Fix/linear pricing (#1812)

* feat: restrict epoch closing to liquiduty admin

* fix: linear pricing

* proof: type unsafety

* revert: type unsafety

* fix: tests and adapt logic to allow dyanmic input

* chore: generic removal

pallets/loans/src/entities/input.rs

@@ -7,6 +7,7 @@ use crate::{
 	entities::pricing::external::ExternalAmount,
 	pallet::{Config, Error},
 	types::RepaidAmount,
+	PriceOf,
 };
 
 #[derive(Encode, Decode, Clone, PartialEq, Eq, TypeInfo, RuntimeDebugNoBound, MaxEncodedLen)]
@@ -61,6 +62,6 @@ impl<T: Config> RepaidInput<T> {
 #[scale_info(skip_type_params(T))]
 pub enum PriceCollectionInput<T: Config> {
 	Empty,
-	Custom(BoundedBTreeMap<T::PriceId, T::Balance, T::MaxActiveLoansPerPool>),
+	Custom(BoundedBTreeMap<T::PriceId, PriceOf<T>, T::MaxActiveLoansPerPool>),
 	FromRegistry,
 }

pallets/loans/src/entities/loans.rs

@@ -31,6 +31,7 @@ use crate::{
 		BorrowLoanError, BorrowRestrictions, CloseLoanError, CreateLoanError, LoanRestrictions,
 		MutationError, RepaidAmount, RepayLoanError, RepayRestrictions, RepaymentSchedule,
 	},
+	PriceOf,
 };
 
 /// Loan information.
@@ -290,7 +291,7 @@ impl<T: Config> ActiveLoan<T> {
 	pub fn present_value_by<Rates>(
 		&self,
 		rates: &Rates,
-		prices: &BTreeMap<T::PriceId, T::Balance>,
+		prices: &BTreeMap<T::PriceId, PriceOf<T>>,
 	) -> Result<T::Balance, DispatchError>
 	where
 		Rates: RateCollection<T::Rate, T::Balance, T::Balance>,
@@ -581,3 +582,101 @@ impl<T: Config> TryFrom<(T::PoolId, ActiveLoan<T>)> for ActiveLoanInfo<T> {
 		})
 	}
 }
+
+/// Adds `with_linear_pricing` to ExternalPricing struct for migration to v4
+pub mod v3 {
+	use cfg_traits::{interest::InterestRate, Seconds};
+	use parity_scale_codec::{Decode, Encode};
+
+	use crate::{
+		entities::{
+			loans::BlockNumberFor,
+			pricing::external::v3::{ActivePricing, Pricing},
+		},
+		types::{LoanRestrictions, RepaidAmount, RepaymentSchedule},
+		AssetOf, Config,
+	};
+
+	#[derive(Encode, Decode)]
+	pub struct ActiveLoan<T: Config> {
+		schedule: RepaymentSchedule,
+		collateral: AssetOf<T>,
+		restrictions: LoanRestrictions,
+		borrower: T::AccountId,
+		write_off_percentage: T::Rate,
+		origination_date: Seconds,
+		pricing: ActivePricing<T>,
+		total_borrowed: T::Balance,
+		total_repaid: RepaidAmount<T::Balance>,
+		repayments_on_schedule_until: Seconds,
+	}
+
+	impl<T: Config> ActiveLoan<T> {
+		pub fn migrate(self, with_linear_pricing: bool) -> super::ActiveLoan<T> {
+			super::ActiveLoan {
+				schedule: self.schedule,
+				collateral: self.collateral,
+				restrictions: self.restrictions,
+				borrower: self.borrower,
+				write_off_percentage: self.write_off_percentage,
+				origination_date: self.origination_date,
+				pricing: self.pricing.migrate(with_linear_pricing),
+				total_borrowed: self.total_borrowed,
+				total_repaid: self.total_repaid,
+				repayments_on_schedule_until: self.repayments_on_schedule_until,
+			}
+		}
+	}
+
+	#[derive(Encode, Decode)]
+	pub struct CreatedLoan<T: Config> {
+		info: LoanInfo<T>,
+		borrower: T::AccountId,
+	}
+
+	impl<T: Config> CreatedLoan<T> {
+		pub fn migrate(self, with_linear_pricing: bool) -> super::CreatedLoan<T> {
+			super::CreatedLoan::<T>::new(self.info.migrate(with_linear_pricing), self.borrower)
+		}
+	}
+
+	#[derive(Encode, Decode)]
+	pub struct ClosedLoan<T: Config> {
+		closed_at: BlockNumberFor<T>,
+		info: LoanInfo<T>,
+		total_borrowed: T::Balance,
+		total_repaid: RepaidAmount<T::Balance>,
+	}
+
+	impl<T: Config> ClosedLoan<T> {
+		pub fn migrate(self, with_linear_pricing: bool) -> super::ClosedLoan<T> {
+			super::ClosedLoan::<T> {
+				closed_at: self.closed_at,
+				info: self.info.migrate(with_linear_pricing),
+				total_borrowed: self.total_borrowed,
+				total_repaid: self.total_repaid,
+			}
+		}
+	}
+
+	#[derive(Encode, Decode)]
+	pub struct LoanInfo<T: Config> {
+		pub schedule: RepaymentSchedule,
+		pub collateral: AssetOf<T>,
+		pub interest_rate: InterestRate<T::Rate>,
+		pub pricing: Pricing<T>,
+		pub restrictions: LoanRestrictions,
+	}
+
+	impl<T: Config> LoanInfo<T> {
+		pub fn migrate(self, with_linear_pricing: bool) -> super::LoanInfo<T> {
+			super::LoanInfo::<T> {
+				pricing: self.pricing.migrate(with_linear_pricing),
+				schedule: self.schedule,
+				collateral: self.collateral,
+				interest_rate: self.interest_rate,
+				restrictions: self.restrictions,
+			}
+		}
+	}
+}

