// List of domains that are not supported as primary domains (trying to prevent long running syncs for now)
const UNSUPPORTED_DOMAINS = ["app.bsky"];

export function validateDomain(domain: string): string | null {
  const trimmedDomain = domain.trim();

  if (!trimmedDomain || trimmedDomain.length === 0) {
    return "Domain is required";
  }

  if (UNSUPPORTED_DOMAINS.includes(trimmedDomain)) {
    return `The domain '${trimmedDomain}' is not supported`;
  }

  // Domain must have at least two parts (e.g. social.grain)
  if (!trimmedDomain.includes(".")) {
    return "Domain must have at least two parts (e.g. social.grain)";
  }

  // Validate domain format
  const domainRegex =
    /^[a-zA-Z0-9]([a-zA-Z0-9-]*[a-zA-Z0-9])?(\.[a-zA-Z0-9]([a-zA-Z0-9-]*[a-zA-Z0-9])?)+$/;
  if (!domainRegex.test(trimmedDomain)) {
    return "Domain must be a valid format (e.g. social.grain)";
  }

  return null; // Valid
}

// Function to get the list of unsupported domains (for debugging/admin purposes)
export function getUnsupportedDomains(): readonly string[] {
  return UNSUPPORTED_DOMAINS;
}