import memoizeOne from 'memoize-one'
import { defaultLocale } from './locale'

// IE11 does not have navigator.language
interface NavigatorCompatible extends Navigator {
  userLanguage?: string
}

const getUserLocaleUnmemoized = (): string => {
  const navigator = window.navigator as NavigatorCompatible
  if (navigator) {
    if (navigator.language && typeof navigator.language === 'string') {
      return navigator.language
    }

    // IE11
    if (navigator.userLanguage && typeof navigator.userLanguage === 'string') {
      return navigator.userLanguage
    }
  }

  return defaultLocale
}
export const getUserLocale = memoizeOne(getUserLocaleUnmemoized)

const getUserLanguageCodeUnmemoized = (): string => {
  const locale = getUserLocale()
  const [languageCode] = locale.split('-')

  return languageCode
}
export const getUserLanguageCode = memoizeOne(getUserLanguageCodeUnmemoized)

const getTimezoneUnmemoized = () =>
  Intl.DateTimeFormat().resolvedOptions().timeZone
export const getTimezone = memoizeOne(getTimezoneUnmemoized)