policies: add AccessDeniedResponse as general response when access was denied

passbook/policies/http.py

@@ -0,0 +1,44 @@
+"""policy http response"""
+from typing import Any, Dict, Optional
+
+from django.http.request import HttpRequest
+from django.template.response import TemplateResponse
+from django.utils.translation import gettext as _
+
+from passbook.core.models import PASSBOOK_USER_DEBUG
+from passbook.policies.types import PolicyResult
+
+
+class AccessDeniedResponse(TemplateResponse):
+    """Response used for access denied messages. Can optionally show an error message,
+    and if the user is a superuser or has user_debug enabled, shows a policy result."""
+
+    title: str
+
+    error_message: Optional[str] = None
+    policy_result: Optional[PolicyResult] = None
+
+    def __init__(self, request: HttpRequest) -> None:
+        # For some reason pyright complains about keyword argument usage here
+        # pyright: reportGeneralTypeIssues=false
+        super().__init__(request=request, template="policies/denied.html")
+        self.title = _("Access denied")
+
+    def resolve_context(
+        self, context: Optional[Dict[str, Any]]
+    ) -> Optional[Dict[str, Any]]:
+        if not context:
+            context = {}
+        context["title"] = self.title
+        if self.error_message:
+            context["error"] = self.error_message
+        # Only show policy result if user is authenticated and
+        # either superuser or has PASSBOOK_USER_DEBUG set
+        if self.policy_result:
+            if self._request.user and self._request.user.is_authenticated:
+                if (
+                    self._request.user.is_superuser
+                    or self._request.user.attributes.get(PASSBOOK_USER_DEBUG, False)
+                ):
+                    context["policy_result"] = self.policy_result
+        return context