import { IAccessToken, IAccessTokenProvider, ITokenContext } from './interfaces';
import { GetJwtCallback, Jwt } from '../Jwt';
/**
 * Implementation of {@link IAccessTokenProvider} that caches the JWT
 * in memory while it's fresh (i.e. not expired) and uses the user-provided
 * callback function to get the JWT when requested by the clients.
 */
export declare class CachingJwtProvider implements IAccessTokenProvider {
    private cachedJwt?;
    private readonly getJwt;
    private jwtPromise?;
    /**
     * Creates a new instance of `CachingJwtProvider`.
     * @param {GetJwtCallback} renewJwtFn - The function that will be called
     * whenever the fresh JWT is needed. If the `renewJwtFn` returns the JWT
     * as a string, it will be converted to {@link Jwt} instance automatically.
     * @param {Jwt|string} [initialToken] - Optional initial JWT.
     */
    constructor(renewJwtFn: GetJwtCallback, initialToken?: Jwt | string);
    /**
     * Returns a `Promise` resolved with the cached token if it's fresh, or the
     * token obtained by the call to the `renewJwtCallback` otherwise. The token
     * obtained from the `renewJwtCallback` is then cached. If the `renewJwtCallback`
     * returns the JWT as a string, it is converted to {@link Jwt} instance before returning.
     * @param {ITokenContext} context
     * @returns {Promise<IAccessToken>}
     */
    getToken(context: ITokenContext): Promise<IAccessToken>;
}