        // because there is a call into JS in the middle and we can't assume
        // that this code won't be reached by some more complex nesting path.
        //
        // NOTE: We *assume* this is single threaded, so we can use a
        // static linked list to do the check.

        static AntiRecursionData* list = nullptr;

        for (AntiRecursionData* p = list; p; p = p->next) {
          if (p->element == aContent && p->iid.Equals(aIID)) {
            *aResult = nullptr;
            return NS_NOINTERFACE;
          }
        }

        AntiRecursionData item(aContent, aIID, list);
        list = &item;

        nsresult rv = wrappedJS->AggregatedQueryInterface(aIID, aResult);

        list = item.next;

        if (*aResult)
          return rv;

        // No result was found, so this must be another XBL interface.
        // Fall through to create a new wrapper.
      }

      // We have never made a wrapper for this implementation.
      // Create an XPC wrapper for the script object and hand it back.
      AutoJSAPI jsapi;
      jsapi.Init();
      JSContext* cx = jsapi.cx();

      nsIXPConnect *xpConnect = nsContentUtils::XPConnect();

      JS::Rooted<JSObject*> jsobj(cx, aContent->GetWrapper());
      NS_ENSURE_TRUE(jsobj, NS_NOINTERFACE);

      // If we're using an XBL scope, we need to use the Xray view to the bound
      // content in order to view the full array of methods defined in the
      // binding, some of which may not be exposed on the prototype of
      // untrusted content. We don't need to consider add-on scopes here
      // because they're chrome-only and no Xrays are involved.
      //
      // If there's no separate XBL scope, or if the reflector itself lives in
      // the XBL scope, we'll end up with the global of the reflector.
      JS::Rooted<JSObject*> xblScope(cx, xpc::GetXBLScopeOrGlobal(cx, jsobj));
      NS_ENSURE_TRUE(xblScope, NS_ERROR_UNEXPECTED);
      JSAutoCompartment ac(cx, xblScope);
      bool ok = JS_WrapObject(cx, &jsobj);
      NS_ENSURE_TRUE(ok, NS_ERROR_OUT_OF_MEMORY);
      MOZ_ASSERT_IF(js::IsWrapper(jsobj), xpc::IsXrayWrapper(jsobj));

      nsresult rv = xpConnect->WrapJSAggregatedToNative(aContent, cx,
                                                        jsobj, aIID, aResult);
      if (NS_FAILED(rv))
        return rv;

      // We successfully created a wrapper.  We will own this wrapper for as long as the binding remains
      // alive.  At the time the binding is cleared out of the bindingManager, we will remove the wrapper
      // from the bindingManager as well.
      nsISupports* supp = static_cast<nsISupports*>(*aResult);
      wrappedJS = do_QueryInterface(supp);
      SetWrappedJS(aContent, wrappedJS);

      return rv;
    }
  }

  *aResult = nullptr;
  return NS_NOINTERFACE;
}

nsresult
nsBindingManager::WalkRules(nsIStyleRuleProcessor::EnumFunc aFunc,
                            ElementDependentRuleProcessorData* aData,
                            bool* aCutOffInheritance)
{
  *aCutOffInheritance = false;

  NS_ASSERTION(aData->mElement, "How did that happen?");

  // Walk the rules in shadow root for :host pseudo-class rules.
  aData->mTreeMatchContext.mOnlyMatchHostPseudo = true;
  aData->mElementIsFeatureless = true;

  ShadowRoot* currentShadow = aData->mElement->GetShadowRoot();

  if (currentShadow) {
    nsXBLBinding* associatedBinding = currentShadow->GetAssociatedBinding();
    if (associatedBinding) {
      aData->mTreeMatchContext.mScopedRoot = aData->mElement;
      associatedBinding->WalkRules(aFunc, aData);
    }
  }

  aData->mElementIsFeatureless = false;
  aData->mTreeMatchContext.mOnlyMatchHostPseudo = false;

  // Walk the rules in shadow root for ::slotted() pseudo-element rules
  // if we have an assigned slot.
  if (aData->mElement->GetAssignedSlot()) {
    aData->mTreeMatchContext.mRestrictToSlottedPseudo = true;

