/***************************************************************************
           UndoManager.h -  manager class for undo/redo handling
			     -------------------
    begin                : Sat Feb 01 2014
    copyright            : (C) 2014 by Thomas Eschenbacher
    email                : Thomas.Eschenbacher@gmx.de
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   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.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef UNDO_MANAGER_H
#define UNDO_MANAGER_H

#include "config.h"

#include <QtGlobal>
#include <QList>
#include <QPointer>

namespace Kwave
{

    class UndoHandler;
    class UndoTransaction;

    class Q_DECL_EXPORT UndoManager
    {
    public:

	/**
	 * Constructor
	 */
	UndoManager();

	/**
	 * Destructor
	 */
	virtual ~UndoManager();

	/**
	 * Register an instance of an undo handler
	 *
	 * @param handler the undo handler to register
	 * @return true if successful, false if failed
	 *         (e.g. duplicate registration or null pointer)
	 */
	bool registerHandler(Kwave::UndoHandler *handler);

	/**
	 * Unregister an instance of an undo handler previously
	 * registered through registerHandler()
	 *
	 * @param handler the undo handler to unregister
	 * @return true if successful, false if failed
	 *         (e.g. if not registered or null pointer)
	 */
	bool unregisterHandler(Kwave::UndoHandler *handler);

	/**
	 * Should be called when a undo transaction has been started,
	 * calls saveUndoData of all undo handlers
	 *
	 * @param transaction the newly created undo transaction (still empty)
	 * @return true if successful, false if failed (e.g. one undo handler
	 *         failed saving it's data)
	 */
	bool startUndoTransaction(Kwave::UndoTransaction *transaction);

	/**
	 * Should be called when a undo transaction is completed
	 *
	 * @param transaction the undo transaction that has been closed
	 * @return true if successful, false if failed
	 */
	bool closeUndoTransaction(Kwave::UndoTransaction *transaction);

    private:

	/** list of all registered undo handlers */
	QList<QPointer<Kwave::UndoHandler> > m_handlers;

    };
}

#endif /* UNDO_MANAGER_H */

//***************************************************************************
//***************************************************************************
