# Orca
#
# Copyright 2023 The Orca Team
# Author: Rynhardt Kruger <rynkruger@gmail.com>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the
# Free Software Foundation, Inc., Franklin Street, Fifth Floor,
# Boston MA  02110-1301 USA.

"""Provides ability to navigate objects hierarchically."""

__id__        = "$Id$"
__version__   = "$Revision$"
__date__      = "$Date$"
__copyright__ = "Copyright (c) 2023 The Orca Team"
__license__   = "LGPL"

from . import cmdnames
from . import debug
from . import input_event
from . import keybindings
from . import messages
from . import orca
from . import orca_state
from .ax_event_synthesizer import AXEventSynthesizer
from .ax_object import AXObject
from .ax_utilities import AXUtilities


class ObjectNavigator:
    """Provides ability to navigate objects hierarchically."""

    def __init__(self):
        self._navigator_focus = None
        self._last_navigator_focus = None
        self._last_locus_of_focus = None
        self._simplify = True
        self._handlers = self._setup_handlers()
        self._bindings = self._setup_bindings()

    def get_bindings(self):
        """Returns the object-navigator keybindings."""

        return self._bindings

    def get_handlers(self):
        """Returns the object-navigator handlers."""

        return self._handlers

    def _setup_bindings(self):
        """Sets up and returns the object-navigator key bindings."""

        bindings = keybindings.KeyBindings()

        bindings.add(
            keybindings.KeyBinding(
                "Up",
                keybindings.defaultModifierMask,
                keybindings.ORCA_CTRL_MODIFIER_MASK,
                self._handlers.get("object_navigator_up")))

        bindings.add(
            keybindings.KeyBinding(
                "Down",
                keybindings.defaultModifierMask,
                keybindings.ORCA_CTRL_MODIFIER_MASK,
                self._handlers.get("object_navigator_down")))

        bindings.add(
            keybindings.KeyBinding(
                "Right",
                keybindings.defaultModifierMask,
                keybindings.ORCA_CTRL_MODIFIER_MASK,
                self._handlers.get("object_navigator_next")))

        bindings.add(
            keybindings.KeyBinding(
                "Left",
                keybindings.defaultModifierMask,
                keybindings.ORCA_CTRL_MODIFIER_MASK,
                self._handlers.get("object_navigator_previous")))

        bindings.add(
            keybindings.KeyBinding(
                "Return",
                keybindings.defaultModifierMask,
                keybindings.ORCA_CTRL_MODIFIER_MASK,
                self._handlers.get("object_navigator_perform_action")))

        bindings.add(
            keybindings.KeyBinding(
                "s",
                keybindings.defaultModifierMask,
                keybindings.ORCA_CTRL_MODIFIER_MASK,
                self._handlers.get("object_navigator_toggle_simplify")))

        return bindings

    def _setup_handlers(self):
        """Sets up and returns the object-navigator input event handlers."""

        handlers = {}

        handlers["object_navigator_up"] = \
            input_event.InputEventHandler(
                self.up,
                cmdnames.NAVIGATOR_UP)

        handlers["object_navigator_down"] = \
            input_event.InputEventHandler(
                self.down,
                cmdnames.NAVIGATOR_DOWN)

        handlers["object_navigator_next"] = \
            input_event.InputEventHandler(
                self.next,
                cmdnames.NAVIGATOR_NEXT)

        handlers["object_navigator_previous"] = \
            input_event.InputEventHandler(
                self.previous,
                cmdnames.NAVIGATOR_PREVIOUS)

        handlers["object_navigator_perform_action"] = \
            input_event.InputEventHandler(
                self.perform_action,
                cmdnames.NAVIGATOR_PERFORM_ACTION)

        handlers["object_navigator_toggle_simplify"] = \
            input_event.InputEventHandler(
                self.toggle_simplify,
                cmdnames.NAVIGATOR_TOGGLE_SIMPLIFIED)

        return handlers

    def _include_in_simple_navigation(self, obj):
        """Returns True if obj should be included in simple navigation."""

        return AXUtilities.is_paragraph(obj)

    def _exclude_from_simple_navigation(self, script, obj):
        """Returns True if obj should be excluded from simple navigation."""

        if self._include_in_simple_navigation(obj):
            tokens = ["OBJECT NAVIGATOR: Not excluding", obj, ": explicit inclusion"]
            debug.printTokens(debug.LEVEL_INFO, tokens, True)
            return False

        # isLayoutOnly should catch things that really should be skipped.
        #
        # You do not want to exclude all sections because they may be focusable, e.g.
        # <div tabindex=0>foo</div> should not be excluded, despite the poor authoring.
        #
        # You do not want to exclude table cells and headers because it will make the
        # selectable items in tables non-navigable (e.g. the mail folders in Evolution)
        if script.utilities.isLayoutOnly(obj):
            tokens = ["OBJECT NAVIGATOR: Excluding", obj, ": is layout only"]
            debug.printTokens(debug.LEVEL_INFO, tokens, True)
            return True

        tokens = ["OBJECT NAVIGATOR: Not excluding", obj]
        debug.printTokens(debug.LEVEL_INFO, tokens, True)
        return False

    def _children(self, script, obj):
        """Returns a list of children for obj, taking simple navigation into account."""

