#pragma once

#include <QGraphicsView>

class QMimeData;

namespace diag {

class DiagramScene;

// Canvas view: draws the rectangular grid, zooms with Ctrl+wheel (anchored
// under the cursor), pans with the middle mouse button, rubber-band selects,
// and accepts node-type drops from the palette.
class GridView : public QGraphicsView {
    Q_OBJECT
public:
    static constexpr const char* kNodeTypeMime = "application/x-diag-nodetype";

    explicit GridView(DiagramScene* scene, QWidget* parent = nullptr);

    void zoomIn();
    void zoomOut();
    void zoomReset();
    void zoomToFit();
    double zoomFactor() const;

    // Decodes a node-type mime payload and drops it at the viewport position;
    // returns true when a node was created. Called from dropEvent.
    bool handleNodeTypeDrop(const QMimeData* mime, QPoint viewportPos);

signals:
    void zoomChanged(double factor);
    void cursorMoved(QPointF scenePos);

protected:
    void drawBackground(QPainter* painter, const QRectF& rect) override;
    void wheelEvent(QWheelEvent* event) override;
    void mousePressEvent(QMouseEvent* event) override;
    void mouseMoveEvent(QMouseEvent* event) override;
    void mouseReleaseEvent(QMouseEvent* event) override;
    void dragEnterEvent(QDragEnterEvent* event) override;
    void dragMoveEvent(QDragMoveEvent* event) override;
    void dropEvent(QDropEvent* event) override;

private:
    void applyZoom(double factor);

    DiagramScene* m_scene;
    bool m_panning = false;
    QPoint m_panStart;
};

}  // namespace diag