feat: add discount loan function (#50)

* feat: implement `discountLoanBatch` function * test: add `discountLoanBatch` function tests * feat: update preview structs * fix: reorder fields of the loan preview structure * test: fix a bug in new tests * test: fix formatting issues in tests * fix: minor formatting issues and reorder codee lines * fix: a minor formatting issue * feat: rename fields in `LoanDiscounted` event * feat: rename `discountLoanBatch` -> `discountLoanForBatch` * feat: update contracts version to `v1.7.0` --------- Co-authored-by: Evgenii Zaitsev <[email protected]>
cloudwalk · Jan 3, 2025 · 73e9569 · 73e9569
1 parent 7cfefaa
commit 73e9569
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Showing 8 changed files with 332 additions and 7 deletions.
diff --git a/contracts/LendingMarket.sol b/contracts/LendingMarket.sol
@@ -334,6 +334,24 @@ contract LendingMarket is
         }
     }
 
+    /// @inheritdoc ILendingMarket
+    function discountLoanForBatch(
+        uint256[] calldata loanIds, // Tools: this comment prevents Prettier from formatting into a single line.
+        uint256[] calldata discountAmounts
+    ) external whenNotPaused {
+        uint256 len = loanIds.length;
+        if (len != discountAmounts.length) {
+            revert Error.ArrayLengthMismatch();
+        }
+        for (uint256 i = 0; i < len; ++i) {
+            uint256 loanId = loanIds[i];
+            Loan.State storage loan = _loans[loanId];
+            _checkIfLoanOngoing(loanId);
+            _checkSender(msg.sender, loan.programId);
+            _discountLoan(loanId, loan, discountAmounts[i]);
+        }
+    }
+
     /// @dev Updates the loan state and makes the necessary transfers when repaying a loan.
     /// @param loanId The unique identifier of the loan to repay.
     /// @param repaymentAmount The amount to repay.
@@ -388,6 +406,47 @@ contract LendingMarket is
         emit LoanRepayment(loanId, repayer, loan.borrower, repaymentAmount, newOutstandingBalance);
     }
 
+    /// @dev Discounts a loan.
+    /// @param loanId The unique identifier of the loan to discount.
+    /// @param loan The storage state of the loan.
+    /// @param discountAmount The amount of the discount.
+    function _discountLoan(
+        uint256 loanId, // Tools: this comment prevents Prettier from formatting into a single line.
+        Loan.State storage loan,
+        uint256 discountAmount
+    ) internal {
+        if (discountAmount == 0) {
+            revert Error.InvalidAmount();
+        }
+
+        (uint256 oldOutstandingBalance, uint256 lateFeeAmount, ) = _outstandingBalance(loan, _blockTimestamp());
+        uint256 roundedOutstandingBalance = Rounding.roundMath(oldOutstandingBalance, Constants.ACCURACY_FACTOR);
+        uint256 newOutstandingBalance = 0; // Full discount by default
+
+        if (discountAmount == type(uint256).max) {
+            discountAmount = roundedOutstandingBalance;
+        } else {
+            if (discountAmount != Rounding.roundMath(discountAmount, Constants.ACCURACY_FACTOR)) {
+                revert Error.InvalidAmount();
+            }
+            if (discountAmount > roundedOutstandingBalance) {
+                revert Error.InvalidAmount();
+            }
+            // Not a full discount
+            if (discountAmount < roundedOutstandingBalance) {
+                newOutstandingBalance = oldOutstandingBalance - discountAmount;
+            }
+            // Else full discount
+        }
+
+        loan.discountAmount += discountAmount.toUint64();
+        loan.trackedBalance = newOutstandingBalance.toUint64();
+        loan.trackedTimestamp = _blockTimestamp().toUint32();
+        _updateStoredLateFee(lateFeeAmount, loan);
+
+        emit LoanDiscounted(loanId, discountAmount, newOutstandingBalance);
+    }
+
     // -------------------------------------------- //
     //  Lender functions                            //
     // -------------------------------------------- //
@@ -1036,6 +1095,7 @@ contract LendingMarket is
         preview.addonAmount = loan.addonAmount;
         preview.repaidAmount = loan.repaidAmount;
         preview.lateFeeAmount += loan.lateFeeAmount;
+        preview.discountAmount = loan.discountAmount;
         preview.programId = loan.programId;
         preview.borrower = loan.borrower;
         preview.previewTimestamp = timestamp;
@@ -1084,6 +1144,7 @@ contract LendingMarket is
             preview.totalAddonAmount += singleLoanPreview.addonAmount;
             preview.totalRepaidAmount += singleLoanPreview.repaidAmount;
             preview.totalLateFeeAmount += singleLoanPreview.lateFeeAmount;
+            preview.totalDiscountAmount += singleLoanPreview.discountAmount;
             preview.installmentPreviews[i] = singleLoanPreview;
             ++loanId;
         }

diff --git a/contracts/common/Versionable.sol b/contracts/common/Versionable.sol
@@ -16,6 +16,6 @@ abstract contract Versionable is IVersionable {
      * @inheritdoc IVersionable
      */
     function $__VERSION() external pure returns (Version memory) {
-        return Version(1, 6, 0);
+        return Version(1, 7, 0);
     }
 }
diff --git a/contracts/common/interfaces/core/ILendingMarket.sol b/contracts/common/interfaces/core/ILendingMarket.sol
@@ -85,6 +85,16 @@ interface ILendingMarket {
     /// @param loanId The unique identifier of the loan.
     event LoanRevoked(uint256 indexed loanId);
 
+    /// @dev Emitted when a loan is discounted.
+    /// @param loanId The unique identifier of the loan.
+    /// @param discountAmount The amount of the discount.
+    /// @param newTrackedBalance The new tracked balance of the loan after the discount.
+    event LoanDiscounted(
+        uint256 indexed loanId, // Tools: this comment prevents Prettier from formatting into a single line.
+        uint256 discountAmount,
+        uint256 newTrackedBalance
+    );
+
     /// @dev Emitted when an installment loan is revoked.
     /// @param firstInstallmentId The ID of the first sub-loan of the installment loan.
     /// @param installmentCount The total number of installments.
@@ -234,6 +244,14 @@ interface ILendingMarket {
         address repayer
     ) external;
 
+    /// @dev Discounts a batch of loans.
+    /// @param loanIds The unique identifiers of the loans to discount.
+    /// @param discountAmounts The amounts to discount for each loan.
+    function discountLoanForBatch(
+        uint256[] calldata loanIds, // Tools: this comment prevents Prettier from formatting into a single line.
+        uint256[] calldata discountAmounts
+    ) external;
+
     // -------------------------------------------- //
     //  Lender functions                            //
     // -------------------------------------------- //

diff --git a/contracts/common/libraries/Loan.sol b/contracts/common/libraries/Loan.sol
@@ -43,6 +43,7 @@ library Loan {
         // uint16 __reserved;         // Reserved for future use.
         // Slot 5
         uint64 lateFeeAmount;         // The late fee amount of the loan or zero if the loan is not defaulted.
+        uint64 discountAmount;        // The discount amount of the loan or zero if the loan is not discounted.
     }
 
     /// @dev A struct that defines the terms of a loan.
@@ -73,6 +74,7 @@ library Loan {
     /// - addonAmount ------------ The addon amount of the loan at the previewed period.
     /// - repaidAmount ----------- The repaid amount of the loan at the previewed period.
     /// - lateFeeAmount ---------- The late fee amount of the loan at the previewed period.
+    /// - discountAmount --------- The discount amount of the loan at the previewed period.
     /// - programId -------------- The program ID of the loan.
     /// - borrower --------------- The borrower of the loan.
     /// - previewTimestamp ------- The preview timestamp.
@@ -92,6 +94,7 @@ library Loan {
         uint256 addonAmount;
         uint256 repaidAmount;
         uint256 lateFeeAmount;
+        uint256 discountAmount;
         uint256 programId;
         address borrower;
         uint256 previewTimestamp;
@@ -121,6 +124,7 @@ library Loan {
     /// - totalRepaidAmount -------- The total repaid amount of all installments.
     /// - totalLateFeeAmount ------- The total late fee amount of all installments.
     /// - installmentPreviews ------ The extended previews of all installments.
+    /// - totalDiscountAmount ------ The total discount amount of all installments.
     ///
     /// The purpose of the fields in the case of ordinary loans:
     ///
@@ -134,6 +138,7 @@ library Loan {
     /// - totalRepaidAmount -------- The repaid amount of the loan.
     /// - totalLateFeeAmount ------- The late fee amount of the loan.
     /// - installmentPreviews ------ The extended preview of the loan as a single item array.
+    /// - totalDiscountAmount ------ The total discount amount of the loan.
 
     /// Notes:
     ///
@@ -150,6 +155,7 @@ library Loan {
         uint256 totalAddonAmount;
         uint256 totalRepaidAmount;
         uint256 totalLateFeeAmount;
+        uint256 totalDiscountAmount;
         PreviewExtended[] installmentPreviews;
     }
 }
diff --git a/contracts/mocks/LendingMarketMock.sol b/contracts/mocks/LendingMarketMock.sol
@@ -114,6 +114,15 @@ contract LendingMarketMock is ILendingMarket {
         revert Error.NotImplemented();
     }
 
+    function discountLoanForBatch(
+        uint256[] calldata loanIds,
+        uint256[] calldata discountAmounts
+    ) external pure {
+        loanIds; // To prevent compiler warning about unused variable
+        discountAmounts; // To prevent compiler warning about unused variable
+        revert Error.NotImplemented();
+    }
+
     function freeze(uint256 loanId) external pure {
         loanId; // To prevent compiler warning about unused variable
         revert Error.NotImplemented();