    AutoTArray<nsXBLBinding*, 2> stack;
    bool foundTopmostScope = false;
    for (nsIContent* parent = aData->mElement->GetFlattenedTreeParent();
         parent;
         parent = parent->GetFlattenedTreeParent()) {
      ShadowRoot* currentShadow = parent->GetShadowRoot();
      if (!currentShadow) {
        continue;
      }

      nsXBLBinding* binding = currentShadow->GetAssociatedBinding();
      if (!binding) {
        continue;
      }
      stack.AppendElement(binding);

      if (!foundTopmostScope) {
        aData->mTreeMatchContext.mScopedRoot = parent;
        foundTopmostScope = true;
      }
    }

    while (!stack.IsEmpty()) {
      uint32_t index = stack.Length() - 1;
      nsXBLBinding* binding = stack.ElementAt(index);
      stack.RemoveElementAt(index);

      aData->mTreeMatchContext.mForAssignedSlot = true;
      aData->mTreeMatchContext.mIsTopmostScope = (index == 0);
      binding->WalkRules(aFunc, aData);
    }

    aData->mTreeMatchContext.mForAssignedSlot = false;
    aData->mTreeMatchContext.mIsTopmostScope = false;
    aData->mTreeMatchContext.mRestrictToSlottedPseudo = false;
  }

  // Walk the binding scope chain, starting with the binding attached to our
  // content, up till we run out of scopes or we get cut off.
  nsIContent *content = aData->mElement;

  do {
    nsXBLBinding *binding = content->GetXBLBinding();
    if (binding &&
         // Unlike XBL, styles in the shadow root are not applied to the host.
	!(content == aData->mElement && binding->IsShadowRootBinding())) {
      aData->mTreeMatchContext.mScopedRoot = content;
      binding->WalkRules(aFunc, aData);
      // If we're not looking at our original content, allow the binding to cut
      // off style inheritance
      if (content != aData->mElement) {
        if (!binding->InheritsStyle()) {
          // Go no further; we're not inheriting style from anything above here
          break;
        }
      }
    }

    if (content->IsRootOfNativeAnonymousSubtree()) {
      break; // Deliberately cut off style inheritance here.
    }

    content = content->GetBindingParent();
  } while (content);

  // If "content" is non-null that means we cut off inheritance at some point
  // in the loop.
  *aCutOffInheritance = (content != nullptr);

  // Null out the scoped root that we set repeatedly
  aData->mTreeMatchContext.mScopedRoot = nullptr;

  return NS_OK;
}

typedef nsTHashtable<nsPtrHashKey<nsIStyleRuleProcessor> > RuleProcessorSet;

static RuleProcessorSet*
GetContentSetRuleProcessors(nsTHashtable<nsRefPtrHashKey<nsIContent>>* aContentSet, bool aOnlyWalkShadowRootRules)
{
  RuleProcessorSet* set = nullptr;

  for (auto iter = aContentSet->Iter(); !iter.Done(); iter.Next()) {
    nsIContent* boundContent = iter.Get()->GetKey();

  // If we are only walking rules for shadow root hosts, skip other types
  // of bound content.
  ShadowRoot *shadowRoot = boundContent->GetShadowRoot();
  if (aOnlyWalkShadowRootRules && !shadowRoot) {
    return set;
  }

  // Bound content may have multiple rule processors, potentially one
  // for its immediate binding, and one more for each binding in the
  // inheritance chain. Additionally, a bound content may host multiple
  // shadow roots, each with its own rule processor.
  for (nsXBLBinding *binding = boundContent->GetXBLBinding(); binding;
       binding = binding->GetBaseBinding()) {
      nsIStyleRuleProcessor* ruleProc =
        binding->PrototypeBinding()->GetRuleProcessor();
      if (ruleProc) {
        if (!set) {
          set = new RuleProcessorSet;
        }
        set->PutEntry(ruleProc);
      }

      if (shadowRoot) {
        binding = shadowRoot->GetAssociatedBinding();
        }
      }
    }

  return set;
}

void
nsBindingManager::WalkAllRules(nsIStyleRuleProcessor::EnumFunc aFunc,
                               ElementDependentRuleProcessorData* aData,
			       bool aOnlyWalkShadowRootRules)
{
  if (!mBoundContentSet) {
    return;
  }

  nsAutoPtr<RuleProcessorSet> set;
  set = GetContentSetRuleProcessors(mBoundContentSet, aOnlyWalkShadowRootRules);
  if (!set) {
    return;
  }

  for (auto iter = set->Iter(); !iter.Done(); iter.Next()) {
    nsIStyleRuleProcessor* ruleProcessor = iter.Get()->GetKey();
    (*(aFunc))(ruleProcessor, aData);
  }
}

