loading lingui catalogs server side

i18n.server.ts

import { I18n, Messages, setupI18n } from '@lingui/core';

import { locales } from './lingui-config';

import { log } from '@/lib/log';

export type SupportedLocales = (typeof locales)[number];

type AllI18nInstances = { [K in SupportedLocales]: I18n };

async function loadCatalog(locale: SupportedLocales): Promise<{
  [k: string]: Messages;
}> {
  const { messages } = await import(`@/locales/${locale}/messages.ts`);
  return {
    [locale]: messages,
  };
}

const catalogs = await Promise.all(locales.map(loadCatalog));

const allMessages = catalogs.reduce((acc, oneCatalog) => {
  log('Loaded catalog:', JSON.stringify(oneCatalog).substring(0, 100));
  return { ...acc, ...oneCatalog };
}, {});

const allI18nInstances: AllI18nInstances = locales.reduce((acc, locale) => {
  const messages = allMessages[locale] ?? {};
  const i18n = setupI18n({
    locale,
    messages: { [locale]: messages },
  });
  return { ...acc, [locale]: i18n };
}, {});

export const getI18nInstance = (locale: SupportedLocales): I18n => {
  if (!allI18nInstances[locale]) {
    throw new Error(`No Messages available for locale: ${locale}`);
  }
  return allI18nInstances[locale];
};