useSet.ts

import {
  useCallback,
  useState,
} from "react"

/**
 * Allows to use a Set as a state more conveniently.
 */
export function useSet<T>(initialValues?: Iterable<T> | null) {
  const [set, setSet] = useState<Set<T>>(new Set(initialValues))

  const add = useCallback((item: T) => {
    setSet((prevSet) => new Set(prevSet).add(item))
  }, [])

  const remove = useCallback((item: T) => {
    setSet((prevSet) => {
      const newSet = new Set(prevSet)
      newSet.delete(item)
      return newSet
    })
  }, [])

  const has = useCallback((item: T) => set.has(item), [set])

  const clear = useCallback(() => setSet(new Set()), [])

  const toggle = useCallback((item: T) => {
    setSet((prevSet) => {
      const newSet = new Set(prevSet)
      if (newSet.has(item)) {
        newSet.delete(item)
      } else {
        newSet.add(item)
      }
      return newSet
    })
  }, [])

  const forEach = useCallback(
    (callback: (item: T) => void) => {
      set.forEach(callback)
    },
    [set]
  )

  const map = useCallback(
    <U>(callback: (item: T) => U): U[] => {
      const result: U[] = []
      set.forEach((item) => result.push(callback(item)))
      return result
    },
    [set]
  )

  const toArray = useCallback(() => Array.from(set), [set])

  const size = set.size
  const isEmpty = size === 0

  return {
    set,
    add,
    remove,
    has,
    clear,
    toggle,
    toArray,
    forEach,
    map,
    size,
    isEmpty
  }
}