// The approach in WalkAllShadowRootHostRules seems reasonable on the surface and reminds me of what is done with mScopedRoot elsewhere. But something important is missing, either here or in the code that would normally use it.

void
nsBindingManager::WalkAllShadowRootHostRules(nsIStyleRuleProcessor::EnumFunc aFunc,
                                         ElementDependentRuleProcessorData* aData)
 {
   aData->mTreeMatchContext.mOnlyMatchHostPseudo = true;
   WalkAllRules(aFunc, aData, true);
   aData->mTreeMatchContext.mOnlyMatchHostPseudo = false;
 }

nsresult
nsBindingManager::MediumFeaturesChanged(nsPresContext* aPresContext,
                                        bool* aRulesChanged)
{
  *aRulesChanged = false;
  if (!mBoundContentSet) {
    return NS_OK;
  }

  nsAutoPtr<RuleProcessorSet> set;
  set = GetContentSetRuleProcessors(mBoundContentSet, false);
  if (!set) {
    return NS_OK;
  }

  for (auto iter = set->Iter(); !iter.Done(); iter.Next()) {
    nsIStyleRuleProcessor* ruleProcessor = iter.Get()->GetKey();
    bool thisChanged = ruleProcessor->MediumFeaturesChanged(aPresContext);
    *aRulesChanged = *aRulesChanged || thisChanged;
  }

  return NS_OK;
}

void
nsBindingManager::AppendAllSheets(nsTArray<StyleSheet*>& aArray)
{
  if (!mBoundContentSet) {
    return;
  }

  for (auto iter = mBoundContentSet->Iter(); !iter.Done(); iter.Next()) {
    nsIContent* boundContent = iter.Get()->GetKey();
    for (nsXBLBinding* binding = boundContent->GetXBLBinding(); binding;
         binding = binding->GetBaseBinding()) {
      binding->PrototypeBinding()->AppendStyleSheetsTo(aArray);
    }
  }
}

static void
InsertAppendedContent(XBLChildrenElement* aPoint,
                      nsIContent* aFirstNewContent)
{
  int32_t insertionIndex;
  if (nsIContent* prevSibling = aFirstNewContent->GetPreviousSibling()) {
    // If we have a previous sibling, then it must already be in aPoint. Find
    // it and insert after it.
    insertionIndex = aPoint->IndexOfInsertedChild(prevSibling);
    MOZ_ASSERT(insertionIndex != -1);

    // Our insertion index is one after our previous sibling's index.
    ++insertionIndex;
  } else {
    // Otherwise, we append.
    // TODO This is wrong for nested insertion points. In that case, we need to
    // keep track of the right index to insert into.
    insertionIndex = aPoint->InsertedChildrenLength();
  }

  // Do the inserting.
  for (nsIContent* currentChild = aFirstNewContent;
       currentChild;
       currentChild = currentChild->GetNextSibling()) {
    aPoint->InsertInsertedChildAt(currentChild, insertionIndex++);
  }
}

void
nsBindingManager::ContentAppended(nsIDocument* aDocument,
                                  nsIContent* aContainer,
                                  nsIContent* aFirstNewContent,
                                  int32_t     aNewIndexInContainer)
{
  if (aNewIndexInContainer == -1) {
    return;
  }

  // Try to find insertion points for all the new kids.
  XBLChildrenElement* point = nullptr;
  nsIContent* parent = aContainer;

  // Handle appending of default content.
  if (parent && parent->IsActiveChildrenElement()) {
    XBLChildrenElement* childrenEl = static_cast<XBLChildrenElement*>(parent);
    if (childrenEl->HasInsertedChildren()) {
      // Appending default content that isn't being used. Ignore.
      return;
    }

    childrenEl->MaybeSetupDefaultContent();
    parent = childrenEl->GetParent();
  }

  bool first = true;
  do {
    nsXBLBinding* binding = GetBindingWithContent(parent);
    if (!binding) {
      break;
    }

    if (binding->HasFilteredInsertionPoints()) {
      // There are filtered insertion points involved, handle each child
      // separately.
      // We could optimize this in the case when we've nested a few levels
      // deep already, without hitting bindings that have filtered insertion
      // points.
      int32_t currentIndex = aNewIndexInContainer;
      for (nsIContent* currentChild = aFirstNewContent; currentChild;
           currentChild = currentChild->GetNextSibling()) {
        HandleChildInsertion(aContainer, currentChild,
                             currentIndex++, true);
      }

      return;
    }

    point = binding->GetDefaultInsertionPoint();
    if (!point) {
      break;
    }

