[feat] Fee Handler (#161)

pallets/payment/src/lib.rs

@@ -15,7 +15,9 @@ mod types;
 
 #[frame_support::pallet]
 pub mod pallet {
-	pub use crate::types::{DisputeResolver, PaymentDetail, PaymentHandler, PaymentState};
+	pub use crate::types::{
+		DisputeResolver, FeeHandler, PaymentDetail, PaymentHandler, PaymentState,
+	};
 	use frame_support::{dispatch::DispatchResultWithPostInfo, pallet_prelude::*};
 	use frame_system::pallet_prelude::*;
 	use orml_traits::{MultiCurrency, MultiReservableCurrency};
@@ -34,7 +36,9 @@ pub mod pallet {
 		type Asset: MultiReservableCurrency<Self::AccountId>;
 		/// Dispute resolution account
 		type DisputeResolver: DisputeResolver<Self::AccountId>;
-
+		/// Fee handler trait
+		type FeeHandler: FeeHandler<Self::AccountId>;
+		/// Incentive percentage - amount witheld from sender
 		#[pallet::constant]
 		type IncentivePercentage: Get<Percent>;
 	}
@@ -177,12 +181,15 @@ pub mod pallet {
 				recipient.clone(),
 				|maybe_payment| -> DispatchResult {
 					let incentive_amount = T::IncentivePercentage::get() * amount;
+					let (fee_recipient, fee_percent) = T::FeeHandler::apply_fees(&from, &recipient);
+					let fee_amount = fee_percent * amount;
 					let new_payment = Some(PaymentDetail {
 						asset,
 						amount,
 						incentive_amount,
 						state: PaymentState::Created,
 						resolver_account: T::DisputeResolver::get_origin(),
+						fee_detail: (fee_recipient, fee_amount),
 					});
 					match maybe_payment {
 						Some(x) => {
@@ -193,8 +200,8 @@ pub mod pallet {
 								x.state != PaymentState::Created,
 								Error::<T>::PaymentAlreadyInProcess
 							);
-							// reserve the incentive amount from the payment creator
-							T::Asset::reserve(asset, &from, incentive_amount)?;
+							// reserve the incentive + fees amount from the payment creator
+							T::Asset::reserve(asset, &from, incentive_amount + fee_amount)?;
 							// transfer amount to recipient
 							T::Asset::transfer(asset, &from, &recipient, amount)?;
 							// reserved the amount in the recipient account
@@ -203,7 +210,7 @@ pub mod pallet {
 						},
 						None => {
 							// reserve the incentive amount from the payment creator
-							T::Asset::reserve(asset, &from, incentive_amount)?;
+							T::Asset::reserve(asset, &from, incentive_amount + fee_amount)?;
 							// transfer amount to recipient
 							T::Asset::transfer(asset, &from, &recipient, amount)?;
 							// reserved the amount in the recipient account
@@ -230,10 +237,20 @@ pub mod pallet {
 					// ensure the payment is in created state
 					ensure!(payment.state == Created, Error::<T>::PaymentAlreadyReleased);
 					// unreserve the incentive amount back to the creator
-					T::Asset::unreserve(payment.asset, &from, payment.incentive_amount);
+					T::Asset::unreserve(
+						payment.asset,
+						&from,
+						payment.incentive_amount + payment.fee_detail.1,
+					);
 					// unreserve the amount to the recipent
 					T::Asset::unreserve(payment.asset, &to, payment.amount);
-
+					// transfer fee amount to marketplace
+					T::Asset::transfer(
+						payment.asset,
+						&from,                 // fee is paid by payment creator
+						&payment.fee_detail.0, // account of fee recipient
+						payment.fee_detail.1,  // amount of fee
+					)?;
 					payment.state = PaymentState::Released;
 
