/** @file Run real workerd processes for tests. */
import { spawn } from "node:child_process";
import { rm } from "node:fs/promises";
import { connect, createServer } from "node:net";
import { join } from "node:path";

export const here = new URL("..", import.meta.url).pathname;
// the package binary, not the .bin shim: the shim forks it, so a kill would orphan workerd
const workerd = join(here, "node_modules/workerd/bin/workerd");

export const freePort = () =>
	new Promise((resolve) => {
		const s = createServer().listen(0, "127.0.0.1", () => {
			const { port } = s.address();
			s.close(() => resolve(port));
		});
	});

/** Resolves once something accepts connections at `opts` (a port or a socket path). */
export const accepting = (opts) =>
	new Promise((resolve) => {
		const s = connect(opts, () => (s.end(), resolve(true)));
		s.on("error", () => resolve(false));
	});

/**
 * Run workerd on `config` until `stop()`; resolves once `listening` accepts.
 *
 * @param {string} config
 * @param {string[]} args socket, directory, and external overrides
 * @param {{ port: number } | { path: string }} listening
 * @param {string[]} stale socket files a crash leaves behind; bind() would fail on them
 */
export const startWorkerd = async (config, args, listening, stale = []) => {
	for (const f of stale) await rm(f, { force: true });
	const child = spawn(workerd, ["serve", "--experimental", join(here, config), ...args], {
		stdio: ["ignore", process.env.WORKERD_LOG ? "inherit" : "ignore", "pipe"],
	});
	let log = "";
	// WORKERD_LOG=1 echoes workerd's stderr, for debugging
	child.stderr.on("data", (c) => (process.env.WORKERD_LOG ? process.stderr.write(c) : (log += c)));
	const exited = new Promise((resolve) => child.on("exit", resolve));
	for (let i = 0; i < 100; i++) {
		// SIGKILL: a crash is the harder durability test
		if (await accepting(listening)) return { stop: () => (child.kill("SIGKILL"), exited) };
		await new Promise((r) => setTimeout(r, 50));
	}
	child.kill("SIGKILL");
	throw new Error(`workerd did not start: ${log}`);
};