Loans: maturity extension support

pallets/loans/src/benchmarking.rs

@@ -137,7 +137,7 @@ where
 	fn base_loan(item_id: T::ItemId) -> LoanInfo<T> {
 		LoanInfo {
 			schedule: RepaymentSchedule {
-				maturity: Maturity::Fixed((T::Time::now() + OFFSET).as_secs()),
+				maturity: Maturity::fixed((T::Time::now() + OFFSET).as_secs()),
 				interest_payments: InterestPayments::None,
 				pay_down_schedule: PayDownSchedule::None,
 			},

pallets/loans/src/entities/loans.rs

@@ -439,6 +439,11 @@ impl<T: Config> ActiveLoan<T> {
 	pub fn mutate_with(&mut self, mutation: LoanMutation<T::Rate>) -> DispatchResult {
 		match mutation {
 			LoanMutation::Maturity(maturity) => self.schedule.maturity = maturity,
+			LoanMutation::MaturityExtension(extension) => self
+				.schedule
+				.maturity
+				.extends(extension)
+				.map_err(|_| Error::<T>::from(MutationError::MaturityExtendedTooMuch))?,
 			LoanMutation::InterestRate(rate) => match &mut self.pricing {
 				ActivePricing::Internal(inner) => inner.interest.set_base_rate(rate)?,
 				ActivePricing::External(inner) => inner.interest.set_base_rate(rate)?,
@@ -458,6 +463,6 @@ impl<T: Config> ActiveLoan<T> {
 
 	#[cfg(feature = "runtime-benchmarks")]
 	pub fn set_maturity(&mut self, duration: Moment) {
-		self.schedule.maturity = crate::types::Maturity::Fixed(duration);
+		self.schedule.maturity = crate::types::Maturity::fixed(duration);
 	}
 }

pallets/loans/src/lib.rs

@@ -986,8 +986,8 @@ pub mod pallet {
 			Ok((loan, count))
 		}
 
-		#[cfg(feature = "runtime-benchmarks")]
 		/// Set the maturity date of the loan to this instant.
+		#[cfg(feature = "runtime-benchmarks")]
 		pub fn expire(pool_id: T::PoolId, loan_id: T::LoanId) -> DispatchResult {
 			Self::update_active_loan(pool_id, loan_id, |loan| {
 				loan.set_maturity(T::Time::now().as_secs());

pallets/loans/src/tests/create_loan.rs

@@ -88,7 +88,7 @@ fn with_wrong_schedule() {
 
 		let loan = LoanInfo {
 			schedule: RepaymentSchedule {
-				maturity: Maturity::Fixed(now().as_secs()),
+				maturity: Maturity::fixed(now().as_secs()),
 				interest_payments: InterestPayments::None,
 				pay_down_schedule: PayDownSchedule::None,
 			},

pallets/loans/src/tests/mutate_loan.rs

@@ -91,48 +91,95 @@ fn with_wrong_permissions() {
 	});
 }
 
-#[test]
-fn with_wrong_dcf_mutation() {
-	new_test_ext().execute_with(|| {
-		let loan_id = util::create_loan(util::base_internal_loan());
-		util::borrow_loan(loan_id, 0);
+mod wrong_mutation {
+	use super::*;
 
-		let mutation =
-			LoanMutation::Internal(InternalMutation::DiscountRate(Rate::from_float(0.5)));
+	#[test]
+	fn with_dcf() {
+		new_test_ext().execute_with(|| {
+			let loan_id = util::create_loan(util::base_internal_loan());
+			util::borrow_loan(loan_id, 0);
 
-		config_mocks(loan_id, &mutation);
-		assert_noop!(
-			Loans::propose_loan_mutation(
-				RuntimeOrigin::signed(LOAN_ADMIN),
-				POOL_A,
-				loan_id,
-				mutation,
-			),
-			Error::<Runtime>::MutationError(MutationError::DiscountedCashFlowExpected)
-		);
-	});
-}
+			let mutation =
+				LoanMutation::Internal(InternalMutation::DiscountRate(Rate::from_float(0.5)));
 
