// Contract: LendingPoolAddressesProvider
// Target function: function transferFlashLoanProtocolFeeInternal(address _token, uint256 _amount) internal
 ) internal {
        reserves[_reserve].updateCumulativeIndexes();

        //increasing reserve total borrows to account for the new borrow balance of the user
        //NOTE: Depending on the previous borrow mode, the borrows might need to be switched from variable to stable or vice versa

        updateReserveTotalBorrowsByRateModeInternal(
            _reserve,
            _user,
            _principalBorrowBalance,
            _balanceIncrease,
            _amountBorrowed,
            _rateMode
        );
    }

    /**
    * @dev updates the state of a user as a consequence of a borrow action.
    * @param _reserve the address of the reserve on which the user is borrowing
    * @param _user the address of the borrower
    * @param _amountBorrowed the amount borrowed
    * @param _balanceIncrease the accrued interest of the user on the previous borrowed amount
    * @param _rateMode the borrow rate mode (stable, variable)
    * @return the final borrow rate for the user. Emitted by the borrow() event
    **/

    function updateUserStateOnBorrowInternal(
        address _reserve,
        address _user,
        uint256 _amountBorrowed,
        uint256 _balanceIncrease,
        uint256 _fee,
        CoreLibrary.InterestRateMode _rateMode
    ) internal {
        CoreLibrary.ReserveData storage reserve = reserves[_reserve];
        CoreLibrary.UserReserveData storage user = usersReserveData[_user][_reserve];

        if (_rateMode == CoreLibrary.InterestRateMode.STABLE) {
            //stable
            //reset the user variable index, and update the stable rate
            user.stableBorrowRate = reserve.currentStableBorrowRate;
            user.lastVariableBorrowCumulativeIndex = 0;
        } else if (_rateMode == CoreLibrary.InterestRateMode.VARIABLE) {
            //variable
            //reset the user stable rate, and store the new borrow index
            user.stableBorrowRate = 0;
            user.lastVariableBorrowCumulativeIndex = reserve.lastVariableBorrowCumulativeIndex;
        } else {
            revert("Invalid borrow rate mode");
        }
        //increase the principal borrows and the origination fee
        user.principalBorrowBalance = user.principalBorrowBalance.add(_amountBorrowed).add(
            _balanceIncrease
        );
        user.originationFee = user.originationFee.add(_fee);

        //solium-disable-next-line
        user.lastUpdateTimestamp = uint40(block.timestamp);

    }

    /**
    * @dev updates the state of the reserve as a consequence of a repay action.
    * @param _reserve the address of the reserve on which the user is repaying
    * @param _user the address of the borrower
    * @param _paybackAmountMinusFees the amount being paid back minus fees
    * @param _balanceIncrease the accrued interest on the borrowed amount
    **/

    function updateReserveStateOnRepayInternal(
        address _reserve,
        address _user,
        uint256 _paybackAmountMinusFees,
        uint256 _balanceIncrease
    ) internal {
        CoreLibrary.ReserveData storage reserve = reserves[_reserve];
        CoreLibrary.UserReserveData storage user = usersReserveData[_reserve][_user];

        CoreLibrary.InterestRateMode borrowRateMode = getUserCurrentBorrowRateMode(_reserve, _user);

        //update the indexes
        reserves[_reserve].updateCumulativeIndexes();

        //compound the cumulated interest to the borrow balance and then subtracting the payback amount
        if (borrowRateMode == CoreLibrary.InterestRateMode.STABLE) {
            reserve.increaseTotalBorrowsStableAndUpdateAverageRate(
                _balanceIncrease,
                user.stableBorrowRate
            );
            reserve.decreaseTotalBorrowsStableAndUpdateAverageRate(
                _paybackAmountMinusFees,
                user.stableBorrowRate
            );
        } else {
            reserve.increaseTotalBorrowsVariable(_balanceIncrease);
            reserve.decreaseTotalBorrowsVariable(_paybackAmountMinusFees);
        }
    }

    /**
    * @dev updates the state of the user as a consequence of a repay action.
    * @param _reserve the address of the reserve on which the user is repaying
    * @param _user the address of the borrower
    * @param _paybackAmountMinusFees the amount being paid back minus fees
    * @param _originationFeeRepaid the fee on the amount that is being repaid
    * @param _balanceIncrease the accrued interest on the borrowed amount
    * @param _repaidWholeLoan true if the user is repaying the whole loan
    **/
    function updateUserStateOnRepayInternal(
        address _reserve,
        address _user,
        uint256 _paybackAmountMinusFees,
        uint256 _originationFeeRepaid,
        uint256 _balanceIncrease,
        bool _repaidWholeLoan
    ) internal {
        CoreLibrary.ReserveData storage reserve = reserves[_reserve];
        CoreLibrary.UserReserveData storage user = usersReserveData[_user][_reserve];

