type ExtractArgs<T extends object> = T[keyof T] extends (...args: infer A) => any ? A : any[];
type EventState<T extends object, Args extends unknown[] = ExtractArgs<T>> = T & {
    (key?: keyof T, fun?: T[keyof T]): EventState<T, Args>;
    (target?: Partial<T>): EventState<T, Args>;
};

interface OnlineState {
    snapshot: [OnlineState];
    online: boolean;
    callback(): void;
    change(): void;
    mount(): void;
    clean(): void;
}
type OnlineArg = Partial<OnlineState> | OnlineState['change'];

declare const onlineEvent: () => EventState<OnlineState>;

export { type OnlineArg, type OnlineState, onlineEvent };