// /utils/errorLocalization.js

const errors = require('./errors.json');
const config = require('../config/config');

const resolveLanguage = (req) => {
  if (req && req.query && req.query.lang) {
    const lang = req.query.lang.toLowerCase();
    if (['fa', 'en'].includes(lang)) return lang;
  }
  if (req && req.headers && req.headers['accept-language']) {
    const headerLang = req.headers['accept-language'].toLowerCase();
    if (headerLang.includes('fa')) return 'fa';
    if (headerLang.includes('en')) return 'en';
  }
  return config.DEFAULT_LANG || 'en';
};

const getLocalizedErrorMessage = (errorCode, req = null) => {
  const lang = resolveLanguage(req);
  const errorDef = errors[errorCode] || errors.INTERNAL_SERVER_ERROR;
  return errorDef[lang] || errorDef.en || 'An unexpected error occurred.';
};

module.exports = {
  resolveLanguage,
  getLocalizedErrorMessage
};