import dns from "node:dns";

/**
 * Node-only：强制优先 / 仅用 IPv4，避免 Cloudflare AAAA ENETUNREACH
 * 与 Happy Eyeballs 并行试 IPv6 时刷 AggregateError。
 */
dns.setDefaultResultOrder("ipv4first");

const nativeLookup = dns.lookup.bind(dns) as (
  hostname: string,
  options?: unknown,
  callback?: unknown,
) => unknown;

// dns.lookup 重载签名在不同 @types/node 版本间不一致，这里按运行时重载包装。
dns.lookup = ((hostname: string, options?: unknown, callback?: unknown) => {
  if (typeof options === "function") {
    return nativeLookup(hostname, { family: 4 }, options);
  }
  if (typeof callback === "function") {
    const opts =
      typeof options === "number"
        ? { family: 4 }
        : { ...(options as object | undefined), family: 4 };
    return nativeLookup(hostname, opts, callback);
  }
  const opts =
    typeof options === "number"
      ? { family: 4 }
      : { ...(options as object | undefined), family: 4 };
  return nativeLookup(hostname, opts);
}) as typeof dns.lookup;