#------------------------------------------------------------------------------
# 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 a drop target editor for the PyQt user interface toolkit. A drop
target editor handles drag and drop operations as a drop target.
"""

#-------------------------------------------------------------------------
#  Imports:
#-------------------------------------------------------------------------

from __future__ import absolute_import
from pyface.qt import QtGui, QtCore

# FIXME: ToolkitEditorFactory is a proxy class defined here just for backward
# compatibility. The class has been moved to the
# traitsui.editors.drop_editor file.
from traitsui.editors.drop_editor import ToolkitEditorFactory

from .text_editor import SimpleEditor as Editor
from .constants import DropColor
from .clipboard import PyMimeData, clipboard

#-------------------------------------------------------------------------
#  'SimpleEditor' class:
#-------------------------------------------------------------------------


class SimpleEditor(Editor):
    """ Simple style of drop editor, which displays a read-only text field that
    contains the string representation of the object trait's value.
    """

    # Background color when it is OK to drop objects.
    ok_color = DropColor

    #-------------------------------------------------------------------------
    #  Finishes initializing the editor by creating the underlying toolkit
    #  widget:
    #-------------------------------------------------------------------------

    def init(self, parent):
        """ Finishes initializing the editor by creating the underlying toolkit
            widget.
        """
        if self.factory.readonly:
            self.control = QtGui.QLineEdit(self.str_value)
            self.control.setReadOnly(True)
            self.set_tooltip()
        else:
            super(SimpleEditor, self).init(parent)

        pal = QtGui.QPalette(self.control.palette())
        pal.setColor(QtGui.QPalette.Base, self.ok_color)
        self.control.setPalette(pal)

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

        self.control._qt4_editor = self

    #-------------------------------------------------------------------------
    #  Returns the text representation of a specified object trait value:
    #-------------------------------------------------------------------------

    def string_value(self, value):
        """ Returns the text representation of a specified object trait value.
        """
        if value is None:
            return ''
        return str(value)

    #-------------------------------------------------------------------------
    #  Handles an error that occurs while setting the object's trait value:
    #-------------------------------------------------------------------------

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


class _DropEventFilter(QtCore.QObject):

    def eventFilter(self, source, event):
        typ = event.type()
        if typ == QtCore.QEvent.Drop:
            self.dropEvent(event)
        elif typ == QtCore.QEvent.DragEnter:
            self.dragEnterEvent(event)
        return super(_DropEventFilter, self).eventFilter(source, event)

    #-------------------------------------------------------------------------
    #  Handles a Python object being dropped on the control:
    #-------------------------------------------------------------------------

    def dropEvent(self, e):
        """ Handles a Python object being dropped on the tree.
        """
        editor = self.parent()._qt4_editor

        klass = editor.factory.klass

        if editor.factory.binding:
            value = getattr(clipboard, 'node', None)
        else:
            value = e.mimeData().instance()

        if (klass is None) or isinstance(value, klass):
            editor._no_update = True
            try:
                if hasattr(value, 'drop_editor_value'):
                    editor.value = value.drop_editor_value()
                else:
                    editor.value = value
                if hasattr(value, 'drop_editor_update'):
                    value.drop_editor_update(self)
                else:
                    self.setText(editor.str_value)
            finally:
                editor._no_update = False

            e.acceptProposedAction()

    #-------------------------------------------------------------------------
    #  Handles a Python object being dragged over the control:
    #-------------------------------------------------------------------------

    def dragEnterEvent(self, e):
        """ Handles a Python object being dragged over the tree.
        """
        editor = self.parent()._qt4_editor

        if editor.factory.binding:
            data = getattr(clipboard, 'node', None)
        else:
            md = e.mimeData()

            if not isinstance(md, PyMimeData):
                return

            data = md.instance()

        try:
            editor.object.base_trait(editor.name).validate(editor.object,
                                                           editor.name, data)
            e.acceptProposedAction()
        except:
            pass


# Define the Text and ReadonlyEditor for use by the editor factory.
TextEditor = ReadonlyEditor = SimpleEditor