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

@@ -9,11 +9,12 @@ use sp_runtime::{
 	traits::{EnsureAdd, EnsureFixedPointNumber, EnsureSub, Zero},
 	ArithmeticError, DispatchError, DispatchResult, FixedPointNumber,
 };
-use sp_std::collections::btree_map::BTreeMap;
+use sp_std::{cmp::min, collections::btree_map::BTreeMap};
 
 use crate::{
 	entities::interest::ActiveInterestRate,
 	pallet::{Config, Error},
+	PriceOf,
 };
 
 #[derive(Encode, Decode, Clone, PartialEq, Eq, TypeInfo, RuntimeDebugNoBound, MaxEncodedLen)]
@@ -76,6 +77,9 @@ pub struct ExternalPricing<T: Config> {
 	/// borrow/repay and the current oracle price.
 	/// See [`ExternalAmount::settlement_price`].
 	pub max_price_variation: T::Rate,
+
+	/// If the pricing is estimated with a linear pricing model.
+	pub with_linear_pricing: bool,
 }
 
 impl<T: Config> ExternalPricing<T> {
@@ -150,23 +154,58 @@ impl<T: Config> ExternalActivePricing<T> {
 		}
 	}
 
-	fn linear_accrual_price(&self, maturity: Seconds) -> Result<T::Balance, DispatchError> {
-		Ok(cfg_utils::math::y_coord_in_rect(
-			(self.settlement_price_updated, self.latest_settlement_price),
-			(maturity, self.info.notional),
-			T::Time::now(),
-		)?)
+	fn maybe_with_linear_accrual_price(
+		&self,
+		maturity: Seconds,
+		price: T::Balance,
+		price_last_updated: Seconds,
+	) -> Result<T::Balance, DispatchError> {
+		if self.info.with_linear_pricing {
+			if min(price_last_updated, maturity) == maturity {
+				// We can not have 2 'xs' with different 'y' in a rect.
+				// That only happens at maturity
+				return Ok(self.info.notional);
+			}
+
+			Ok(cfg_utils::math::y_coord_in_rect(
+				(min(price_last_updated, maturity), price),
+				(maturity, self.info.notional),
+				min(T::Time::now(), maturity),
+			)?)
+		} else {
+			Ok(price)
+		}
 	}
 