        //update the user principal borrow balance, adding the cumulated interest and then subtracting the payback amount
        user.principalBorrowBalance = user.principalBorrowBalance.add(_balanceIncrease).sub(
            _paybackAmountMinusFees
        );
        user.lastVariableBorrowCumulativeIndex = reserve.lastVariableBorrowCumulativeIndex;

        //if the balance decrease is equal to the previous principal (user is repaying the whole loan)
        //and the rate mode is stable, we reset the interest rate mode of the user
        if (_repaidWholeLoan) {
            user.stableBorrowRate = 0;
            user.lastVariableBorrowCumulativeIndex = 0;
        }
        user.originationFee = user.originationFee.sub(_originationFeeRepaid);

        //solium-disable-next-line
        user.lastUpdateTimestamp = uint40(block.timestamp);

    }

    /**
    * @dev updates the state of the user as a consequence of a swap rate action.
    * @param _reserve the address of the reserve on which the user is performing the rate swap
    * @param _user the address of the borrower
    * @param _principalBorrowBalance the the principal amount borrowed by the user
    * @param _compoundedBorrowBalance the principal amount plus the accrued interest
    * @param _currentRateMode the rate mode at which the user borrowed
    **/
    function updateReserveStateOnSwapRateInternal(
        address _reserve,
        address _user,
        uint256 _principalBorrowBalance,
        uint256 _compoundedBorrowBalance,
        CoreLibrary.InterestRateMode _currentRateMode
    ) internal {
        CoreLibrary.ReserveData storage reserve = reserves[_reserve];
        CoreLibrary.UserReserveData storage user = usersReserveData[_user][_reserve];

        //compounding reserve indexes
        reserve.updateCumulativeIndexes();

        if (_currentRateMode == CoreLibrary.InterestRateMode.STABLE) {
            uint256 userCurrentStableRate = user.stableBorrowRate;

            //swap to variable
            reserve.decreaseTotalBorrowsStableAndUpdateAverageRate(
                _principalBorrowBalance,
                userCurrentStableRate
            ); //decreasing stable from old principal balance
            reserve.increaseTotalBorrowsVariable(_compoundedBorrowBalance); //increase variable borrows
        } else if (_currentRateMode == CoreLibrary.InterestRateMode.VARIABLE) {
            //swap to stable
            uint256 currentStableRate = reserve.currentStableBorrowRate;
            reserve.decreaseTotalBorrowsVariable(_principalBorrowBalance);
            reserve.increaseTotalBorrowsStableAndUpdateAverageRate(
                _compoundedBorrowBalance,
                currentStableRate
            );

        } else {
            revert("Invalid rate mode received");
        }
    }

    /**
    * @dev updates the state of the user as a consequence of a swap rate action.
    * @param _reserve the address of the reserve on which the user is performing the swap
    * @param _user the address of the borrower
    * @param _balanceIncrease the accrued interest on the borrowed amount
    * @param _currentRateMode the current rate mode of the user
    **/

    function updateUserStateOnSwapRateInternal(
        address _reserve,
        address _user,
        uint256 _balanceIncrease,
        CoreLibrary.InterestRateMode _currentRateMode
    ) internal returns (CoreLibrary.InterestRateMode) {
        CoreLibrary.UserReserveData storage user = usersReserveData[_user][_reserve];
        CoreLibrary.ReserveData storage reserve = reserves[_reserve];

        CoreLibrary.InterestRateMode newMode = CoreLibrary.InterestRateMode.NONE;

        if (_currentRateMode == CoreLibrary.InterestRateMode.VARIABLE) {
            //switch to stable
            newMode = CoreLibrary.InterestRateMode.STABLE;
            user.stableBorrowRate = reserve.currentStableBorrowRate;
            user.lastVariableBorrowCumulativeIndex = 0;
        } else if (_currentRateMode == CoreLibrary.InterestRateMode.STABLE) {
            newMode = CoreLibrary.InterestRateMode.VARIABLE;
            user.stableBorrowRate = 0;
            user.lastVariableBorrowCumulativeIndex = reserve.lastVariableBorrowCumulativeIndex;
        } else {
            revert("Invalid interest rate mode received");
        }
        //compounding cumulated interest
        user.principalBorrowBalance = user.principalBorrowBalance.add(_balanceIncrease);
        //solium-disable-next-line
        user.lastUpdateTimestamp = uint40(block.timestamp);

