# (C) Copyright 2009-2021 Enthought, Inc., Austin, TX
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in LICENSE.txt and may be redistributed only under
# the conditions described in the aforementioned license. The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
#
# Thanks for using Enthought open source!

# ------------------------------------------------------------------------------
# Copyright (c) 2008, Riverbank Computing Limited
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD license.
# However, when used with the GPL version of PyQt the additional terms
# described in the PyQt GPL exception also apply

#
# Author: Riverbank Computing Limited
# ------------------------------------------------------------------------------

""" Defines the various instance editors and the instance editor factory for
    the PyQt user interface toolkit..
"""


from pyface.qt import QtCore, QtGui

from traits.api import HasTraits, Instance, Property

from traitsui.ui_traits import AView
from traitsui.helper import user_name_for
from traitsui.handler import Handler
from traitsui.instance_choice import InstanceChoiceItem
from .editor import Editor
from .drop_editor import _DropEventFilter
from .constants import DropColor
from .helper import position_window


OrientationMap = {
    "default": None,
    "horizontal": QtGui.QBoxLayout.LeftToRight,
    "vertical": QtGui.QBoxLayout.TopToBottom,
}


class CustomEditor(Editor):
    """ Custom style of editor for instances. If selection among instances is
    allowed, the editor displays a combo box listing instances that can be
    selected. If the current instance is editable, the editor displays a panel
    containing trait editors for all the instance's traits.
    """

    #: Background color when an item can be dropped on the editor:
    ok_color = DropColor

    #: The orientation of the instance editor relative to the instance selector:
    orientation = QtGui.QBoxLayout.TopToBottom

    #: Class constant:
    extra = 0

    # -------------------------------------------------------------------------
    #  Trait definitions:
    # -------------------------------------------------------------------------

    #: List of InstanceChoiceItem objects used by the editor
    items = Property()

    #: The view to use for displaying the instance
    view = AView

    def init(self, parent):
        """ Finishes initializing the editor by creating the underlying toolkit
            widget.
        """
        factory = self.factory
        if factory.name != "":
            self._object, self._name, self._value = self.parse_extended_name(
                factory.name
            )

        # Create a panel to hold the object trait's view:
        if factory.editable:
            self.control = self._panel = parent = QtGui.QWidget()

        # Build the instance selector if needed:
        selectable = factory.selectable
        droppable = factory.droppable
        items = self.items
        for item in items:
            droppable |= item.is_droppable()
            selectable |= item.is_selectable()

        if selectable:
            self._object_cache = {}
            item = self.item_for(self.value)
            if item is not None:
                self._object_cache[id(item)] = self.value

            self._choice = QtGui.QComboBox()
            self._choice.activated.connect(self.update_object)

            self.set_tooltip(self._choice)

            if factory.name != "":
                self._object.observe(
                    self.rebuild_items, self._name + ".items", dispatch="ui"
                )

            factory.observe(
                self.rebuild_items, "values.items", dispatch="ui"
            )

            self.rebuild_items()

        elif droppable:
            self._choice = QtGui.QLineEdit()
            self._choice.setReadOnly(True)
            self.set_tooltip(self._choice)

        if droppable:
            # Install EventFilter on control to handle DND events.
            drop_event_filter = _DropEventFilter(self.control)
            self.control.installEventFilter(drop_event_filter)

        orientation = OrientationMap[factory.orientation]
        if orientation is None:
            orientation = self.orientation

        if (selectable or droppable) and factory.editable:
            layout = QtGui.QBoxLayout(orientation, parent)
            layout.setContentsMargins(0, 0, 0, 0)
            layout.addWidget(self._choice)

            if orientation == QtGui.QBoxLayout.TopToBottom:
                hline = QtGui.QFrame()
                hline.setFrameShape(QtGui.QFrame.HLine)
                hline.setFrameShadow(QtGui.QFrame.Sunken)

                layout.addWidget(hline)

            self.create_editor(parent, layout)
        elif self.control is None:
            if self._choice is None:
                self._choice = QtGui.QComboBox()
                self._choice.activated[int].connect(self.update_object)

            self.control = self._choice
        else:
            layout = QtGui.QBoxLayout(orientation, parent)
            layout.setContentsMargins(0, 0, 0, 0)
            self.create_editor(parent, layout)

