use fmt;
use sdl2;
use math;

def CHUNKSIZE = 512;
def NCHUNKS = 4;

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 offs: [_]pos = [
		(0,0), (0,CHUNKSIZE), (CHUNKSIZE,0), (CHUNKSIZE,CHUNKSIZE),
	];

	let pictures: []picture = alloc([],NCHUNKS);
	for (let i = 0z; i < NCHUNKS; i +=1){
		const surf = sdl2::SDL_CreateRGBSurface(0,
			CHUNKSIZE, CHUNKSIZE, 32, 0xff0000, 0xff00, 0xff, 0)!;
		append(pictures, picture_from_surface(surf, offs[i]));
	};

	let dstate = drawing_state {
		drawing = false,
		pos = (0,0),
		pictures = pictures,
	};

	let camera_pos: pos = (25, 50);

	for (let i = 0z; i < 4; i += 1) {
		const p = &dstate.pictures[i];
		clear_picture(p, 0xffffff);
		outline_picture(p);
	};

	let quit = false;
	let n = 0;
	let lasttime = sdl2::SDL_GetTicks();
	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 edata = ev.button;
				dstate.pos = (edata.x + camera_pos.0, edata.y + camera_pos.1);
				if (edata.button == 1)
					dstate.drawing = (edata.state == 1);
			case sdl2::SDL_EventType::MOUSEMOTION =>
				const edata = ev.motion;
				dstate.pos = (edata.x + camera_pos.0, edata.y + camera_pos.1);
			case => void;
		};

		movement(&camera_pos);
		do_drawing(&dstate);

		for (let i = 0z; i < len(dstate.pictures); i+=1)
			render_picture(&dstate.pictures[i], wsurf, camera_pos);

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

fn render_picture(pic: *picture, winsurf: *sdl2::SDL_Surface, camera_pos: pos) void = {
	sdl2::SDL_BlitSurface(pic.surf, null, winsurf, &sdl2::SDL_Rect{
		x = pic.pos.0 - camera_pos.0, y = pic.pos.1 - camera_pos.1, ...
	})!;
};


def SPEED = 17;
def DIAG_SPEED = 12;  // thereabouts

fn movement(pos: *pos) void = {
	const kb = sdl2::SDL_GetKeyboardState();
	let dx = 0;
	let dy = 0;
	if (kb[sdl2::SDL_Scancode::W]) dy -= 1;
	if (kb[sdl2::SDL_Scancode::S]) dy += 1;
	if (kb[sdl2::SDL_Scancode::A]) dx -= 1;
	if (kb[sdl2::SDL_Scancode::D]) dx += 1;

	let speed = SPEED;
	if (dx != 0 && dy != 0) speed = DIAG_SPEED;

	pos.0 += dx * speed;
	pos.1 += dy * speed;
};