feat: prepared for liquidation protocol fee configuration

contracts/interfaces/ILendingPoolConfigurator.sol

@@ -159,6 +159,13 @@ interface ILendingPoolConfigurator {
    **/
   event SupplyCapChanged(address indexed asset, uint256 supplyCap);
 
+  /**
+   * @dev Emitted when the protocol fee on liquidation is updated 
+   * @param asset The address of the underlying asset of the reserve
+   * @param fee The new fee
+   **/
+  event LiquidationProtocolFeeChanged(address indexed asset, uint256 fee);
+
   /**
    * @dev Emitted when the reserve decimals are updated
    * @param asset The address of the underlying asset of the reserve
@@ -387,6 +394,13 @@ interface ILendingPoolConfigurator {
    **/
   function setSupplyCap(address asset, uint256 supplyCap) external;
 
+  /**
+   * @dev Sets the protocol fee on liquidation
+   * @param asset The address of the underlying asset of the reserve
+   * @param fee The fee on liquidaton bonus
+   **/
+  function setReserveLiquidationProtocolFee(address asset, uint256 fee) external;
+
   /**
    * @dev Registers a new admin with rights on risk related configurations
    * @param admin The address of the admin to register

contracts/protocol/lendingpool/LendingPoolCollateralManager.sol

@@ -40,10 +40,10 @@ contract LendingPoolCollateralManager is
   using PercentageMath for uint256;
   using ReserveLogic for DataTypes.ReserveCache;
 
-  uint256 public constant STD_LIQUIDATION_CLOSE_FACTOR = 5000;
+  uint256 public constant DEFAULT_LIQUIDATION_CLOSE_FACTOR = 5000;
   uint256 public constant MAX_LIQUIDATION_CLOSE_FACTOR = 10000;
 
-  uint256 public constant CLOSE_FACTOR_HF_THRESHOLD = 0.95 * 1e18;
+  uint256 public constant CLOSE_FACTOR_HF_THRESHOLD = 0.98 * 1e18;
 
   struct LiquidationCallLocalVars {
     uint256 userCollateralBalance;
@@ -59,6 +59,7 @@ contract LendingPoolCollateralManager is
     uint256 healthFactor;
     uint256 liquidatorPreviousATokenBalance;
     uint256 closeFactor;
+    uint256 protocolFee;
     IAToken collateralAtoken;
     IPriceOracleGetter oracle;
     bool isCollateralEnabled;
@@ -130,7 +131,7 @@ contract LendingPoolCollateralManager is
     vars.userCollateralBalance = vars.collateralAtoken.balanceOf(user);
 
     vars.closeFactor = vars.healthFactor > CLOSE_FACTOR_HF_THRESHOLD
-      ? STD_LIQUIDATION_CLOSE_FACTOR
+      ? DEFAULT_LIQUIDATION_CLOSE_FACTOR
       : MAX_LIQUIDATION_CLOSE_FACTOR;
 
     vars.maxLiquidatableDebt = vars.userStableDebt.add(vars.userVariableDebt).percentMul(
@@ -143,7 +144,8 @@ contract LendingPoolCollateralManager is
 
     (
       vars.maxCollateralToLiquidate,
-      vars.debtAmountNeeded
+      vars.debtAmountNeeded,
+      vars.protocolFee
     ) = _calculateAvailableCollateralToLiquidate(
       collateralReserve,
       debtReserveCache,
@@ -271,6 +273,9 @@ contract LendingPoolCollateralManager is
     uint256 maxAmountCollateralToLiquidate;
     uint256 debtAssetDecimals;
     uint256 collateralDecimals;
+    uint256 collateralProtocolFee;
+    uint256 collateralAmount;
+    uint256 debtAmountNeeded;
   }
 