 					Ok(())
@@ -261,7 +278,11 @@ pub mod pallet {
 						Error::<T>::PaymentAlreadyReleased
 					);
 					// unreserve the incentive amount from the owner account
-					T::Asset::unreserve(payment.asset, &from, payment.incentive_amount);
+					T::Asset::unreserve(
+						payment.asset,
+						&from,
+						payment.incentive_amount + payment.fee_detail.1,
+					);
 					T::Asset::unreserve(payment.asset, &to, payment.amount);
 					// transfer amount to creator
 					match T::Asset::transfer(payment.asset, &to, &from, payment.amount) {

pallets/payment/src/mock.rs

@@ -19,6 +19,8 @@ pub const PAYMENT_CREATOR: AccountId = 10;
 pub const PAYMENT_RECIPENT: AccountId = 11;
 pub const CURRENCY_ID: u32 = 1u32;
 pub const RESOLVER_ACCOUNT: AccountId = 12;
+pub const FEE_RECIPIENT_ACCOUNT: AccountId = 20;
+pub const PAYMENT_RECIPENT_FEE_CHARGED: AccountId = 21;
 
 frame_support::construct_runtime!(
 	pub enum Test where
@@ -98,6 +100,16 @@ impl crate::types::DisputeResolver<AccountId> for MockDisputeResolver {
 	}
 }
 
+pub struct MockFeeHandler;
+impl crate::types::FeeHandler<AccountId> for MockFeeHandler {
+	fn apply_fees(_from: &AccountId, to: &AccountId) -> (AccountId, Percent) {
+		match to {
+			&PAYMENT_RECIPENT_FEE_CHARGED => (FEE_RECIPIENT_ACCOUNT, Percent::from_percent(10)),
+			_ => (FEE_RECIPIENT_ACCOUNT, Percent::from_percent(0)),
+		}
+	}
+}
+
 parameter_types! {
 	pub const IncentivePercentage: Percent = Percent::from_percent(10);
 }
@@ -107,6 +119,7 @@ impl payment::Config for Test {
 	type Asset = Tokens;
 	type DisputeResolver = MockDisputeResolver;
 	type IncentivePercentage = IncentivePercentage;
+	type FeeHandler = MockFeeHandler;
 }
 
 // Build genesis storage according to the mock runtime.

pallets/payment/src/tests.rs

@@ -27,7 +27,8 @@ fn test_create_payment_works() {
 				amount: 20,
 				incentive_amount: 2,
 				state: PaymentState::Created,
-				resolver_account: RESOLVER_ACCOUNT
+				resolver_account: RESOLVER_ACCOUNT,
+				fee_detail: (FEE_RECIPIENT_ACCOUNT, 0)
 			})
 		);
 		// the payment amount should be reserved correctly
@@ -52,14 +53,15 @@ fn test_create_payment_works() {
 				amount: 20,
 				incentive_amount: 2,
 				state: PaymentState::Created,
-				resolver_account: RESOLVER_ACCOUNT
+				resolver_account: RESOLVER_ACCOUNT,
+				fee_detail: (FEE_RECIPIENT_ACCOUNT, 0)
 			})
 		);
 	});
 }
 
 #[test]
-fn test_release_payment_works() {
+fn test_cancel_payment_works() {
 	new_test_ext().execute_with(|| {
 		// should be able to create a payment with available balance
 		assert_ok!(Payment::create(
@@ -75,7 +77,8 @@ fn test_release_payment_works() {
 				amount: 40,
 				incentive_amount: 4,
 				state: PaymentState::Created,
-				resolver_account: RESOLVER_ACCOUNT
+				resolver_account: RESOLVER_ACCOUNT,
+				fee_detail: (FEE_RECIPIENT_ACCOUNT, 0)
 			})
 		);
 		// the payment amount should be reserved
@@ -103,7 +106,8 @@ fn test_release_payment_works() {
 				amount: 40,
 				incentive_amount: 4,
 				state: PaymentState::Cancelled,
-				resolver_account: RESOLVER_ACCOUNT
+				resolver_account: RESOLVER_ACCOUNT,
+				fee_detail: (FEE_RECIPIENT_ACCOUNT, 0)
 			})
 		);
 		// cannot call cancel again
@@ -115,7 +119,7 @@ fn test_release_payment_works() {
 }
 
