Loans: Add Runtime API (#1457)

* update types diagram

* add ActiveLoanInfo

* add decl runtime api for loans

* add API to development runtime

* add serialization capability to loans structs

* add rpc & service

* minor rename

* compiling for development runtime

* taplo fmt

* add support for altair & centrifuge

* fix clippy

* Remove RPC support

pallets/loans/docs/types.md

@@ -5,28 +5,14 @@ set namespaceSeparator ::
 hide methods
 
 enum Maturity {
-    Fixed: Moment
+    Fixed::date: Moment
+    Fixed::extension: Moment
 }
 
-enum CalendarEvent {
-    End
-}
-
-enum ReferenceDate{
-    CalendarDate: CalendarEvent,
-    OriginationDate
-}
-
-ReferenceDate *--> CalendarEvent
-
 enum InterestPayments {
     None
-    Monthly: ReferenceDate
-    SemiAnnually: ReferenceDate
 }
 
-InterestPayments *-----> ReferenceDate
-
 enum PayDownSchedule {
     None
 }
@@ -38,8 +24,8 @@ class RepaymentSchedule {
 }
 
 RepaymentSchedule *--> Maturity
-RepaymentSchedule *--> PayDownSchedule
-RepaymentSchedule *--> InterestPayments
+RepaymentSchedule *---> PayDownSchedule
+RepaymentSchedule *----> InterestPayments
 
 enum BorrowRestrictions {
     NoWrittenOff
@@ -59,24 +45,27 @@ class LoanRestrictions {
 LoanRestrictions *--> BorrowRestrictions
 LoanRestrictions *--> RepayRestrictions
 
-enum CompoundingCadence {
-    Secondly: ReferenceDate
-}
-
-CompoundingCadence *-r-> ReferenceDate
-
-enum InterestRate {
-    Fixed: Rate, CompoundingCadence
-}
-
-InterestRate *--> CompoundingCadence
-
 class RepaidAmount {
     principal: Balance
     interest: Balance
     unscheduled: Balance
 }
 
+node traits {
+    package interest {
+        enum CompoundingSchedule {
+            Secondly
+        }
+
+        enum InterestRate {
+            Fixed::rate_per_year: Rate
+            Fixed::compounding: CompoundingSchedule
+        }
+
+        InterestRate *--> CompoundingSchedule
+    }
+}
+
 package portfolio {
     class PortfolioValuation {
         value: Balance

pallets/loans/src/entities/loans.rs

@@ -489,3 +489,45 @@ impl<T: Config> ActiveLoan<T> {
 		self.schedule.maturity = crate::types::Maturity::fixed(duration);
 	}
 }
+
+/// Data containing an active loan with extra computed.
+#[derive(Encode, Decode, Clone, PartialEq, Eq, RuntimeDebugNoBound, TypeInfo, MaxEncodedLen)]
+#[scale_info(skip_type_params(T))]
+pub struct ActiveLoanInfo<T: Config> {
+	/// Related active loan
+	active_loan: ActiveLoan<T>,
+
+	/// Interest accrued for this loan
+	interest_accrued: T::Balance,
+
+	/// Present value of the loan
+	present_value: T::Balance,
+}
+
+impl<T: Config> TryFrom<ActiveLoan<T>> for ActiveLoanInfo<T> {
+	type Error = DispatchError;
+
+	fn try_from(active_loan: ActiveLoan<T>) -> Result<Self, Self::Error> {
+		let (interest_accrued, present_value) = match &active_loan.pricing {
+			ActivePricing::Internal(inner) => {
+				let principal = active_loan
+					.total_borrowed
+					.ensure_sub(active_loan.total_repaid.principal)?;
+
+				let maturity_date = active_loan.schedule.maturity.date();
+
+				(
+					inner.current_interest(principal)?,
+					inner.present_value(active_loan.origination_date, maturity_date)?,
+				)
+			}
+			ActivePricing::External(inner) => (inner.current_interest()?, inner.present_value()?),
+		};
+
+		Ok(Self {
+			active_loan,
+			interest_accrued,
+			present_value,
+		})
+	}
+}

pallets/loans/src/lib.rs

@@ -84,7 +84,7 @@ pub mod pallet {
 	};
 	use codec::HasCompact;
 	use entities::{
-		loans::{self, ActiveLoan, LoanInfo},
+		loans::{self, ActiveLoan, ActiveLoanInfo, LoanInfo},
 		pricing::{PricingAmount, RepaidPricingAmount},
 	};
 	use frame_support::{
@@ -120,7 +120,7 @@ pub mod pallet {
 		<T as Config>::PriceId,
 		<T as Config>::PoolId,
 	>>::Collection;
-
+	pub type PortfolioInfoOf<T> = Vec<(<T as Config>::LoanId, ActiveLoanInfo<T>)>;
 	pub type AssetOf<T> = (<T as Config>::CollectionId, <T as Config>::ItemId);
 	pub type PriceOf<T> = (<T as Config>::Balance, Moment);
 	pub type PriceResultOf<T> = Result<PriceOf<T>, DispatchError>;
@@ -145,27 +145,14 @@ pub mod pallet {
 		type CurrencyId: Parameter + Copy + MaxEncodedLen;
 
