import { HealthCheckResponse, TokenResponsePayload } from './http';
export type ClientOptions = {
    clientId: string;
    clientSecret: string;
    apiHost: string;
    redirectUrl: string;
    useDuoCodeAttribute?: boolean;
};
export declare class Client {
    readonly HEALTH_CHECK_ENDPOINT = "/oauth/v1/health_check";
    readonly AUTHORIZE_ENDPOINT = "/oauth/v1/authorize";
    readonly TOKEN_ENDPOINT = "/oauth/v1/token";
    private clientId;
    private clientSecret;
    private apiHost;
    private baseURL;
    private redirectUrl;
    private useDuoCodeAttribute;
    private axios;
    constructor(options: ClientOptions);
    /**
     * Validate that the clientId and clientSecret are the proper length.
     *
     * @private
     * @param {ClientOptions} options
     * @memberof Client
     */
    private validateInitialConfig;
    /**
     * Retrieves exception message for DuoException from HTTPS result message.
     *
     * @private
     * @param {*} result
     * @returns {string}
     * @memberof Client
     */
    private getExceptionFromResult;
    /**
     * Create client JWT payload
     *
     * @private
     * @param {string} audience
     * @returns {string}
     * @memberof Client
     */
    private createJwtPayload;
    /**
     * Verify JWT token
     *
     * @private
     * @template T
     * @param {string} token
     * @returns {Promise<T>}
     * @memberof Client
     */
    private verifyToken;
    /**
     * Error handler to throw relevant error
     *
     * @private
     * @param {unknown} error
     * @returns {never}
     * @memberof Client
     */
    private handleErrorResponse;
    /**
     * Generate a random hex string with a length of DEFAULT_STATE_LENGTH.
     *
     * @returns {string}
     * @memberof Client
     */
    generateState(): string;
    /**
     * Makes a call to HEALTH_CHECK_ENDPOINT to see if Duo is available.
     *
     * @returns {Promise<HealthCheckResponse>}
     * @memberof Client
     */
    healthCheck(): Promise<HealthCheckResponse>;
    /**
     * Generate URI to redirect to for the Duo prompt.
     *
     * @param {string} username
     * @param {string} state
     * @returns {string}
     * @memberof Client
     */
    createAuthUrl(username: string, state: string): string;
    /**
     * Exchange a code returned by Duo for a token that contains information about the authorization.
     *
     * @param {string} code
     * @param {string} username
     * @param {(string | null)} [nonce=null]
     * @returns {Promise<TokenResponsePayload>}
     * @memberof Client
     */
    exchangeAuthorizationCodeFor2FAResult(code: string, username: string, nonce?: string | null): Promise<TokenResponsePayload>;
}