#pragma once

#include <optional>
#include <random>
#include <vector>

#include <QElapsedTimer>
#include <QOpenGLWidget>
#include <QTimer>
#include <QVector2D>

#include "EventHandler.h"
#include "WeaponFiredEvent.h"

#include "entt/entity/entity.hpp"
#include "EntitySelectedEvent.h"
#include "Tick.h"
#include "TickDriver.h"
#include "VisualsConfig.h"

class ArenaSimulation;
class QPainter;

class ArenaView : public QOpenGLWidget,
                  public EventHandler<WeaponFiredEvent>
{
    Q_OBJECT

public:
    ArenaView(ArenaSimulation* sim, const VisualsConfig* visuals,
              QWidget* parent = nullptr);
    ~ArenaView() override;

    void setGameSpeed(double multiplier);
    double gameSpeed() const;
    void togglePause();
    void stopRendering();

protected:
    void paintGL() override;
    void mousePressEvent(QMouseEvent* event) override;

private slots:
    void onFrame();

private:
    void handleEvent(std::shared_ptr<const WeaponFiredEvent> event) override;

    void drawTiles(QPainter& painter);
    void drawBuildings(QPainter& painter);
    void drawStations(QPainter& painter);
    void drawScrap(QPainter& painter);
    void drawShips(QPainter& painter);
    void drawBeams(QPainter& painter);

    float tilePx() const;
    QPointF worldToWidget(QVector2D worldPos) const;
    QPointF tileToWidget(QPoint tile) const;
    QRectF tileRect(QPoint tile) const;

    std::optional<QVector2D> entityPosition(entt::entity entity) const;
    QVector2D widgetToWorld(QPoint widgetPt) const;

    struct ActiveBeam
    {
        WeaponFiredEvent event;
        qint64    emittedWallMs;
        QVector2D targetOffset;
    };

    static constexpr qint64 kBeamLifetimeMs = 300;

    ArenaSimulation*     m_sim;
    const VisualsConfig* m_visuals;

    TickDriver    m_tickDriver;
    QElapsedTimer m_frameTimer;
    qint64        m_wallMs;
    std::mt19937  m_rng;
    double        m_gameSpeedMultiplier;
    double        m_prevNonZeroSpeed;

    QTimer* m_renderTimer;

    std::vector<ActiveBeam> m_activeBeams;
    bool m_finishedEmitted;

    std::optional<entt::entity> m_selectedEntity;
};