 		/// Identify a non fungible collection
-		type CollectionId: Parameter
-			+ Member
-			+ MaybeSerializeDeserialize
-			+ Default
-			+ TypeInfo
-			+ Copy
-			+ MaxEncodedLen;
+		type CollectionId: Parameter + Member + Default + TypeInfo + Copy + MaxEncodedLen;
 
 		/// Identify a non fungible item
-		type ItemId: Parameter
-			+ Member
-			+ MaybeSerializeDeserialize
-			+ Default
-			+ TypeInfo
-			+ Copy
-			+ MaxEncodedLen;
+		type ItemId: Parameter + Member + Default + TypeInfo + Copy + MaxEncodedLen;
 
 		/// Identify a loan in the pallet
 		type LoanId: Parameter
 			+ Member
-			+ MaybeSerializeDeserialize
 			+ Default
 			+ TypeInfo
 			+ MaxEncodedLen
@@ -174,20 +161,10 @@ pub mod pallet {
 			+ One;
 
 		/// Identify a loan in the pallet
-		type PriceId: Parameter
-			+ Member
-			+ MaybeSerializeDeserialize
-			+ TypeInfo
-			+ Copy
-			+ MaxEncodedLen;
+		type PriceId: Parameter + Member + TypeInfo + Copy + MaxEncodedLen;
 
 		/// Defines the rate type used for math computations
-		type Rate: Parameter
-			+ Member
-			+ MaybeSerializeDeserialize
-			+ FixedPointNumber
-			+ TypeInfo
-			+ MaxEncodedLen;
+		type Rate: Parameter + Member + FixedPointNumber + TypeInfo + MaxEncodedLen;
 
 		/// Defines the balance type used for math computations
 		type Balance: tokens::Balance + FixedPointOperand;
@@ -992,6 +969,26 @@ pub mod pallet {
 			Ok((loan, count))
 		}
 
+		pub fn get_active_loans_info(
+			pool_id: T::PoolId,
+		) -> Result<PortfolioInfoOf<T>, DispatchError> {
+			ActiveLoans::<T>::get(pool_id)
+				.into_iter()
+				.map(|(loan_id, loan)| Ok((loan_id, loan.try_into()?)))
+				.collect()
+		}
+
+		pub fn get_active_loan_info(
+			pool_id: T::PoolId,
+			loan_id: T::LoanId,
+		) -> Result<Option<ActiveLoanInfo<T>>, DispatchError> {
+			ActiveLoans::<T>::get(pool_id)
+				.into_iter()
+				.find(|(id, _)| *id == loan_id)
+				.map(|(_, loan)| loan.try_into())
+				.transpose()
+		}
+
 		/// 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 {

runtime/altair/src/lib.rs

@@ -1823,6 +1823,14 @@ impl fp_rpc::ConvertTransaction<sp_runtime::OpaqueExtrinsic> for TransactionConv
 	}
 }
 
+#[cfg(not(feature = "disable-runtime-api"))]
+mod __runtime_api_use {
+	pub use pallet_loans::entities::loans::ActiveLoanInfo;
+}
+
+#[cfg(not(feature = "disable-runtime-api"))]
+use __runtime_api_use::*;
+
 #[cfg(not(feature = "disable-runtime-api"))]
 impl_runtime_apis! {
 	impl sp_api::Core<Block> for Runtime {
@@ -2010,6 +2018,21 @@ impl_runtime_apis! {
 		}
 	}
 
+	impl runtime_common::apis::LoansApi<Block, PoolId, LoanId, ActiveLoanInfo<Runtime>> for Runtime {
+		fn portfolio(
+			pool_id: PoolId
+		) -> Vec<(LoanId, ActiveLoanInfo<Runtime>)> {
+			Loans::get_active_loans_info(pool_id).unwrap_or_default()
+		}
+
+		fn portfolio_loan(
+			pool_id: PoolId,
+			loan_id: LoanId
+		) -> Option<ActiveLoanInfo<Runtime>> {
+			Loans::get_active_loan_info(pool_id, loan_id).ok().flatten()
+		}
+	}
+
 	// Frontier APIs
 	impl fp_rpc::EthereumRuntimeRPCApi<Block> for Runtime {
 		fn chain_id() -> u64 {

runtime/centrifuge/src/lib.rs

@@ -1912,6 +1912,14 @@ impl fp_rpc::ConvertTransaction<sp_runtime::OpaqueExtrinsic> for TransactionConv
 	}
 }
 
