nextjs i18n

intl.ts

import { useRouter } from 'next/router';

export const locales = ['it', 'en'] as const;

export type Locale = typeof locales[number];

export const isLocale = (locale: string): locale is Locale => {
  return (locales as unknown as string[]).includes(locale);
};

export type LocalizedValue<T> = { [key in Locale]: T };

export const useLocale = (): Locale => {
  const router = useRouter();
  return router.locale && isLocale(router.locale) ? router.locale : 'en';
};

export const useIntl = () => {
  const router = useRouter();
  const locale = useLocale();

  const setLocale = (value: string) => {
    if (isLocale(value) && value !== locale) {
      document.cookie = `NEXT_LOCALE=${locale};path=/`;
      router.replace(router.pathname, router.asPath, { locale: value });
    }
  };

  return {
    locale,
    setLocale,
  };
};

export type Txs<
  BaseDef extends Record<string, unknown>,
  Def = { [key in keyof BaseDef]: BaseDef[key] }
> = {
  en: BaseDef;
} & LocalizedValue<Def>;

export const useTxs = <T extends Record<string, unknown>>(txs: Txs<T>): T => {
  const locale = useLocale();
  return txs[locale];
};

export const createTxs = <T extends Record<string, unknown>>(def: Txs<T>) => {
  return () => useTxs(def);
};