Memorialize borrower threshold price at time of kick to calculate bpf…

… on take
ajna-finance · Nov 10, 2023 · 020fa96 · 020fa96
1 parent 50aa42f
commit 020fa96
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Showing 5 changed files with 20 additions and 25 deletions.
diff --git a/src/interfaces/pool/commons/IPoolState.sol b/src/interfaces/pool/commons/IPoolState.sol
@@ -413,6 +413,7 @@ struct Liquidation {
     address next;           // next liquidated borrower in auctions queue
     uint160 bondSize;       // [WAD] liquidation bond size
     uint96  neutralPrice;   // [WAD] Neutral Price when liquidation was started
+    uint256 thresholdPrice; // [WAD] Threshold Price when liquidation was started
 }
 
 /// @dev Struct holding kicker state.

diff --git a/src/libraries/external/KickerActions.sol b/src/libraries/external/KickerActions.sol
@@ -27,7 +27,6 @@ import {
 import {
     MAX_INFLATED_PRICE,
     _bondParams,
-    _bpf,
     _claimableReserves,
     _isCollateralized,
     _priceAt,
@@ -334,6 +333,9 @@ library KickerActions {
             vars.neutralPrice
         );
 
+        // store borrower Threshold price
+        liquidation.thresholdPrice = Maths.wdiv(vars.borrowerDebt, vars.borrowerCollateral);
+
         // update escrowed bonds balances and get the difference needed to cover bond (after using any kick claimable funds if any)
         kickResult_.amountToCoverBond = _updateEscrowedBonds(auctions_, vars.bondSize);
 

diff --git a/src/libraries/external/TakerActions.sol b/src/libraries/external/TakerActions.sol
@@ -345,7 +345,6 @@ library TakerActions {
         vars_ = _prepareTake(
             liquidation,
             borrower_.t0Debt,
-            borrower_.collateral,
             params_.inflator
         );
 
@@ -428,7 +427,6 @@ library TakerActions {
         vars_= _prepareTake(
             liquidation,
             borrower_.t0Debt,
-            borrower_.collateral,
             params_.inflator
         );
 
@@ -681,14 +679,12 @@ library TakerActions {
      *              - loan is not in auction NoAuction()
      *  @param  liquidation_ Liquidation struct holding auction details.
      *  @param  t0Debt_      Borrower t0 debt.
-     *  @param  collateral_  Borrower collateral.
      *  @param  inflator_    The pool's inflator, used to calculate borrower debt.
      *  @return vars         The prepared vars for take action.
      */
     function _prepareTake(
         Liquidation memory liquidation_,
         uint256 t0Debt_,
-        uint256 collateral_,
         uint256 inflator_
     ) internal view returns (TakeLocalVars memory vars) {
 
@@ -704,8 +700,7 @@ library TakerActions {
         vars.auctionPrice = _auctionPrice(liquidation_.referencePrice, kickTime);
         vars.bondFactor   = liquidation_.bondFactor;
         vars.bpf          = _bpf(
-            vars.borrowerDebt,
-            collateral_,
+            liquidation_.thresholdPrice,
             neutralPrice,
             liquidation_.bondFactor,
             vars.auctionPrice

diff --git a/src/libraries/helpers/PoolHelper.sol b/src/libraries/helpers/PoolHelper.sol
@@ -372,32 +372,28 @@ import { Maths }   from '../internal/Maths.sol';
     /**
      *  @notice Calculates bond penalty factor.
      *  @dev    Called in kick and take.
-     *  @param debt_         Borrower debt.
-     *  @param collateral_   Borrower collateral.
-     *  @param neutralPrice_ `NP` of auction.
-     *  @param bondFactor_   Factor used to determine bondSize.
-     *  @param auctionPrice_ Auction price at the time of call.
-     *  @return bpf_         Factor used in determining bond `reward` (positive) or `penalty` (negative).
+     *  @param thresholdPrice_ Borrower tp at time of kick.
+     *  @param neutralPrice_   `NP` of auction.
+     *  @param bondFactor_     Factor used to determine bondSize.
+     *  @param auctionPrice_   Auction price at the time of call.
+     *  @return bpf_           Factor used in determining bond `reward` (positive) or `penalty` (negative).
      */
     function _bpf(
-        uint256 debt_,
-        uint256 collateral_,
+        uint256 thresholdPrice_,
         uint256 neutralPrice_,
         uint256 bondFactor_,
         uint256 auctionPrice_
     ) pure returns (int256) {
-        int256 thresholdPrice = int256(Maths.wdiv(debt_, collateral_));
-
         int256 sign;
-        if (thresholdPrice < int256(neutralPrice_)) {
+        if (int256(thresholdPrice_) < int256(neutralPrice_)) {
             // BPF = BondFactor * min(1, max(-1, (neutralPrice - price) / (neutralPrice - thresholdPrice)))
             sign = Maths.minInt(
                 1e18,
                 Maths.maxInt(
                     -1 * 1e18,
                     PRBMathSD59x18.div(
                         int256(neutralPrice_) - int256(auctionPrice_),
-                        int256(neutralPrice_) - thresholdPrice
+                        int256(neutralPrice_) - int256(thresholdPrice_)
                     )
                 )
             );

diff --git a/tests/forge/unit/Auctions.t.sol b/tests/forge/unit/Auctions.t.sol
@@ -14,13 +14,14 @@ contract AuctionsTest is DSTestPlus {
         uint256 collateral = 1000 * 1e18;
         uint256 neutralPrice = 15 * 1e18;
         uint256 bondFactor = 0.1 *  1e18;
+        uint256 thresholdPrice = Maths.wdiv(debt, collateral);
 
-        assertEq(_bpf(debt, collateral, neutralPrice, bondFactor, price),             0.1 * 1e18);
-        assertEq(_bpf(9000 * 1e18, collateral, neutralPrice, bondFactor, price),      0.083333333333333333 * 1e18);
-        assertEq(_bpf(debt, collateral, neutralPrice, bondFactor, 9.5 * 1e18),        0.1 * 1e18);
-        assertEq(_bpf(9000 * 1e18, collateral, neutralPrice, bondFactor, 9.5 * 1e18), 0.091666666666666667 * 1e18);
-        assertEq(_bpf(9000 * 1e18, collateral, 10 * 1e18, bondFactor, 10.5 * 1e18),   -0.05 * 1e18);
-        assertEq(_bpf(debt, collateral, 5 * 1e18, bondFactor, 10.5 * 1e18),           -0.1 * 1e18);
+        assertEq(_bpf(Maths.wdiv(debt, collateral), neutralPrice, bondFactor, price),             0.1 * 1e18);
+        assertEq(_bpf(Maths.wdiv(9000 * 1e18, collateral), neutralPrice, bondFactor, price),      0.083333333333333333 * 1e18);
+        assertEq(_bpf(Maths.wdiv(debt, collateral), neutralPrice, bondFactor, 9.5 * 1e18),        0.1 * 1e18);
+        assertEq(_bpf(Maths.wdiv(9000 * 1e18, collateral), neutralPrice, bondFactor, 9.5 * 1e18), 0.091666666666666667 * 1e18);
+        assertEq(_bpf(Maths.wdiv(9000 * 1e18, collateral), 10 * 1e18, bondFactor, 10.5 * 1e18),   -0.05 * 1e18);
+        assertEq(_bpf(Maths.wdiv(debt, collateral), 5 * 1e18, bondFactor, 10.5 * 1e18),           -0.1 * 1e18);
     }
 
     /**