// Contract: AggregatorDataProvider
// Target function: function borrowAsset(
,
                _results.newFullUtilizationRate
            );
            emit AddInterest(_interestEarned, _results.newRate, _feesAmount, _feesShare);

            // overwrite original values
            _currentRateInfo.ratePerSec = _results.newRate;
            _currentRateInfo.fullUtilizationRate = _results.newFullUtilizationRate;
            _currentRateInfo.lastTimestamp = uint64(block.timestamp);
            _currentRateInfo.lastBlock = uint32(block.number);

            // Effects: write to state
            currentRateInfo = _currentRateInfo;
            totalAsset = _results.totalAsset;
            totalBorrow = _results.totalBorrow;
            if (_feesShare > 0) _mint(address(this), _feesShare);
        }
    }

    // ============================================================================================
    // Functions: ExchangeRate
    // ============================================================================================

    /// @notice The ```UpdateExchangeRate``` event is emitted when the Collateral:Asset exchange rate is updated
    /// @param lowExchangeRate The low exchange rate
    /// @param highExchangeRate The high exchange rate
    event UpdateExchangeRate(uint256 lowExchangeRate, uint256 highExchangeRate);

    /// @notice The ```WarnOracleData``` event is emitted when one of the oracles has stale or otherwise problematic data
    /// @param oracle The oracle address
    event WarnOracleData(address oracle);

    /// @notice The ```updateExchangeRate``` function is the external implementation of _updateExchangeRate.
    /// @dev This function is invoked at most once per block as these queries can be expensive
    /// @return _isBorrowAllowed True if deviation is within bounds
    /// @return _lowExchangeRate The low exchange rate
    /// @return _highExchangeRate The high exchange rate
    function updateExchangeRate()
        external
        nonReentrant
        returns (bool _isBorrowAllowed, uint256 _lowExchangeRate, uint256 _highExchangeRate)
    {
        return _updateExchangeRate();
    }

    /// @notice The ```_updateExchangeRate``` function retrieves the latest exchange rate. i.e how much collateral to buy 1e18 asset.
    /// @dev This function is invoked at most once per block as these queries can be expensive
    /// @return _isBorrowAllowed True if deviation is within bounds
    /// @return _lowExchangeRate The low exchange rate
    /// @return _highExchangeRate The high exchange rate

    function _updateExchangeRate()
        internal
        returns (bool _isBorrowAllowed, uint256 _lowExchangeRate, uint256 _highExchangeRate)
    {
        // Pull from storage to save gas and set default return values
        ExchangeRateInfo memory _exchangeRateInfo = exchangeRateInfo;

        // Short circuit if already updated this block
        if (_exchangeRateInfo.lastTimestamp != block.timestamp) {
            // Get the latest exchange rate from the dual oracle
            bool _oneOracleBad;
            (_oneOracleBad, _lowExchangeRate, _highExchangeRate) = IDualOracle(_exchangeRateInfo.oracle).getPrices();

            // If one oracle is bad data, emit an event for off-chain monitoring
            if (_oneOracleBad) emit WarnOracleData(_exchangeRateInfo.oracle);

            // Effects: Bookkeeping and write to storage
            _exchangeRateInfo.lastTimestamp = uint184(block.timestamp);
            _exchangeRateInfo.lowExchangeRate = _lowExchangeRate;
            _exchangeRateInfo.highExchangeRate = _highExchangeRate;
            exchangeRateInfo = _exchangeRateInfo;
            emit UpdateExchangeRate(_lowExchangeRate, _highExchangeRate);
        } else {
            // Use default return values if already updated this block
            _lowExchangeRate = _exchangeRateInfo.lowExchangeRate;
            _highExchangeRate = _exchangeRateInfo.highExchangeRate;
        }

        uint256 _deviation = (DEVIATION_PRECISION *
            (_exchangeRateInfo.highExchangeRate - _exchangeRateInfo.lowExchangeRate)) /
            _exchangeRateInfo.highExchangeRate;
        if (_deviation <= _exchangeRateInfo.maxOracleDeviation) {
            _isBorrowAllowed = true;
        }
    }

    // ============================================================================================
    // Functions: Lending
    // ============================================================================================

    /// @notice The ```Deposit``` event fires when a user deposits assets to the pair
    /// @param caller the msg.sender
    /// @param owner the account the fTokens are sent to
    /// @param assets the amount of assets deposited
    /// @param shares the number of fTokens minted
    event Deposit(address indexed caller, address indexed owner, uint256 assets, uint256 shares);

