#include "dialog.h"

#include <QDebug>
#include <QApplication>
#include <QHBoxLayout>

#include <QLabel>

#include <QGraphicsScene>
#include <QGraphicsView>
#include <QGraphicsProxyWidget>
#include <QGraphicsSceneDragDropEvent>

#include <QDrag>
#include <QMimeData>

class Scene : public QGraphicsScene
{
    public:

    void dragMoveEvent( QGraphicsSceneDragDropEvent* event ) override
    {
        bool acceptOnBlank = true;

        if( acceptOnBlank || itemAt( event->scenePos(), QTransform() ) ) // if item under cursor the event should be propagated further
        {
            event->accept();
        }
        else
        {
            QGraphicsScene::dragMoveEvent( event );
        }
    }
};

class Widget : public QWidget
{
public:

    Widget()
        : QWidget( nullptr )
    {
        setAcceptDrops( true );

        QHBoxLayout* mainLayout = new QHBoxLayout;

        mainLayout->addWidget( new QLabel( "TEST" ) );

        setLayout( mainLayout );
    }

    void mouseMoveEvent( QMouseEvent* event )
    {
        if( !( event->buttons() & Qt::LeftButton ) )
        {
            event->accept();
            return;
        }

        if( ( event->pos() - mDragStartPosition ).manhattanLength() < QApplication::startDragDistance() )
        {
            event->accept();
            return;
        }

        QDrag* drag			= new QDrag( this );
        QMimeData* mimeData = new QMimeData;

        drag->setMimeData( mimeData );

        QPixmap pixmap( this->rect().size() );
        this->render( &pixmap, QPoint(), this->rect() );
        drag->setPixmap( pixmap );

        drag->exec();
    }

    void mousePressEvent( QMouseEvent *event )
    {
        if( event->button() == Qt::LeftButton )
        {
            mDragStartPosition = event->pos();
        }

        event->accept();
    }

public:

    QPointF								mDragStartPosition;
};

class Proxy : public QGraphicsProxyWidget
{
public:

    Proxy()
        : QGraphicsProxyWidget( nullptr )
    {
        setFlag( QGraphicsItem::ItemIsMovable, true );
        setFlag( QGraphicsItem::ItemIsSelectable, true );
        setAcceptDrops( true );

        setWidget( new Widget );
    }

    void dragLeaveEvent( QGraphicsSceneDragDropEvent* /*event*/ ) override
    {
        qDebug() << "dragLeaveEvent";
    }

};


Dialog::Dialog(QWidget *parent) :
    QDialog(parent)
{
    QGraphicsScene* scene = new Scene();

    QGraphicsView* sceneView = new QGraphicsView;
    sceneView->setScene( scene );

    QHBoxLayout* mainLayout = new QHBoxLayout;

    mainLayout->addWidget( sceneView );

    setLayout( mainLayout );

    // Add Items

    scene->addItem( new  Proxy );
}

Dialog::~Dialog()
{
}