 	pub fn current_price(
 		&self,
 		pool_id: T::PoolId,
 		maturity: Seconds,
 	) -> Result<T::Balance, DispatchError> {
-		Ok(match T::PriceRegistry::get(&self.info.price_id, &pool_id) {
-			Ok(data) => data.0,
-			Err(_) => self.linear_accrual_price(maturity)?,
-		})
+		self.current_price_inner(
+			maturity,
+			T::PriceRegistry::get(&self.info.price_id, &pool_id).ok(),
+		)
+	}
+
+	fn current_price_inner(
+		&self,
+		maturity: Seconds,
+		oracle: Option<PriceOf<T>>,
+	) -> Result<T::Balance, DispatchError> {
+		if let Some((oracle_price, oracle_provided_at)) = oracle {
+			self.maybe_with_linear_accrual_price(
+				maturity,
+				oracle_price,
+				oracle_provided_at.into_seconds(),
+			)
+		} else {
+			self.maybe_with_linear_accrual_price(
+				maturity,
+				self.latest_settlement_price,
+				self.settlement_price_updated,
+			)
+		}
 	}
 
 	pub fn outstanding_principal(
@@ -197,13 +236,10 @@ impl<T: Config> ExternalActivePricing<T> {
 
 	pub fn present_value_cached(
 		&self,
-		cache: &BTreeMap<T::PriceId, T::Balance>,
+		cache: &BTreeMap<T::PriceId, PriceOf<T>>,
 		maturity: Seconds,
 	) -> Result<T::Balance, DispatchError> {
-		let price = match cache.get(&self.info.price_id) {
-			Some(data) => *data,
-			None => self.linear_accrual_price(maturity)?,
-		};
+		let price = self.current_price_inner(maturity, cache.get(&self.info.price_id).copied())?;
 		Ok(self.outstanding_quantity.ensure_mul_int(price)?)
 	}
 
@@ -288,3 +324,95 @@ impl<T: Config> ExternalActivePricing<T> {
 		Ok(())
 	}
 }
+
+/// Adds `with_linear_pricing` to ExternalPricing struct for migration to v4
+pub mod v3 {
+	use cfg_traits::Seconds;
+	use parity_scale_codec::{Decode, Encode};
+
+	use crate::{
+		entities::{
+			interest::ActiveInterestRate,
+			pricing::{external::MaxBorrowAmount, internal, internal::InternalActivePricing},
+		},
+		Config,
+	};
+
+	#[derive(Encode, Decode)]
+	pub enum Pricing<T: Config> {
+		Internal(internal::InternalPricing<T>),
+		External(ExternalPricing<T>),
+	}
+
+	impl<T: Config> Pricing<T> {
+		pub fn migrate(self, with_linear_pricing: bool) -> crate::entities::pricing::Pricing<T> {
+			match self {
+				Pricing::Internal(i) => crate::entities::pricing::Pricing::Internal(i),
+				Pricing::External(e) => {
+					crate::entities::pricing::Pricing::External(e.migrate(with_linear_pricing))
+				}
+			}
+		}
+	}
+
+	#[derive(Encode, Decode)]
+	pub struct ExternalPricing<T: Config> {
+		pub price_id: T::PriceId,
+		pub max_borrow_amount: MaxBorrowAmount<T::Quantity>,
+		pub notional: T::Balance,
+		pub max_price_variation: T::Rate,
+	}
+
+	#[derive(Encode, Decode)]
+	pub enum ActivePricing<T: Config> {
+		Internal(InternalActivePricing<T>),
+		External(ExternalActivePricing<T>),
+	}
+
+	impl<T: Config> ActivePricing<T> {
+		pub fn migrate(
+			self,
+			with_linear_pricing: bool,
+		) -> crate::entities::pricing::ActivePricing<T> {
+			match self {
+				ActivePricing::Internal(i) => crate::entities::pricing::ActivePricing::Internal(i),
+				ActivePricing::External(e) => crate::entities::pricing::ActivePricing::External(
+					e.migrate(with_linear_pricing),
+				),
+			}
+		}
+	}
+
+	#[derive(Encode, Decode)]
+	pub struct ExternalActivePricing<T: Config> {
+		info: ExternalPricing<T>,
+		outstanding_quantity: T::Quantity,
+		pub interest: ActiveInterestRate<T>,
+		latest_settlement_price: T::Balance,
+		settlement_price_updated: Seconds,
+	}
+
+	impl<T: Config> ExternalActivePricing<T> {
+		pub fn migrate(self, with_linear_pricing: bool) -> super::ExternalActivePricing<T> {
+			super::ExternalActivePricing {
+				info: self.info.migrate(with_linear_pricing),
+				outstanding_quantity: self.outstanding_quantity,
+				interest: self.interest,
+				latest_settlement_price: self.latest_settlement_price,
+				settlement_price_updated: self.settlement_price_updated,
+			}
+		}
+	}
+
+	impl<T: Config> ExternalPricing<T> {
+		pub fn migrate(self, with_linear_pricing: bool) -> super::ExternalPricing<T> {
+			super::ExternalPricing {
+				price_id: self.price_id,
+				max_borrow_amount: self.max_borrow_amount,
+				notional: self.notional,
+				max_price_variation: self.max_price_variation,
+				with_linear_pricing,
+			}
+		}
+	}
+}

