index.ts

import type {Dispatch, SetStateAction} from 'react';
import {useCallback, useState} from 'react';
import {useSyncedRef} from '../useSyncedRef/index.js';

export function useFunctionalState<S>(initialState: S | (() => S)): [() => S, Dispatch<SetStateAction<S>>];
export function useFunctionalState<S = undefined>(): [() => S | undefined, Dispatch<SetStateAction<S | undefined>>];

/**
 * Like `useState` but instead of raw state, state getter returned.
 */
export function useFunctionalState<S>(
	initialState?: S | (() => S),
): [() => S | undefined, Dispatch<SetStateAction<S | undefined>>] {
	const [state, setState] = useState(initialState);
	const stateRef = useSyncedRef(state);

	// eslint-disable-next-line react-hooks/exhaustive-deps
	return [useCallback(() => stateRef.current, []), setState];
}