refactor: removed balanceDecreaseAllowed

contracts/protocol/lendingpool/LendingPool.sol

@@ -156,16 +156,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
       amountToWithdraw = userBalance;
     }
 
-    ValidationLogic.validateWithdraw(
+    ValidationLogic.validateWithdraw(reserve, amountToWithdraw, userBalance);
-      asset,
-      amountToWithdraw,
-      userBalance,
-      _reserves,
-      _usersConfig[msg.sender],
-      _reservesList,
-      _reservesCount,
-      _addressesProvider.getPriceOracle()
-    );
 
     reserve.updateState();
 
@@ -178,6 +169,15 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
 
     IAToken(aToken).burn(msg.sender, to, amountToWithdraw, reserve.liquidityIndex);
 
+    ValidationLogic.validateHealthFactor(
+      msg.sender,
+      _reserves,
+      _usersConfig[msg.sender],
+      _reservesList,
+      _reservesCount,
+      _addressesProvider.getPriceOracle()
+    );
+
     emit Withdraw(asset, msg.sender, to, amountToWithdraw);
 
     return amountToWithdraw;
@@ -391,22 +391,22 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
   {
     DataTypes.ReserveData storage reserve = _reserves[asset];
 
-    ValidationLogic.validateSetUseReserveAsCollateral(
+    ValidationLogic.validateSetUseReserveAsCollateral(reserve);
-      reserve,
-      asset,
-      useAsCollateral,
-      _reserves,
-      _usersConfig[msg.sender],
-      _reservesList,
-      _reservesCount,
-      _addressesProvider.getPriceOracle()
-    );
 
     _usersConfig[msg.sender].setUsingAsCollateral(reserve.id, useAsCollateral);
 
     if (useAsCollateral) {
       emit ReserveUsedAsCollateralEnabled(asset, msg.sender);
     } else {
+      ValidationLogic.validateHealthFactor(
+        msg.sender,
+        _reserves,
+        _usersConfig[msg.sender],
+        _reservesList,
+        _reservesCount,
+        _addressesProvider.getPriceOracle()
+      );
+
       emit ReserveUsedAsCollateralDisabled(asset, msg.sender);
     }
   }
@@ -713,7 +713,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
   }
 
   /**
-   * @dev Returns the fee on flash loans 
+   * @dev Returns the fee on flash loans
    */
   function FLASHLOAN_PREMIUM_TOTAL() public view returns (uint256) {
     return _flashLoanPremiumTotal;
@@ -746,7 +746,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
   ) external override whenNotPaused {
     require(msg.sender == _reserves[asset].aTokenAddress, Errors.LP_CALLER_MUST_BE_AN_ATOKEN);
 
-    ValidationLogic.validateTransfer(
+    ValidationLogic.validateHealthFactor(
       from,
       _reserves,
       _usersConfig[from],

contracts/protocol/libraries/helpers/Errors.sol

@@ -30,7 +30,6 @@ library Errors {
   string public constant VL_RESERVE_FROZEN = '3'; // 'Action cannot be performed because the reserve is frozen'
   string public constant VL_CURRENT_AVAILABLE_LIQUIDITY_NOT_ENOUGH = '4'; // 'The current liquidity is not enough'
   string public constant VL_NOT_ENOUGH_AVAILABLE_USER_BALANCE = '5'; // 'User cannot withdraw more than the available balance'
-  string public constant VL_TRANSFER_NOT_ALLOWED = '6'; // 'Transfer cannot be allowed.'
   string public constant VL_BORROWING_NOT_ENABLED = '7'; // 'Borrowing is not enabled'
   string public constant VL_INVALID_INTEREST_RATE_MODE_SELECTED = '8'; // 'Invalid interest rate mode selected'
   string public constant VL_COLLATERAL_BALANCE_IS_0 = '9'; // 'The collateral balance is 0'

contracts/protocol/libraries/logic/GenericLogic.sol

@@ -28,94 +28,6 @@ library GenericLogic {
 
   uint256 public constant HEALTH_FACTOR_LIQUIDATION_THRESHOLD = 1 ether;
 