pallets/loans/src/lib.rs

@@ -118,7 +118,7 @@ pub mod pallet {
 	pub type AssetOf<T> = (<T as Config>::CollectionId, <T as Config>::ItemId);
 	pub type PriceOf<T> = (<T as Config>::Balance, <T as Config>::Moment);
 
-	const STORAGE_VERSION: StorageVersion = StorageVersion::new(3);
+	const STORAGE_VERSION: StorageVersion = StorageVersion::new(4);
 
 	#[pallet::pallet]
 	#[pallet::storage_version(STORAGE_VERSION)]
@@ -169,7 +169,7 @@ pub mod pallet {
 		type Time: TimeAsSecs;
 
 		/// Generic time type
-		type Moment: Parameter + Member + IntoSeconds;
+		type Moment: Parameter + Member + Copy + IntoSeconds;
 
 		/// Used to mint, transfer, and inspect assets.
 		type NonFungible: Transfer<Self::AccountId>
@@ -232,7 +232,7 @@ pub mod pallet {
 
 	/// Storage for loans that has been created but are not still active.
 	#[pallet::storage]
-	pub(crate) type CreatedLoan<T: Config> = StorageDoubleMap<
+	pub type CreatedLoan<T: Config> = StorageDoubleMap<
 		_,
 		Blake2_128Concat,
 		T::PoolId,
@@ -259,7 +259,7 @@ pub mod pallet {
 	/// No mutations are expected in this storage.
 	/// Loans are stored here for historical purposes.
 	#[pallet::storage]
-	pub(crate) type ClosedLoan<T: Config> = StorageDoubleMap<
+	pub type ClosedLoan<T: Config> = StorageDoubleMap<
 		_,
 		Blake2_128Concat,
 		T::PoolId,
@@ -1050,15 +1050,15 @@ pub mod pallet {
 
 		pub fn registered_prices(
 			pool_id: T::PoolId,
-		) -> Result<BTreeMap<T::PriceId, T::Balance>, DispatchError> {
+		) -> Result<BTreeMap<T::PriceId, PriceOf<T>>, DispatchError> {
 			let collection = T::PriceRegistry::collection(&pool_id)?;
 			Ok(ActiveLoans::<T>::get(pool_id)
 				.iter()
 				.filter_map(|(_, loan)| loan.price_id())
 				.filter_map(|price_id| {
 					collection
 						.get(&price_id)
-						.map(|price| (price_id, price.0))
+						.map(|price| (price_id, (price.0, price.1)))
 						.ok()
 				})
 				.collect::<BTreeMap<_, _>>())