 #[test]
-fn test_cancel_payment_works() {
+fn test_release_payment_works() {
 	new_test_ext().execute_with(|| {
 		// should be able to create a payment with available balance
 		assert_ok!(Payment::create(
@@ -131,7 +135,8 @@ fn test_cancel_payment_works() {
 				amount: 40,
 				incentive_amount: 4,
 				state: PaymentState::Created,
-				resolver_account: RESOLVER_ACCOUNT
+				resolver_account: RESOLVER_ACCOUNT,
+				fee_detail: (FEE_RECIPIENT_ACCOUNT, 0)
 			})
 		);
 		// the payment amount should be reserved
@@ -153,7 +158,8 @@ fn test_cancel_payment_works() {
 				amount: 40,
 				incentive_amount: 4,
 				state: PaymentState::Released,
-				resolver_account: RESOLVER_ACCOUNT
+				resolver_account: RESOLVER_ACCOUNT,
+				fee_detail: (FEE_RECIPIENT_ACCOUNT, 0)
 			})
 		);
 		// cannot call release again
@@ -218,7 +224,8 @@ fn test_set_state_payment_works() {
 				amount: 40,
 				incentive_amount: 4,
 				state: PaymentState::Released,
-				resolver_account: RESOLVER_ACCOUNT
+				resolver_account: RESOLVER_ACCOUNT,
+				fee_detail: (FEE_RECIPIENT_ACCOUNT, 0)
 			})
 		);
 
@@ -250,8 +257,81 @@ fn test_set_state_payment_works() {
 				amount: 40,
 				incentive_amount: 4,
 				state: PaymentState::Cancelled,
-				resolver_account: RESOLVER_ACCOUNT
+				resolver_account: RESOLVER_ACCOUNT,
+				fee_detail: (FEE_RECIPIENT_ACCOUNT, 0)
+			})
+		);
+	});
+}
+
+#[test]
+fn test_charging_fee_payment_works() {
+	new_test_ext().execute_with(|| {
+		// should be able to create a payment with available balance
+		assert_ok!(Payment::create(
+			Origin::signed(PAYMENT_CREATOR),
+			PAYMENT_RECIPENT_FEE_CHARGED,
+			CURRENCY_ID,
+			40,
+		));
+		assert_eq!(
+			PaymentStore::<Test>::get(PAYMENT_CREATOR, PAYMENT_RECIPENT_FEE_CHARGED),
+			Some(PaymentDetail {
+				asset: CURRENCY_ID,
+				amount: 40,
+				incentive_amount: 4,
+				state: PaymentState::Created,
+				resolver_account: RESOLVER_ACCOUNT,
+				fee_detail: (FEE_RECIPIENT_ACCOUNT, 4)
+			})
+		);
+		// the payment amount should be reserved
+		assert_eq!(Tokens::free_balance(CURRENCY_ID, &PAYMENT_CREATOR), 52);
+		assert_eq!(Tokens::free_balance(CURRENCY_ID, &PAYMENT_RECIPENT_FEE_CHARGED), 0);
+
+		// should succeed for valid payment
+		assert_ok!(Payment::release(Origin::signed(PAYMENT_CREATOR), PAYMENT_RECIPENT_FEE_CHARGED));
+		// the payment amount should be transferred
+		assert_eq!(Tokens::free_balance(CURRENCY_ID, &PAYMENT_CREATOR), 56);
+		assert_eq!(Tokens::total_balance(CURRENCY_ID, &PAYMENT_CREATOR), 56);
+		assert_eq!(Tokens::free_balance(CURRENCY_ID, &PAYMENT_RECIPENT_FEE_CHARGED), 40);
+		assert_eq!(Tokens::free_balance(CURRENCY_ID, &FEE_RECIPIENT_ACCOUNT), 4);
+		assert_eq!(Tokens::total_issuance(CURRENCY_ID), 100);
+	});
+}
+
+#[test]
+fn test_charging_fee_payment_works_when_canceled() {
+	new_test_ext().execute_with(|| {
+		// should be able to create a payment with available balance
+		assert_ok!(Payment::create(
+			Origin::signed(PAYMENT_CREATOR),
+			PAYMENT_RECIPENT_FEE_CHARGED,
+			CURRENCY_ID,
+			40,
+		));
+		assert_eq!(
+			PaymentStore::<Test>::get(PAYMENT_CREATOR, PAYMENT_RECIPENT_FEE_CHARGED),
+			Some(PaymentDetail {
+				asset: CURRENCY_ID,
+				amount: 40,
+				incentive_amount: 4,
+				state: PaymentState::Created,
+				resolver_account: RESOLVER_ACCOUNT,
+				fee_detail: (FEE_RECIPIENT_ACCOUNT, 4)
 			})
 		);
+		// the payment amount should be reserved
+		assert_eq!(Tokens::free_balance(CURRENCY_ID, &PAYMENT_CREATOR), 52);
+		assert_eq!(Tokens::free_balance(CURRENCY_ID, &PAYMENT_RECIPENT_FEE_CHARGED), 0);
+
+		// should succeed for valid payment
+		assert_ok!(Payment::cancel(Origin::signed(PAYMENT_RECIPENT_FEE_CHARGED), PAYMENT_CREATOR));
+		// the payment amount should be transferred
+		assert_eq!(Tokens::free_balance(CURRENCY_ID, &PAYMENT_CREATOR), 100);
+		assert_eq!(Tokens::total_balance(CURRENCY_ID, &PAYMENT_CREATOR), 100);
+		assert_eq!(Tokens::free_balance(CURRENCY_ID, &PAYMENT_RECIPENT_FEE_CHARGED), 0);
+		assert_eq!(Tokens::free_balance(CURRENCY_ID, &FEE_RECIPIENT_ACCOUNT), 0);
+		assert_eq!(Tokens::total_issuance(CURRENCY_ID), 100);
 	});
 }

