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31import 'server-only'
import { cookies, headers } from 'next/headers'
import Negotiator from 'negotiator'
import { match } from '@formatjs/intl-localematcher'
import type { Locale } from '.'
import { i18n } from '.'
export const getLocaleOnServer = async (): Promise<Locale> => {
// @ts-expect-error locales are readonly
const locales: string[] = i18n.locales
let languages: string[] | undefined
// get locale from cookie
const localeCookie = (await cookies()).get('locale')
languages = localeCookie?.value ? [localeCookie.value] : []
if (!languages.length) {
// Negotiator expects plain object so we need to transform headers
const negotiatorHeaders: Record<string, string> = {}
const headersList = await headers()
headersList.forEach((value, key) => (negotiatorHeaders[key] = value))
// Use negotiator and intl-localematcher to get best locale
languages = new Negotiator({ headers: negotiatorHeaders }).languages()
}
// match locale
const matchedLocale = match(languages, locales, i18n.defaultLocale) as Locale
return matchedLocale
}