import { createI18n } from 'vue-i18n';
import bootstrapZh from './bootstrap-zh-CN';

export const LOCALE_OPTIONS = [
  { label: '中文', value: 'zh-CN' },
  { label: 'English', value: 'en-US' },
];

const defaultLocale = localStorage.getItem('arco-locale') || 'zh-CN';

const fullLocaleLoaded = new Set<string>(['zh-CN-bootstrap']);

const i18n = createI18n({
  locale: defaultLocale === 'en-US' ? 'zh-CN' : defaultLocale,
  fallbackLocale: 'zh-CN',
  legacy: false,
  allowComposition: true,
  messages: {
    'zh-CN': bootstrapZh,
  },
  silentTranslationWarn: true,
  missingWarn: false,
  fallbackWarn: false,
});

async function loadBootstrapEn() {
  if (fullLocaleLoaded.has('en-US-bootstrap')) return;
  const mod = await import('./bootstrap-en-US');
  i18n.global.setLocaleMessage('en-US', mod.default);
  fullLocaleLoaded.add('en-US-bootstrap');
}

/** 按需加载完整业务语言包（进系统前调用） */
export async function ensureFullLocaleMessages(
  locale: string = i18n.global.locale.value,
): Promise<void> {
  const key = `${locale}-full`;
  if (fullLocaleLoaded.has(key)) return;

  if (locale === 'zh-CN') {
    const mod = await import('./zh-CN');
    i18n.global.setLocaleMessage('zh-CN', mod.default);
    fullLocaleLoaded.add(key);
    return;
  }

  if (locale === 'en-US') {
    await loadBootstrapEn();
    const mod = await import('./en-US');
    i18n.global.setLocaleMessage('en-US', mod.default);
    fullLocaleLoaded.add(key);
  }
}

/** 登录页切换语言：优先轻量包，后台补全量 */
export async function ensureLocaleMessages(locale: string): Promise<void> {
  if (locale === 'zh-CN') {
    // 已有 bootstrap；若已进过系统则已是 full
    return;
  }
  if (locale === 'en-US') {
    if (fullLocaleLoaded.has('en-US-full')) return;
    await loadBootstrapEn();
    // 后台拉全量，不堵切换
    void ensureFullLocaleMessages('en-US');
  }
}

/** 启动时若偏好英文，先加载英文轻量包再切语言 */
export async function initPreferredLocale(): Promise<void> {
  if (defaultLocale !== 'en-US') return;
  await loadBootstrapEn();
  i18n.global.locale.value = 'en-US';
}

export default i18n;