    /// @notice The ```_deposit``` function is the internal implementation for lending assets
    /// @dev Caller must invoke ```ERC20.approve``` on the Asset Token contract prior to calling function
    /// @param _totalAsset An in memory VaultAccount struct representing the total amounts and shares for the Asset Token
    /// @param _amount The amount of Asset Token to be transferred
    /// @param _shares The amount of Asset Shares (fTokens) to be minted
    /// @param _receiver The address to receive the Asset Shares (fTokens)
    function _deposit(VaultAccount memory _totalAsset, uint128 _amount, uint128 _shares, address _receiver) internal {
        // Effects: bookkeeping
        _totalAsset.amount += _amount;
        _totalAsset.shares += _shares;

        // Effects: write back to storage
        _mint(_receiver, _shares);
        totalAsset = _totalAsset;

        // Interactions
        assetContract.safeTransferFrom(msg.sender, address(this), _amount);
        emit Deposit(msg.sender, _receiver, _amount, _shares);
    }

    function previewDeposit(uint256 _assets) external view returns (uint256 _sharesReceived) {
        (, , , , VaultAccount memory _totalAsset, ) = previewAddInterest();
        _sharesReceived = _totalAsset.toShares(_assets, false);
    }

    /// @notice The ```deposit``` function allows a user to Lend Assets by specifying the amount of Asset Tokens to lend
    /// @dev Caller must invoke ```ERC20.approve``` on the Asset Token contract prior to calling function
    /// @param _amount The amount of Asset Token to transfer to Pair
    /// @param _receiver The address to receive the Asset Shares (fTokens)
    /// @return _sharesReceived The number of fTokens received for the deposit
    function deposit(uint256 _amount, address _receiver) external nonReentrant returns (uint256 _sharesReceived) {
        if (_receiver == address(0)) revert InvalidReceiver();

        // Accrue interest if necessary
        _addInterest();

        // Pull from storage to save gas
        VaultAccount memory _totalAsset = totalAsset;

        // Check if this deposit will violate the deposit limit
        if (depositLimit < _totalAsset.amount + _amount) revert ExceedsDepositLimit();

        // Calculate the number of fTokens to mint
        _sharesReceived = _totalAsset.toShares(_amount, false);

        // Execute the deposit effects
        _deposit(_totalAsset, _amount.toUint128(), _sharesReceived.toUint128(), _receiver);
    }

    function previewMint(uint256 _shares) external view returns (uint256 _amount) {
        (, , , , VaultAccount memory _totalAsset, ) = previewAddInterest();
        _amount = _totalAsset.toAmount(_shares, false);
    }

    function mint(uint256 _shares, address _receiver) external nonReentrant returns (uint256 _amount) {
        if (_receiver == address(0)) revert InvalidReceiver();

        // Accrue interest if necessary
        _addInterest();

        // Pull from storage to save gas
        VaultAccount memory _totalAsset = totalAsset;

        // Calculate the number of assets to transfer based on the shares to mint
        _amount = _totalAsset.toAmount(_shares, false);

        // Check if this deposit will violate the deposit limit
        if (depositLimit < _totalAsset.amount + _amount) revert ExceedsDepositLimit();

        // Execute the deposit effects
        _deposit(_totalAsset, _amount.toUint128(), _shares.toUint128(), _receiver);
    }

    /// @notice The ```Withdraw``` event fires when a user redeems their fTokens for the underlying asset
    /// @param caller the msg.sender
    /// @param receiver The address to which the underlying asset will be transferred to
    /// @param owner The owner of the fTokens
    /// @param assets The assets transferred
    /// @param shares The number of fTokens burned
    event Withdraw(
        address indexed caller,
        address indexed receiver,
        address indexed owner,
        uint256 assets,
        uint256 shares
    );

