Compass/web/lib/locale-cookie.ts

import {defaultLocale, Locale, supportedLocales} from 'common/constants'

let cachedLocale: string | null | undefined = null

export const resetCachedLocale = () => {
  cachedLocale = null
}

export function getLocale(): string {
  // req?: IncomingMessage
  if (cachedLocale) return cachedLocale
  // console.log('cachedLocale', cachedLocale)
  let cookie = null
  // Server
  // if (req?.headers?.cookie) {
  //   cookie = req.headers.cookie
  // }

  // Client
  if (typeof document !== 'undefined') {
    cookie = document.cookie
  }

  if (cookie) {
    // console.log('Cookie', cookie)
    cachedLocale = cookie
      .split(' ')
      .find((c) => c.startsWith('lang='))
      ?.split('=')[1]
      ?.split(' ')[0]
      ?.replace(';', '')
    // console.log('Locale cookie', cachedLocale)
  }

  if (!cachedLocale) {
    cachedLocale = getBrowserLocale()
  }

  // console.log('Locale cookie browser', getBrowserLocale())

  return cachedLocale ?? defaultLocale
}

export function getBrowserLocale(): Locale | null {
  if (typeof navigator === 'undefined') return null

  const languages = navigator.languages ?? [navigator.language]
  // console.log('Browser languages', languages, navigator.language)

  for (const lang of languages) {
    const base = lang.split('-')[0] as Locale
    if (supportedLocales.includes(base)) {
      return base
    }
  }

  return null
}