/// <reference lib="deno.desktop" />

// the desktop app: the web client in a bundled chromium (deno desktop's cef backend), so people whose browser has no
// webgpu (firefox) can still play. it joins servers like the browser does, and runs its own game server for
// singleplayer, like minecraft java. build it with deno task desktop, see the desktop/ docs for how deno desktop works
import { fromFileUrl, join } from "@std/path";
import { type Host, serve_static, start_host } from "../server/host.ts";

// where the project was built from: build/ and server_mods/ (the .bmod files) are bundled into the app with --include
const ROOT = fromFileUrl(new URL("../", import.meta.url));
const BUILD_DIR = join(ROOT, "build");

// the server the address field starts with. "" leaves it empty for the player to fill in
const config: { server?: string } = JSON.parse(
	await Deno.readTextFile(new URL("./config.json", import.meta.url)),
);
const default_server = Deno.env.get("BWORLD_SERVER") ?? config.server ?? "";

const win = new Deno.BrowserWindow({ title: "bworld", width: 1280, height: 720 });

// the singleplayer game server, started the first time singleplayer connects so players who only join other servers
// don't get a world made for them. it plays the .bmod files the app was built with
let host: Promise<Host> | undefined;

function singleplayer_host(): Promise<Host> {
	host ??= (async () => {
		const worlds = join(data_dir(), "worlds");
		Deno.mkdirSync(worlds, { recursive: true });
		return await start_host({
			build_dir: BUILD_DIR,
			server_mods_dir: join(ROOT, "server_mods"),
			world_file: join(worlds, "world.json"),
			on_fatal(message) {
				console.error(message);
				alert(`The singleplayer world stopped: ${message}`);
				Deno.exit(1);
			},
		});
	})();
	return host;
}

// the world gets saved before the app closes
win.addEventListener("close", async (event) => {
	if (!host) {
		return;
	}
	event.preventDefault();
	try {
		await (await host).shutdown();
	} catch (e) {
		console.error((e as Error).message);
	}
	Deno.exit(0);
});

// deno desktop binds this to a private local address and opens the window on it, the port given here is ignored
Deno.serve(async (req) => {
	const url = new URL(req.url);
	if (url.pathname === "/") {
		// ?server= fills in the address field, without it the field would start with this app's own address.
		// ?singleplayer shows the singleplayer button, which joins this app's own server
		const start = new URL("/client/", url);
		start.searchParams.set("server", default_server);
		start.searchParams.set("singleplayer", "");
		return Response.redirect(start, 302);
	}
	// the singleplayer server's socket and its .bmod downloads
	if (url.pathname === "/ws" || url.pathname.startsWith("/mods/")) {
		try {
			return (await singleplayer_host()).handle(req);
		} catch (e) {
			// its mods have problems, the title screen shows why the connection failed
			console.error((e as Error).message);
			host = undefined;
			return new Response((e as Error).message, { status: 500 });
		}
	}
	return serve_static(BUILD_DIR, req, url);
});

// where the app keeps its worlds, the usual place for app data on each os
function data_dir() {
	const home = Deno.env.get("HOME") ?? Deno.env.get("USERPROFILE") ?? ".";
	switch (Deno.build.os) {
		case "windows":
			return join(Deno.env.get("APPDATA") ?? join(home, "AppData", "Roaming"), "bworld");
		case "darwin":
			return join(home, "Library", "Application Support", "bworld");
		default:
			return join(Deno.env.get("XDG_DATA_HOME") ?? join(home, ".local", "share"), "bworld");
	}
}