import { KiotVietClientConfig } from '../types';
export declare class TokenManager {
    private config;
    private _accessToken;
    private _tokenExpiresAt;
    private _isFetchingToken;
    private _tokenPromise;
    constructor(config: KiotVietClientConfig);
    getValidToken(): Promise<string>;
    refreshToken(): Promise<string>;
    private fetchNewToken;
}