feat: include total_grantee_reimbursement_amount in invitation letter template

Add the grant's total_grantee_reimbursement_amount as a template variable
available in invitation letter dynamic documents. This allows the invitation
letter to display the post-conference reimbursement amount for grantees.

Changes:
- Add total_grantee_reimbursement_amount property to InvitationLetterRequest
  model (returns None if no grant, otherwise delegates to the grant model)
- Pass total_grantee_reimbursement_amount in the template context for
  dynamic document rendering
- Add tests for the new property and template variable rendering

Closes #4550

Co-authored-by: Marco Acierno <marcoacierno@users.noreply.github.com>

Author: github-actions[bot]

backend/visa/models.py

@@ -122,6 +122,15 @@ def grant_approved_type(self) -> str | None:
 
         return "_".join(sorted(categories)) if len(categories) > 1 else categories[0]
 
+    @property
+    def total_grantee_reimbursement_amount(self):
+        grant = self.user_grant
+
+        if not grant:
+            return None
+
+        return grant.total_grantee_reimbursement_amount
+
     @cached_property
     def user_grant(self):
         return Grant.objects.for_conference(self.conference).of_user(self.user).first()

backend/visa/tasks.py

@@ -151,6 +151,7 @@ def _render_content(content, invitation_letter_request, config):
                 "grant_approved_type": invitation_letter_request.grant_approved_type,
                 "has_accommodation_via_grant": invitation_letter_request.has_accommodation_via_grant(),
                 "has_travel_via_grant": invitation_letter_request.has_travel_via_grant(),
+                "total_grantee_reimbursement_amount": invitation_letter_request.total_grantee_reimbursement_amount,
                 # conference
                 "conference": invitation_letter_request.conference,
             }

backend/visa/tests/test_models.py

@@ -26,6 +26,7 @@ def test_request_on_behalf_of_other():
     assert request.user is None
     assert request.role == "Attendee"
     assert request.has_grant is False
+    assert request.total_grantee_reimbursement_amount is None
 
     # With matching user, it is found
     user = UserFactory(email="example@example.org")
@@ -87,6 +88,13 @@ def test_request_grant_info(
     assert request.has_travel_via_grant() == expected_has_travel
     # grant_approved_type returns sorted categories joined by underscore
     assert request.grant_approved_type == expected_type
+    # total_grantee_reimbursement_amount excludes ticket
+    expected_amount = Decimal(0)
+    if "travel" in categories:
+        expected_amount += Decimal("500")
+    if "accommodation" in categories:
+        expected_amount += Decimal("200")
+    assert request.total_grantee_reimbursement_amount == expected_amount
 
 
 def test_role_for_speakers():

backend/visa/tests/test_tasks.py

@@ -187,6 +187,66 @@ def test_process_invitation_letter_request_accomodation_doc_with_no_accommodatio
     assert output.pages[0].extract_text() == "Thisisasampleticket pdf"
 
 
+@override_settings(PRETIX_API="https://pretix/api/")
+def test_process_invitation_letter_request_renders_total_grantee_reimbursement_amount(
+    mock_ticket_present,
+):
+    config = InvitationLetterConferenceConfigFactory()
+    InvitationLetterDocumentFactory(
+        invitation_letter_conference_config=config,
+        document=None,
+        dynamic_document={
+            "header": {"content": "header", "margin": "0", "align": "top-left"},
+            "footer": {"content": "footer", "margin": "0", "align": "bottom-left"},
+            "page_layout": {"margin": "0"},
+            "pages": [
+                {
+                    "content": "Reimbursement: {{total_grantee_reimbursement_amount}}"
+                },
+            ],
+        },
+    )
+
+    request = InvitationLetterRequestFactory(
+        conference=config.conference, nationality="Italian"
+    )
+    mock_ticket_present(request)
+
+    grant = GrantFactory(
+        conference=config.conference,
+        user=request.requester,
+    )
+    GrantReimbursementFactory(
+        grant=grant,
+        category__conference=config.conference,
+        category__ticket=True,
+        granted_amount=Decimal("100"),
+    )
+    GrantReimbursementFactory(
+        grant=grant,
+        category__conference=config.conference,
+        category__travel=True,
+        granted_amount=Decimal("500"),
+    )
+    GrantReimbursementFactory(
+        grant=grant,
+        category__conference=config.conference,
+        category__accommodation=True,
+        granted_amount=Decimal("200"),
+    )
+
+    process_invitation_letter_request(invitation_letter_request_id=request.id)
+
+    request.refresh_from_db()
+
+    assert request.status == InvitationLetterRequestStatus.PROCESSED
+
+    output = PdfReader(request.invitation_letter.open())
+    assert output.get_num_pages() == 2
+    assert output.pages[0].extract_text() == "Reimbursement: 700 \nheader\nfooter"
+    assert output.pages[1].extract_text() == "Thisisasampleticket pdf"
+
+
 @override_settings(PRETIX_API="https://pretix/api/")
 def test_process_invitation_letter_request_with_doc_only_for_accommodation(
     mock_ticket_present,