import Memcached from 'memcached';
import { Store, Options as Options$1, IncrementResponse } from 'express-rate-limit';

/**
 * A memcached client.
 */
type MemcachedClient = {
    get: (key: string, cb: (error: any, data: any) => void) => void;
    set: (key: string, value: any, time: number, cb: (error: any) => void) => void;
    add: (key: string, value: any, time: number, cb: (error: any) => void) => void;
    del: (key: string, cb: (error: any) => void) => void;
    incr: (key: string, amount: number, cb: (error: any) => void) => void;
    decr: (key: string, amount: number, cb: (error: any) => void) => void;
};
/**
 * The configuration options for the store.
 */
type Options = {
    /**
     * The text to prepend to the key.
     */
    prefix: string;
    /**
     * The `memcached` client to use.
     */
    client: MemcachedClient;
    /**
     * A list of memcached server URLs to store the keys in, passed to the default
     * memcached client.
     *
     * Note that the default client is only used if another client is not passed
     * to the store.
     */
    locations: string[];
    /**
     * The configuration to pass to the default client, along with the `locations`.
     */
    config: Memcached.options;
};

/**
 * The promisifed version of the `MemcachedClient`.
 */
type PromisifiedMemcachedClient = {
    get: <T>(key: string) => Promise<T | undefined>;
    set: (key: string, value: any, time: number) => Promise<void>;
    add: (key: string, value: any, time: number) => Promise<void>;
    del: (key: string) => Promise<boolean | undefined>;
    incr: (key: string, amount: number) => Promise<boolean | number>;
    decr: (key: string, amount: number) => Promise<boolean | number>;
};
/**
 * A `Store` for the `express-rate-limit` package that stores hit counts in
 * Memcached.
 */
declare class MemcachedStore implements Store {
    /**
     * The number of seconds to remember a client's requests.
     */
    expiration: number;
    /**
     * The text to prepend to the key.
     */
    prefix: string;
    /**
     * The `memcached` client to use.
     */
    client: MemcachedClient;
    /**
     * The promisifed functions from the `client` object.
     */
    fns: PromisifiedMemcachedClient;
    /**
     * @constructor for `MemcachedStore`.
     *
     * @param options {Options} - The options used to configure the store's behaviour.
     */
    constructor(options?: Partial<Options>);
    /**
     * Method that actually initializes the store.
     *
     * @param options {RateLimitConfiguration} - The options used to setup the middleware.
     *
     * @impl
     */
    init(options: Options$1): void;
    /**
     * Method to prefix the keys with the given text.
     *
     * @param key {string} - The key.
     *
     * @returns {string} - The text + the key.
     */
    prefixKey(key: string): string;
    /**
     * Method that returns the name of the key used to store the reset timestamp
     * for the given key.
     *
     * @param key {string} - The key.
     *
     * @returns {string} - The expiry key's name.
     */
    expiryKey(key: string): string;
    /**
     * Method to increment a client's hit counter.
     *
     * @param key {string} - The identifier for a client.
     *
     * @returns {IncrementResponse} - The number of hits and reset time for that client.
     */
    increment(key: string): Promise<IncrementResponse>;
    /**
     * Method to decrement a client's hit counter.
     *
     * @param key {string} - The identifier for a client
     */
    decrement(key: string): Promise<void>;
    /**
     * Method to reset a client's hit counter.
     *
     * @param key {string} - The identifier for a client.
     */
    resetKey(key: string): Promise<void>;
}

export { MemcachedClient, MemcachedStore, Options };