askirmas / react-classnaming

import { EMPTY_ARRAY } from "./consts"

import type { ClassValue, Falsy } from "./defs"

const {keys: $keys} = Object

export {

  truthyKeys,

  dehash,

  joinWithLead

}

function dehash<K extends string>(source: Record<K, unknown>, keys: string[] = $keys(source)) :string[] {

  for (let i = keys.length; i--;) {

    const key = keys[i] as K

    , value = source[key]

    if (typeof value === "string")

      keys[i] = value

  }

  return keys

}

//TODO TS is not working interesting

function truthyKeys<T>(source: Falsy) :T[];

function truthyKeys<T extends Record<string, unknown>>(source: Readonly<T>): (

  {[K in keyof typeof source]: typeof source[K] extends Falsy ? never : K}[keyof typeof source]

)[];

function truthyKeys<T>(source: T): [T];

function truthyKeys<T>(source: T) {

  if (source === null || typeof source !== "object")

    return source

    ? [source]

    : EMPTY_ARRAY

  const filtered = (

    $keys(source) as (keyof T)[]

  )

  //TODO consider `delete` and further `flat` in case of perf

  .filter(key => source[key])

  return filtered

}

//TODO Consider undefined

function joinWithLead(value: Falsy|ClassValue, arr: readonly string[]) :string {

  const str1 = value || ""

  if (!arr.length)

    return str1

  const str2  = arr.join(" ")

  if (!str1)

    return str2

  return `${str1} ${str2}`

}