Initial commit: teaching institution management API.

Express/MongoDB backend with JWT auth, RBAC, S3 uploads, notifications, and scheduled jobs.

utils/errorLocalization.js

@@ -0,0 +1,28 @@
+// /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
+};