    // Even though we're in ContentAppended, nested insertion points force us
    // to deal with this append as an insertion except in the outermost
    // binding.
    if (first) {
      first = false;
      for (nsIContent* child = aFirstNewContent; child;
           child = child->GetNextSibling()) {
        point->AppendInsertedChild(child);
      }
    } else {
      InsertAppendedContent(point, aFirstNewContent);
    }

    nsIContent* newParent = point->GetParent();
    if (newParent == parent) {
      break;
    }
    parent = newParent;
  } while (parent);
}

void
nsBindingManager::ContentInserted(nsIDocument* aDocument,
                                  nsIContent* aContainer,
                                  nsIContent* aChild,
                                  int32_t aIndexInContainer)
{
  if (aIndexInContainer == -1) {
    return;
  }

  HandleChildInsertion(aContainer, aChild, aIndexInContainer, false);
}

void
nsBindingManager::ContentRemoved(nsIDocument* aDocument,
                                 nsIContent* aContainer,
                                 nsIContent* aChild,
                                 int32_t aIndexInContainer,
                                 nsIContent* aPreviousSibling)
{
  aChild->SetXBLInsertionParent(nullptr);

  XBLChildrenElement* point = nullptr;
  nsIContent* parent = aContainer;

  // Handle appending of default content.
  if (parent && parent->IsActiveChildrenElement()) {
    XBLChildrenElement* childrenEl = static_cast<XBLChildrenElement*>(parent);
    if (childrenEl->HasInsertedChildren()) {
      // Removing default content that isn't being used. Ignore.
      return;
    }

    parent = childrenEl->GetParent();
  }

  do {
    nsXBLBinding* binding = GetBindingWithContent(parent);
    if (!binding) {
      // If aChild is XBL content, it might have <xbl:children> elements
      // somewhere under it. We need to inform those elements that they're no
      // longer in the tree so they can tell their distributed children that
      // they're no longer distributed under them.
      // XXX This is wrong. We need to do far more work to update the parent
      // binding's list of insertion points and to get the new insertion parent
      // for the newly-distributed children correct.
      if (aChild->GetBindingParent()) {
        ClearInsertionPointsRecursively(aChild);
      }
      return;
    }

    point = binding->FindInsertionPointFor(aChild);
    if (!point) {
      break;
    }

    point->RemoveInsertedChild(aChild);

    nsIContent* newParent = point->GetParent();
    if (newParent == parent) {
      break;
    }
    parent = newParent;
  } while (parent);
}

void
nsBindingManager::ClearInsertionPointsRecursively(nsIContent* aContent)
{
  if (aContent->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL)) {
    static_cast<XBLChildrenElement*>(aContent)->ClearInsertedChildren();
  }

  for (nsIContent* child = aContent->GetFirstChild(); child;
       child = child->GetNextSibling()) {
    ClearInsertionPointsRecursively(child);
  }
}

void
nsBindingManager::DropDocumentReference()
{
  mDestroyed = true;

  // Make sure to not run any more XBL constructors
  mProcessingAttachedStack = true;
  if (mProcessAttachedQueueEvent) {
    mProcessAttachedQueueEvent->Revoke();
  }

  if (mBoundContentSet) {
    mBoundContentSet->Clear();
  }

  mDocument = nullptr;
}

void
nsBindingManager::Traverse(nsIContent *aContent,
                           nsCycleCollectionTraversalCallback &cb)
{
  if (!aContent->HasFlag(NODE_MAY_BE_IN_BINDING_MNGR) ||
      !aContent->IsElement()) {
    // Don't traverse if content is not in this binding manager.
    // We also don't traverse non-elements because there should not
    // be bindings (checking the flag alone is not sufficient because
    // the flag is also set on children of insertion points that may be
    // non-elements).
    return;
  }

  if (mBoundContentSet && mBoundContentSet->Contains(aContent)) {
    NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "[via binding manager] mBoundContentSet entry");
    cb.NoteXPCOMChild(aContent);
  }

