Desktop/scripts/gen-locales-config.mjs

// Copyright 2023 Signal Messenger, LLC
// SPDX-License-Identifier: AGPL-3.0-only
// @ts-check
import fs from 'node:fs/promises';
import path from 'node:path';
import fastGlob from 'fast-glob';
import * as LocaleMatcher from '@formatjs/intl-localematcher';

const ROOT_DIR = path.join(import.meta.dirname, '..');

/**
 * @param {string} input
 * @param {string} expected
 */
function matches(input, expected) {
  const match = LocaleMatcher.match([input], [expected], 'en', {
    algorithm: 'best fit',
  });
  return match === expected;
}

const dirEntries = await fastGlob('_locales/*', {
  cwd: ROOT_DIR,
  onlyDirectories: true,
});

const localeDirNames = [];

for (const dirEntry of dirEntries) {
  const dirName = path.basename(dirEntry);
  const locale = new Intl.Locale(dirName);

  // Smartling doesn't always use the correct language tag, so this check and
  // reverse check are to make sure we don't accidentally add a locale that
  // doesn't match its directory name (using LocaleMatcher).
  //
  // If this check ever fails, we may need to update our get-strings script to
  // manually rename language tags before writing them to disk.
  //
  // Such is the case for Smartling's "zh-YU" locale, which we renamed to
  // "yue" to match the language tag used by... everyone else.

  if (!matches(dirName, locale.baseName)) {
    throw new Error(
      `Matched locale "${dirName}" does not match its resolved name "${locale.baseName}"`
    );
  }
  if (!matches(locale.baseName, dirName)) {
    throw new Error(
      `Matched locale "${dirName}" does not match its dir name "${dirName}"`
    );
  }

  localeDirNames.push(dirName);
}

const jsonPath = path.join(ROOT_DIR, 'build', 'available-locales.json');
console.log(`Writing to "${jsonPath}"...`);
await fs.writeFile(jsonPath, `${JSON.stringify(localeDirNames, null, 2)}\n`);