-#[test]
-fn with_wrong_interest_rate() {
-	new_test_ext().execute_with(|| {
-		let loan_id = util::create_loan(util::base_internal_loan());
-		util::borrow_loan(loan_id, 0);
+			config_mocks(loan_id, &mutation);
+			assert_noop!(
+				Loans::propose_loan_mutation(
+					RuntimeOrigin::signed(LOAN_ADMIN),
+					POOL_A,
+					loan_id,
+					mutation,
+				),
+				Error::<Runtime>::MutationError(MutationError::DiscountedCashFlowExpected)
+			);
+		});
+	}
+
+	#[test]
+	fn with_internal() {
+		new_test_ext().execute_with(|| {
+			let loan_id = util::create_loan(util::base_external_loan());
+			util::borrow_loan(loan_id, 0);
+
+			let mutation =
+				LoanMutation::Internal(InternalMutation::DiscountRate(Rate::from_float(0.5)));
 
-		// Too high
-		let mutation = LoanMutation::InterestRate(Rate::from_float(3.0));
+			config_mocks(loan_id, &mutation);
+			assert_noop!(
+				Loans::propose_loan_mutation(
+					RuntimeOrigin::signed(LOAN_ADMIN),
+					POOL_A,
+					loan_id,
+					mutation,
+				),
+				Error::<Runtime>::MutationError(MutationError::InternalPricingExpected)
+			);
+		});
+	}
+
+	#[test]
+	fn with_maturity_extension() {
+		new_test_ext().execute_with(|| {
+			let loan_id = util::create_loan(util::base_internal_loan());
+			util::borrow_loan(loan_id, 0);
+
+			let mutation = LoanMutation::MaturityExtension(YEAR.as_secs());
 
-		config_mocks(loan_id, &mutation);
-		assert_noop!(
-			Loans::propose_loan_mutation(
-				RuntimeOrigin::signed(LOAN_ADMIN),
-				POOL_A,
-				loan_id,
-				mutation,
-			),
-			pallet_interest_accrual::Error::<Runtime>::InvalidRate
-		);
-	});
+			config_mocks(loan_id, &mutation);
+			assert_noop!(
+				Loans::propose_loan_mutation(
+					RuntimeOrigin::signed(LOAN_ADMIN),
+					POOL_A,
+					loan_id,
+					mutation,
+				),
+				Error::<Runtime>::MutationError(MutationError::MaturityExtendedTooMuch)
+			);
+		});
+	}
+
+	#[test]
+	fn with_interest_rate() {
+		new_test_ext().execute_with(|| {
+			let loan_id = util::create_loan(util::base_internal_loan());
+			util::borrow_loan(loan_id, 0);
+
+			// Too high
+			let mutation = LoanMutation::InterestRate(Rate::from_float(3.0));
+
+			config_mocks(loan_id, &mutation);
+			assert_noop!(
+				Loans::propose_loan_mutation(
+					RuntimeOrigin::signed(LOAN_ADMIN),
+					POOL_A,
+					loan_id,
+					mutation,
+				),
+				pallet_interest_accrual::Error::<Runtime>::InvalidRate
+			);
+		});
+	}
 }
 
 #[test]
@@ -157,7 +204,10 @@ fn with_successful_mutation_application() {
 	new_test_ext().execute_with(|| {
 		let loan = LoanInfo {
 			schedule: RepaymentSchedule {
-				maturity: Maturity::Fixed((now() + YEAR).as_secs()),
+				maturity: Maturity::Fixed {
+					date: (now() + YEAR).as_secs(),
+					extension: YEAR.as_secs(),
+				},
 				interest_payments: InterestPayments::None,
 				pay_down_schedule: PayDownSchedule::None,
 			},
@@ -179,7 +229,11 @@ fn with_successful_mutation_application() {
 		let mutations = vec![
 			// LoanMutation::InterestPayments(..), No changes, only one variant
 			// LoanMutation::PayDownSchedule(..), No changes, only one variant
-			LoanMutation::Maturity(Maturity::Fixed((now() + YEAR * 2).as_secs())),
+			LoanMutation::Maturity(Maturity::Fixed {
+				date: (now() + YEAR * 2).as_secs(),
+				extension: (YEAR * 2).as_secs(),
+			}),
+			LoanMutation::MaturityExtension(YEAR.as_secs()),
 			LoanMutation::InterestRate(Rate::from_float(0.5)),
 			LoanMutation::Internal(InternalMutation::ProbabilityOfDefault(Rate::from_float(
 				0.5,

