menu

class AYONMenu(object):
    """Object representing AYON menu.

    """

    def __init__(self):
        super().__init__()
        self.main_widget = self.get_main_widget()
        self.menu = None

        timer = QtCore.QTimer()
        # set number of event loops to wait.
        timer.setInterval(1)
        timer.timeout.connect(self._on_timer)
        timer.start()

        self._timer = timer
        self._counter = 0

    def _on_timer(self):
        if self._counter < 1:
            self._counter += 1
            return

        self._counter = 0
        self._timer.stop()
        self._build_ayon_menu()

    @staticmethod
    def get_main_widget():
        """Get motion builder main window."""
        top_widgets = QtWidgets.QApplication.topLevelWidgets()
        for widget in top_widgets:
            if widget.inherits("QMainWindow"):
                return widget
        raise RuntimeError('Cannot find motion builder main window.')

    def get_main_menubar(self) -> QtWidgets.QMenuBar:
        """Get main Menubar by motion builder main window."""
        return list(self.main_widget.findChildren(QtWidgets.QMenuBar))[0]

    def _get_or_create_ayon_menu(
            self, name: str = "&AYON",
            before: str = "&Help") -> QtWidgets.QAction:
        """Create AYON menu.

        Args:
            name (str, Optional): AYON menu name.
            before (str, Optional): Name of the motion builder main menu
                item to add AYON menu before.

        Returns:
            QtWidgets.QAction: AYON menu action.

        """
        if self.menu is not None:
            return self.menu

        menu_bar = self.get_main_menubar()
        menu_items = menu_bar.findChildren(
            QtWidgets.QMenu, options=QtCore.Qt.FindDirectChildrenOnly)
        help_action = None
        for item in menu_items:
            if name in item.title():
                # we already have AYON menu
                return item

            if before in item.title():
                help_action = item.menuAction()
        tab_menu_label = os.environ.get("AYON_MENU_LABEL") or "AYON"
        op_menu = QtWidgets.QMenu("&{}".format(tab_menu_label))
        menu_bar.insertMenu(help_action, op_menu)

        self.menu = op_menu
        return op_menu

    def _build_ayon_menu(self) -> QtWidgets.QAction:
        """Build items in AYON menu."""
        ayon_menu = self._get_or_create_ayon_menu()
        load_action = QtWidgets.QAction("Load...", ayon_menu)
        load_action.triggered.connect(self.load_callback)
        ayon_menu.addAction(load_action)

        publish_action = QtWidgets.QAction("Publish...", ayon_menu)
        publish_action.triggered.connect(self.publish_callback)
        ayon_menu.addAction(publish_action)

        manage_action = QtWidgets.QAction("Manage...", ayon_menu)
        manage_action.triggered.connect(self.manage_callback)
        ayon_menu.addAction(manage_action)

        library_action = QtWidgets.QAction("Library...", ayon_menu)
        library_action.triggered.connect(self.library_callback)
        ayon_menu.addAction(library_action)

        ayon_menu.addSeparator()
        ayon_menu = self._get_or_create_ayon_menu()
        workfiles_action = QtWidgets.QAction("Work Files...", ayon_menu)
        workfiles_action.triggered.connect(self.workfiles_callback)
        ayon_menu.addAction(workfiles_action)

    def load_callback(self):
        """Callback to show Loader tool."""
        host_tools.show_loader(parent=self.main_widget)

    def publish_callback(self):
        """Callback to show Publisher tool."""
        host_tools.show_publisher(parent=self.main_widget)

    def manage_callback(self):
        """Callback to show Scene Manager/Inventory tool."""
        host_tools.show_scene_inventory(parent=self.main_widget)

    def library_callback(self):
        """Callback to show Library Loader tool."""
        host_tools.show_library_loader(parent=self.main_widget)

    def workfiles_callback(self):
        """Callback to show Workfiles tool."""
        host_tools.show_workfiles(parent=self.main_widget)