// Adapted from the vrdashboard template (FrameAssistant commit 4a5b090),
// verified on the Steam Frame. See docs/steamframe/DESIGN.md, section 3.

#pragma once

#include <QOffscreenSurface>
#include <QOpenGLContext>

#include "RenderBackend.h"

class OpenGLRenderBackend final : public RenderBackend
{
public:
    OpenGLRenderBackend() = default;
    ~OpenGLRenderBackend() override;

    QString name() const override
    {
        return QStringLiteral( "OpenGL" );
    }
    QSGRendererInterface::GraphicsApi graphicsApi() const override
    {
        return QSGRendererInterface::OpenGL;
    }

    bool initialize( const RenderInterop& interop, QString* error ) override;
    void configureWindow( QQuickWindow* window ) override;
    bool attachWindow( QQuickWindow* window, QString* error ) override;
    void detachWindow() override
    {
        releaseRenderTarget();
    }
    QString deviceName() const override
    {
        return m_deviceName;
    }

    bool makeCurrent() override;
    void doneCurrent() override;

    QQuickRenderTarget createRenderTarget( QSize size ) override;
    void releaseRenderTarget() override;
    void beginFrame() override {}
    void finishFrame() override;
    void waitForGpu() override;

    vr::Texture_t vrTexture() override;
    vr::VRTextureBounds_t vrTextureBounds() const override;
    QImage readback() override;

private:
    std::unique_ptr<QOpenGLContext> m_context;
    std::unique_ptr<QOffscreenSurface> m_surface;
    unsigned int m_texture = 0; // GLuint
    QSize m_size;
    QString m_deviceName;
};