//  ************************************************************************************************
//
//  BornAgain: simulate and fit reflection and scattering
//
//! @file      GUI/View/Overlay/IMaskOverlay.cpp
//! @brief     Implements interfaces IMaskOverlay.
//!
//! @homepage  http://www.bornagainproject.org
//! @license   GNU General Public License v3 or higher (see COPYING)
//! @copyright Forschungszentrum Jülich GmbH 2018
//! @authors   Scientific Computing Group at MLZ (see CITATION, AUTHORS)
//
//  ************************************************************************************************

#include "GUI/View/Overlay/IMaskOverlay.h"
#include "GUI/Model/Mask/MaskItems.h"
#include "GUI/View/Overlay/OverlayStyle.h"
#include "GUI/View/Plotter/ColorMap.h"
#include <QGraphicsScene>

namespace {

bool itemMaskValue(const OverlayItem* item)
{
    ASSERT(item);
    if (const auto* maskItem = dynamic_cast<const MaskItem*>(item))
        return maskItem->maskValue();
    return false;
}

void subtractTransmittingMasks(QPainterPath& result, qreal z, QVector<QGraphicsItem*> items)
{
    for (const QGraphicsItem* item : items) {
        const auto* overlay = dynamic_cast<const IOverlay*>(item);
        if (!overlay)
            continue;
        if (!dynamic_cast<const IMaskOverlay*>(overlay))
            continue;
        if (::itemMaskValue(overlay->parameterizedItem()))
            continue;
        if (const auto* mask_item = dynamic_cast<const MaskItem*>(overlay->parameterizedItem()))
            if (!mask_item->isVisible())
                continue;
        if (overlay->zValue() <= z)
            continue;

        const QPainterPath mask_shape = overlay->mapToScene(overlay->shape());
        if (!mask_shape.intersects(result))
            continue;

        // Item lays on top and is non-masking -> subtract the path of the item
        result = result.subtracted(mask_shape);
    }
}

} // namespace

IMaskOverlay::IMaskOverlay(ColorMap* plot)
    : IOverlay(plot)
{
    setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsMovable
             | QGraphicsItem::ItemSendsGeometryChanges);
}

void IMaskOverlay::paint(QPainter* painter, const QStyleOptionGraphicsItem*, QWidget*)
{
    const bool is_masked = ::itemMaskValue(parameterizedItem());
    painter->setBrush(GUI::Overlay::getMaskBrush(is_masked));
    painter->setPen(GUI::Overlay::getMaskPen(is_masked));
    painter->setRenderHints(QPainter::Antialiasing);
    painter->drawPath(maskedShape());
}

QPainterPath IMaskOverlay::maskedShape() const
{
    QPainterPath result = mapToScene(shape());
    ::subtractTransmittingMasks(result, zValue(), scene()->items());
    return mapFromScene(result);
}
