"use client";

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

import enCommon from "./locales/en/common.json";
import enEntry from "./locales/en/entry.json";
import enLayout from "./locales/en/layout.json";
import enPlayer from "./locales/en/player.json";
import neCommon from "./locales/ne/common.json";
import neEntry from "./locales/ne/entry.json";
import neLayout from "./locales/ne/layout.json";
import nePlayer from "./locales/ne/player.json";
import zhCommon from "./locales/zh/common.json";
import zhEntry from "./locales/zh/entry.json";
import zhLayout from "./locales/zh/layout.json";
import zhPlayer from "./locales/zh/player.json";
import {
  DEFAULT_LANGUAGE,
  normalizeLanguage,
  type AppLanguage,
} from "@/i18n/language";
export {
  DEFAULT_LANGUAGE,
  normalizeLanguage,
  SUPPORTED_LANGUAGES,
  type AppLanguage,
} from "@/i18n/language";

const namespaces = ["common", "entry", "layout", "player"] as const;

const resources = {
  en: {
    common: enCommon,
    entry: enEntry,
    layout: enLayout,
    player: enPlayer,
  },
  ne: {
    common: neCommon,
    entry: neEntry,
    layout: neLayout,
    player: nePlayer,
  },
  zh: {
    common: zhCommon,
    entry: zhEntry,
    layout: zhLayout,
    player: zhPlayer,
  },
} satisfies Record<
  AppLanguage,
  Record<(typeof namespaces)[number], Record<string, unknown>>
>;

export function syncDocumentLanguage(lang: AppLanguage): void {
  if (typeof document === "undefined") return;

  document.documentElement.lang = lang;
}

export function syncPreferredLanguage(): void {
  if (typeof window === "undefined") return;

  const stored = window.localStorage.getItem("i18nextLng");
  const preferred = normalizeLanguage(stored ?? window.navigator.language);
  const current = normalizeLanguage(i18n.resolvedLanguage ?? i18n.language);

  if (preferred !== current) {
    void i18n.changeLanguage(preferred);
  }
}

if (!i18n.isInitialized) {
  i18n.use(initReactI18next).init({
    resources,
    fallbackLng: DEFAULT_LANGUAGE,
    supportedLngs: ["en", "ne", "zh"],
    defaultNS: "common",
    ns: [...namespaces],
    /** 与 SSR 一致：首屏固定默认语言，hydration 后再由 syncPreferredLanguage 切换 */
    load: "languageOnly",
    lng: DEFAULT_LANGUAGE,
    initAsync: false,

    interpolation: {
      escapeValue: false,
    },

    react: {
      useSuspense: false,
    },
  });

  syncDocumentLanguage(normalizeLanguage(i18n.resolvedLanguage ?? i18n.language));

  i18n.on("languageChanged", (lang) => {
    const next = normalizeLanguage(lang);
    syncDocumentLanguage(next);

    if (typeof window !== "undefined") {
      window.localStorage.setItem("i18nextLng", next);
    }
  });
}

export default i18n;