import type { MachinatChannel, MachinatUser } from '../types';
export interface StateAccessor {
    /**
     * Fetch the value of a specific key. Return `undefined` if no value is
     * stored.
     */
    get<T>(key: string): Promise<undefined | T>;
    /**
     * Store the value on a specific key. Return `true` if the old value is
     * updated, `false` if it's newly stored on the key.
     */
    set<T>(key: string, value: T): Promise<boolean>;
    /**
     * Update the value of a specific key by an undator funcction. The updator
     * receives the original value (`undefined` if not existed) and return the new
     * value. Depends on the new value, 3 kinds of action will be executed:
     * - `undefined`; delete the data on the key.
     * - original value (compared with `===`); no changes.
     * - any other value; the new value will be stored.
     */
    update<T>(key: string, updator: (state: undefined | T) => T): Promise<T>;
    update<T>(key: string, updator: (state: undefined | T) => undefined | T): Promise<undefined | T>;
    delete(key: string): Promise<boolean>;
    keys(): Promise<string[]>;
    getAll<T>(): Promise<Map<string, T>>;
    clear(): Promise<undefined | number>;
}
/**
 * @category Base
 */
export interface BaseStateController {
    /**
     * Return the {@link StateAccessor} of a channel
     */
    channelState(
    /** The channel object or uid of the channel */
    channel: string | MachinatChannel): StateAccessor;
    /**
     * Return the {@link StateAccessor} of a user
     */
    userState(
    /** The user object or uid of the user */
    user: string | MachinatUser): StateAccessor;
    /**
     * Return the {@link StateAccessor} of a global name
     */
    globalState(name: string): StateAccessor;
}
declare const StateControllerI: import("../service").SingularServiceInterface<BaseStateController>;
declare type StateControllerI = BaseStateController;
export default StateControllerI;