import AsyncStorage from "@react-native-async-storage/async-storage";
import * as Localization from "expo-localization";
import i18n from "i18next";
import { initReactI18next } from "react-i18next";

import en from "./locales/en.json";
import zh from "./locales/zh.json";

const RESOURCES = {
  en: { translation: en },
  zh: { translation: zh },
};

const LANGUAGE_STORAGE_KEY = "user_language_preference";

const initI18n = async () => {
  let savedLanguage = null;
  try {
    savedLanguage = await AsyncStorage.getItem(LANGUAGE_STORAGE_KEY);
  } catch (error) {
    console.warn("Failed to load language preference", error);
  }

  // Get device language (e.g. "en-US" -> "en")
  // Prefer Localization.getLocales()[0].languageCode; fall back to 'en'
  const locales = Localization.getLocales?.() ?? [];
  const deviceLanguageCode = locales[0]?.languageCode ?? "en";

  const languageToUse = savedLanguage || deviceLanguageCode || "en";

  i18n.use(initReactI18next).init({
    resources: RESOURCES,
    lng: languageToUse,
    fallbackLng: "en",
    interpolation: {
      escapeValue: false,
    },
    react: {
      useSuspense: false, // For React Native compatibility
    },
  });
};

initI18n();

export default i18n;

export const changeLanguage = async (lang: string) => {
  try {
    await i18n.changeLanguage(lang);
    await AsyncStorage.setItem(LANGUAGE_STORAGE_KEY, lang);
  } catch (error) {
    console.warn("Failed to change/save language", error);
  }
};