session-desktop/ts/node/locale.ts

import fs from 'fs';
import _ from 'lodash';
import path from 'path';
import type { LocalizerDictionary } from '../types/Localizer';
import { getAppRootPath } from './getRootPath';

function normalizeLocaleName(locale: string) {
  const dashedLocale = locale.replaceAll('_', '-');

  // Note: this is a pain, but we somehow needs to keep in sync this logic and the LOCALE_PATH_MAPPING from
  // https://github.com/oxen-io/session-shared-scripts/blob/main/crowdin/generate_desktop_strings.py
  // What we do, is keep as is, anything given in LOCALE_PATH_MAPPING, but otherwise, keep only the first part of the locale.
  // So `es-419` is allowed, but `es-es` is hardcoded to es, fr_FR is hardcoded to fr, and so on.
  if (
    /^es-419/.test(dashedLocale) ||
    /^hy-AM/.test(dashedLocale) ||
    /^kmr-TR/.test(dashedLocale) ||
    /^pt-BR/.test(dashedLocale) ||
    /^pt-PT/.test(dashedLocale) ||
    /^zh-CN/.test(dashedLocale) ||
    /^zh-TW/.test(dashedLocale)
  ) {
    return dashedLocale;
  }
  const firstDash = dashedLocale.indexOf('-');
  if (firstDash > 0) {
    return dashedLocale.slice(0, firstDash);
  }
  return dashedLocale;
}

function getLocaleMessages(locale: string): LocalizerDictionary {
  if (locale.includes('_')) {
    throw new Error(
      "getLocaleMessages: expected locale to not have a '_' in it. Those should have been replaced to -"
    );
  }

  const targetFile = path.join(getAppRootPath(), '_locales', locale, 'messages.json');

  return JSON.parse(fs.readFileSync(targetFile, 'utf-8'));
}

export function load({ appLocale, logger }: { appLocale?: string; logger?: any } = {}): {
  name: string;
  messages: LocalizerDictionary;
} {
  if (!appLocale) {
    throw new TypeError('`appLocale` is required');
  }

  if (!logger || !logger.error) {
    throw new TypeError('`logger.error` is required');
  }

  const english = getLocaleMessages('en');
  const normalizedLocaleName = normalizeLocaleName(appLocale);

  try {
    // Load locale - if we can't load messages for the current locale, we
    // default to 'en'
    //
    // possible locales:
    // https://github.com/electron/electron/blob/master/docs/api/locales.md

    // We start with english, then overwrite that with anything present in locale
    const messages = _.merge(english, getLocaleMessages(normalizedLocaleName));
    return {
      name: normalizedLocaleName,
      messages,
    };
  } catch (e) {
    logger.error(`Problem loading messages for locale ${normalizedLocaleName} ${e.stack}`);
    logger.error('Falling back to en locale');

    return {
      name: 'en',
      messages: english,
    };
  }
}