import type { Predicate, Static } from '../types'
import { isObjectLike } from '../predicates/isObjectLike'

export const at =
  <K extends PropertyKey, T extends Predicate<any>>(key: K, predicate: T) =>
  (value: unknown): value is StaticAt<K, T> =>
    isObjectLike(value) && predicate(value[key])

type StaticAt<K extends PropertyKey, T extends Predicate<any>> = Extract<
  Static<T>,
  undefined
> extends never
  ? { [P in K]: Static<T> }
  : { [P in K]?: Static<T> }