  nsIXPConnectWrappedJS *value = GetWrappedJS(aContent);
  if (value) {
    NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "[via binding manager] mWrapperTable key");
    cb.NoteXPCOMChild(aContent);
    NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "[via binding manager] mWrapperTable value");
    cb.NoteXPCOMChild(value);
  }
}

void
nsBindingManager::HandleChildInsertion(nsIContent* aContainer,
                                       nsIContent* aChild,
                                       uint32_t aIndexInContainer,
                                       bool aAppend)
{
  NS_PRECONDITION(aChild, "Must have child");
  NS_PRECONDITION(!aContainer ||
                  uint32_t(aContainer->IndexOf(aChild)) == aIndexInContainer,
                  "Child not at the right index?");

  XBLChildrenElement* point = nullptr;
  nsIContent* parent = aContainer;

  // Handle insertion of default content.
  if (parent && parent->IsActiveChildrenElement()) {
    XBLChildrenElement* childrenEl = static_cast<XBLChildrenElement*>(parent);
    if (childrenEl->HasInsertedChildren()) {
      // Inserting default content that isn't being used. Ignore.
      return;
    }

    childrenEl->MaybeSetupDefaultContent();
    parent = childrenEl->GetParent();
  }

  while (parent) {
    nsXBLBinding* binding = GetBindingWithContent(parent);
    if (!binding) {
      break;
    }

    point = binding->FindInsertionPointFor(aChild);
    if (!point) {
      break;
    }

    // Insert the child into the proper insertion point.
    // TODO If there were multiple insertion points, this approximation can be
    // wrong. We need to re-run the distribution algorithm. In the meantime,
    // this should work well enough.
    uint32_t index = aAppend ? point->InsertedChildrenLength() : 0;
    for (nsIContent* currentSibling = aChild->GetPreviousSibling();
         currentSibling;
         currentSibling = currentSibling->GetPreviousSibling()) {
      // If we find one of our previous siblings in the insertion point, the
      // index following it is the correct insertion point. Otherwise, we guess
      // based on whether we're appending or inserting.
      int32_t pointIndex = point->IndexOfInsertedChild(currentSibling);
      if (pointIndex != -1) {
        index = pointIndex + 1;
        break;
      }
    }

    point->InsertInsertedChildAt(aChild, index);

    nsIContent* newParent = point->GetParent();
    if (newParent == parent) {
      break;
    }

    parent = newParent;
  }
}


nsIContent*
nsBindingManager::FindNestedInsertionPoint(nsIContent* aContainer,
                                           nsIContent* aChild)
{
  NS_PRECONDITION(aChild->GetParent() == aContainer,
                  "Wrong container");

  nsIContent* parent = aContainer;
  if (aContainer->IsActiveChildrenElement()) {
    if (static_cast<XBLChildrenElement*>(aContainer)->
          HasInsertedChildren()) {
      return nullptr;
    }
    parent = aContainer->GetParent();
  }

  while (parent) {
    nsXBLBinding* binding = GetBindingWithContent(parent);
    if (!binding) {
      break;
    }

    XBLChildrenElement* point = binding->FindInsertionPointFor(aChild);
    if (!point) {
      return nullptr;
    }

    nsIContent* newParent = point->GetParent();
    if (newParent == parent) {
      break;
    }
    parent = newParent;
  }

  return parent;
}

nsIContent*
nsBindingManager::FindNestedSingleInsertionPoint(nsIContent* aContainer,
                                                 bool* aMulti)
{
  *aMulti = false;

  nsIContent* parent = aContainer;
  if (aContainer->IsActiveChildrenElement()) {
    if (static_cast<XBLChildrenElement*>(aContainer)->
          HasInsertedChildren()) {
      return nullptr;
    }
    parent = aContainer->GetParent();
  }

  while(parent) {
    nsXBLBinding* binding = GetBindingWithContent(parent);
    if (!binding) {
      break;
    }

    if (binding->HasFilteredInsertionPoints()) {
      *aMulti = true;
      return nullptr;
    }

    XBLChildrenElement* point = binding->GetDefaultInsertionPoint();
    if (!point) {
      return nullptr;
    }

    nsIContent* newParent = point->GetParent();
    if (newParent == parent) {
      break;
    }
    parent = newParent;
  }

  return parent;
}