/* -*- 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 "IDTracker.h"

#include "mozilla/Encoding.h"

#include "nsContentUtils.h"

#include "nsIURI.h"

#include "nsBindingManager.h"

#include "nsEscape.h"

#include "nsXBLPrototypeBinding.h"

#include "nsCycleCollectionParticipant.h"

namespace mozilla {

namespace dom {

static DocumentOrShadowRoot*

DocOrShadowFromContent(nsIContent& aContent)

{

  ShadowRoot* shadow = aContent.GetContainingShadow();

  // We never look in <svg:use> shadow trees, for backwards compat.

  while (shadow && shadow->Host()->IsSVGElement(nsGkAtoms::use)) {

    shadow = shadow->Host()->GetContainingShadow();

  }

  if (shadow) {

    return shadow;

  }

  return aContent.OwnerDoc();

}

void

IDTracker::Reset(nsIContent* aFromContent, nsIURI* aURI,nsIURI* aReferrer,

                 uint32_t aReferrerPolicy,

                 bool aWatch, bool aReferenceImage)

{

  MOZ_ASSERT(aFromContent, "Reset() expects non-null content pointer");

  Unlink();

  if (!aURI)

    return;

  nsAutoCString refPart;

  aURI->GetRef(refPart);

  // Unescape %-escapes in the reference. The result will be in the

  // document charset, hopefully...

  NS_UnescapeURL(refPart);

  // Get the thing to observe changes to.

  nsIDocument* doc = aFromContent->OwnerDoc();

  DocumentOrShadowRoot* docOrShadow = DocOrShadowFromContent(*aFromContent);

  auto encoding = doc->GetDocumentCharacterSet();

  nsAutoString ref;

  nsresult rv = encoding->DecodeWithoutBOMHandling(refPart, ref);

  if (NS_FAILED(rv) || ref.IsEmpty()) {

    return;

  }

  rv = NS_OK;

  nsIContent* bindingParent = aFromContent->GetBindingParent();

  if (bindingParent && !aFromContent->IsInShadowTree()) {

    nsXBLBinding* binding = bindingParent->GetXBLBinding();

    if (!binding) {

      // This happens, for example, if aFromContent is part of the content

      // inserted by a call to nsIDocument::InsertAnonymousContent, which we

      // also want to handle.  (It also happens for <use>'s anonymous

      // content etc.)

      Element* anonRoot =

        doc->GetAnonRootIfInAnonymousContentContainer(aFromContent);

      if (anonRoot) {

        mElement = nsContentUtils::MatchElementId(anonRoot, ref);

        // We don't have watching working yet for anonymous content, so bail out here.

        return;

      }

    } else {

      bool isEqualExceptRef;

      rv = aURI->EqualsExceptRef(binding->PrototypeBinding()->DocURI(),

                                 &isEqualExceptRef);

      if (NS_SUCCEEDED(rv) && isEqualExceptRef) {

        // XXX sXBL/XBL2 issue

        // Our content is an anonymous XBL element from a binding inside the

        // same document that the referenced URI points to. In order to avoid

        // the risk of ID collisions we restrict ourselves to anonymous

        // elements from this binding; specifically, URIs that are relative to

        // the binding document should resolve to the copy of the target

        // element that has been inserted into the bound document.

        // If the URI points to a different document we don't need this

        // restriction.

        nsINodeList* anonymousChildren =

          doc->BindingManager()->GetAnonymousNodesFor(bindingParent);

        if (anonymousChildren) {

          uint32_t length = anonymousChildren->Length();

          for (uint32_t i = 0; i < length && !mElement; ++i) {

            mElement =

              nsContentUtils::MatchElementId(anonymousChildren->Item(i), ref);

          }

        }

        // We don't have watching working yet for XBL, so bail out here.

        return;

      }

    }

  }

  bool isEqualExceptRef;

  rv = aURI->EqualsExceptRef(doc->GetDocumentURI(), &isEqualExceptRef);

  if (NS_FAILED(rv) || !isEqualExceptRef) {

    RefPtr<nsIDocument::ExternalResourceLoad> load;

    doc = doc->RequestExternalResource(aURI, aReferrer, aReferrerPolicy,

                                       aFromContent, getter_AddRefs(load));

    docOrShadow = doc;

    if (!doc) {

      if (!load || !aWatch) {

        // Nothing will ever happen here

        return;

      }

      DocumentLoadNotification* observer =

        new DocumentLoadNotification(this, ref);

      mPendingNotification = observer;

      load->AddObserver(observer);

