/*
    Scan Tailor - Interactive post-processing tool for scanned pages.
    Copyright (C)  Joseph Artsimovich <joseph.artsimovich@gmail.com>

    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 3 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, see <http://www.gnu.org/licenses/>.
*/

#ifndef BACKGROUNDTASK_H_
#define BACKGROUNDTASK_H_

#include "AbstractCommand.h"
#include "IntrusivePtr.h"
#include "FilterResult.h"
#include "TaskStatus.h"
#include <QAtomicInt>
#include <exception>

class BackgroundTask : public AbstractCommand0<FilterResultPtr>, public TaskStatus
{
public:
    enum Type { INTERACTIVE, BATCH };

    class CancelledException : public std::exception
    {
    public:
        virtual char const* what() const throw();
    };

    BackgroundTask(Type type) : m_type(type) {}

    Type type() const
    {
        return m_type;
    }

    virtual void cancel()
    {
        m_cancelFlag.fetchAndStoreRelaxed(1);
    }

    virtual bool isCancelled() const
    {
        return m_cancelFlag.fetchAndAddRelaxed(0) != 0;
    }

    /**
     * \brief If cancelled, throws CancelledException.
     */
    virtual void throwIfCancelled() const;
private:
    mutable QAtomicInt m_cancelFlag;
    Type const m_type;
};

typedef IntrusivePtr<BackgroundTask> BackgroundTaskPtr;

#endif
