/* 
   Copyright (C) 2006 Hans Fugal & Paul Davis

    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., 675 Mass Ave, Cambridge, MA 02139, USA.

    $Id: /local/undo/libs/pbd3/pbd/undo.h 132 2006-06-29T18:45:16.609763Z fugalh  $
*/

#ifndef __lib_pbd_memento_command_h__
#define __lib_pbd_memento_command_h__

#include <pbd/command.h>
#include <sigc++/slot.h>

/** This command class is initialized with before and after mementos 
 * (from Stateful::get_state()), so undo becomes restoring the before
 * memento, and redo is restoring the after memento.
 */
template <class obj_T>
class MementoCommand : public Command
{
    public:
        MementoCommand(obj_T &obj, 
                       XMLNode &before,
                       XMLNode &after
                       ) 
            : obj(obj), before(before), after(after) {}
        void operator() () { obj.set_state(after); }
        void undo() { obj.set_state(before); }
        virtual XMLNode &serialize() 
        {
            // obj.id
            // key is "MementoCommand" or something
            // before and after mementos
        }
        // TODO does this need a copy constructor?
    protected:
        obj_T &obj;
        XMLNode &before, &after;
};

template <class obj_T>
class MementoUndoCommand : public MementoCommand<obj_T>
{
public:
    MementoUndoCommand(obj_T &obj, 
                       XMLNode &before)
        : obj(obj), before(before) {}
    void operator() () { /* noop */ }
    void undo() { obj.set_state(before); }
    virtual XMLNode &serialize() 
    {
        // obj.id
        // key is "MementoCommand" or something
        // before and after mementos
    }
}

template <class obj_T>
class MementoRedoCommand : public MementoCommand<obj_T>
{
public:
    MementoUndoCommand(obj_T &obj, 
                       XMLNode &after)
        : obj(obj), after(after) {}
    void operator() () { obj.set_state(after); }
    void undo() { /* noop */ }
    virtual XMLNode &serialize() 
    {
        // obj.id
        // key is "MementoCommand" or something
        // before and after mementos
    }
}

#endif // __lib_pbd_memento_h__