   function receiveFlashLoan(address[] memory tokens,
        uint256[] memory amounts, uint256[] memory feeAmounts, bytes memory userData
    ) external {
 @>     if (msg.sender != address(_balancerVault)) revert InvalidFlashLoadLender();
        if (tokens.length != 1) revert InvalidTokenList();
        if (amounts.length != 1) revert InvalidAmountList();
        if (feeAmounts.length != 1) revert InvalidFeesAmount();

        //@audit originalCallData is not verified
        (address borrower, bytes memory originalCallData) = abi.decode(userData, (address, bytes));
        address asset = tokens[0];
        uint256 amount = amounts[0];
        uint256 fee = feeAmounts[0];
        // Transfer the loan received to borrower
        IERC20(asset).safeTransfer(borrower, amount);

@>      if (IERC3156FlashBorrowerUpgradeable(borrower).onFlashLoan(borrower,
                tokens[0], amounts[0], feeAmounts[0], originalCallData
            ) != CALLBACK_SUCCESS
        ) {
            revert BorrowerCallbackFailed();
        }
        ....
    }
    _balancerVault.flashLoan(address(this), tokens, amounts, abi.encode(borrower, data));
    function onFlashLoan(address initiator,address token,uint256 amount, uint256 fee, bytes memory callData
    ) external returns (bytes32) {
        if (msg.sender != flashLenderA()) revert InvalidFlashLoanSender();
        if (initiator != address(this)) revert InvalidLoanInitiator();
        // Only Allow WETH Flash Loans
        if (token != wETHA()) revert InvalidFlashLoanAsset();
        //loanAmount = leverage - msg.value;
@>      FlashLoanData memory data = abi.decode(callData, (FlashLoanData));
        if (data.action == FlashLoanAction.SUPPLY_BOORROW) {
            _supplyBorrow(data.originalAmount, amount, fee);
            // Use the Borrowed to pay ETH and deleverage
        } else if (data.action == FlashLoanAction.PAY_DEBT_WITHDRAW) {
            // originalAmount = deltaCollateralInETH
            _repayAndWithdraw(data.originalAmount, amount, fee, payable(data.receiver));
        } else if (data.action == FlashLoanAction.PAY_DEBT) {
            _payDebt(amount, fee);
        }
        return _SUCCESS_MESSAGE;
    }
