Add support for auto-booking transferwise cashback

Transferwise re-invented interest and call it cashback (it's the same as
interest..), and we already knew how to classify these transactions. So
instead of leaving them as pending, automatically book them against a
predefined account.

Author: mhagander

postgresqleu/transferwise/management/commands/transferwise_fetch_transactions.py

@@ -170,6 +170,12 @@ def handle_method(self, method, startdate):
                                                       entry)
                     else:
                         create_accounting_entry(accrows)
+                elif trans.transtype == 'BALANCE_CASHBACK' and pm.config('accounting_cashback'):
+                    accrows = [
+                        (pm.config('bankaccount'), trans.paymentref, trans.amount, None),
+                        (pm.config('accounting_cashback'), trans.paymentref, -trans.amount, None),
+                    ]
+                    create_accounting_entry(accrows)
                 else:
                     # Else register a pending bank transaction. This may immediately match an invoice
                     # if it was an invoice payment, in which case the entire process will complete.

postgresqleu/util/payment/transferwise.py

@@ -44,12 +44,15 @@ class BackendTransferwiseForm(BaseManagedBankPaymentForm):
                                          help_text="Send monthly PDF statements by email")
     accounting_payout = forms.ChoiceField(required=False, choices=[(None, '---')] + get_account_choices(),
                                           label="Payout account")
+    accounting_cashback = forms.ChoiceField(required=False, choices=[(None, '---')] + get_account_choices(),
+                                            label="Cashback account",
+                                            help_text="Accounting account that any cashback payments are booked against")
     webhookurl = forms.CharField(label="Webhook URL", widget=StaticTextWidget)
 
     exclude_fields_from_validation = ('generatekey', )
     config_readonly = ['webhookurl', ]
     managed_fields = ['apikey', 'canrefund', 'notification_receiver', 'autopayout', 'autopayouttrigger',
-                      'autopayoutlimit', 'autopayoutname', 'autopayoutiban', 'accounting_payout',
+                      'autopayoutlimit', 'autopayoutname', 'autopayoutiban', 'accounting_payout', 'accounting_cashback',
                       'send_statements', 'public_key', 'private_key', 'generatekey', ]
     managed_fieldsets = [
         {
@@ -70,6 +73,14 @@ class BackendTransferwiseForm(BaseManagedBankPaymentForm):
         },
     ]
 
+    @property
+    def config_fieldsets(self):
+        fss = super().config_fieldsets
+        for fs in fss:
+            if fs['id'] == 'accounting':
+                fs['fields'].append('accounting_cashback')
+        return fss
+
     def fix_fields(self):
         super().fix_fields()
         self.fields['generatekey'].callback = self.generate_keypair