pub struct Engine {
    events: EventPump,
    canvas: Canvas<Window>,
    texture_creator: TextureCreator<WindowContext>,
    ttf_context: Sdl2TtfContext,
}

pub fn run(&mut self) -> Result<(), Box<dyn Error>> {
    self.canvas.set_draw_color(Color::RGB(127, 197, 255));
    self.canvas.clear();
    self.canvas.present();

    let mut current_time = Instant::now();
    let mut dt = 0.0;

    let mut font = self.ttf_context.load_font(r#"fonts/carlito/Carlito-Regular.ttf"#, 128)?;

    'running: loop {
        let new_time = Instant::now();
        let frame_time = (new_time.duration_since(current_time).subsec_nanos()) as f32 / 1_000_000_000.0;
        current_time = new_time;
        dt += frame_time;

        if !self.handle_input() { break 'running; }

        self.canvas.set_draw_color(Color::RGB(0, 0, 0));
        self.canvas.clear();

        let surface = font.render("Hello Rust!")
            .blended(Color::RGBA(255, 0, 0, 255)).map_err(|e| e.to_string())?;
        let texture = self.texture_creator.create_texture_from_surface(&surface)
            .map_err(|e| e.to_string())?;

        let TextureQuery { width, height, .. } = texture.query();
        let target = Rect::new(0, 0, width, height);
        self.canvas.copy(&texture, None, Some(target))?;

        self.canvas.present();
    }

    Ok(())
}