   /**
@@ -297,9 +302,7 @@ contract LendingPoolCollateralManager is
     uint256 userCollateralBalance,
     IPriceOracleGetter oracle
   ) internal view returns (uint256, uint256) {
-    uint256 collateralAmount = 0;
+ 
-    uint256 debtAmountNeeded = 0;
-
     AvailableCollateralToLiquidateLocalVars memory vars;
 
     vars.collateralPrice = oracle.getAssetPrice(collateralAsset);
@@ -308,8 +311,10 @@ contract LendingPoolCollateralManager is
     (, , vars.liquidationBonus, vars.collateralDecimals, ) = collateralReserve
       .configuration
       .getParams();
+    
     vars.debtAssetDecimals = debtReserveCache.reserveConfiguration.getDecimalsMemory();
 
+
     // This is the maximum possible amount of the selected collateral that can be liquidated, given the
     // max amount of liquidatable debt
     vars.maxAmountCollateralToLiquidate = vars
@@ -320,16 +325,16 @@ contract LendingPoolCollateralManager is
       .div(vars.collateralPrice.mul(10**vars.debtAssetDecimals));
 
     if (vars.maxAmountCollateralToLiquidate > userCollateralBalance) {
-      collateralAmount = userCollateralBalance;
+      vars.collateralAmount = userCollateralBalance;
-      debtAmountNeeded = vars
+      vars.debtAmountNeeded = vars
         .collateralPrice
         .mul(collateralAmount)
         .mul(10**vars.debtAssetDecimals)
         .div(vars.debtAssetPrice.mul(10**vars.collateralDecimals))
         .percentDiv(vars.liquidationBonus);
     } else {
-      collateralAmount = vars.maxAmountCollateralToLiquidate;
+      vars.collateralAmount = vars.maxAmountCollateralToLiquidate;
-      debtAmountNeeded = debtToCover;
+      vars.debtAmountNeeded = debtToCover;
     }
     return (collateralAmount, debtAmountNeeded);
   }

contracts/protocol/lendingpool/LendingPoolConfigurator.sol

@@ -442,6 +442,21 @@ contract LendingPoolConfigurator is VersionedInitializable, ILendingPoolConfigur
     emit ReserveFactorChanged(asset, reserveFactor);
   }
 
+  /// @inheritdoc ILendingPoolConfigurator
+  function setReserveLiquidationProtocolFee(address asset, uint256 fee)
+    external
+    override
+    onlyRiskOrPoolAdmins
+  {
+    DataTypes.ReserveConfigurationMap memory currentConfig = _pool.getConfiguration(asset);
+
+    currentConfig.setLiquidationProtocolFee(fee);
+
+    _pool.setConfiguration(asset, currentConfig.data);
+
+    emit LiquidationProtocolFeeChanged(asset, fee);
+  }
+
   ///@inheritdoc ILendingPoolConfigurator
   function setBorrowCap(address asset, uint256 borrowCap) external override onlyRiskOrPoolAdmins {
     DataTypes.ReserveConfigurationMap memory currentConfig = _pool.getConfiguration(asset);

contracts/protocol/libraries/configuration/ReserveConfiguration.sol

@@ -356,6 +356,30 @@ library ReserveConfiguration {
     return (self.data & ~BORROW_CAP_MASK) >> BORROW_CAP_START_BIT_POSITION;
   }
 
+  /**
+   * @dev Sets the borrow cap of the reserve
+   * @param self The reserve configuration
+   * @param borrowCap The borrow cap
+   **/
+  function setLiquidationProtocolFee(DataTypes.ReserveConfigurationMap memory self, uint256 borrowCap)
+    internal
+    pure
+  {
+  }
+
+  /**
+   * @dev Gets the liquidation protocol fee
+   * @param self The reserve configuration
+   * @return The liquidation protocol fee
+   **/
+  function getLiquidationProtocolFee(DataTypes.ReserveConfigurationMap storage self)
+    internal
+    view
+    returns (uint256)
+  {
+    return 0;
+  }
+
   /**
    * @dev Sets the supply cap of the reserve
    * @param self The reserve configuration