fix domain

apps/course/views/course.py

@@ -334,7 +334,7 @@ class CourseOnlineClassTokenAPIView(GenericAPIView):
         })
 
         redirect_path = serializer.validated_data.get('redirect_path')
-        base_url = self._build_base_url(redirect_path)
+        base_url = self._build_base_url(request, redirect_path)
         entry_url = manager.build_entry_url(token, base_url=base_url)
 
         return Response({
@@ -343,12 +343,13 @@ class CourseOnlineClassTokenAPIView(GenericAPIView):
             'expires_in': getattr(settings, 'ONLINE_CLASS_TOKEN_TTL', 300),
         }, status=status.HTTP_201_CREATED)
 
-    def _build_base_url(self, redirect_path=None) -> str:
-        domain = getattr(settings, 'ONLINE_CLASS_FRONTEND_DOMAIN', getattr(settings, 'SITE_DOMAIN', '')).rstrip('/')
-        if redirect_path:
-            sanitized = redirect_path.strip('/')
-            return f"{domain}/{sanitized}" if domain else f"/{sanitized}"
-        return domain
+    def _build_base_url(self, request, redirect_path=None) -> str:
+        base_uri = request.build_absolute_uri('/')
+        domain = base_uri.rstrip('/')
+        default_path = getattr(settings, 'ONLINE_CLASS_DEFAULT_PATH', 'join-class')
+        target_path = redirect_path or default_path
+        sanitized = str(target_path).strip('/')
+        return f"{domain}/{sanitized}" if sanitized else domain
 
     @staticmethod
     def _user_has_access(user, course: Course) -> bool: