import { type Logger } from '@just-web/app';
import { type AnyFunction } from 'type-plus';
import type { Updater } from './types.js';
export type SetStateValue<T> = T | Updater<T>;
/**
 * set or update the state.
 */
export type SetState<T> = <V extends SetStateValue<T> = SetStateValue<T>>(value: V) => V extends AnyFunction<any, Promise<any>> ? Promise<T> : T;
export type StateChangeHandler<T> = (value: T, prev: T) => void;
export type OnStateChange<T> = (handler: StateChangeHandler<T>) => () => void;
export type ResetState = () => void;
export type StateMeta = {
    logger?: Logger;
};
/**
 * creates a functional style state to track changes of a value.
 *
 * @param init initial value T
 * @param meta optional meta data for custom logger.
 * @returns [value: T, set: SetState<T>, onChange: OnStateChange<T>, reset: ResetState]
 *
 * @example
 * ```ts
 * const [value, set, onChange, reset] = app.states.createState(0)
 *
 * value // 0
 * set(1) // value: 1
 * onChange(v => console.log(v)) // trigger when set
 * reset() // reset value to the initial value
 * ```
 */
export declare function createState<T>(init: T, meta?: StateMeta): [value: T, set: SetState<T>, onChange: OnStateChange<T>, reset: ResetState];
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