Add invoice enums

Distribution/Models/Enums.cs

@@ -23,6 +23,12 @@ namespace Distribution.Models
 
     public enum OrderStatus { Pending, PartiallyFulfilled, Fulfilled, Cancelled }
 
+    public enum InvoiceStatus { Draft, Printed, Finalized }
+
+    public enum InvoiceCreationMode { A, B }
+
+    public enum DiscountType { Amount, Percentage }
+
     public enum PaymentStatus { Pending, PartiallyPaid, Paid }
 
     public enum PaymentMethod { Cash, Credit }