        if not AXObject.get_child_count(obj):
            return []

        children = list(AXObject.iter_children(obj))
        if not self._simplify:
            return children

        # Add the children of excluded objects to our list of children.
        functional_children = []
        for child in children:
            if self._exclude_from_simple_navigation(script, child):
                functional_children.extend(self._children(script, child))
            else:
                functional_children.append(child)

        return functional_children

    def _parent(self, script, obj):
        """Returns the parent for obj, taking simple navigation into account."""

        parent = AXObject.get_parent(obj)
        if not self._simplify:
            return parent

        # The first non-excluded ancestor is the functional parent.
        while parent is not None and self._exclude_from_simple_navigation(script, parent):
            parent = AXObject.get_parent(parent)

        return parent

    def _set_navigator_focus(self, obj):
        """Changes the navigator focus, storing the previous focus."""

        self._last_navigator_focus = self._navigator_focus
        self._navigator_focus = obj

    def update(self):
        """Updates the navigator focus to Orca's object of interest."""

        mode, region = orca.getActiveModeAndObjectOfInterest()
        obj = region or orca_state.locusOfFocus
        if self._last_locus_of_focus == obj or (region is None and mode == orca.FLAT_REVIEW):
            return

        self._navigator_focus = obj
        self._last_locus_of_focus = obj

    def present(self, script):
        """Presents the current navigator focus to the user."""

        tokens = ["OBJECT NAVIGATOR: Presenting", self._navigator_focus]
        debug.printTokens(debug.LEVEL_INFO, tokens, True)
        orca.emitRegionChanged(self._navigator_focus, mode=orca.OBJECT_NAVIGATOR)
        script.presentObject(self._navigator_focus, priorObj=self._last_navigator_focus)

    def up(self, script, event=None):
        """Moves the navigator focus to the parent of the current focus."""

        self.update()
        parent = self._parent(script, self._navigator_focus)
        if parent is not None:
            self._set_navigator_focus(parent)
            self.present(script)
        else:
            script.presentMessage(messages.NAVIGATOR_NO_PARENT)

    def down(self, script, event=None):
        """Moves the navigator focus to the first child of the current focus."""

        self.update()
        children = self._children(script, self._navigator_focus)
        if not children:
            script.presentMessage(messages.NAVIGATOR_NO_CHILDREN)
            return

        self._set_navigator_focus(children[0])
        self.present(script)

    def next(self, script, event=None):
        """Moves the navigator focus to the next sibling of the current focus."""

        self.update()
        parent = self._parent(script, self._navigator_focus)
        if parent is None:
            script.presentMessage(messages.NAVIGATOR_NO_NEXT)
            return

        siblings = self._children(script, parent)
        if self._navigator_focus in siblings:
            index = siblings.index(self._navigator_focus)
            if index < len(siblings) - 1:
                self._set_navigator_focus(siblings[index+1])
                self.present(script)
            else:
                script.presentMessage(messages.NAVIGATOR_NO_NEXT)
        else:
            self._set_navigator_focus(parent)
            self.present(script)

    def previous(self, script, event=None):
        """Moves the navigator focus to the previous sibling of the current focus."""

        self.update()
        parent = self._parent(script, self._navigator_focus)
        if parent is None:
            script.presentMessage(messages.NAVIGATOR_NO_PREVIOUS)
            return

        siblings = self._children(script, parent)
        if self._navigator_focus in siblings:
            index = siblings.index(self._navigator_focus)
            if index > 0:
                self._set_navigator_focus(siblings[index-1])
                self.present(script)
            else:
                script.presentMessage(messages.NAVIGATOR_NO_PREVIOUS)
        else:
            self._set_navigator_focus(parent)
            self.present(script)

    def toggle_simplify(self, script, event=None):
        """Toggles simplified navigation."""

        self._simplify = not self._simplify
        if self._simplify:
            script.presentMessage(messages.NAVIGATOR_SIMPLIFIED_ENABLED)
        else:
            script.presentMessage(messages.NAVIGATOR_SIMPLIFIED_DISABLED)
        return True

    def perform_action(self, script, event=None):
        """Attempts to click on the current focus."""
        if AXEventSynthesizer.try_all_clickable_actions(self._navigator_focus):
            return True

        AXEventSynthesizer.click_object(self._navigator_focus, 1)
        return True


_navigator = ObjectNavigator()
def getNavigator():
    """Returns the Object Navigator"""

    return _navigator