      // Keep going so we set up our watching stuff a bit

    }

  }

  if (aWatch) {

    mWatchID = NS_Atomize(ref);

  }

  mReferencingImage = aReferenceImage;

  HaveNewDocumentOrShadowRoot(docOrShadow, aWatch, ref);

}

void

IDTracker::ResetWithID(Element& aFrom, nsAtom* aID, bool aWatch)

{

  MOZ_ASSERT(aID);

  if (aWatch) {

    mWatchID = aID;

  }

  mReferencingImage = false;

  DocumentOrShadowRoot* docOrShadow = DocOrShadowFromContent(aFrom);

  HaveNewDocumentOrShadowRoot(docOrShadow, aWatch, nsDependentAtomString(aID));

}

void

IDTracker::HaveNewDocumentOrShadowRoot(

  DocumentOrShadowRoot* aDocOrShadow,

  bool aWatch,

  const nsString& aRef)

{

  if (aWatch) {

    mWatchDocumentOrShadowRoot = nullptr;

    if (aDocOrShadow) {

      mWatchDocumentOrShadowRoot = &aDocOrShadow->AsNode();

      mElement = aDocOrShadow->AddIDTargetObserver(mWatchID, Observe, this, mReferencingImage);

    }

    return;

  }

  if (!aDocOrShadow) {

    return;

  }

  Element* e = mReferencingImage ? aDocOrShadow->LookupImageElement(aRef)

                                 : aDocOrShadow->GetElementById(aRef);

  if (e) {

    mElement = e;

  }

}

void

IDTracker::Traverse(nsCycleCollectionTraversalCallback* aCB)

{

  NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(*aCB, "mWatchDocumentOrShadowRoot");

  aCB->NoteXPCOMChild(mWatchDocumentOrShadowRoot);

  NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(*aCB, "mElement");

  aCB->NoteXPCOMChild(mElement);

}

void

IDTracker::Unlink()

{

  if (mWatchID) {

    if (DocumentOrShadowRoot* docOrShadow = GetWatchDocOrShadowRoot()) {

      docOrShadow->RemoveIDTargetObserver(

        mWatchID, Observe, this, mReferencingImage);

    }

  }

  if (mPendingNotification) {

    mPendingNotification->Clear();

    mPendingNotification = nullptr;

  }

  mWatchDocumentOrShadowRoot = nullptr;

  mWatchID = nullptr;

  mElement = nullptr;

  mReferencingImage = false;

}

bool

IDTracker::Observe(Element* aOldElement, Element* aNewElement, void* aData)

{

  IDTracker* p = static_cast<IDTracker*>(aData);

  if (p->mPendingNotification) {

    p->mPendingNotification->SetTo(aNewElement);

  } else {

    NS_ASSERTION(aOldElement == p->mElement, "Failed to track content!");

    ChangeNotification* watcher =

      new ChangeNotification(p, aOldElement, aNewElement);

    p->mPendingNotification = watcher;

    nsContentUtils::AddScriptRunner(watcher);

  }

  bool keepTracking = p->IsPersistent();

  if (!keepTracking) {

    p->mWatchDocumentOrShadowRoot = nullptr;

    p->mWatchID = nullptr;

  }

  return keepTracking;

}

NS_IMPL_ISUPPORTS_INHERITED0(IDTracker::ChangeNotification, mozilla::Runnable)

NS_IMPL_ISUPPORTS(IDTracker::DocumentLoadNotification, nsIObserver)

NS_IMETHODIMP

IDTracker::DocumentLoadNotification::Observe(nsISupports* aSubject,

                                             const char* aTopic,

                                             const char16_t* aData)

{

  NS_ASSERTION(PL_strcmp(aTopic, "external-resource-document-created") == 0,

               "Unexpected topic");

  if (mTarget) {

    nsCOMPtr<nsIDocument> doc = do_QueryInterface(aSubject);

    mTarget->mPendingNotification = nullptr;

    NS_ASSERTION(!mTarget->mElement, "Why do we have content here?");

    // If we got here, that means we had Reset() called with aWatch ==

    // true.  So keep watching if IsPersistent().

    mTarget->HaveNewDocumentOrShadowRoot(doc, mTarget->IsPersistent(), mRef);

    mTarget->ElementChanged(nullptr, mTarget->mElement);

  }

  return NS_OK;

}

} // namespace dom

} // namespace mozilla