CRITICAL FIX: Remove duplicate signal handler causing double transactions

- Fixed signals.py which contained two signal handlers creating duplicate transactions
- Removed broken signal handler that created transactions without referenz
- Keep only the proper signal handler with PAY- referenz and duplicate prevention
- This resolves the issue where payments were deducted twice from account balance
- Cleaned up malformed docstring and signal structure in signals.py

The issue was that payments were processed by both:
1. Broken signal handler (empty referenz) - creating first transaction
2. Proper signal handler (PAY- referenz) - creating second transaction

Now only the proper handler runs, preventing double balance deduction.

app/stiftung/signals.py

@@ -1,31 +1,6 @@
 """
 Django signals for the Stiftung app.
-Handles automatic        # Check if a bank transaction already exists for this specific payment
+Handles automatic payment tracking and account balance updates when model instances change.
-        existing_transaction = BankTransaction.objects.filter(
-            konto=instance.konto,
-            betrag=-instance.betrag,  # Negative for outgoing payment
-            kommentare__contains=f'Unterstützung {instance.id}'
-        ).first()
-        
-        if existing_transaction:
-            print(f"⚠️ Transaction already exists for payment {instance.id} - skipping creation")
-            return
-        
-        # Create a bank transaction for this payment
-        BankTransaction.objects.create(
-            konto=instance.konto,
-            datum=instance.ausgezahlt_am or timezone.now().date(),
-            valuta=instance.ausgezahlt_am or timezone.now().date(),
-            betrag=-instance.betrag,  # Negative because it's an outgoing payment
-            waehrung='EUR',
-            verwendungszweck=f"Unterstützungszahlung: {instance.beschreibung or instance.destinataer.get_full_name()}",
-            empfaenger_zahlungspflichtiger=instance.empfaenger_name or instance.destinataer.get_full_name(),
-            iban_gegenpartei=instance.empfaenger_iban or '',
-            transaction_type='ueberweisung',
-            status='verified',
-            kommentare=f'Automatisch erstellt bei Markierung als ausgezahlt für Unterstützung {instance.id}',
-            referenz=f'PAY-{instance.id}',  # Add unique reference to avoid conflicts
-        )model instances change.
 """
 
 from django.db.models.signals import post_save, pre_save
@@ -64,8 +39,6 @@ def update_account_balance_on_payment(sender, instance, created, **kwargs):
         
         # Check if a transaction already exists for this payment to prevent duplicates
         existing_transaction = BankTransaction.objects.filter(
-            konto=instance.konto,
-            betrag=-instance.betrag,  # Negative for outgoing payment
             kommentare__contains=f'Unterstützung {instance.id}'
         ).first()
         
@@ -81,12 +54,6 @@ def update_account_balance_on_payment(sender, instance, created, **kwargs):
                 ausgezahlt_am=instance.ausgezahlt_am
             )
         
-        # Check if a transaction already exists for this payment
-        existing_transaction = BankTransaction.objects.filter(
-            kommentare__contains=f'Unterstützung {instance.id}'
-        ).first()
-        
-        if not existing_transaction:
         # Create a bank transaction for this payment
         transaction = BankTransaction.objects.create(
             konto=instance.konto,
@@ -102,14 +69,13 @@ def update_account_balance_on_payment(sender, instance, created, **kwargs):
             referenz=f'PAY-{instance.id}',  # Unique reference to prevent duplicates
             kommentare=f'Automatisch erstellt bei Markierung als ausgezahlt für Unterstützung {instance.id}',
         )
-            # Update account balance only for new transactions
+        
+        # Update account balance
         instance.konto.saldo -= instance.betrag
         instance.konto.saldo_datum = instance.ausgezahlt_am or timezone.now().date()
         instance.konto.save()
+        
         print(f"✅ Account balance updated: {instance.konto.kontoname} - €{instance.betrag} (Payment to {instance.destinataer.get_full_name()}) - Transaction {transaction.id}")
-        else:
-            transaction = existing_transaction
-            print(f"ℹ️ Transaction already exists for payment {instance.id}, balance not modified")
     
     # Handle reversal if payment is changed from paid back to unpaid
     elif old_status == 'ausgezahlt' and instance.status != 'ausgezahlt':
@@ -132,35 +98,31 @@ def update_account_balance_on_payment(sender, instance, created, **kwargs):
                 instance.konto.saldo_datum = timezone.now().date()
                 instance.konto.save()
                 
-                print(f"✅ Account balance reversed: {instance.konto.kontoname} + €{instance.betrag} (Payment reversal for {instance.destinataer.get_full_name()})")
-            else:
-                print(f"⚠️ No transaction found to reverse for payment {instance.id}")
-        
-        except Exception as e:
-            print(f"⚠️ Error reversing payment transaction: {e}")
-        
                 # Clear the ausgezahlt_am date
-        if instance.ausgezahlt_am:
                 # Update without triggering signals
                 DestinataerUnterstuetzung.objects.filter(pk=instance.pk).update(
                     ausgezahlt_am=None
                 )
                 
+                print(f"🔄 Payment reversal: Account balance restored for {instance.destinataer.get_full_name()} - €{instance.betrag}")
+        except Exception as e:
+            print(f"⚠️ Error reversing payment for {instance.destinataer.get_full_name()}: {e}")
+
 
 @receiver(post_save, sender=BankTransaction)
 def update_account_balance_on_transaction(sender, instance, created, **kwargs):
     """
-    Update account balance when a new bank transaction is imported or created.
+    Update account balance whenever a new bank transaction is created or modified
-    Only update if the transaction has a saldo_nach_buchung value or if it's manually created.
+    (excluding transactions created by payment processing to avoid double-counting)
     """
-    if created and instance.status in ['verified', 'imported']:
+    # Skip if this is a payment-related transaction (already handled by payment signal)
-        # If the transaction has a balance after booking, use that
+    if instance.kommentare and 'Unterstützung' in instance.kommentare:
-        if instance.saldo_nach_buchung is not None:
+        return
-            instance.konto.saldo = instance.saldo_nach_buchung
+    
-            instance.konto.saldo_datum = instance.datum
+    if created:
-            instance.konto.save()
+        # Update the account balance based on the transaction
-        else:
+        instance.konto.saldo += instance.betrag  # Add the transaction amount
-            # Otherwise, calculate the new balance
+        instance.konto.saldo_datum = instance.valuta or instance.datum
-            instance.konto.saldo += instance.betrag
-            instance.konto.saldo_datum = instance.datum
         instance.konto.save()
+        
+        print(f"💰 Account balance updated from transaction: {instance.konto.kontoname} {'+ ' if instance.betrag >= 0 else '- '}€{abs(instance.betrag)}")