import { create } from "zustand";
import { Language } from "@/constant";
import { LOCALE_STORAGE_KEY } from "@/constant/storage";

type LanguageType = (typeof Language)[keyof typeof Language];

type LanguageStore = {
  language: LanguageType;
  setLanguage: (language: LanguageType) => void;
  toggleLanguage: () => void;
};

const getInitialLanguage = (): LanguageType => {
  // Try to get language setting from localStorage
  const savedLanguage = localStorage.getItem(
    LOCALE_STORAGE_KEY
  ) as LanguageType;
  if (savedLanguage && Object.values(Language).includes(savedLanguage)) {
    return savedLanguage;
  }

  // If no valid language setting in localStorage, try to get browser language
  const browserLanguage = navigator.language.toLowerCase();
  if (browserLanguage.startsWith("zh")) {
    return Language.ZH_CN;
  } else if (browserLanguage.startsWith("en")) {
    return Language.EN_US;
  }

  // Default to Chinese
  return Language.ZH_CN;
};

export const useLanguageStore = create<LanguageStore>((set) => ({
  language: getInitialLanguage(),
  setLanguage: (language) => {
    localStorage.setItem(LOCALE_STORAGE_KEY, language);
    set({ language });
  },
  toggleLanguage: () =>
    set((state) => {
      const newLanguage =
        state.language === Language.ZH_CN ? Language.EN_US : Language.ZH_CN;
      localStorage.setItem(LOCALE_STORAGE_KEY, newLanguage);
      return { language: newLanguage };
    }),
}));