#include <QApplication>
#include <QBoxLayout>
#include <QLabel>
#include <QScreen>
#include <QWindow>
#include <QDesktopWidget>
#include <qpa/qplatformscreen.h>

#include <windows.h>

class QScaledWidget : public QWidget
{
public:
    QScaledWidget()
    {
        m_layout = new QVBoxLayout(this);

        QFrame* frame = new QFrame();
        frame->setFrameShape(QFrame::Box);
        QBoxLayout* frameLayout = new QHBoxLayout(frame);

        m_label = new QLabel("TEST");

        m_square1 = new QFrame();
        m_square1->setFrameShape(QFrame::Box);

        m_square2 = new QFrame();
        m_square2->setFrameShape(QFrame::Box);

        frameLayout->addWidget(m_square1);
        frameLayout->addWidget(m_label);
        frameLayout->addWidget(m_square2);

        m_layout->addWidget(frame);

        setMetricsWithoutScaling();
    }

    void setMetricsWithoutScaling()
    {
        m_layout->setMargin(50);

        QFont f;
        f.setPixelSize(50);
        m_label->setFont(f);

        m_square1->setFixedSize(40, 40);
        m_square2->setFixedSize(40, 40);
    }

    void updateMetrics()
    {
        m_layout->setMargin(m_currentFactor*50);

        QFont f;
        f.setPixelSize(m_currentFactor*50);
        m_label->setFont(f);

        m_square1->setFixedSize(m_currentFactor*40, m_currentFactor*40);
        m_square2->setFixedSize(m_currentFactor*40, m_currentFactor*40);
    }

    void updateFactor()
    {
        QScreen* screen = window()->windowHandle()->screen();
        qreal dpr = screen->devicePixelRatio();
        qreal pdpi = screen->handle()->logicalDpi().first;
        qreal factor = pdpi / (dpr * 96.0);
        if (!qFuzzyCompare(1 + factor, 1 + m_currentFactor))
        {
            m_currentFactor = factor;
            printf("new factor %f\n", factor);
            updateMetrics();
        }
    }

    virtual bool event(QEvent *e) override
    {
        if (qApp->arguments().contains("scaled") && e->type() == QEvent::Paint)
        {
            updateFactor();
        }

        return QWidget::event(e);
    }


    QVBoxLayout* m_layout;
    QVBoxLayout* m_frameLayout;
    QLabel* m_label;
    QFrame* m_square1;
    QFrame* m_square2;
    qreal m_currentFactor = 0.0;
};

int main(int argc, char *argv[])
{
    QString appName = "none";
    if (argc > 1) 
    {
        if (argv[1] == std::string("scaled") || argv[1] == std::string("qtscaled"))
        {
            QApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
        } else if (argv[1] == std::string("aware"))
        {
            SetProcessDPIAware();
            QApplication::setAttribute(Qt::AA_DisableHighDpiScaling);
        }
        appName = argv[1];
    }

    QApplication a(argc, argv);

    QScaledWidget widget;
    widget.setWindowTitle(appName);

    widget.show();
    return a.exec();
}