Add service layer for approving and declining ProjectRequest with transactional logic

input/services.py

@@ -0,0 +1,75 @@
+from datetime import date
+from django.db import transaction
+from .models import ProjectRequest, ProjectsDeclined, Project, Account
+
+def approve_project_request(request_id: int, decided_by: str, account_code: str) -> Project:
+    # Use a DB transaction so either all changes commit, or none (atomic workflow).
+    with transaction.atomic():
+        # SELECT ... FOR UPDATE: lock the row to avoid concurrent approvals/declines.
+        req = ProjectRequest.objects.select_for_update().get(pk=request_id)
+
+        # Mark the request as approved and persist the decision metadata.
+        req.decision = 'APPROVED'
+        req.decision_date = date.today()   # For DateField a date is fine; prefer timezone.localdate() if TZ-sensitive.
+        req.decided_by = decided_by
+        req.save()
+
+        # The Account (Kostenstelle) must be assigned by WMDE in the admin workflow.
+        # .get() will raise DoesNotExist/MultipleObjectsReturned if data integrity is broken.
+        account = Account.objects.get(code=account_code)
+
+        # Create the actual Project from the request data.
+        # Project.save() will generate pid/finance_id/end_quartal according to your model logic.
+        proj = Project.objects.create(
+            realname=req.realname,
+            email=req.email,
+            end_mail_send=False,
+            name=req.name,
+            description=req.description,
+            start=req.start,
+            end=req.end,
+            page=req.page,
+            group=req.group,
+            location=req.location,
+            participants_estimated=req.participants_estimated,
+            insurance=req.insurance,
+            cost=req.cost,
+            account=account,
+            notes=req.notes,
+            granted=True,
+            granted_date=date.today(),   # Consider timezone.localdate() if you care about time zones.
+            granted_from=decided_by,
+        )
+
+        # After successful creation we remove the original request (it has been fulfilled).
+        # Because we're inside an atomic block, both operations succeed/fail together.
+        req.delete()
+
+        # Return the created project for further processing in the caller if needed.
+        return proj
+
+
+def decline_project_request(request_id: int, reason: str | None = None):
+    # Same transactional guarantees for declines.
+    with transaction.atomic():
+        # Lock the row to prevent concurrent decisions.
+        req = ProjectRequest.objects.select_for_update().get(pk=request_id)
+
+        # Mark as declined and persist decision date.
+        req.decision = 'DECLINED'
+        req.decision_date = date.today()
+        req.save()
+
+        # Archive minimal relevant information in a dedicated table.
+        # No pid/finance_id should be created for declined items.
+        ProjectsDeclined.objects.create(
+            original_request_id=req.id,
+            name=req.name,
+            realname=req.realname,
+            email=req.email,
+            decision_date=req.decision_date,
+            reason=reason or '',
+        )
+
+        # Remove the original request after archiving.
+        req.delete()