#------------------------------------------------------------------------------
# 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 pyface.qt import QtGui

# 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

#-------------------------------------------------------------------------------
#  '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)

        # Patch the type of the control to insert the DND event handlers.
        self.control.__class__ = type(_DropWidget.__name__,
                (type(self.control), ), dict(_DropWidget.__dict__))

        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 _DropWidget(object):

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

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