        # Synchronize the 'view' to use:
        # fixme: A normal assignment can cause a crash (for unknown reasons) in
        # some cases, so we make sure that no notifications are generated:
        self.trait_setq(view=factory.view)
        self.sync_value(factory.view_name, "view", "from")

    def create_editor(self, parent, layout):
        """ Creates the editor control.
        """
        self._panel = QtGui.QWidget()
        layout.addWidget(self._panel)

    def _get_items(self):
        """ Gets the current list of InstanceChoiceItem items.
        """
        if self._items is not None:
            return self._items

        factory = self.factory
        if self._value is not None:
            values = self._value() + factory.values
        else:
            values = factory.values

        items = []
        adapter = factory.adapter
        for value in values:
            if not isinstance(value, InstanceChoiceItem):
                value = adapter(object=value)
            items.append(value)

        self._items = items

        return items

    def rebuild_items(self, event=None):
        """ Rebuilds the object selector list.
        """
        # Clear the current cached values:
        self._items = None

        # Rebuild the contents of the selector list:
        name = -1
        value = self.value
        choice = self._choice
        choice.clear()
        for i, item in enumerate(self.items):
            if item.is_selectable():
                choice.addItem(item.get_name())
                if item.is_compatible(value):
                    name = i

        # Reselect the current item if possible:
        if name >= 0:
            choice.setCurrentIndex(name)
        else:
            # Otherwise, current value is no longer valid, try to discard it:
            try:
                self.value = None
            except:
                pass

    def item_for(self, object):
        """ Returns the InstanceChoiceItem for a specified object.
        """
        for item in self.items:
            if item.is_compatible(object):
                return item

        return None

    def view_for(self, object, item):
        """ Returns the view to use for a specified object.
        """
        view = ""
        if item is not None:
            view = item.get_view()

        if view == "":
            view = self.view

        return self.ui.handler.trait_view_for(
            self.ui.info, view, object, self.object_name, self.name
        )

    def update_object(self, index):
        """ Handles the user selecting a new value from the combo box.
        """
        item = self.items[index]
        id_item = id(item)
        object = self._object_cache.get(id_item)
        if object is None:
            object = item.get_object()
            if (not self.factory.editable) and item.is_factory:
                view = self.view_for(object, self.item_for(object))
                view.ui(object, self.control, "modal")

            if self.factory.cachable:
                self._object_cache[id_item] = object

        self.value = object
        self.resynch_editor()

    def update_editor(self):
        """ Updates the editor when the object trait changes externally to the
            editor.
        """
        # Synchronize the editor contents:
        self.resynch_editor()

        # Update the selector (if any):
        choice = self._choice
        item = self.item_for(self.value)
        if (choice is not None) and (item is not None):
            name = item.get_name(self.value)
            if self._object_cache is not None:
                idx = choice.findText(name)
                if idx < 0:
                    idx = choice.count()
                    choice.addItem(name)

                choice.setCurrentIndex(idx)
            else:
                choice.setText(name)

    def resynch_editor(self):
        """ Resynchronizes the contents of the editor when the object trait
        changes externally to the editor.
        """
        panel = self._panel
        if panel is not None:
            # Dispose of the previous contents of the panel:
            layout = panel.layout()
            if layout is None:
                layout = QtGui.QVBoxLayout(panel)
                layout.setContentsMargins(0, 0, 0, 0)
            elif self._ui is not None:
                self._ui.dispose()
                self._ui = None
            else:
                child = layout.takeAt(0)
                while child is not None:
                    child = layout.takeAt(0)

                del child

            # Create the new content for the panel:
            stretch = 0
            value = self.value
            if not isinstance(value, HasTraits):
                str_value = ""
                if value is not None:
                    str_value = self.str_value
                control = QtGui.QLabel(str_value)
            else:
                view = self.view_for(value, self.item_for(value))
                context = value.trait_context()
                handler = None
                if isinstance(value, Handler):
                    handler = value
                context.setdefault("context", self.object)
                context.setdefault("context_handler", self.ui.handler)
                self._ui = ui = view.ui(
                    context,
                    panel,
                    "subpanel",
                    value.trait_view_elements(),
                    handler,
                    self.factory.id,
                )
                control = ui.control
                self.scrollable = ui._scrollable
                ui.parent = self.ui

                if view.resizable or view.scrollable or ui._scrollable:
                    stretch = 1

