packages/cli/src/cli-ui-locale.ts

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import {
  isUiLocalePreference,
  resolveSystemUiLocale,
  resolveUiLocale,
  type UiLocale,
} from '@maka/core/ui-locale';

type CliEnvironment = Readonly<Record<string, string | undefined>>;

export type CliUiLocaleResolution =
  | { readonly ok: true; readonly locale: UiLocale }
  | { readonly ok: false; readonly message: string };

/** Resolve the interactive TUI locale without changing the top-level CLI grammar. */
export function resolveCliUiLocale(environment: CliEnvironment): CliUiLocaleResolution {
  const rawPreference = environment.MAKA_LOCALE?.trim();
  const normalizedPreference = rawPreference?.replaceAll('_', '-').toLowerCase() || 'auto';
  const preference =
    normalizedPreference === 'zh' || normalizedPreference === 'zh-cn'
      ? 'zh-CN'
      : normalizedPreference === 'zh-tw'
        ? 'zh-TW'
        : normalizedPreference;
  if (!isUiLocalePreference(preference)) {
    return {
      ok: false,
      message: `Invalid MAKA_LOCALE ${JSON.stringify(rawPreference)}. Expected zh-CN, zh-TW, en, or auto.`,
    };
  }

  // POSIX locale variables are authorities, not a preference list. Once a
  // higher-priority variable is set, a lower-priority one must not override it.
  const systemLanguage = [environment.LC_ALL, environment.LC_MESSAGES, environment.LANG]
    .map((value) => value?.trim())
    .find((value): value is string => Boolean(value));
  const systemLocale = resolveSystemUiLocale(systemLanguage ? [systemLanguage] : []);
  return { ok: true, locale: resolveUiLocale(preference, systemLocale) };
}