feat: enhance error handling and logging in VisioneCompleteView

relying_party/relying_party/visione_views.py

@@ -1,6 +1,7 @@
 import hashlib
 import hmac
 import json
+import logging
 import urllib.error
 import urllib.request
 from urllib.parse import urlencode
@@ -9,6 +10,8 @@ from django.conf import settings
 from django.http import HttpResponseBadRequest, HttpResponseRedirect, HttpResponseServerError
 from django.views import View
 
+logger = logging.getLogger(__name__)
+
 
 class _NoRedirectHandler(urllib.request.HTTPRedirectHandler):
     def redirect_request(self, req, fp, code, msg, headers, newurl):
@@ -24,6 +27,15 @@ def _normalize_fiscal_code(value):
     return fiscal_code
 
 
+def _body_preview(raw_body, limit=512):
+    if not raw_body:
+        return ""
+    preview = raw_body[:limit].decode("utf-8", errors="replace").strip()
+    if len(raw_body) > limit:
+        return f"{preview}..."
+    return preview
+
+
 class VisioneStartView(View):
     def get(self, request):
         state = request.GET.get("state")
@@ -95,21 +107,38 @@ class VisioneCompleteView(View):
                 return HttpResponseServerError("Visione backend returned redirect without location")
             error_body = ""
             try:
-                error_body = exc.read().decode("utf-8").strip()
+                error_body = _body_preview(exc.read())
             except Exception:
                 error_body = ""
-            detail = f" {error_body}" if error_body else ""
+            detail = f" body={error_body}" if error_body else ""
             return HttpResponseServerError(
                 f"Visione backend exchange failed: {exc.code}{detail}"
             )
         except Exception as exc:
             return HttpResponseServerError(f"Visione backend exchange failed: {exc}")
 
+        location = response.headers.get("Location")
+        if location:
+            return HttpResponseRedirect(location)
+
         try:
-            payload = response.read().decode("utf-8")
+            raw_payload = response.read()
+            payload = raw_payload.decode("utf-8") if raw_payload else ""
+            content_type = response.headers.get("Content-Type", "")
+            if payload and "json" not in content_type.lower():
+                logger.warning(
+                    "Visione backend exchange returned non-JSON response "
+                    "status=%s content_type=%s body_preview=%s",
+                    getattr(response, "status", None),
+                    content_type,
+                    _body_preview(raw_payload),
+                )
             data = json.loads(payload) if payload else {}
         except Exception:
-            return HttpResponseServerError("Visione backend exchange did not redirect")
+            logger.exception("Visione backend exchange response could not be parsed")
+            return HttpResponseServerError(
+                "Visione backend exchange returned invalid JSON"
+            )
 
         redirect_url = data.get("redirect_url")
         if redirect_url: