Revert on zero amounts

docs/Functions.md

@@ -66,7 +66,7 @@
  reverts on:
  - deposits locked RemoveDepositLockedByAuctionDebt()
  - LenderActions.moveQuoteToken():
- - same index MoveToSamePrice()
+ - same index MoveToSameIndex()
  - dust amount DustAmountNotExceeded()
  - invalid index InvalidIndex()
 
@@ -264,6 +264,40 @@
  - Auctions.takeReserves():
  - ReserveAuction
 
+### stampLoan
+ external libraries call:
+ - BorrowerActions.stampLoan()
+
+ write state:
+ - _accruePoolInterest():
+ - PoolCommons.accrueInterest():
+ - Deposits.mult (scale Fenwick tree with new interest accrued):
+ - update scaling array state
+ - increment reserveAuction.totalInterestEarned accumulator
+ - BorrowerActions.stampLoan():
+ - Loans.update():
+ - _upsert():
+ - insert or update loan in loans array
+ - remove():
+ - remove loan from loans array
+ - update borrower in address => borrower mapping
+ - _updateInterestState():
+ - PoolCommons.updateInterestRate():
+ - interest debt and lup * collateral EMAs accumulators
+ - interest rate accumulator and interestRateUpdate state
+ - pool inflator and inflatorUpdate state
+
+ reverts on:
+ - BorrowerActions.stampLoan()
+ - loan in auction AuctionActive()
+ - borrower under collateralized BorrowerUnderCollateralized()
+
+ emit events:
+ - BorrowerActions.stampLoan():
+ - LoanStamped
+ - PoolCommons.updateInterestRate():
+ - UpdateInterestRate
+
 ## ERC20Pool contract
 
 ### addCollateral

src/base/Pool.sol

@@ -11,6 +11,7 @@ import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol"
 import {
  IPool,
  IPoolImmutables,
+ IPoolBorrowerActions,
  IPoolLenderActions,
  IPoolState,
  IPoolLiquidationActions,
@@ -326,6 +327,30 @@ abstract contract Pool is Clone, ReentrancyGuard, Multicall, IPool {
  );
  }
 
+ /// @inheritdoc IPoolLenderActions
+ function updateInterest() external override nonReentrant {
+ PoolState memory poolState = _accruePoolInterest();
+ _updateInterestState(poolState, _lup(poolState.debt));
+ }
+
+ /***********************************/
+ /*** Borrower External Functions ***/
+ /***********************************/
+
+ /// @inheritdoc IPoolBorrowerActions
+ function stampLoan() external override nonReentrant {
+ PoolState memory poolState = _accruePoolInterest();
+
+ uint256 newLup = BorrowerActions.stampLoan(
+ auctions,
+ deposits,
+ loans,
+ poolState
+ );
+
+ _updateInterestState(poolState, newLup);
+ }
+
  /*****************************/
  /*** Liquidation Functions ***/
  /*****************************/

src/interfaces/pool/IPool.sol

@@ -2,6 +2,7 @@
 
 pragma solidity 0.8.14;
 
+import { IPoolBorrowerActions } from './commons/IPoolBorrowerActions.sol';
 import { IPoolLenderActions } from './commons/IPoolLenderActions.sol';
 import { IPoolLiquidationActions } from './commons/IPoolLiquidationActions.sol';
 import { IPoolReserveAuctionActions } from './commons/IPoolReserveAuctionActions.sol';
@@ -16,6 +17,7 @@ import { IERC3156FlashLender } from './IERC3156FlashLender.sol';
  * @title Base Pool
  */
 interface IPool is
+ IPoolBorrowerActions,
  IPoolLenderActions,
  IPoolLiquidationActions,
  IPoolReserveAuctionActions,

src/interfaces/pool/commons/IPoolBorrowerActions.sol

@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity 0.8.14;
+
+/**
+ * @title Pool Borrower Actions
+ */
+interface IPoolBorrowerActions {
+
+ /**
+ * @notice Called by fully colalteralized borrowers to restamp the Neutral Price of the loan (only if loan is fully collateralized and not in auction).
+ * @notice The reason for stamping the neutral price on the loan is to provide some certainty to the borrower as to at what price they can expect to be liquidated.
+ * @notice This action can restamp only the loan of `msg.sender`.
+ */
+ function stampLoan() external;
+
+}

src/interfaces/pool/commons/IPoolErrors.sol

@@ -112,6 +112,11 @@ interface IPoolErrors {
  */
  error InvalidIndex();
 
+ /**
+ * @notice The amount used for performed action should be greater than 0.
+ */
+ error InvalidAmount();
+
  /**
  * @notice Borrower is attempting to borrow more quote token than is available before the supplied limitIndex.
  */
@@ -129,9 +134,9 @@ interface IPoolErrors {
  error LUPGreaterThanTP();
 
  /**
- * @notice FromIndex_ and toIndex_ arguments to move are the same.
+ * @notice From index and to index arguments to move are the same.
  */
- error MoveToSamePrice();
+ error MoveToSameIndex();
 
  /**
  * @notice Owner of the LPs must have approved the new owner prior to transfer.

src/interfaces/pool/commons/IPoolEvents.sol

@@ -138,6 +138,14 @@ interface IPoolEvents {
  uint256 bond
  );
 
+ /**
+ * @notice Emitted when a loan Neutral Price is restamped.
+ * @param borrower Identifies the loan to update the Neutral Price.
+ */
+ event LoanStamped(
+ address indexed borrower
+ );
+
  /**
  * @notice Emitted when lender moves quote token from a bucket price to another.
  * @param lender Recipient that moved quote tokens.

src/interfaces/pool/commons/IPoolLenderActions.sol

@@ -103,4 +103,9 @@ interface IPoolLenderActions {
  address newOwner,
  uint256[] calldata indexes
  ) external;
+
+ /**
+ * @notice Called by lenders to update pool interest rate (can be updated only once in a 12 hours period of time).
+ */
+ function updateInterest() external;
 }

src/libraries/external/Auctions.sol

@@ -162,6 +162,7 @@ library Auctions {
  error CollateralRoundingNeededButNotPossible();
  error InsufficientLiquidity();
  error InsufficientCollateral();
+ error InvalidAmount();
  error NoAuction();
  error NoReserves();
  error NoReservesAuction();
@@ -559,10 +560,12 @@ library Auctions {
  uint256 collateral_,
  uint256 collateralScale_
  ) external returns (TakeResult memory result_) {
+ // revert if no amount to take
+ if (collateral_ == 0) revert InvalidAmount();
+
  Borrower memory borrower = loans_.borrowers[borrowerAddress_];
 
  if (
- (collateral_ == 0) || // revert if amount to take is 0
  (poolState_.poolType == uint8(PoolType.ERC721) && borrower.collateral < 1e18) || // revert in case of NFT take when there isn't a full token to be taken
  (poolState_.poolType == uint8(PoolType.ERC20) && borrower.collateral == 0) // revert in case of ERC20 take when no collateral to be taken
  ) {
@@ -693,6 +696,9 @@ library Auctions {
  ReserveAuctionState storage reserveAuction_,
  uint256 maxAmount_
  ) external returns (uint256 amount_, uint256 ajnaRequired_) {
+ // revert if no amount to be taken
+ if (maxAmount_ == 0) revert InvalidAmount();
+
  uint256 kicked = reserveAuction_.kicked;
 
  if (kicked != 0 && block.timestamp - kicked <= 72 hours) {