feat: now user can top up via redemption code (close #9)

common/constants.go

@@ -93,6 +93,12 @@ const (
 	TokenStatusExhausted = 4
 )
 
+const (
+	RedemptionCodeStatusEnabled  = 1 // don't use 0, 0 is the default value!
+	RedemptionCodeStatusDisabled = 2 // also don't use 0
+	RedemptionCodeStatusUsed     = 3 // also don't use 0
+)
+
 const (
 	ChannelStatusUnknown  = 0
 	ChannelStatusEnabled  = 1 // don't use 0, 0 is the default value!