use fmt;
use sdl2;

export fn main() void = {
	sdl2::SDL_Init(sdl2::SDL_INIT_VIDEO)!;
	defer sdl2::SDL_Quit();


	const win = sdl2::SDL_CreateWindow("hi", sdl2::SDL_WINDOWPOS_UNDEFINED, sdl2::SDL_WINDOWPOS_UNDEFINED, 640, 480, sdl2::SDL_WindowFlags::NONE)!;
	defer sdl2::SDL_DestroyWindow(win);

	const wsurf = sdl2::SDL_GetWindowSurface(win)!;
	const format = wsurf.format;
	assert(format.bytesperpixel == 4, "can only work with u32 pixels");
	fmt::printfln("got format {}. bytes per pixel {}. r{:x} g{:x} b{:x} a{:x}",
		format.format, format.bytesperpixel, format.rmask, format.gmask, format.bmask, format.amask)!;
	fmt::printfln("red: {:x} green {:x} blue {:x}",
		sdl2::SDL_MapRGB(format, 255, 0, 0),
		sdl2::SDL_MapRGB(format, 0, 255, 0),
		sdl2::SDL_MapRGB(format, 0, 0, 255))!;
	fmt::println(wsurf.w * wsurf.h)!;
	fmt::println(sdl2::SDL_GetPixelFormatName(format.format))!;

	const pic = picture_from_surface(wsurf);

	let quit = false;
	let n = 0z;
	let lasttime = sdl2::SDL_GetTicks();
	let drawing = false;
	let mousex = 0;
	let mousey = 0;
	for (!quit) {
		let ev = sdl2::event { ... };
		for (sdl2::SDL_PollEvent(&ev)! == 1) switch (ev.event_type) {
			case sdl2::SDL_EventType::QUIT => quit = true;
			case sdl2::SDL_EventType::KEYDOWN =>
				const keysym = ev.key.keysym.sym;
				if (keysym == sdl2::SDL_Keycode::ESCAPE) quit = true;
			case sdl2::SDL_EventType::MOUSEBUTTONDOWN,
					sdl2::SDL_EventType::MOUSEBUTTONUP =>
				const d = ev.button;
				mousex = d.x;
				mousey = d.y;
				if (d.button == 1)
					drawing = (d.state == 1);
			case sdl2::SDL_EventType::MOUSEMOTION =>
				const d = ev.motion;
				mousex = d.x;
				mousey = d.y;
			case => void;
		};


		if (drawing) circle(pic, mousex, mousey, 25, 0x00ffff);

		// circle(pic, 100, 100, n:int, 0xff0000);

		sdl2::SDL_UpdateWindowSurface(win)!;
		n += 1;
		sdl2::SDL_Delay(1000/60);

		// if (n % 100 == 0) {
		// 	const thistime = sdl2::SDL_GetTicks();
		// 	const dt = (thistime - lasttime): f64;
		// 	lasttime = thistime;
		// 	const dt = dt / 100.0;
		// 	const fps = 1000.0/dt;
		// 	fmt::printfln("fps: {}",fps)!;
		// };
	};
};

def WHITE = 0x556602;
def BLACK = 0x0;

type picture = struct {
	d: []u32,
	w: size,
	h: size,
};
fn pidx(pic: picture, x: size, y: size) size = (pic.w*y)+x;
fn pic_set(pic: picture, x: size, y: size, val: u32) void = pic.d[pidx(pic,x,y)] = val;
fn picture_from_surface(surf: *sdl2::SDL_Surface) picture = picture {
	w = surf.w: size,
	h = surf.h: size,
	d = (surf.pixels as *opaque: *[*]u32)[..surf.w*surf.h],
};

fn min(a: int, b: int) int = if (a<b) a else b;
fn max(a: int, b: int) int = if (a<b) b else a;

fn circle(pic: picture, cx: int, cy: int, r: int, color: u32) void = {
	const ymin = max(0, cy-r);
	const ymax = min(pic.h:int-1, cy+r);
	const xmin = max(0, cx-r);
	const xmax = min(pic.w:int-1, cx+r);

	const r2 = r*r + r;

	for (let y = ymin; y<=ymax; y+=1) {
		const yd = y-cy;
		for (let x = xmin; x<=xmax; x+=1) {
			const xd = x-cx;
			if (yd*yd + xd*xd <= r2) {
				// we already made sure x and y are both greater than 0
				pic_set(pic, x:size, y:size, color);
			};
		};
	};

};