# Copyright (C) 2009, Tutorius.org
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
"""
This module defines Actions that can be done and undone on a state
"""

from dialog import TutoriusDialog


class Action(object):
    """Base class for Actions"""
    def __init__(self):
        object.__init__(self)

    def do(self):
        """
        Perform the action
        """
        raise NotImplementedError("Not implemented")

    def undo(self):
        """
        Revert anything the action has changed
        """
        pass #Should raise NotImplemented?


class OnceWrapper(object):
    """
    Wraps a class to perform an action once only

    This ConcreteActions's do() method will only be called on the first do()
    and the undo() will be callable after do() has been called
    """
    def __init__(self, action):
        self._action = action
        self._called = False
        self._need_undo = False

    def do(self):
        """
        Do the action only on the first time
        """
        if not self._called:
            self._called = True
            self._action.do()
            self._need_undo = True
            
    def undo(self):
        """
        Undo the action if it's been done
        """
        if self._need_undo:
            self._action.undo()
            self._need_undo = False

class DialogMessage(Action):
    """
    Shows a dialog with a given text, at the given position on the screen.

    @param message A string to display to the user
    @param pos A list of the form [x, y]
    """
    def __init__(self, message, pos=[0,0]):
        super(DialogMessage, self).__init__()
        self._message = message
        self.position = pos
        self._dialog = None

    def do(self):
        """
            Show the dialog
        """
        self._dialog = TutoriusDialog(self._message)
        self._dialog.set_button_clicked_cb(self._dialog.close_self)
        self._dialog.set_modal(False)
        self._dialog.move(self.position[0], self.position[1])
        self._dialog.show()

    def undo(self):
        """
            Destroy the dialog
        """
        if self._dialog:
            self._dialog.destroy()
            self._dialog = None