use std::num::NonZeroU32;
use std::rc::Rc;
use winit::event::{Event, KeyEvent, WindowEvent};
use winit::event_loop::{ControlFlow, EventLoop};
use winit::keyboard::{Key, NamedKey};
use winit::window::WindowBuilder;

const BUFFER_WIDTH: usize = 256;
const BUFFER_HEIGHT: usize = 128;

fn main() {
    let event_loop = EventLoop::new().unwrap();
    let window = Rc::new(WindowBuilder::new().build(&event_loop).unwrap());

    #[cfg(target_arch = "wasm32")]
    {
        use winit::platform::web::WindowExtWebSys;

        web_sys::window()
            .unwrap()
            .document()
            .unwrap()
            .body()
            .unwrap()
            .append_child(&window.canvas().unwrap())
            .unwrap();
    }

    let context = softbuffer::Context::new(window.clone()).unwrap();
    let mut surface = softbuffer::Surface::new(&context, window.clone()).unwrap();

    event_loop
        .run(move |event, elwt| {
            elwt.set_control_flow(ControlFlow::Wait);

            match event {
                Event::WindowEvent {
                    window_id,
                    event: WindowEvent::RedrawRequested,
                } if window_id == window.id() => {
                    surface
                        .resize(
                            NonZeroU32::new(BUFFER_WIDTH as u32).unwrap(),
                            NonZeroU32::new(BUFFER_HEIGHT as u32).unwrap(),
                        )
                        .unwrap();

                    let mut buffer = surface.buffer_mut().unwrap();
                    for y in 0..BUFFER_HEIGHT {
                        for x in 0..BUFFER_WIDTH {
                            let red = x as u32 % 255;
                            let green = y as u32 % 255;
                            let blue = (x as u32 * y as u32) % 255;

                            let color = blue | (green << 8) | (red << 16);
                            buffer[y * BUFFER_WIDTH + x] = color;
                        }
                    }
                    buffer.present().unwrap();
                }
                Event::WindowEvent {
                    event:
                        WindowEvent::CloseRequested
                        | WindowEvent::KeyboardInput {
                            event:
                                KeyEvent {
                                    logical_key: Key::Named(NamedKey::Escape),
                                    ..
                                },
                            ..
                        },
                    window_id,
                } if window_id == window.id() => {
                    elwt.exit();
                }
                _ => {}
            }
        })
        .unwrap();
}