+#[cfg(not(feature = "disable-runtime-api"))]
+mod __runtime_api_use {
+	pub use pallet_loans::entities::loans::ActiveLoanInfo;
+}
+
+#[cfg(not(feature = "disable-runtime-api"))]
+use __runtime_api_use::*;
+
 #[cfg(not(feature = "disable-runtime-api"))]
 impl_runtime_apis! {
 	impl sp_api::Core<Block> for Runtime {
@@ -2100,6 +2108,21 @@ impl_runtime_apis! {
 		}
 	}
 
+	impl runtime_common::apis::LoansApi<Block, PoolId, LoanId, ActiveLoanInfo<Runtime>> for Runtime {
+		fn portfolio(
+			pool_id: PoolId
+		) -> Vec<(LoanId, ActiveLoanInfo<Runtime>)> {
+			Loans::get_active_loans_info(pool_id).unwrap_or_default()
+		}
+
+		fn portfolio_loan(
+			pool_id: PoolId,
+			loan_id: LoanId
+		) -> Option<ActiveLoanInfo<Runtime>> {
+			Loans::get_active_loan_info(pool_id, loan_id).ok().flatten()
+		}
+	}
+
 	// Frontier APIs
 	impl fp_rpc::EthereumRuntimeRPCApi<Block> for Runtime {
 		fn chain_id() -> u64 {

runtime/common/src/apis/loans.rs

@@ -0,0 +1,29 @@
+// Copyright 2023 Centrifuge Foundation (centrifuge.io).
+// This file is part of Centrifuge chain project.
+
+// Centrifuge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version (see http://www.gnu.org/licenses).
+
+// Centrifuge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+use codec::Codec;
+use sp_api::decl_runtime_apis;
+use sp_std::vec::Vec;
+
+decl_runtime_apis! {
+	/// Runtime API for the rewards pallet.
+	pub trait LoansApi<PoolId, LoanId, Loan>
+	where
+		PoolId: Codec,
+		LoanId: Codec,
+		Loan: Codec,
+	{
+		fn portfolio(pool_id: PoolId) -> Vec<(LoanId, Loan)>;
+		fn portfolio_loan(pool_id: PoolId, loan_id: LoanId) -> Option<Loan>;
+	}
+}

runtime/common/src/apis/mod.rs

@@ -12,9 +12,11 @@
 
 //! Runtime apis useful in the Centrifuge ecosystem
 pub use anchors::*;
+pub use loans::*;
 pub use pools::*;
 pub use rewards::*;
 
 mod anchors;
+mod loans;
 mod pools;
 mod rewards;

runtime/development/src/lib.rs

@@ -2090,6 +2090,14 @@ impl fp_rpc::ConvertTransaction<sp_runtime::OpaqueExtrinsic> for TransactionConv
 	}
 }
 
+#[cfg(not(feature = "disable-runtime-api"))]
+mod __runtime_api_use {
+	pub use pallet_loans::entities::loans::ActiveLoanInfo;
+}
+
+#[cfg(not(feature = "disable-runtime-api"))]
+use __runtime_api_use::*;
+
 #[cfg(not(feature = "disable-runtime-api"))]
 impl_runtime_apis! {
 	impl sp_api::Core<Block> for Runtime {
@@ -2281,6 +2289,21 @@ impl_runtime_apis! {
 		}
 	}
 
+	impl runtime_common::apis::LoansApi<Block, PoolId, LoanId, ActiveLoanInfo<Runtime>> for Runtime {
+		fn portfolio(
+			pool_id: PoolId
+		) -> Vec<(LoanId, ActiveLoanInfo<Runtime>)> {
+			Loans::get_active_loans_info(pool_id).unwrap_or_default()
+		}
+
+		fn portfolio_loan(
+			pool_id: PoolId,
+			loan_id: LoanId
+		) -> Option<ActiveLoanInfo<Runtime>> {
+			Loans::get_active_loan_info(pool_id, loan_id).ok().flatten()
+		}
+	}
+
 	// Frontier APIs
 	impl fp_rpc::EthereumRuntimeRPCApi<Block> for Runtime {
 		fn chain_id() -> u64 {