""" The 'View' menu """


# Standard library imports.
import logging

# Enthought library imports.
from pyface.action.api import Group, MenuManager
from traits.api import Any, Bool, Instance, List, Str, Unicode
from traits.api import on_trait_change

# Local imports.
from .perspective_menu_manager import PerspectiveMenuManager
from .show_view_action import ShowViewAction
from .toggle_view_visibility_action import ToggleViewVisibilityAction


# Logging.
logger = logging.getLogger(__name__)


class ViewMenuManager(MenuManager):
    """ The 'View' menu.

    By default, this menu is displayed on the main menu bar.

    """

    #### 'ActionManager' interface ############################################

    # All of the groups in the manager.
    groups = List(Group)

    # The manager's unique identifier (if it has one).
    id = Str('View')

    #### 'MenuManager' interface ##############################################

    # The menu manager's name (if the manager is a sub-menu, this is what its
    # label will be).
    name = Unicode('&View')

    #### 'ViewMenuManager' interface ##########################################

    # Should the perspective menu be shown?
    show_perspective_menu = Bool(True)

    # The workbench window that the menu is part of.
    window = Instance('pyface.workbench.api.WorkbenchWindow')

    #### 'Private' interface ##################################################

    # The group containing the view hide/show actions.
    _view_group = Any

    ###########################################################################
    # 'ActionManager' interface.
    ###########################################################################

    def _groups_default(self):
        """ Trait initializer. """

        groups = []

        # Add a group containing the perspective menu (if requested).
        if self.show_perspective_menu and len(self.window.perspectives) > 0:
            groups.append(Group(PerspectiveMenuManager(window=self.window)))

        # Add a group containing a 'toggler' for all visible views.
        self._view_group = self._create_view_group(self.window)
        groups.append(self._view_group)

        # Add a group containing an 'Other...' item that will launch a dialog
        # to allow the user to choose a view to show.
        groups.append(self._create_other_group(self.window))

        return groups

    ###########################################################################
    # 'ViewMenuManager' interface.
    ###########################################################################

    @on_trait_change(
        'window.active_perspective,window.active_part,'
        'window.views,window.views_items'
    )
    def refresh(self):
        """ Refreshes the checked state of the actions in the menu. """

        logger.debug('refreshing view menu')

        if self._view_group is not None:
            self._clear_group(self._view_group)
            self._initialize_view_group(self.window, self._view_group)
            self.changed = True

        return

    ###########################################################################
    # Private interface.
    ###########################################################################

    def _clear_group(self, group):
        """ Remove all items in a group. """

        # fixme: Fix this API in PyFace so there is only one call!
        group.destroy()
        group.clear()

        return

    def _create_other_group(self, window):
        """ Creates a group containing the 'Other...' action. """

        group = Group()
        group.append(ShowViewAction(name='Other...', window=window))

        return group

    def _create_view_group(self, window):
        """ Creates a group containing the view 'togglers'. """

        group = Group()
        self._initialize_view_group(window, group)

        return group

    def _initialize_view_group(self, window, group):
        """ Initializes a group containing the view 'togglers'. """

        views = window.views[:]
        views.sort(key=lambda view: view.name)

        for view in views:
            # fixme: It seems a little smelly to be reaching in to the window
            # layout here. Should the 'contains_view' method be part of the
            # window interface?
            if window.layout.contains_view(view):
                group.append(
                    ToggleViewVisibilityAction(view=view, window=window)
                )

        return

#### EOF ######################################################################