-  struct balanceDecreaseAllowedLocalVars {
-    uint256 decimals;
-    uint256 liquidationThreshold;
-    uint256 totalCollateralInETH;
-    uint256 totalDebtInETH;
-    uint256 avgLiquidationThreshold;
-    uint256 amountToDecreaseInETH;
-    uint256 collateralBalanceAfterDecrease;
-    uint256 liquidationThresholdAfterDecrease;
-    uint256 healthFactorAfterDecrease;
-    bool reserveUsageAsCollateralEnabled;
-  }
-
-  /**
-   * @dev Checks if a specific balance decrease is allowed
-   * (i.e. doesn't bring the user borrow position health factor under HEALTH_FACTOR_LIQUIDATION_THRESHOLD)
-   * @param asset The address of the underlying asset of the reserve
-   * @param user The address of the user
-   * @param amount The amount to decrease
-   * @param reservesData The data of all the reserves
-   * @param userConfig The user configuration
-   * @param reserves The list of all the active reserves
-   * @param oracle The address of the oracle contract
-   * @return true if the decrease of the balance is allowed
-   **/
-  function balanceDecreaseAllowed(
-    address asset,
-    address user,
-    uint256 amount,
-    mapping(address => DataTypes.ReserveData) storage reservesData,
-    DataTypes.UserConfigurationMap calldata userConfig,
-    mapping(uint256 => address) storage reserves,
-    uint256 reservesCount,
-    address oracle
-  ) external view returns (bool) {
-    if (!userConfig.isBorrowingAny() || !userConfig.isUsingAsCollateral(reservesData[asset].id)) {
-      return true;
-    }
-
-    balanceDecreaseAllowedLocalVars memory vars;
-
-    (, vars.liquidationThreshold, , vars.decimals, ) = reservesData[asset]
-      .configuration
-      .getParams();
-
-    if (vars.liquidationThreshold == 0) {
-      return true;
-    }
-
-    (
-      vars.totalCollateralInETH,
-      vars.totalDebtInETH,
-      ,
-      vars.avgLiquidationThreshold,
-
-    ) = calculateUserAccountData(user, reservesData, userConfig, reserves, reservesCount, oracle);
-
-    if (vars.totalDebtInETH == 0) {
-      return true;
-    }
-
-    vars.amountToDecreaseInETH = IPriceOracleGetter(oracle).getAssetPrice(asset).mul(amount).div(
-      10**vars.decimals
-    );
-
-    vars.collateralBalanceAfterDecrease = vars.totalCollateralInETH.sub(vars.amountToDecreaseInETH);
-
-    //if there is a borrow, there can't be 0 collateral
-    if (vars.collateralBalanceAfterDecrease == 0) {
-      return false;
-    }
-
-    vars.liquidationThresholdAfterDecrease = vars
-      .totalCollateralInETH
-      .mul(vars.avgLiquidationThreshold)
-      .sub(vars.amountToDecreaseInETH.mul(vars.liquidationThreshold))
-      .div(vars.collateralBalanceAfterDecrease);
-
-    uint256 healthFactorAfterDecrease =
-      calculateHealthFactorFromBalances(
-        vars.collateralBalanceAfterDecrease,
-        vars.totalDebtInETH,
-        vars.liquidationThresholdAfterDecrease
-      );
-
-    return healthFactorAfterDecrease >= GenericLogic.HEALTH_FACTOR_LIQUIDATION_THRESHOLD;
-  }
-
   struct CalculateUserAccountDataVars {
     uint256 assetPrice;
     uint256 assetUnit;
@@ -220,8 +132,7 @@ library GenericLogic {
           IERC20(currentReserve.stableDebtTokenAddress).balanceOf(user)
         );
         vars.userDebtETH = vars.assetPrice.mul(vars.userDebt).div(vars.assetUnit);
-        vars.totalDebtInETH = vars.totalDebtInETH.add(vars.userDebtETH);
+        vars.totalDebtInETH = vars.totalDebtInETH.add(vars.userDebtETH);         
-          
       }
     }
 

contracts/protocol/libraries/logic/ValidationLogic.sol

@@ -38,7 +38,7 @@ library ValidationLogic {
    * @param reserve The reserve object on which the user is depositing
    * @param amount The amount to be deposited
    */
-  function validateDeposit(DataTypes.ReserveData storage reserve, uint256 amount) external view {
+  function validateDeposit(DataTypes.ReserveData storage reserve, uint256 amount) internal view {
     (bool isActive, bool isFrozen, , ) = reserve.configuration.getFlags();
 
     require(amount != 0, Errors.VL_INVALID_AMOUNT);
@@ -46,46 +46,23 @@ library ValidationLogic {
     require(!isFrozen, Errors.VL_RESERVE_FROZEN);
   }
 
+
   /**
    * @dev Validates a withdraw action
-   * @param reserveAddress The address of the reserve
+   * @param reserve The reserve object
    * @param amount The amount to be withdrawn
    * @param userBalance The balance of the user
-   * @param reservesData The reserves state
-   * @param userConfig The user configuration
-   * @param reserves The addresses of the reserves
-   * @param reservesCount The number of reserves
-   * @param oracle The price oracle
    */
   function validateWithdraw(
-    address reserveAddress,
+    DataTypes.ReserveData storage reserve,
     uint256 amount,
-    uint256 userBalance,
+    uint256 userBalance
-    mapping(address => DataTypes.ReserveData) storage reservesData,
+  ) internal view {
-    DataTypes.UserConfigurationMap storage userConfig,
-    mapping(uint256 => address) storage reserves,
-    uint256 reservesCount,
-    address oracle
-  ) external view {
     require(amount != 0, Errors.VL_INVALID_AMOUNT);
     require(amount <= userBalance, Errors.VL_NOT_ENOUGH_AVAILABLE_USER_BALANCE);
 
