import { en } from './locales/en';
import { ko } from './locales/ko';
import { DeepPartial, Language, Strings } from './types';

let currentLang: Language = 'en';
let listeners: Array<() => void> = [];

function deepMerge<T extends object>(...sources: Array<DeepPartial<T>>): T {
  const result: any = {};

  for (const source of sources) {
    for (const key in source) {
      if (Object.prototype.hasOwnProperty.call(source, key)) {
        const value = source[key];
        if (
          value &&
          typeof value === 'object' &&
          !Array.isArray(value) &&
          typeof value !== 'function'
        ) {
          if (!result[key] || typeof result[key] !== 'object') {
            result[key] = {};
          }
          result[key] = deepMerge(result[key], value as any);
        } else {
          result[key] = value;
        }
      }
    }
  }
  return result as T;
}

const dictionaries: Record<Language, Strings> = {
  en: en,
  ko: deepMerge(en, ko) as Strings,
};

export const strings = new Proxy(en, {
  get: (target, prop) => {
    const dict = dictionaries[currentLang];
    return dict[prop as keyof Strings];
  },
});

export const setLanguage = (lang: Language) => {
  if (currentLang !== lang) {
    currentLang = lang;
    if (lang === 'ko') {
      dictionaries.ko = deepMerge(en, ko) as Strings;
    }
    listeners.forEach(l => l());
  }
};

export const getLanguage = () => currentLang;

export const subscribeLanguageChange = (listener: () => void) => {
  listeners.push(listener);
  return () => {
    listeners = listeners.filter(l => l !== listener);
  };
};