    /// @notice The ```_redeem``` function is an internal implementation which allows a Lender to pull their Asset Tokens out of the Pair
    /// @dev Caller must invoke ```ERC20.approve``` on the Asset Token contract prior to calling function
    /// @param _totalAsset An in-memory VaultAccount struct which holds the total amount of Asset Tokens and the total number of Asset Shares (fTokens)
    /// @param _amountToReturn The number of Asset Tokens to return
    /// @param _shares The number of Asset Shares (fTokens) to burn
    /// @param _receiver The address to which the Asset Tokens will be transferred
    /// @param _owner The owner of the Asset Shares (fTokens)
    function _redeem(
        VaultAccount memory _totalAsset,
        uint128 _amountToReturn,
        uint128 _shares,
        address _receiver,
        address _owner
    ) internal {
        // Check for sufficient allowance/approval if necessary
        if (msg.sender != _owner) {
            uint256 allowed = allowance(_owner, msg.sender);
            // NOTE: This will revert on underflow ensuring that allowance > shares
            if (allowed != type(uint256).max) _approve(_owner, msg.sender, allowed - _shares);
        }

        // Check for sufficient withdraw liquidity (not strictly necessary because balance will underflow)
        uint256 _assetsAvailable = _totalAssetAvailable(_totalAsset, totalBorrow);
        if (_assetsAvailable < _amountToReturn) {
            revert InsufficientAssetsInContract(_assetsAvailable, _amountToReturn);
        }

        // Effects: bookkeeping
        _totalAsset.amount -= _amountToReturn;
        _totalAsset.shares -= _shares;

        // Effects: write to storage
        totalAsset = _totalAsset;
        _burn(_owner, _shares);

        // Interactions
        assetContract.safeTransfer(_receiver, _amountToReturn);
        emit Withdraw(msg.sender, _receiver, _owner, _amountToReturn, _shares);
    }

    function previewRedeem(uint256 _shares) external view returns (uint256 _assets) {
        (, , , , VaultAccount memory _totalAsset, ) = previewAddInterest();
        _assets = _totalAsset.toAmount(_shares, false);
    }

    /// @notice The ```redeem``` function allows the caller to redeem their Asset Shares for Asset Tokens
    /// @param _shares The number of Asset Shares (fTokens) to burn for Asset Tokens
    /// @param _receiver The address to which the Asset Tokens will be transferred
    /// @param _owner The owner of the Asset Shares (fTokens)
    /// @return _amountToReturn The amount of Asset Tokens to be transferred
    function redeem(
        uint256 _shares,
        address _receiver,
        address _owner
    ) external nonReentrant returns (uint256 _amountToReturn) {
        if (_receiver == address(0)) revert InvalidReceiver();

        // Check if withdraw is paused and revert if necessary
        if (isWithdrawPaused) revert WithdrawPaused();

        // Accrue interest if necessary
        _addInterest();

        // Pull from storage to save gas
        VaultAccount memory _totalAsset = totalAsset;

        // Calculate the number of assets to transfer based on the shares to burn
        _amountToReturn = _totalAsset.toAmount(_shares, false);

        // Execute the withdraw effects
        _redeem(_totalAsset, _amountToReturn.toUint128(), _shares.toUint128(), _receiver, _owner);
    }

    /// @notice The ```previewWithdraw``` function returns the number of Asset Shares (fTokens) that would be burned for a given amount of Asset Tokens
    /// @param _amount The amount of Asset Tokens to be withdrawn
    /// @return _sharesToBurn The number of shares that would be burned
    function previewWithdraw(uint256 _amount) external view returns (uint256 _sharesToBurn) {
        (, , , , VaultAccount memory _totalAsset, ) = previewAddInterest();
        _sharesToBurn = _totalAsset.toShares(_amount, true);
    }

    /// @notice The ```withdraw``` function allows the caller to withdraw their Asset Tokens for a given amount of fTokens
    /// @param _amount The amount to withdraw
    /// @param _receiver The address to which the Asset Tokens will be transferred
    /// @param _owner The owner of the Asset Shares (fTokens)
    /// @return _sharesToBurn The number of shares (fTokens) that were burned
    function withdraw(
        uint256 _amount,
        address _receiver,
        address _owner
    ) external nonReentrant returns (uint256 _sharesToBurn) {
        if (_receiver == address(0)) revert InvalidReceiver();

        // Check if withdraw is paused and revert if necessary
        if (isWithdrawPaused) revert WithdrawPaused();

        // Accrue interest if necessary
        _addInterest();

        // Pull from storage to save gas
        VaultAccount memory _totalAsset = totalAsset;

        // Calculate the number of shares to burn based on the amount to withdraw
        _sharesToBurn = _totalAsset.toShares(_amount, true);

        // Execute the withdraw effects
        _redeem(_totalAsset, _amount.toUint128(), _sharesToBurn.toUint128(), _receiver, _owner);
    }

