Estimate message fee api (#600)

* estimate_message_delivery_and_dispatch_fee runtime API

* auto-determine message fees in relay

* remove fee argument from relay calls

* Fix import of weight contant

Co-authored-by: Hernando Castano <castano.ha@gmail.com>

bridges/bin/rialto/runtime/src/lib.rs

@@ -36,6 +36,9 @@ pub mod kovan;
 pub mod millau_messages;
 pub mod rialto_poa;
 
+use crate::millau_messages::{ToMillauMessagePayload, WithMillauMessageBridge};
+
+use bridge_runtime_common::messages::{source::estimate_message_dispatch_and_delivery_fee, MessageBridge};
 use codec::Decode;
 use pallet_grandpa::{fg_primitives, AuthorityId as GrandpaId, AuthorityList as GrandpaAuthorityList};
 use sp_api::impl_runtime_apis;
@@ -695,7 +698,17 @@ impl_runtime_apis! {
 		}
 	}
 
-	impl bp_millau::ToMillauOutboundLaneApi<Block> for Runtime {
+	impl bp_millau::ToMillauOutboundLaneApi<Block, Balance, ToMillauMessagePayload> for Runtime {
+		fn estimate_message_delivery_and_dispatch_fee(
+			_lane_id: bp_message_lane::LaneId,
+			payload: ToMillauMessagePayload,
+		) -> Option<Balance> {
+			estimate_message_dispatch_and_delivery_fee::<WithMillauMessageBridge>(
+				&payload,
+				WithMillauMessageBridge::RELAYER_FEE_PERCENT,
+			).ok()
+		}
+
 		fn messages_dispatch_weight(
 			lane: bp_message_lane::LaneId,
 			begin: bp_message_lane::MessageNonce,

bridges/bin/rialto/runtime/src/millau_messages.rs

@@ -125,9 +125,9 @@ impl MessageBridge for WithMillauMessageBridge {
 		<crate::Runtime as pallet_transaction_payment::Config>::WeightToFee::calc(&weight) as _
 	}
 
-	fn this_balance_to_bridged_balance(this_balance: bp_rialto::Balance) -> bp_millau::Balance {
+	fn bridged_balance_to_this_balance(bridged_balance: bp_millau::Balance) -> bp_rialto::Balance {
 		// 1:1 conversion that will probably change in the future
-		this_balance as _
+		bridged_balance as _
 	}
 }