weseek__growi/apps/app/src/server/service/i18next.ts

import path from 'path';

import type { Lang } from '@growi/core';
import type { InitOptions, TFunction, i18n } from 'i18next';
import { createInstance } from 'i18next';
import resourcesToBackend from 'i18next-resources-to-backend';

import * as i18nextConfig from '^/config/i18next.config';

import { resolveFromRoot } from '~/utils/project-dir-utils';

import { configManager } from './config-manager';


const relativePathToLocalesRoot = path.relative(__dirname, resolveFromRoot('public/static/locales'));

const initI18next = async(overwriteOpts: InitOptions) => {
  const i18nInstance = createInstance();
  await i18nInstance
    .use(
      resourcesToBackend(
        (language: string, namespace: string) => {
          return import(path.join(relativePathToLocalesRoot, language, `${namespace}.json`));
        },
      ),
    )
    .init({
      ...i18nextConfig.initOptions,
      ...overwriteOpts,
    });
  return i18nInstance;
};

type Translation = {
  t: TFunction,
  i18n: i18n
}

type Opts = {
  lang?: Lang,
  ns?: string | readonly string[],
}

export async function getTranslation(opts?: Opts): Promise<Translation> {
  const globalLang = configManager.getConfig('crowi', 'app:globalLang') as Lang;
  const fixedLang = opts?.lang ?? globalLang;

  const initOptions: InitOptions = {
    fallbackLng: [fixedLang, i18nextConfig.defaultLang],
  };

  // set ns if not null
  // cz: 'ns: unefined' causes
  //   TypeError: Cannot read properties of undefined (reading 'forEach')
  //     at /workspace/growi/node_modules/.pnpm/i18next@23.16.5/node_modules/i18next/dist/cjs/i18next.js:1613:18"
  if (opts?.ns != null) {
    initOptions.ns = opts.ns;
  }

  const i18nextInstance = await initI18next(initOptions);

  return {
    t: i18nextInstance.getFixedT(fixedLang, opts?.ns),
    i18n: i18nextInstance,
  };
}