Payment provider fee calculation

src/pretix/base/payment.py

@@ -1,3 +1,5 @@
+from decimal import Decimal
+
 from pretix.base.settings import SettingsSandbox
 
 
@@ -13,6 +15,23 @@ class BasePaymentProvider:
     def __str__(self):
         return self.identifier
 
+    @property
+    def is_enabled(self):
+        """
+        Returns, whether or whether not this payment provider is enabled.
+        By default, this is determined by the value of a setting.
+        """
+        return self.settings.get('_enabled', as_type=bool)
+
+    def calculate_fee(self, price):
+        """
+        Calculate the fee for this payment provider which will be added to
+        the final price if the price before fees (but after taxes) is 'price'.
+        """
+        fee_abs = self.settings.get('_fee_abs', as_type=Decimal, default=0)
+        fee_percent = self.settings.get('_fee_percent', as_type=Decimal, default=0)
+        return price * fee_percent / 100 + fee_abs
+
     @property
     def verbose_name(self) -> str:
         """