/*
Copyright (C) 2001-2006, William Joseph.
All Rights Reserved.

This file is part of GtkRadiant.

GtkRadiant 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.

GtkRadiant 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 GtkRadiant; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

#if !defined(INCLUDED_IUNDO_H)
#define INCLUDED_IUNDO_H

/// \file
/// \brief The undo-system interface. Uses the 'memento' pattern.

#include <cstddef>
#include "generic/constant.h"

class UndoMemento
{
public:
  virtual void release() = 0;
};

class Undoable
{
public:
  virtual UndoMemento* exportState() const = 0;
  virtual void importState(const UndoMemento* state) = 0;
};

class UndoObserver
{
public:
  virtual void save(Undoable* undoable) = 0;
};

class Callback;

class UndoTracker
{
public:
  virtual void clear() = 0;
  virtual void begin() = 0;
  virtual void undo() = 0;
  virtual void redo() = 0;
};

class UndoSystem
{
public:
  INTEGER_CONSTANT(Version, 1);
  STRING_CONSTANT(Name, "undo");

  virtual UndoObserver* observer(Undoable* undoable) = 0;
  virtual void release(Undoable* undoable) = 0;

  virtual std::size_t size() const = 0;
  virtual void start() = 0;
  virtual void finish(const char* command) = 0;
  virtual void undo() = 0;
  virtual void redo() = 0;
  virtual void clear() = 0;

  virtual void trackerAttach(UndoTracker& tracker) = 0;
  virtual void trackerDetach(UndoTracker& tracker) = 0;
};

#include "modulesystem.h"

template<typename Type>
class GlobalModule;
typedef GlobalModule<UndoSystem> GlobalUndoModule;

template<typename Type>
class GlobalModuleRef;
typedef GlobalModuleRef<UndoSystem> GlobalUndoModuleRef;

inline UndoSystem& GlobalUndoSystem()
{
  return GlobalUndoModule::getTable();
}

class UndoableCommand
{
  const char* m_command;
public:
  UndoableCommand(const char* command) : m_command(command)
  {
    GlobalUndoSystem().start();
  }
  ~UndoableCommand()
  {
    GlobalUndoSystem().finish(m_command);
  }
};


#endif
