/** Compare the address players enter in Minecraft; never resolve DNS aliases. */
export function normalizeServerAddress(
  value: string | null | undefined,
): string | null {
  const input = value?.trim().toLowerCase();
  if (!input) return null;
  if (input.length > 255) throw new Error("Server address is too long");
  const match = /^(\[[0-9a-f:]+\]|[a-z0-9.-]+)(?::([0-9]{1,5}))?$/.exec(input);
  if (!match)
    throw new Error("Use a Minecraft hostname or IP, with an optional port");
  let host = match[1];
  if (host.startsWith("[")) {
    try {
      new URL(`http://${host}`);
    } catch {
      throw new Error("Invalid IPv6 address");
    }
  } else {
    host = host.replace(/\.$/, "");
    if (
      host.length > 253 ||
      host
        .split(".")
        .some((label) => !/^[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?$/.test(label))
    )
      throw new Error("Invalid server hostname");
  }
  const port = match[2] ? Number(match[2]) : 25565;
  if (port < 1 || port > 65535)
    throw new Error("Server port must be between 1 and 65535");
  return host + (port === 25565 ? "" : `:${port}`);
}