            # FIXME: Handle stretch.
            layout.addWidget(control)

    def dispose(self):
        """ Disposes of the contents of an editor.
        """
        # Make sure we aren't hanging on to any object refs:
        self._object_cache = None

        if self._ui is not None:
            self._ui.dispose()

        if self._choice is not None:
            if self._object is not None:
                self._object.observe(
                    self.rebuild_items,
                    self._name + ".items",
                    remove=True,
                    dispatch="ui"
                )

            self.factory.observe(
                self.rebuild_items, "values.items", remove=True, dispatch="ui"
            )

        super().dispose()

    def error(self, excp):
        """ Handles an error that occurs while setting the object's trait value.
        """
        pass

    def get_error_control(self):
        """ Returns the editor's control for indicating error status.
        """
        return self._choice or self.control

    # -- UI preference save/restore interface ---------------------------------

    def restore_prefs(self, prefs):
        """ Restores any saved user preference information associated with the
            editor.
        """
        ui = self._ui
        if (ui is not None) and (prefs.get("id") == ui.id):
            ui.set_prefs(prefs.get("prefs"))

    def save_prefs(self):
        """ Returns any user preference information associated with the editor.
        """
        ui = self._ui
        if (ui is not None) and (ui.id != ""):
            return {"id": ui.id, "prefs": ui.get_prefs()}

        return None

    # -- Traits event handlers ------------------------------------------------

    def _view_changed(self, view):
        self.resynch_editor()


class SimpleEditor(CustomEditor):
    """ Simple style of editor for instances, which displays a button. Clicking
    the button displays a dialog box in which the instance can be edited.
    """

    #: The ui instance for the currently open editor dialog
    _dialog_ui = Instance("traitsui.ui.UI")

    #: Class constants:
    orientation = QtGui.QBoxLayout.LeftToRight
    extra = 2

    def create_editor(self, parent, layout):
        """ Creates the editor control (a button).
        """
        self._button = QtGui.QPushButton()
        self._button.setAutoDefault(False)
        layout.addWidget(self._button)
        self._button.clicked.connect(self.edit_instance)
        # Make sure the editor is properly disposed if parent UI is closed
        self._button.destroyed.connect(self._parent_closed)

    def edit_instance(self):
        """ Edit the contents of the object trait when the user clicks the
            button.
        """
        # Create the user interface:
        factory = self.factory
        view = self.ui.handler.trait_view_for(
            self.ui.info, factory.view, self.value, self.object_name, self.name
        )
        self._dialog_ui = self.value.edit_traits(
            view, kind=factory.kind, id=factory.id
        )

        # Check to see if the view was 'modal', in which case it will already
        # have been closed (i.e. is None) by the time we get control back:
        if self._dialog_ui.control is not None:
            # Position the window on the display:
            position_window(self._dialog_ui.control)

            # Chain our undo history to the new user interface if it does not
            # have its own:
            if self._dialog_ui.history is None:
                self._dialog_ui.history = self.ui.history

        else:
            self._dialog_ui = None

    def resynch_editor(self):
        """ Resynchronizes the contents of the editor when the object trait
            changes externally to the editor.
        """
        button = self._button
        if button is not None:
            label = self.factory.label
            if label == "":
                label = user_name_for(self.name)

            button.setText(label)
            button.setEnabled(isinstance(self.value, HasTraits))

    def _parent_closed(self):
        if self._dialog_ui is not None:
            if self._dialog_ui.control is not None:
                self._dialog_ui.control.close()
            self._dialog_ui.dispose()
            self._dialog_ui = None