import { useRef } from "react"

/**
 * Creates a constant value over the lifecycle of a component.
 *
 * Even if `useMemo` is provided an empty array as its final argument, it doesn't offer
 * a guarantee that it won't re-run for performance reasons later on. By using `useConstant`
 * you can ensure that initialisers don't execute twice or more.
 */
export function useConst<T extends any | (() => any)>(init: T) {
  const ref = useRef<T | null>(null)

  if (ref.current === null) {
    ref.current = typeof init === "function" ? init() : init
  }

  return ref.current as T
}