/** Errors of the infrastructure itself: waiting is the cure, not skipping. */
const TRANSIENT_NAMES =
  /^(Mongo(Network|NetworkTimeout|ServerSelection|NotConnected|TopologyClosed|PoolCleared)Error|MaxRetriesPerRequestError)$/;
const TRANSIENT_CODES = new Set([
  'ECONNREFUSED',
  'ECONNRESET',
  'ETIMEDOUT',
  'EPIPE',
  'EHOSTUNREACH',
  'ENETUNREACH',
  'ENOTFOUND',
  'EAI_AGAIN',
]);
const TRANSIENT_MESSAGES =
  /connection (is )?closed|connection refused|timed out|getaddrinfo|socket hang up/i;

/**
 * Whether an error comes from a database or the network being down (and
 * will go away by itself) rather than from the event or the code that
 * handles it. Follows `cause`, as drivers wrap the original error.
 */
export function isTransientError(error: unknown): boolean {
  for (let current = error, depth = 0; current && depth < 5; depth++) {
    const e = current as {
      name?: string;
      code?: string;
      message?: string;
      cause?: unknown;
    };
    if (e.name && TRANSIENT_NAMES.test(e.name)) return true;
    if (e.code && TRANSIENT_CODES.has(e.code)) return true;
    if (e.message && TRANSIENT_MESSAGES.test(e.message)) return true;
    current = e.cause;
  }
  return false;
}