import { WebSocketServer, WebSocket } from "ws";

const APP_DOWN_ERROR_MESSAGE = "App is currently down";
export const APP_BACK_ALIVE_SIGNAL = "app-back-alive";

const sleep = (time: number) =>
	new Promise((resolve) => {
		setTimeout(resolve, time);
	});

async function get_status(
	app_port: number
): Promise<{ started_at: number; status: string }> {
	const r = await fetch(`http://127.0.0.1:${app_port}/status.json`);
	return (await r.json()) as { started_at: number; status: string };
}

async function wait_for_run_id_to_change(app_port: number) {
	let first_timestamp: number;
	try {
		const { started_at } = await get_status(app_port);
		first_timestamp = started_at;
	} catch (_e) {
		await wait_for_app_to_be_stable(app_port);
		return;
	}

	if (!first_timestamp) {
		throw new Error(APP_DOWN_ERROR_MESSAGE);
	}

	while (true) {
		// eslint-disable-next-line no-await-in-loop
		const { started_at } = await get_status(app_port).catch(() => ({
			started_at: first_timestamp,
		}));
		if (started_at !== first_timestamp) {
			return;
		}
		// eslint-disable-next-line no-await-in-loop
		await sleep(100);
	}
}

async function wait_for_app_to_be_stable(app_port: number, n = 3) {
	// eslint-disable-next-line no-console
	console.log("Waiting for app to be stable....");
	let counter = 0;

	while (true) {
		// eslint-disable-next-line no-await-in-loop
		const { status } = await get_status(app_port).catch(() => ({
			status: "down",
		}));
		if (status == "running") {
			// eslint-disable-next-line no-console
			console.log(counter);
			counter++;
		} else {
			counter = 0;
		}
		if (counter == n) {
			return;
		}
		// eslint-disable-next-line no-await-in-loop
		await sleep(100);
	}
}

let restart_promise: Promise<void> | null = null;

async function wait_for_app_restart(app_port: number) {
	if (restart_promise) {
		return restart_promise;
	}
	try {
		restart_promise = wait_for_run_id_to_change(app_port);
		await restart_promise;
	} catch (e) {
		// eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
		if (e.message !== APP_DOWN_ERROR_MESSAGE) {
			throw e;
		}
	}
	restart_promise = null;
	await wait_for_app_to_be_stable(app_port);
}

export function make_notifier(port: number, app_port: number) {
	const server = new WebSocketServer({
		port,
	});

	let sockets: WebSocket[] = [];
	server.on("connection", function (socket) {
		sockets.push(socket);

		// When a socket closes, or disconnects, remove it from the array.
		socket.on("close", function () {
			sockets = sockets.filter((s) => s !== socket);
		});
	});

	console.info(
		"🔔 Build notifier listening on websocket at port " + port.toString()
	);
	return function notify(message: string) {
		sockets.forEach((s) => s.send(message));
		void wait_for_app_restart(app_port).then(() => {
			sockets.forEach((s) => s.send(APP_BACK_ALIVE_SIGNAL));
		});
	};
}