pallets/loans/src/tests/util.rs

@@ -74,7 +74,10 @@ pub fn base_internal_pricing() -> InternalPricing<Runtime> {
 pub fn base_internal_loan() -> LoanInfo<Runtime> {
 	LoanInfo {
 		schedule: RepaymentSchedule {
-			maturity: Maturity::Fixed((now() + YEAR).as_secs()),
+			maturity: Maturity::Fixed {
+				date: (now() + YEAR).as_secs(),
+				extension: (YEAR / 2).as_secs(),
+			},
 			interest_payments: InterestPayments::None,
 			pay_down_schedule: PayDownSchedule::None,
 		},
@@ -99,7 +102,7 @@ pub fn base_external_pricing() -> ExternalPricing<Runtime> {
 pub fn base_external_loan() -> LoanInfo<Runtime> {
 	LoanInfo {
 		schedule: RepaymentSchedule {
-			maturity: Maturity::Fixed((now() + YEAR).as_secs()),
+			maturity: Maturity::fixed((now() + YEAR).as_secs()),
 			interest_payments: InterestPayments::None,
 			pay_down_schedule: PayDownSchedule::None,
 		},

pallets/loans/src/types/mod.rs

@@ -18,7 +18,7 @@ use codec::{Decode, Encode, MaxEncodedLen};
 use frame_support::{storage::bounded_vec::BoundedVec, PalletError, RuntimeDebug};
 use scale_info::TypeInfo;
 use sp_runtime::{
-	traits::{EnsureAdd, Get},
+	traits::{EnsureAdd, EnsureAddAssign, EnsureSubAssign, Get},
 	ArithmeticError,
 };
 
@@ -85,25 +85,45 @@ pub enum MutationError {
 	DiscountedCashFlowExpected,
 	/// Emits when a modification expect the loan to have an iternal pricing.
 	InternalPricingExpected,
+	/// Maturity extensions exceed max extension allowed.
+	MaturityExtendedTooMuch,
 }
 
 /// Specify the expected repayments date
 #[derive(Encode, Decode, Clone, PartialEq, Eq, TypeInfo, RuntimeDebug, MaxEncodedLen)]
 pub enum Maturity {
 	/// Fixed point in time, in secs
-	Fixed(Moment),
+	Fixed {
+		/// Secs when maturity ends
+		date: Moment,
+		/// Extension in secs, without special permissions
+		extension: Moment,
+	},
 }
 
 impl Maturity {
+	pub fn fixed(date: Moment) -> Self {
+		Self::Fixed { date, extension: 0 }
+	}
+
 	pub fn date(&self) -> Moment {
 		match self {
-			Maturity::Fixed(moment) => *moment,
+			Maturity::Fixed { date, .. } => *date,
 		}
 	}
 
 	pub fn is_valid(&self, now: Moment) -> bool {
 		match self {
-			Maturity::Fixed(moment) => *moment > now,
+			Maturity::Fixed { date, .. } => *date > now,
+		}
+	}
+
+	pub fn extends(&mut self, value: Moment) -> Result<(), ArithmeticError> {
+		match self {
+			Maturity::Fixed { date, extension } => {
+				date.ensure_add_assign(value)?;
+				extension.ensure_sub_assign(value)
+			}
 		}
 	}
 }
@@ -186,6 +206,7 @@ pub enum InternalMutation<Rate> {
 #[derive(Encode, Decode, Clone, PartialEq, Eq, TypeInfo, RuntimeDebug, MaxEncodedLen)]
 pub enum LoanMutation<Rate> {
 	Maturity(Maturity),
+	MaturityExtension(Moment),
 	InterestRate(Rate),
 	InterestPayments(InterestPayments),
 	PayDownSchedule(PayDownSchedule),

runtime/common/src/lib.rs

@@ -424,6 +424,7 @@ pub mod changes {
 				// <https://docs.google.com/spreadsheets/d/1RJ5RLobAdumXUK7k_ugxy2eDAwI5akvtuqUM2Tyn5ts>
 				LoansChangeOf::<T>::Loan(_, loan_mutation) => match loan_mutation {
 					LoanMutation::Maturity(_) => vec![week, blocked],
+					LoanMutation::MaturityExtension(_) => vec![],
 					LoanMutation::InterestPayments(_) => vec![week, blocked],
 					LoanMutation::PayDownSchedule(_) => vec![week, blocked],
 					LoanMutation::InterestRate(_) => vec![epoch],

runtime/integration-tests/src/utils/loans.rs

@@ -115,7 +115,7 @@ pub fn issue_default_loan(
 ) -> Vec<RuntimeCall> {
 	let loan_info = LoanInfo {
 		schedule: RepaymentSchedule {
-			maturity: Maturity::Fixed(maturity),
+			maturity: Maturity::fixed(maturity),
 			interest_payments: InterestPayments::None,
 			pay_down_schedule: PayDownSchedule::None,
 		},