pallets/payment/src/types.rs

@@ -1,23 +1,39 @@
 #![allow(unused_qualifications)]
 use parity_scale_codec::{Decode, Encode};
 use scale_info::TypeInfo;
-use sp_runtime::DispatchResult;
+use sp_runtime::{DispatchResult, Percent};
 
+/*
+The PaymentDetail struct stores information about the payment/escrow
+A "payment" in virto network is similar to an escrow, it is used to guarantee proof of funds
+and can be released once an agreed upon condition has reached between the payment creator
+and recipient. The payment lifecycle is tracked using the state field.
+*/
 #[derive(Encode, Decode, Debug, Clone, PartialEq, Eq, TypeInfo)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct PaymentDetail<Asset, Amount, Account> {
+	/// type of asset used for payment
 	pub asset: Asset,
+	/// amount of asset used for payment
 	pub amount: Amount,
+	/// incentive amount that is credited to creator for resolving
 	pub incentive_amount: Amount,
+	/// enum to track payment lifecycle [Created, Released, Cancelled, NeedsReview]
 	pub state: PaymentState,
+	/// account that can settle any disputes created in the payment
 	pub resolver_account: Account,
+	/// fee charged and recipient account details
+	pub fee_detail: (Account, Amount),
 }
 
 #[derive(Encode, Decode, Debug, Clone, PartialEq, Eq, TypeInfo)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub enum PaymentState {
+	/// Amounts have been reserved and waiting for release/cancel
 	Created,
+	/// Payment has been completed and amount transferred
 	Released,
+	/// All funds unreserved and sent to original owners
 	Cancelled,
 	/// A judge needs to review and release manually
 	NeedsReview,
@@ -59,3 +75,9 @@ pub trait DisputeResolver<Account> {
 	/// Get a DisputeResolver (Judge) account
 	fn get_origin() -> Account;
 }
+
+/// Fee Handler trait that defines how to handle marketplace fees to every payment/swap
+pub trait FeeHandler<Account> {
+	/// Get the distribution of fees to marketplace participants
+	fn apply_fees(from: &Account, to: &Account) -> (Account, Percent);
+}

runtime/src/lib.rs

@@ -602,6 +602,14 @@ impl virto_payment::DisputeResolver<AccountId> for VirtoDisputeResolver {
 	}
 }
 
+pub struct VirtoFeeHandler;
+impl virto_payment::FeeHandler<AccountId> for VirtoFeeHandler {
+	fn apply_fees(_from: &AccountId, _to: &AccountId) -> (AccountId, Percent) {
+		const VIRTO_MARKETPLACE_FEE_PERCENT: Percent = Percent::from_percent(0);
+		(Sudo::key(), VIRTO_MARKETPLACE_FEE_PERCENT)
+	}
+}
+
 parameter_types! {
 	pub const IncentivePercentage: Percent = Percent::from_percent(10);
 }
@@ -611,6 +619,7 @@ impl virto_payment::Config for Runtime {
 	type Asset = Assets;
 	type DisputeResolver = VirtoDisputeResolver;
 	type IncentivePercentage = IncentivePercentage;
+	type FeeHandler = VirtoFeeHandler;
 }
 
 parameter_types! {