-    (bool isActive, , , ) = reservesData[reserveAddress].configuration.getFlags();
+    (bool isActive, , , ) = reserve.configuration.getFlags();
     require(isActive, Errors.VL_NO_ACTIVE_RESERVE);
-
-    require(
-      GenericLogic.balanceDecreaseAllowed(
-        reserveAddress,
-        msg.sender,
-        amount,
-        reservesData,
-        userConfig,
-        reserves,
-        reservesCount,
-        oracle
-      ),
-      Errors.VL_TRANSFER_NOT_ALLOWED
-    );
   }
 
   struct ValidateBorrowLocalVars {
@@ -130,7 +107,7 @@ library ValidationLogic {
     mapping(uint256 => address) storage reserves,
     uint256 reservesCount,
     address oracle
-  ) external view {
+  ) internal view {
     ValidateBorrowLocalVars memory vars;
 
     (vars.isActive, vars.isFrozen, vars.borrowingEnabled, vars.stableRateBorrowingEnabled) = reserve
@@ -227,7 +204,7 @@ library ValidationLogic {
     address onBehalfOf,
     uint256 stableDebt,
     uint256 variableDebt
-  ) external view {
+  ) internal view {
     bool isActive = reserve.configuration.getActive();
 
     require(isActive, Errors.VL_NO_ACTIVE_RESERVE);
@@ -306,7 +283,7 @@ library ValidationLogic {
     IERC20 stableDebtToken,
     IERC20 variableDebtToken,
     address aTokenAddress
-  ) external view {
+  ) internal view {
     (bool isActive, , , ) = reserve.configuration.getFlags();
 
     require(isActive, Errors.VL_NO_ACTIVE_RESERVE);
@@ -335,40 +312,13 @@ library ValidationLogic {
   /**
    * @dev Validates the action of setting an asset as collateral
    * @param reserve The state of the reserve that the user is enabling or disabling as collateral
-   * @param reserveAddress The address of the reserve
-   * @param reservesData The data of all the reserves
-   * @param userConfig The state of the user for the specific reserve
-   * @param reserves The addresses of all the active reserves
-   * @param oracle The price oracle
    */
   function validateSetUseReserveAsCollateral(
-    DataTypes.ReserveData storage reserve,
+    DataTypes.ReserveData storage reserve
-    address reserveAddress,
+  ) internal view {
-    bool useAsCollateral,
-    mapping(address => DataTypes.ReserveData) storage reservesData,
-    DataTypes.UserConfigurationMap storage userConfig,
-    mapping(uint256 => address) storage reserves,
-    uint256 reservesCount,
-    address oracle
-  ) external view {
     uint256 underlyingBalance = IERC20(reserve.aTokenAddress).balanceOf(msg.sender);
 
     require(underlyingBalance > 0, Errors.VL_UNDERLYING_BALANCE_NOT_GREATER_THAN_0);
-
-    require(
-      useAsCollateral ||
-        GenericLogic.balanceDecreaseAllowed(
-          reserveAddress,
-          msg.sender,
-          underlyingBalance,
-          reservesData,
-          userConfig,
-          reserves,
-          reservesCount,
-          oracle
-        ),
-      Errors.VL_DEPOSIT_ALREADY_IN_USE
-    );
   }
 
   /**
@@ -436,14 +386,14 @@ library ValidationLogic {
   }
 
   /**
-   * @dev Validates an aToken transfer
+   * @dev Validates the health factor of a user
    * @param from The user from which the aTokens are being transferred
    * @param reservesData The state of all the reserves
    * @param userConfig The state of the user for the specific reserve
    * @param reserves The addresses of all the active reserves
    * @param oracle The price oracle
    */
-  function validateTransfer(
+  function validateHealthFactor(
     address from,
     mapping(address => DataTypes.ReserveData) storage reservesData,
     DataTypes.UserConfigurationMap storage userConfig,
@@ -463,7 +413,7 @@ library ValidationLogic {
 
     require(
       healthFactor >= GenericLogic.HEALTH_FACTOR_LIQUIDATION_THRESHOLD,
-      Errors.VL_TRANSFER_NOT_ALLOWED
+      Errors.VL_HEALTH_FACTOR_LOWER_THAN_LIQUIDATION_THRESHOLD
     );
   }
 }