export interface TokenOptions {
    clientId: string;
    clientSecret: string;
    tokenUrl?: string;
    scope?: string;
    expirationBuffer?: number;
}
export interface TokenResponse {
    access_token: string;
    expires_in: number;
    token_type: string;
}
export declare class TokenManager {
    private tokenUrl;
    private clientId;
    private clientSecret;
    private scope;
    private expirationBuffer;
    private currentToken;
    private expiresAt;
    private isRefreshing;
    private refreshPromise;
    constructor(options: TokenOptions);
    /**
     * get a valid access token
     * if the token does not exist or has expired or is about to expire, get a new token
     */
    getToken(): Promise<string>;
    /**
     * get a new access token
     */
    private fetchNewToken;
    /**
     * 토큰을 강제로 갱신합니다.
     * force refresh the token
     */
    refreshToken(): Promise<string>;
    /**
     * 현재 토큰의 만료 시간을 확인합니다.
     * check the expiration time of the current token
     */
    getTokenExpiresAt(): number;
    /**
     * 토큰이 유효한지 확인합니다.
     * check if the token is valid
     */
    isTokenValid(): boolean;
}