// ─────────────────────────────────────────────────────────────────────────────
// i18n.ts — i18next configuration
//
// Import this file once at the application entry point (main.tsx) BEFORE any
// component is rendered. The side-effect initializes i18next synchronously so
// that `useTranslation()` is ready on first render.
//
// Locale layout (split for maintainability — merged at boot into a single
// `translation` namespace so all existing `t('home.welcome')`-style calls
// keep working without changes):
//
//   locales/<lang>/{common,nav,errors,languageSelector,themeToggle}.json
//   locales/<lang>/pages/{home,templates,login,resetPassword,verifyEmail}.json
//   locales/<lang>/components/{assistant,sidebar,media,projectCard,
//                              profileCard,notificationCard,activityCard,
//                              stats,team}.json
//
// The chunks for each language are gathered via `import.meta.glob` (resolved
// statically at build time by Vite — no runtime fetch, fully tree-shakable),
// so adding a new JSON file under `locales/<lang>/...` is picked up
// automatically without touching this file.
//
// Adding a language — three options:
//
// Option A) Drop-in via LanguageProvider (recommended for app consumers):
//   <LanguageProvider availableLanguages={[
//     ...DEFAULT_LANGUAGES,
//     { code: 'fr', label: 'Français', resources: frJson },
//   ]}>
//   The provider calls i18n.addResourceBundle() automatically.
//
// Option B) Manual registration via the helper exported below:
//   import { registerLanguageResource } from 'xertica-ui';
//   registerLanguageResource('fr', frJson);
//
// Option C) Add it here statically (only for the library itself):
//   1. Create the new locales/<code>/ folder (mirror an existing language)
//   2. Add one more `import.meta.glob` call below + an entry in `resources`.
// ─────────────────────────────────────────────────────────────────────────────

import i18n from 'i18next';
import { initReactI18next } from 'react-i18next';

// ─────────────────────────────────────────────────────────────────────────────
// Build a single { key: contents } bundle from a Vite glob result.
//
// Input  (Vite glob output): { './locales/pt-BR/common.json': {...},
//                              './locales/pt-BR/pages/home.json': {...},
//                              './locales/pt-BR/components/assistant.json': {...},
//                              ... }
// Output (bundle for i18n) : { common: {...}, home: {...}, assistant: {...}, ... }
//
// Keys are derived from the file basename — folder (pages/components) is
// discarded because the legacy flat JSON had a single namespace.
// ─────────────────────────────────────────────────────────────────────────────
function bundleLang(chunks: Record<string, unknown>): Record<string, unknown> {
  const out: Record<string, unknown> = {};
  for (const [filePath, value] of Object.entries(chunks)) {
    const base = filePath.split('/').pop();
    if (!base) continue;
    const key = base.replace(/\.json$/, '');
    out[key] = value;
  }
  return out;
}

// `import.meta.glob` requires a literal pattern — we expand it once per
// language. `eager: true` inlines the JSON at build time. `import: 'default'`
// returns the JSON value directly instead of `{ default: ... }`.
const ptBR = bundleLang(
  import.meta.glob('./locales/pt-BR/**/*.json', { eager: true, import: 'default' })
);
const en = bundleLang(
  import.meta.glob('./locales/en/**/*.json', { eager: true, import: 'default' })
);
const es = bundleLang(
  import.meta.glob('./locales/es/**/*.json', { eager: true, import: 'default' })
);

const STORAGE_KEY = 'xertica_language';
const DEFAULT_FALLBACK = 'pt-BR';

const savedLanguage =
  typeof window !== 'undefined'
    ? (localStorage.getItem(STORAGE_KEY) ?? DEFAULT_FALLBACK)
    : DEFAULT_FALLBACK;

i18n.use(initReactI18next).init({
  resources: {
    'pt-BR': { translation: ptBR },
    en: { translation: en },
    es: { translation: es },
  },
  lng: savedLanguage,
  fallbackLng: DEFAULT_FALLBACK,
  interpolation: {
    // React already escapes values — no need for i18next to double-escape
    escapeValue: false,
  },
});

/**
 * Register an additional locale at runtime. Useful when an app wants to add a
 * language without editing the i18n.ts file itself. Safe to call multiple
 * times — a bundle is only added the first time it appears for a given
 * `(code, namespace)` pair.
 *
 * @param code   BCP-47 language code (e.g. `'fr'`, `'ja'`, `'pt-PT'`)
 * @param json   Translation object — same shape as the bundled `<lang>` object
 *               above (top-level keys `common`, `nav`, `home`, etc.)
 * @param ns     Translation namespace (defaults to `'translation'`, which is
 *               the only namespace used by Xertica UI)
 */
export function registerLanguageResource(
  code: string,
  json: Record<string, unknown>,
  ns: string = 'translation'
): void {
  if (!i18n.hasResourceBundle(code, ns)) {
    i18n.addResourceBundle(code, ns, json, true, true);
  }
}

export default i18n;