import { Alert } from 'react-native';
import { I18nManager } from 'react-native';
import { create } from 'zustand';
import AsyncStorage from '@react-native-async-storage/async-storage';
import i18n from '../lib/i18n';

export type AppLanguage = 'de' | 'en' | 'fr' | 'ar';

const STORAGE_KEY = '@rebreak/language';

type LanguageState = {
  language: AppLanguage;
  setLanguage: (lang: AppLanguage) => Promise<void>;
  init: () => Promise<void>;
};

function applyRTL(lang: AppLanguage) {
  const isRTL = lang === 'ar';
  if (I18nManager.isRTL !== isRTL) {
    I18nManager.forceRTL(isRTL);
    return true;
  }
  return false;
}

export const useLanguageStore = create<LanguageState>((set) => ({
  language: 'en',

  init: async () => {
    const stored = await AsyncStorage.getItem(STORAGE_KEY);
    if (stored === 'de' || stored === 'en' || stored === 'fr' || stored === 'ar') {
      applyRTL(stored);
      await i18n.changeLanguage(stored);
      set({ language: stored });
    } else {
      // Kein expliziter Wert gespeichert — i18n.ts hat bereits via deviceLocale
      // initialisiert (Localization.getLocales()). NICHT auf 'en' overriden.
      const detected =
        i18n.language === 'de'
          ? 'de'
          : i18n.language === 'fr'
            ? 'fr'
            : i18n.language === 'ar'
              ? 'ar'
              : 'en';
      applyRTL(detected as AppLanguage);
      set({ language: detected as AppLanguage });
    }
  },

  setLanguage: async (lang) => {
    await AsyncStorage.setItem(STORAGE_KEY, lang);
    await i18n.changeLanguage(lang);
    set({ language: lang });
    const needsReload = applyRTL(lang);
    if (needsReload) {
      Alert.alert(
        i18n.t('settings.rtl_restart_title'),
        i18n.t('settings.rtl_restart_body'),
      );
    }
  },
}));

// Auto-sync language from session.user.user_metadata.locale beim Sign-In.
// Wenn AsyncStorage @rebreak/language LEER ist (kein explicit user-choice)
// und Server-side metadata.locale gesetzt — silent apply (kein Restart-Alert).
// Respektiert User-Choice: AsyncStorage gewinnt immer wenn gesetzt.
export async function syncLanguageFromUserMetadata(
  user: { user_metadata?: { locale?: string | null } | null } | null,
): Promise<void> {
  if (!user) return;
  const raw = user.user_metadata?.locale;
  if (!raw) return;
  const short = String(raw).split('-')[0].toLowerCase();
  const valid: AppLanguage[] = ['de', 'en', 'fr', 'ar'];
  if (!(valid as readonly string[]).includes(short)) return;
  const lang = short as AppLanguage;

  const stored = await AsyncStorage.getItem(STORAGE_KEY);
  if (stored) return; // explicit user-choice wins

  if (i18n.language === lang) {
    await AsyncStorage.setItem(STORAGE_KEY, lang);
    return;
  }

  await AsyncStorage.setItem(STORAGE_KEY, lang);
  await i18n.changeLanguage(lang);
  applyRTL(lang);
  useLanguageStore.setState({ language: lang });
}