[VISIBILITY] FECFILE-2806: proposed addition to the recent aggregation refactor

django-backend/fecfiler/transactions/models.py

@@ -1,3 +1,4 @@
+from decimal import Decimal
 from django.db import models
 from django.db.models import Q
 from django.contrib.postgres.fields import ArrayField
@@ -15,6 +16,7 @@
 )
 from fecfiler.transactions.utils_aggregation_service import (
     update_aggregates_for_affected_transactions,
+    calculate_loan_payment_to_date,
 )
 from fecfiler.transactions.schedule_a.models import ScheduleA
 from fecfiler.transactions.schedule_b.models import ScheduleB
@@ -418,6 +420,107 @@ def _handle_debt_aggregation(self):
 
             process_aggregation_for_debts(self)
 
+    def _handle_loan_aggregation_on_delete(self):
+        # Loan repayment delete must explicitly trigger reaggregation to keep
+        # loan_payment_to_date/loan_balance in sync with create/update behavior.
+        # This keeps delete-path behavior in parity with create/update service flow.
+        if self.transaction_type_identifier != "LOAN_REPAYMENT_MADE":
+            return
+
+        if self.loan_id is None or self.schedule_c_id is not None:
+            logger.warning(
+                "Skipped loan aggregation on repayment delete",
+                transaction_id=self.id,
+                loan_id=self.loan_id,
+                hook_executed=False,
+                skip_reason="not_loan_repayment",
+            )
+            return
+
+        if getattr(self, "schedule_b_id", None) is None:
+            logger.warning(
+                "Skipped loan aggregation on repayment delete",
+                transaction_id=self.id,
+                loan_id=self.loan_id,
+                hook_executed=False,
+                skip_reason="missing_schedule_b",
+                transaction_type_identifier=self.transaction_type_identifier,
+            )
+            return
+
+        updated_count = calculate_loan_payment_to_date(Transaction, self.loan_id)
+
+        # Keep normal-path cost low; only run invariant verification when no
+        # row was updated on delete.
+        expected_total = None
+        persisted_total = None
+        if updated_count == 0:
+            loan = Transaction.objects.filter(
+                id=self.loan_id,
+                deleted__isnull=True,
+            ).only("id", "loan_payment_to_date").first()
+
+            if loan is None:
+                logger.warning(
+                    "Skipped loan aggregation verification on repayment delete",
+                    transaction_id=self.id,
+                    loan_id=self.loan_id,
+                    hook_executed=True,
+                    skip_reason="loan_not_found",
+                    updated_count=updated_count,
+                )
+                return
+
+            expected_total = (
+                Transaction.objects.filter(
+                    loan_id=self.loan_id,
+                    transaction_type_identifier="LOAN_REPAYMENT_MADE",
+                    deleted__isnull=True,
+                    schedule_b__isnull=False,
+                ).aggregate(total=models.Sum("schedule_b__expenditure_amount"))["total"]
+                or Decimal("0")
+            )
+            persisted_total = loan.loan_payment_to_date or Decimal("0")
+
+            if persisted_total != expected_total:
+                logger.warning(
+                    "Loan repayment delete aggregation invariant mismatch",
+                    transaction_id=self.id,
+                    loan_id=self.loan_id,
+                    hook_executed=True,
+                    updated_count=updated_count,
+                    expected_total=str(expected_total),
+                    persisted_total=str(persisted_total),
+                )
+                corrective_updated_count = calculate_loan_payment_to_date(
+                    Transaction, self.loan_id
+                )
+                loan.refresh_from_db(fields=["loan_payment_to_date"])
+                persisted_total = loan.loan_payment_to_date or Decimal("0")
+                logger.info(
+                    "Loan repayment delete aggregation corrective pass",
+                    transaction_id=self.id,
+                    loan_id=self.loan_id,
+                    hook_executed=True,
+                    corrective_updated_count=corrective_updated_count,
+                    expected_total=str(expected_total),
+                    persisted_total=str(persisted_total),
+                )
+
+        logger.info(
+            "Processed loan aggregation on repayment delete",
+            transaction_id=self.id,
+            loan_id=self.loan_id,
+            hook_executed=True,
+            updated_count=updated_count,
+            expected_total=str(expected_total)
+            if expected_total is not None
+            else None,
+            persisted_total=str(persisted_total)
+            if persisted_total is not None
+            else None,
+        )
+
     def save(self, *args, **kwargs):
         # Check if old_snapshot was passed from view (for Schedule A, B, F)
         # This is needed because schedule is saved before transaction,
@@ -479,7 +582,7 @@ def save(self, *args, **kwargs):
             try:
                 action = "create" if is_create else "update"
                 update_aggregates_for_affected_transactions(
-                    Transaction, self, action
+                    Transaction, self, action, old_snapshot
                 )
             except Exception as e:
                 logger.error(
@@ -562,6 +665,18 @@ def delete(self):
                     error=str(e),
                     exc_info=True,
                 )
+
+            # Handle loan repayment aggregation after marking deleted
+            try:
+                self._handle_loan_aggregation_on_delete()
+            except Exception as e:
+                logger.error(
+                    "Failed to process loan aggregation on delete",
+                    transaction_id=self.id,
+                    loan_id=self.loan_id,
+                    error=str(e),
+                    exc_info=True,
+                )
             self.delete_children()
             self.delete_debts()
             self.delete_loans()