//! Example how to use `egui_glium`.

#![cfg_attr(not(debug_assertions), windows_subsystem = "windows")] // hide console window on Windows in release

use glium::glutin;

fn main() {
    let event_loop = glutin::event_loop::EventLoop::with_user_event();
    let display = create_display(&event_loop);

    let mut egui_glium = egui_glium::EguiGlium::new(&display, &event_loop);

    event_loop.run(move |event, _, control_flow| {
        let mut redraw = || {
            let mut quit = false;

            let repaint_after = egui_glium.run(&display, |egui_ctx| {
                egui::SidePanel::left("my_side_panel").show(egui_ctx, |ui| {
                    ui.heading("Hello World!");
                    if ui.button("Quit").clicked() {
                        quit = true;
                    }
                });
            });

            *control_flow = if quit {
                glutin::event_loop::ControlFlow::Exit
            } else if repaint_after.is_zero() {
                display.gl_window().window().request_redraw();
                glutin::event_loop::ControlFlow::Poll
            } else if let Some(repaint_after_instant) =
                std::time::Instant::now().checked_add(repaint_after)
            {
                glutin::event_loop::ControlFlow::WaitUntil(repaint_after_instant)
            } else {
                glutin::event_loop::ControlFlow::Wait
            };

            {
                use glium::Surface as _;
                let mut target = display.draw();

                let color = egui::Rgba::from_rgb(0.1, 0.3, 0.2);
                target.clear_color(color[0], color[1], color[2], color[3]);

                // draw things behind egui here

                egui_glium.paint(&display, &mut target);

                // draw things on top of egui here

                target.finish().unwrap();
            }
        };

        match event {
            // Platform-dependent event handlers to workaround a winit bug
            // See: https://github.com/rust-windowing/winit/issues/987
            // See: https://github.com/rust-windowing/winit/issues/1619
            glutin::event::Event::RedrawEventsCleared if cfg!(windows) => redraw(),
            glutin::event::Event::RedrawRequested(_) if !cfg!(windows) => redraw(),

            glutin::event::Event::WindowEvent { event, .. } => {
                use glutin::event::WindowEvent;
                if matches!(event, WindowEvent::CloseRequested | WindowEvent::Destroyed) {
                    *control_flow = glutin::event_loop::ControlFlow::Exit;
                }

                egui_glium.on_event(&event);

                display.gl_window().window().request_redraw(); // TODO(emilk): ask egui if the events warrants a repaint instead
            }
            glutin::event::Event::NewEvents(glutin::event::StartCause::ResumeTimeReached {
                ..
            }) => {
                display.gl_window().window().request_redraw();
            }
            _ => (),
        }
    });
}

fn create_display(event_loop: &glutin::event_loop::EventLoop<()>) -> glium::Display {
    let window_builder = glutin::window::WindowBuilder::new()
        .with_resizable(true)
        .with_inner_size(glutin::dpi::LogicalSize {
            width: 800.0,
            height: 600.0,
        })
        .with_title("egui_glium example");

    let context_builder = glutin::ContextBuilder::new()
        .with_depth_buffer(0)
        .with_srgb(true)
        .with_stencil_buffer(0)
        .with_vsync(true);

    glium::Display::new(window_builder, context_builder, event_loop).unwrap()
}
