feat: init

i18n/server.ts

@@ -0,0 +1,29 @@
+import '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 = (): Locale => {
+  // @ts-expect-error locales are readonly
+  const locales: string[] = i18n.locales
+
+  let languages: string[] | undefined
+  // get locale from cookie
+  const localeCookie = 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> = {}
+    headers().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
+}