/**
 * This is called when we receive a drop or a dragover.
 */
NS_IMETHODIMP
nsFileControlFrame::DnDListener::HandleEvent(nsIDOMEvent* aEvent)
{
  NS_ASSERTION(mFrame, "We should have been unregistered");

  bool defaultPrevented = false;
  aEvent->GetDefaultPrevented(&defaultPrevented);
  if (defaultPrevented) {
    return NS_OK;
  }

  nsCOMPtr<nsIDOMDragEvent> dragEvent = do_QueryInterface(aEvent);
  if (!dragEvent) {
    return NS_OK;
  }

  nsCOMPtr<nsIDOMDataTransfer> dataTransfer;
  dragEvent->GetDataTransfer(getter_AddRefs(dataTransfer));
  if (!IsValidDropData(dataTransfer)) {
    return NS_OK;
  }


  nsCOMPtr<nsIContent> content = mFrame->GetContent();
  bool supportsMultiple = content && content->HasAttr(kNameSpaceID_None, nsGkAtoms::multiple);
  if (!CanDropTheseFiles(dataTransfer, supportsMultiple)) {
    dataTransfer->SetDropEffect(NS_LITERAL_STRING("none"));
    aEvent->StopPropagation();
    return NS_OK;
  }

  nsAutoString eventType;
  aEvent->GetType(eventType);
  if (eventType.EqualsLiteral("dragover")) {
    // Prevent default if we can accept this drag data
    aEvent->PreventDefault();
    return NS_OK;
  }

  if (eventType.EqualsLiteral("drop")) {
    aEvent->StopPropagation();
    aEvent->PreventDefault();

    NS_ASSERTION(content, "The frame has no content???");

    HTMLInputElement* inputElement = HTMLInputElement::FromContent(content);
    NS_ASSERTION(inputElement, "No input element for this file upload control frame!");

    nsCOMPtr<nsIDOMFileList> fileList;
    dataTransfer->GetFiles(getter_AddRefs(fileList));

    RefPtr<BlobImpl> webkitDir;
    nsresult rv =
      GetBlobImplForWebkitDirectory(fileList, getter_AddRefs(webkitDir));
    NS_ENSURE_SUCCESS(rv, NS_OK);

    nsTArray<OwningFileOrDirectory> array;
    if (webkitDir) {
      AppendBlobImplAsDirectory(array, webkitDir, content);
      inputElement->MozSetDndFilesAndDirectories(array);
    } else {
      bool blinkFileSystemEnabled =
        Preferences::GetBool("dom.webkitBlink.filesystem.enabled", false);
      if (blinkFileSystemEnabled) {
        FileList* files = static_cast<FileList*>(fileList.get());
        if (files) {
          for (uint32_t i = 0; i < files->Length(); ++i) {
            File* file = files->Item(i);
            if (file) {
              if (file->Impl() && file->Impl()->IsDirectory()) {
                AppendBlobImplAsDirectory(array, file->Impl(), content);
              } else {
                OwningFileOrDirectory* element = array.AppendElement();
                element->SetAsFile() = file;
              }
            }
          }
        }
      }

      // This is rather ugly. Pass the directories as Files using SetFiles,
      // but then if blink filesystem API is enabled, it wants
      // FileOrDirectory array.
      inputElement->SetFiles(fileList, true);
      if (blinkFileSystemEnabled) {
        inputElement->UpdateEntries(array);
      }
      nsContentUtils::DispatchTrustedEvent(content->OwnerDoc(), content,
                                           NS_LITERAL_STRING("input"), true,
                                           false);
      nsContentUtils::DispatchTrustedEvent(content->OwnerDoc(), content,
                                           NS_LITERAL_STRING("change"), true,
                                           false);
    }
  }

  return NS_OK;
}