            if (_lowerCurveDiff >= msg.value) {
                _purchaseReturn = _buySecondaryCurve(msg.value, _totalSupply);
            } else {
                //Gas Optimization
                _purchaseReturn = _initialTokenSupply - _totalSupply;
                secondaryReserveBalance += _lowerCurveDiff;
                // _purchaseReturn = _buySecondaryCurve(_to, _lowerCurveDiff);
                _purchaseReturn += _buyPrimaryCurve(msg.value - _lowerCurveDiff, _totalSupply + _purchaseReturn);
            } 
            if (_lowerCurveDiff >= _caculateFeeSecondaryCurve(msg.value)) {
                _purchaseReturn = _buySecondaryCurve(msg.value, _totalSupply);
            } else {
                //Gas Optimization
                _purchaseReturn = _initialTokenSupply - _totalSupply;
                secondaryReserveBalance += _lowerCurveDiff;
                uint256 _amount = _reverseFeeSecondaryCurve(_lowerCurveDiff);
                _chargeFeeSecondaryCurve(_amount);
                // _purchaseReturn = _buySecondaryCurve(_to, _lowerCurveDiff);
                _purchaseReturn += _buyPrimaryCurve(msg.value - _amount, _totalSupply + _purchaseReturn);
            } 
    function _caculateFeeSecondaryCurve(uint256 _amount) private returns(uint256) {
       address payable _factory = factory;
        uint256 _adminFeeAmt = NibblVaultFactory(_factory).feeAdmin();
        uint256 _feeAdmin = (_amount * _adminFeeAmt) / SCALE ;
        uint256 _feeCurator = (_amount * curatorFee) / SCALE ;
        return _amount - (_feeAdmin + _feeCurator);
    }
    function _reverseFeeSecondaryCurve(uint256 _amount) private returns(uint256) {
       address payable _factory = factory;
        uint256 _adminFeeAmt = NibblVaultFactory(_factory).feeAdmin();
        return _amount * SCALE / (SCALE - (_adminFeeAmt + curatorFee));
    }
