import { Netmask } from 'netmask';
import { TokenBucket } from './tokenBucket';
import { TokenStorageEngine } from './tokenTable';
export declare type Maybe<T> = T | undefined;
export declare const hasValues: (ip: boolean | undefined, xff: boolean | undefined, user: boolean | undefined) => boolean;
export declare const isNetBlock: (mask: Netmask) => boolean;
export declare const handleNetmasks: (overrides: any) => any;
export interface Overrides {
    [key: string]: BaseConfiguration;
}
export interface BaseConfiguration {
    burst: number;
    rate: number;
    ip?: boolean;
    user?: boolean;
    xff?: boolean;
    block?: any;
}
export declare type Configuration = BaseConfiguration & {
    tokensTable?: TokenStorageEngine<TokenBucket>;
    maxKeys?: number;
    message?: string;
    overrides?: Overrides;
};
/**
 * Express middleware that requires an Options object containing
 * at least a burst and rate property.
 *
 * @example
 * throttle({
 *   burst: 10,
 *   rate: 1,
 *   ip: true,
 * })
 *
 * @param {Configuration} options
 * @returns {*}
 */
declare const slowDown: (config: Configuration) => any;
export default slowDown;