Features: 1) Update callback URL to exclude gateway parameter; 2) Process callback using associated transaction's gateway integration class;

Fixes: 1) Remove unused import for `UnknownGatewayError`;

Extra: 1) Cleanup unreachable code and obsolete comments in `CallbackAPIView`.

engine/payments/urls.py

@@ -12,5 +12,5 @@ payment_router.register(prefix=r"transactions", viewset=TransactionViewSet, base
 urlpatterns = [
     path(r"", include(payment_router.urls)),
     path(r"deposit/", DepositView.as_view()),
-    path(r"<str:uuid>/callback/<str:gateway>/", CallbackAPIView.as_view()),
+    path(r"<str:uuid>/callback/", CallbackAPIView.as_view()),
 ]

engine/payments/views.py

@@ -9,7 +9,6 @@ from rest_framework.response import Response
 from rest_framework.views import APIView
 
 from engine.payments.docs.drf.views import DEPOSIT_SCHEMA
-from engine.payments.gateways import UnknownGatewayError
 from engine.payments.models import Transaction
 from engine.payments.serializers import DepositSerializer, TransactionProcessSerializer
 
@@ -72,14 +71,10 @@ class CallbackAPIView(APIView):
 
     def post(self, request: Request, *args: list[Any], **kwargs: dict[Any, Any]) -> Response:
         try:
-            gateway = kwargs.get("gateway", "")
-            # noinspection PyUnreachableCode
-            match gateway:
-                case "gateway":
-                    # Gateway.process_callback(request.data)
-                    return Response(status=status.HTTP_200_OK)
-                case _:
-                    raise UnknownGatewayError(f"Couldn't match '{gateway}' any gateway")
+            transaction = Transaction.objects.get(uuid=kwargs.get("uuid"))
+            gateway = transaction.gateway.get_integration_class_object()
+            gateway.process_callback(request.data)
+            return Response(status=status.HTTP_202_ACCEPTED)
         except Exception as e:
             return Response(
                 status=status.HTTP_500_INTERNAL_SERVER_ERROR, data={"error": f"{e}; {traceback.format_exc()}"}