import { refreshAccessToken } from '@/lib/api/auth';

let inFlight: Promise<boolean> | null = null;

/**
 * 并发 401 时共享同一次 refresh，避免重复 POST /oauth/token。
 * refresh 失败会清空 token（由调用方传入的 setTokens 执行）。
 */
export function refreshTokensShared(
  getRefreshToken: () => string | null,
  setTokens: (access: string | null, refresh: string | null) => void
): Promise<boolean> {
  if (inFlight) {
    return inFlight;
  }
  inFlight = (async () => {
    try {
      const rt = getRefreshToken();
      if (!rt) {
        return false;
      }
      const pair = await refreshAccessToken(rt);
      setTokens(pair.accessToken, pair.refreshToken);
      return true;
    } catch {
      setTokens(null, null);
      return false;
    } finally {
      inFlight = null;
    }
  })();
  return inFlight;
}