Auto-fill billing details from person if not in invoice

aleksis/apps/tezor/models/invoice.py

@@ -83,6 +83,28 @@ class Invoice(BasePayment, PureDjangoModel):
     )
     items = models.ManyToManyField("InvoiceItem", verbose_name=_("Invoice items"))
 
+    def save(self, *args, **kwargs):
+        if self.person:
+            person = self.person
+        elif self.for_object and getattr(self.for_object, "person", None):
+            person = self.for_object.person
+        else:
+            person = None
+
+        if person:
+            if not self.billing_last_name:
+                self.billing_last_name = person.last_name
+            if not self.billing_first_name:
+                self.billing_first_name = person.first_name
+            if not self.billing_address_1:
+                self.billing_address_1 = f"{person.street} {person.housenumber}"
+            if not self.billing_city:
+                self.billing_city = person.place
+            if not self.billing_postcode:
+                self.billing_postcode = person.postal_code
+
+        super().save(*args, **kwargs)
+
     @classmethod
     def get_variant_choices(cls):
         choices = []