        return newMode;
    }

    /**
    * @dev updates the state of the principal reserve as a consequence of a liquidation action.
    * @param _principalReserve the address of the principal reserve that is being repaid
    * @param _user the address of the borrower
    * @param _amountToLiquidate the amount being repaid by the liquidator
    * @param _balanceIncrease the accrued interest on the borrowed amount
    **/

    function updatePrincipalReserveStateOnLiquidationInternal(
        address _principalReserve,
        address _user,
        uint256 _amountToLiquidate,
        uint256 _balanceIncrease
    ) internal {
        CoreLibrary.ReserveData storage reserve = reserves[_principalReserve];
        CoreLibrary.UserReserveData storage user = usersReserveData[_user][_principalReserve];

        //update principal reserve data
        reserve.updateCumulativeIndexes();

        CoreLibrary.InterestRateMode borrowRateMode = getUserCurrentBorrowRateMode(
            _principalReserve,
            _user
        );

        if (borrowRateMode == CoreLibrary.InterestRateMode.STABLE) {
            //increase the total borrows by the compounded interest
            reserve.increaseTotalBorrowsStableAndUpdateAverageRate(
                _balanceIncrease,
                user.stableBorrowRate
            );

            //decrease by the actual amount to liquidate
            reserve.decreaseTotalBorrowsStableAndUpdateAverageRate(
                _amountToLiquidate,
                user.stableBorrowRate
            );

        } else {
            //increase the total borrows by the compounded interest
            reserve.increaseTotalBorrowsVariable(_balanceIncrease);

            //decrease by the actual amount to liquidate
            reserve.decreaseTotalBorrowsVariable(_amountToLiquidate);
        }

    }

    /**
    * @dev updates the state of the collateral reserve as a consequence of a liquidation action.
    * @param _collateralReserve the address of the collateral reserve that is being liquidated
    **/
    function updateCollateralReserveStateOnLiquidationInternal(
        address _collateralReserve
    ) internal {
        //update collateral reserve
        reserves[_collateralReserve].updateCumulativeIndexes();

    }

    /**
    * @dev updates the state of the user being liquidated as a consequence of a liquidation action.
    * @param _reserve the address of the principal reserve that is being repaid
    * @param _user the address of the borrower
    * @param _amountToLiquidate the amount being repaid by the liquidator
    * @param _feeLiquidated the amount of origination fee being liquidated
    * @param _balanceIncrease the accrued interest on the borrowed amount
    **/
    function updateUserStateOnLiquidationInternal(
        address _reserve,
        address _user,
        uint256 _amountToLiquidate,
        uint256 _feeLiquidated,
        uint256 _balanceIncrease
    ) internal {
        CoreLibrary.UserReserveData storage user = usersReserveData[_user][_reserve];
        CoreLibrary.ReserveData storage reserve = reserves[_reserve];
        //first increase by the compounded interest, then decrease by the liquidated amount
        user.principalBorrowBalance = user.principalBorrowBalance.add(_balanceIncrease).sub(
            _amountToLiquidate
        );

        if (
            getUserCurrentBorrowRateMode(_reserve, _user) == CoreLibrary.InterestRateMode.VARIABLE
        ) {
            user.lastVariableBorrowCumulativeIndex = reserve.lastVariableBorrowCumulativeIndex;
        }

        if(_feeLiquidated > 0){
            user.originationFee = user.originationFee.sub(_feeLiquidated);
        }

        //solium-disable-next-line
        user.lastUpdateTimestamp = uint40(block.timestamp);
    }

    /**
    * @dev updates the state of the reserve as a consequence of a stable rate rebalance
    * @param _reserve the address of the principal reserve where the user borrowed
    * @param _user the address of the borrower
    * @param _balanceIncrease the accrued interest on the borrowed amount
    **/

    function updateReserveStateOnRebalanceInternal(
        address _reserve,
        address _user,
        uint256 _balanceIncrease
    ) internal {
        CoreLibrary.ReserveData storage reserve = reserves[_reserve];
        CoreLibrary.UserReserveData storage user = usersReserveData[_user][_reserve];

        reserve.updateCumulativeIndexes();

        reserve.increaseTotalBorrowsStableAndUpdateAverageRate(
            _balanceIncrease,
            user.stableBorrowRate
        );