    // ============================================================================================
    // Functions: Borrowing
    // ============================================================================================

    /// @notice The ```BorrowAsset``` event is emitted when a borrower increases their position
    /// @param _borrower The borrower whose account was debited
    /// @param _receiver The address to which the Asset Tokens were transferred
    /// @param _borrowAmount The amount of Asset Tokens transferred
    /// @param _sharesAdded The number of Borrow Shares the borrower was debited
    event BorrowAsset(
        address indexed _borrower,
        address indexed _receiver,
        uint256 _borrowAmount,
        uint256 _sharesAdded
    );

    /// @notice The ```_borrowAsset``` function is the internal implementation for borrowing assets
    /// @param _borrowAmount The amount of the Asset Token to borrow
    /// @param _receiver The address to receive the Asset Tokens
    /// @return _sharesAdded The amount of borrow shares the msg.sender will be debited
    function _borrowAsset(uint128 _borrowAmount, address _receiver) internal returns (uint256 _sharesAdded) {
        // Get borrow accounting from storage to save gas
        VaultAccount memory _totalBorrow = totalBorrow;

        // Check available capital (not strictly necessary because balance will underflow, but better revert message)
        uint256 _assetsAvailable = _totalAssetAvailable(totalAsset, _totalBorrow);
        if (_assetsAvailable < _borrowAmount) {
            revert InsufficientAssetsInContract(_assetsAvailable, _borrowAmount);
        }

        // Calculate the number of shares to add based on the amount to borrow
        _sharesAdded = _totalBorrow.toShares(_borrowAmount, true);

        // Effects: Bookkeeping to add shares & amounts to total Borrow accounting
        _totalBorrow.amount += _borrowAmount;
        _totalBorrow.shares += uint128(_sharesAdded);
        // NOTE: we can safely cast here because shares are always less than amount and _borrowAmount is uint128

        // Effects: write back to storage
        totalBorrow = _totalBorrow;
        userBorrowShares[msg.sender] += _sharesAdded;

        // Interactions
        if (_receiver != address(this)) {
            assetContract.safeTransfer(_receiver, _borrowAmount);
        }
        emit BorrowAsset(msg.sender, _receiver, _borrowAmount, _sharesAdded);
    }

    /// @notice The ```_borrowAssetOnBehalfOf``` function is the internal implementation for borrowing assets on behalf of borrower
    /// @dev msg.sender will receive the Asset Tokens
    /// @param _borrowAmount The amount of the Asset Token to borrow
    /// @param _onBehalfOf The address which will receive the debt. Should be the address of the borrower itself
    /// @return _sharesAdded The amount of borrow shares the _onBehalfOf will be debited
    function _borrowAssetOnBehalfOf(uint128 _borrowAmount, address _onBehalfOf) internal returns (uint256 _sharesAdded) {
        // Get borrow accounting from storage to save gas
        VaultAccount memory _totalBorrow = totalBorrow;

        // Check available capital (not strictly necessary because balance will underflow, but better revert message)
        uint256 _assetsAvailable = _totalAssetAvailable(totalAsset, _totalBorrow);
        if (_assetsAvailable < _borrowAmount) {
            revert InsufficientAssetsInContract(_assetsAvailable, _borrowAmount);
        }

        // decrease borrowAllowance (borrowing power)
        uint256 newAllowance = userBorrowAllowances[_onBehalfOf][msg.sender] - _borrowAmount;
        userBorrowAllowances[_onBehalfOf][msg.sender] = newAllowance;
        emit UserBorrowAllowanceDelegated(_onBehalfOf, msg.sender, newAllowance);

        // Calculate the number of shares to add based on the amount to borrow
        _sharesAdded = _totalBorrow.toShares(_borrowAmount, true);

        // Effects: Bookkeeping to add shares & amounts to total Borrow accounting
        _totalBorrow.amount += _borrowAmount;
        _totalBorrow.shares += uint128(_sharesAdded);
        // NOTE: we can safely cast here because shares are always less than amount and _borrowAmount is uint128

        // Effects: write back to storage
        totalBorrow = _totalBorrow;
        userBorrowShares[_onBehalfOf] += _sharesAdded;

        // Interactions
        assetContract.safeTransfer(msg.sender, _borrowAmount);

        emit BorrowAsset(_onBehalfOf, msg.sender, _borrowAmount, _sharesAdded);
    }