Loans: unlimit external pricing borrows

pallets/loans/src/entities/loans.rs

@@ -285,7 +285,7 @@ impl<T: Config> ActiveLoan<T> {
 	fn ensure_can_borrow(&self, amount: T::Balance) -> DispatchResult {
 		let max_borrow_amount = match &self.pricing {
 			ActivePricing::Internal(inner) => inner.max_borrow_amount(self.total_borrowed)?,
-			ActivePricing::External(inner) => inner.max_borrow_amount()?,
+			ActivePricing::External(inner) => inner.max_borrow_amount(amount)?,
 		};
 
 		ensure!(

pallets/loans/src/entities/pricing/external.rs

@@ -5,7 +5,7 @@ use cfg_traits::{
 };
 use cfg_types::adjustments::Adjustment;
 use codec::{Decode, Encode, MaxEncodedLen};
-use frame_support::{self, ensure, RuntimeDebugNoBound};
+use frame_support::{self, ensure, RuntimeDebug, RuntimeDebugNoBound};
 use scale_info::TypeInfo;
 use sp_runtime::{
 	traits::{
@@ -16,15 +16,25 @@ use sp_runtime::{
 
 use crate::pallet::{Config, Error, PoolIdOf, PriceOf};
 
+/// Define the max borrow amount of a loan
+#[derive(Encode, Decode, Clone, PartialEq, Eq, TypeInfo, RuntimeDebug, MaxEncodedLen)]
+pub enum MaxBorrowAmount<Balance> {
+	/// You can borrow until the pool reserve
+	NoLimit,
+
+	/// Maximum number of items associated with the loan of the pricing.
+	Quantity(Balance),
+}
+
 /// External pricing method
 #[derive(Encode, Decode, Clone, PartialEq, Eq, TypeInfo, RuntimeDebugNoBound, MaxEncodedLen)]
 #[scale_info(skip_type_params(T))]
 pub struct ExternalPricing<T: Config> {
 	/// Id of an external price
 	pub price_id: T::PriceId,
 
-	/// Maximum number of items associated with the loan of the pricing.
-	pub max_borrow_quantity: T::Balance,
+	/// Maximum amount that can be borrowed.
+	pub max_borrow_amount: MaxBorrowAmount<T::Balance>,
 }
 
 impl<T: Config> ExternalPricing<T> {
@@ -78,13 +88,18 @@ impl<T: Config> ExternalActivePricing<T> {
 		Ok(prices.get(&self.info.price_id)?.0)
 	}
 
-	pub fn max_borrow_amount(&self) -> Result<T::Balance, DispatchError> {
-		let price = self.calculate_price()?;
-		let available = self
-			.info
-			.max_borrow_quantity
-			.ensure_sub(self.outstanding_quantity)?;
-		Ok(price.ensure_mul_int(available)?)
+	pub fn max_borrow_amount(
+		&self,
+		desired_amount: T::Balance,
+	) -> Result<T::Balance, DispatchError> {
+		match self.info.max_borrow_amount {
+			MaxBorrowAmount::Quantity(quantity) => {
+				let price = self.calculate_price()?;
+				let available = quantity.ensure_sub(self.outstanding_quantity)?;
+				Ok(price.ensure_mul_int(available)?)
+			}
+			MaxBorrowAmount::NoLimit => Ok(desired_amount),
+		}
 	}
 
 	pub fn last_updated(&self) -> Result<Moment, DispatchError> {

pallets/loans/src/tests/borrow_loan.rs

@@ -209,7 +209,7 @@ fn with_unregister_price_id() {
 		let loan = LoanInfo {
 			pricing: Pricing::External(ExternalPricing {
 				price_id: UNREGISTER_PRICE_ID,
-				max_borrow_quantity: QUANTITY,
+				max_borrow_amount: ExtMaxBorrowAmount::Quantity(QUANTITY),
 			}),
 			..util::base_external_loan()
 		};
@@ -274,6 +274,31 @@ fn with_correct_amount_external_pricing() {
 	});
 }
 
+#[test]
+fn with_unlimited_amount_external_pricing() {
+	new_test_ext().execute_with(|| {
+		let loan = LoanInfo {
+			pricing: Pricing::External(ExternalPricing {
+				price_id: REGISTER_PRICE_ID,
+				max_borrow_amount: ExtMaxBorrowAmount::NoLimit,
+			}),
+			..util::base_external_loan()
+		};
+
+		let loan_id = util::create_loan(loan);
+
+		let amount = PRICE_VALUE.saturating_mul_int(2 /* Could be any value */);
+		config_mocks(amount);
+
+		assert_ok!(Loans::borrow(
+			RuntimeOrigin::signed(BORROWER),
+			POOL_A,
+			loan_id,
+			amount
+		));
+	});
+}
+
 #[test]
 fn twice() {
 	new_test_ext().execute_with(|| {

pallets/loans/src/tests/create_loan.rs

@@ -153,7 +153,7 @@ fn with_unregister_price_id() {
 		let loan = LoanInfo {
 			pricing: Pricing::External(ExternalPricing {
 				price_id: UNREGISTER_PRICE_ID,
-				max_borrow_quantity: QUANTITY,
+				max_borrow_amount: ExtMaxBorrowAmount::Quantity(QUANTITY),
 			}),
 			..util::base_external_loan()
 		};

pallets/loans/src/tests/mod.rs

@@ -9,8 +9,8 @@ use super::{
 	entities::{
 		loans::{ActiveLoan, LoanInfo},
 		pricing::{
-			external::ExternalPricing,
-			internal::{InternalPricing, MaxBorrowAmount},
+			external::{ExternalPricing, MaxBorrowAmount as ExtMaxBorrowAmount},
+			internal::{InternalPricing, MaxBorrowAmount as IntMaxBorrowAmount},
 			ActivePricing, Pricing,
 		},
 	},

pallets/loans/src/tests/util.rs

@@ -1,13 +1,13 @@
 use super::*;
 
-pub fn total_borrowed_rate(value: f64) -> MaxBorrowAmount<Rate> {
-	MaxBorrowAmount::UpToTotalBorrowed {
+pub fn total_borrowed_rate(value: f64) -> IntMaxBorrowAmount<Rate> {
+	IntMaxBorrowAmount::UpToTotalBorrowed {
 		advance_rate: Rate::from_float(value),
 	}
 }
 
-pub fn outstanding_debt_rate(value: f64) -> MaxBorrowAmount<Rate> {
-	MaxBorrowAmount::UpToOutstandingDebt {
+pub fn outstanding_debt_rate(value: f64) -> IntMaxBorrowAmount<Rate> {
+	IntMaxBorrowAmount::UpToOutstandingDebt {
 		advance_rate: Rate::from_float(value),
 	}
 }
@@ -96,7 +96,7 @@ pub fn base_external_loan() -> LoanInfo<Runtime> {
 		collateral: ASSET_AA,
 		pricing: Pricing::External(ExternalPricing {
 			price_id: REGISTER_PRICE_ID,
-			max_borrow_quantity: QUANTITY,
+			max_borrow_amount: ExtMaxBorrowAmount::Quantity(QUANTITY),
 		}),
 		restrictions: LoanRestrictions {
 			borrows: BorrowRestrictions::NotWrittenOff,