    }

    /**
    * @dev updates the state of the user as a consequence of a stable rate rebalance
    * @param _reserve the address of the principal reserve where the user borrowed
    * @param _user the address of the borrower
    * @param _balanceIncrease the accrued interest on the borrowed amount
    **/

    function updateUserStateOnRebalanceInternal(
        address _reserve,
        address _user,
        uint256 _balanceIncrease
    ) internal {
        CoreLibrary.UserReserveData storage user = usersReserveData[_user][_reserve];
        CoreLibrary.ReserveData storage reserve = reserves[_reserve];

        user.principalBorrowBalance = user.principalBorrowBalance.add(_balanceIncrease);
        user.stableBorrowRate = reserve.currentStableBorrowRate;

        //solium-disable-next-line
        user.lastUpdateTimestamp = uint40(block.timestamp);
    }

    /**
    * @dev updates the state of the user as a consequence of a stable rate rebalance
    * @param _reserve the address of the principal reserve where the user borrowed
    * @param _user the address of the borrower
    * @param _balanceIncrease the accrued interest on the borrowed amount
    * @param _amountBorrowed the accrued interest on the borrowed amount
    **/
    function updateReserveTotalBorrowsByRateModeInternal(
        address _reserve,
        address _user,
        uint256 _principalBalance,
        uint256 _balanceIncrease,
        uint256 _amountBorrowed,
        CoreLibrary.InterestRateMode _newBorrowRateMode
    ) internal {
        CoreLibrary.InterestRateMode previousRateMode = getUserCurrentBorrowRateMode(
            _reserve,
            _user
        );
        CoreLibrary.ReserveData storage reserve = reserves[_reserve];

        if (previousRateMode == CoreLibrary.InterestRateMode.STABLE) {
            CoreLibrary.UserReserveData storage user = usersReserveData[_user][_reserve];
            reserve.decreaseTotalBorrowsStableAndUpdateAverageRate(
                _principalBalance,
                user.stableBorrowRate
            );
        } else if (previousRateMode == CoreLibrary.InterestRateMode.VARIABLE) {
            reserve.decreaseTotalBorrowsVariable(_principalBalance);
        }

        uint256 newPrincipalAmount = _principalBalance.add(_balanceIncrease).add(_amountBorrowed);
        if (_newBorrowRateMode == CoreLibrary.InterestRateMode.STABLE) {
            reserve.increaseTotalBorrowsStableAndUpdateAverageRate(
                newPrincipalAmount,
                reserve.currentStableBorrowRate
            );
        } else if (_newBorrowRateMode == CoreLibrary.InterestRateMode.VARIABLE) {
            reserve.increaseTotalBorrowsVariable(newPrincipalAmount);
        } else {
            revert("Invalid new borrow rate mode");
        }
    }

    /**
    * @dev Updates the reserve current stable borrow rate Rf, the current variable borrow rate Rv and the current liquidity rate Rl.
    * Also updates the lastUpdateTimestamp value. Please refer to the whitepaper for further information.
    * @param _reserve the address of the reserve to be updated
    * @param _liquidityAdded the amount of liquidity added to the protocol (deposit or repay) in the previous action
    * @param _liquidityTaken the amount of liquidity taken from the protocol (redeem or borrow)
    **/

    function updateReserveInterestRatesAndTimestampInternal(
        address _reserve,
        uint256 _liquidityAdded,
        uint256 _liquidityTaken
    ) internal {
        CoreLibrary.ReserveData storage reserve = reserves[_reserve];
        (uint256 newLiquidityRate, uint256 newStableRate, uint256 newVariableRate) = IReserveInterestRateStrategy(
            reserve
                .interestRateStrategyAddress
        )
            .calculateInterestRates(
            _reserve,
            getReserveAvailableLiquidity(_reserve).add(_liquidityAdded).sub(_liquidityTaken),
            reserve.totalBorrowsStable,
            reserve.totalBorrowsVariable,
            reserve.currentAverageStableBorrowRate
        );

        reserve.currentLiquidityRate = newLiquidityRate;
        reserve.currentStableBorrowRate = newStableRate;
        reserve.currentVariableBorrowRate = newVariableRate;

        //solium-disable-next-line
        reserve.lastUpdateTimestamp = uint40(block.timestamp);

        emit ReserveUpdated(
            _reserve,
            newLiquidityRate,
            newStableRate,
            newVariableRate,
            reserve.lastLiquidityCumulativeIndex,
            reserve.lastVariableBorrowCumulativeIndex
        );
    }