/** ===========================================================
 * @file
 *
 * This file is a part of digiKam project
 * <a href="http://www.digikam.org">http://www.digikam.org</a>
 *
 * @date  2013-05-18
 * @brief Wrapper class for face recongition
 *
 * @author Copyright (C) 2013 by Marcel Wiesweg
 *         <a href="mailto:marcel dot wiesweg at gmx dot de">marcel dot wiesweg at gmx dot de</a>
 *
 * 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, 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.
 *
 * ============================================================ */

#ifndef KFACE_DATAPROVIDERS_H
#define KFACE_DATAPROVIDERS_H

// Qt includes

#include <QImage>
#include <QList>

// Local includes

#include "libkface_export.h"
#include "identity.h"

namespace KFaceIface
{

class KFACE_EXPORT ImageListProvider
{
public:
    /**
     * This class provides access to a list of unspecified entities,
     * where for each entry a QImage can be provided.
     * Only forward iteration is required.
     */
    virtual ~ImageListProvider() {}

    virtual int  size() const           = 0;
    virtual bool atEnd() const          = 0;
    virtual void proceed(int steps = 1) = 0;
    virtual QImage image()              = 0;
};

/// A wrapper implementation for ImageListProvider if you have a QList of QImages

class KFACE_EXPORT QListImageListProvider : public ImageListProvider
{
public:
    QListImageListProvider(const QList<QImage>& lst)
        : list(lst),
          it(list.constBegin())
    {
    }

    QListImageListProvider()
        : it(list.constBegin())
    {
    }

    virtual int  size() const                   { return list.size(); }
    virtual bool atEnd() const                  { return it == list.constEnd(); }
    virtual void proceed(int steps = 1)         { it += steps; }

    void reset()                                { it = list.constBegin(); }

    virtual QImage image()                      { return *it; }

public:

    QList<QImage>                 list;
    QList<QImage>::const_iterator it;
};

class KFACE_EXPORT EmptyImageListProvider : public ImageListProvider
{
public:

    virtual int  size() const           { return 0;    }
    virtual bool atEnd() const          { return true; }
    virtual void proceed(int steps = 1) { Q_UNUSED(steps)  }
    virtual QImage image()              { return QImage(); }
};

// ----------------------------------------------------------------------------------------

class KFACE_EXPORT TrainingDataProvider
{
public:

    /**
     * A TrainingDataProvider provides a call-back interface
     * for the training process to retrieve the necessary information.
     * It is not specified, but depends on the backend which of the methods
     * in which order and for which identities will be called.
     */

    virtual ~TrainingDataProvider() {}

    /**
     * Provides those images for the given identity that have not yet been
     * supplied for training.
     * Ownership of the returned object stays with the TrainingDataProvider.
     */
    virtual ImageListProvider* newImages(const Identity& identity) = 0;

    /**
     * Provides all images known for the given identity.
     * Ownership of the returned object stays with the TrainingDataProvider.
     */
    virtual ImageListProvider* images(const Identity& identity) = 0;
};

} // namespace KFaceIface

#endif // KFACE_DATAPROVIDERS_H
