pragma solidity 0.6.12;

library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }
}

abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

interface IERC20 {
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address recipient, uint256 amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return _functionCallWithValue(target, data, 0, errorMessage);
    }

    function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

contract ERC20 is Context, IERC20 {
    using SafeMath for uint256;
    using Address for address;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for {name} and {symbol}, initializes {decimals} with
     * a default value of 18.
     *
     * To select a different value for {decimals}, use {_setupDecimals}.
     *
     * All three of these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name, string memory symbol) public {
        _name = name;
        _symbol = symbol;
        _decimals = 18;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
     * called.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20};
     *
     * Requirements:
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be to transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

interface IVault is IERC20 {
    function token() external view returns (address);

    function claimInsurance() external; // NOTE: Only yDelegatedVault implements this

    function getRatio() external view returns (uint256);

    function deposit(uint256) external;

    function withdraw(uint256) external;

    function earn() external;
}

interface UniswapRouterV2 {
    function swapExactTokensForTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);

    function getAmountsOut(uint256 amountIn, address[] calldata path)
        external
        view
        returns (uint256[] memory amounts);
}

interface IController {
    function vaults(address) external view returns (address);

    function devfund() external view returns (address);

    function treasury() external view returns (address);
}

interface IMasterchef {
    function notifyBuybackReward(uint256 _amount) external;
}

// Strategy Contract Basics
abstract contract StrategyBase {
    using SafeERC20 for IERC20;
    using Address for address;
    using SafeMath for uint256;
    
    // caller whom this strategy trust 
    mapping(address => bool) public benignCallers;

    // Perfomance fee 30% to buyback
    uint256 public performanceFee = 30000;
    uint256 public constant performanceMax = 100000;

    // Withdrawal fee 0.00% to buyback
    // - 0.00% to treasury
    // - 0.00% to dev fund
    uint256 public treasuryFee = 0;
    uint256 public constant treasuryMax = 100000;

    uint256 public devFundFee = 0;
    uint256 public constant devFundMax = 100000;

    // delay yield profit realization
    uint256 public delayBlockRequired = 1000;
    uint256 public lastHarvestBlock;
    uint256 public lastHarvestInWant;

    // buyback ready
    bool public buybackEnabled = true;
    address public mmToken = 0xa283aA7CfBB27EF0cfBcb2493dD9F4330E0fd304;
    address public masterChef = 0xf8873a6080e8dbF41ADa900498DE0951074af577;

    // Tokens
    address public want;
    address public constant weth = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;

    // User accounts
    address public governance;
    address public controller;
    address public strategist;
    address public timelock;

    // Dex
    address public univ2Router2 = 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D;

    //Sushi
    address public sushiRouter = 0xd9e1cE17f2641f24aE83637ab66a2cca9C378B9F;

    constructor(
        address _want,
        address _governance,
        address _strategist,
        address _controller,
        address _timelock
    ) public {
        require(_want != address(0));
        require(_governance != address(0));
        require(_strategist != address(0));
        require(_controller != address(0));
        require(_timelock != address(0));

        want = _want;
        governance = _governance;
        strategist = _strategist;
        controller = _controller;
        timelock = _timelock;
    }

    // **** Modifiers **** //

    modifier onlyBenevolent {
        // https://github.com/ethereum/EIPs/blob/master/EIPS/eip-3074.md#allowing-txorigin-as-signer
        require(msg.sender == governance || msg.sender == strategist);
        _;
    }
    
    modifier onlyBenignCallers {
        require(msg.sender == governance || msg.sender == strategist || benignCallers[msg.sender]);
        _;
    }

    // **** Views **** //

    function balanceOfWant() public view returns (uint256) {
        return IERC20(want).balanceOf(address(this));
    }

    function balanceOfPool() public virtual view returns (uint256);

    function balanceOf() public view returns (uint256) {
        uint256 delayReduction = 0;
        uint256 currentBlock = block.number;
        if (delayBlockRequired > 0 && lastHarvestInWant > 0 && currentBlock.sub(lastHarvestBlock) < delayBlockRequired){
            uint256 diffBlock = lastHarvestBlock.add(delayBlockRequired).sub(currentBlock);
            delayReduction = lastHarvestInWant.mul(diffBlock).mul(1e18).div(delayBlockRequired).div(1e18);
        }
        return balanceOfWant().add(balanceOfPool()).sub(delayReduction);
    }

    function getName() external virtual pure returns (string memory);

    // **** Setters **** //

    function setBenignCallers(address _caller, bool _enabled) external{
        require(msg.sender == governance, "!governance");
        benignCallers[_caller] = _enabled;
    }

    function setDelayBlockRequired(uint256 _delayBlockRequired) external {
        require(msg.sender == governance, "!governance");
        delayBlockRequired = _delayBlockRequired;
    }

    function setDevFundFee(uint256 _devFundFee) external {
        require(msg.sender == timelock, "!timelock");
        devFundFee = _devFundFee;
    }

    function setTreasuryFee(uint256 _treasuryFee) external {
        require(msg.sender == timelock, "!timelock");
        treasuryFee = _treasuryFee;
    }

    function setPerformanceFee(uint256 _performanceFee) external {
        require(msg.sender == timelock, "!timelock");
        performanceFee = _performanceFee;
    }

    function setStrategist(address _strategist) external {
        require(msg.sender == governance, "!governance");
        strategist = _strategist;
    }

    function setGovernance(address _governance) external {
        require(msg.sender == governance, "!governance");
        governance = _governance;
    }

    function setTimelock(address _timelock) external {
        require(msg.sender == timelock, "!timelock");
        timelock = _timelock;
    }

    function setController(address _controller) external {
        require(msg.sender == timelock, "!timelock");
        controller = _controller;
    }

    function setBuybackEnabled(bool _buybackEnabled) external {
        require(msg.sender == governance, "!governance");
        buybackEnabled = _buybackEnabled;
    }

    function setMasterChef(address _masterChef) external {
        require(msg.sender == governance, "!governance");
        masterChef = _masterChef;
    }

    // **** State mutations **** //
    function deposit() public virtual;

    function withdraw(IERC20 _asset) external virtual returns (uint256 balance);

    // Controller only function for creating additional rewards from dust
    function _withdrawNonWantAsset(IERC20 _asset) internal returns (uint256 balance) {
        require(msg.sender == controller, "!controller");
        require(want != address(_asset), "want");
        balance = _asset.balanceOf(address(this));
        _asset.safeTransfer(controller, balance);
    }

    // Withdraw partial funds, normally used with a vault withdrawal
    function withdraw(uint256 _amount) external {
        require(msg.sender == controller, "!controller");
        uint256 _balance = IERC20(want).balanceOf(address(this));
        if (_balance < _amount) {
            _amount = _withdrawSome(_amount.sub(_balance));
            _amount = _amount.add(_balance);
        }
				
        uint256 _feeDev = _amount.mul(devFundFee).div(devFundMax);
        uint256 _feeTreasury = _amount.mul(treasuryFee).div(treasuryMax);

        address _vault = IController(controller).vaults(address(want));
        require(_vault != address(0), "!vault"); // additional protection so we don't burn the funds

        if (buybackEnabled == true && (_feeDev > 0 || _feeTreasury > 0)) {
            (address _buybackPrinciple, uint256 _buybackAmount) = _convertWantToBuyback(_feeDev.add(_feeTreasury));
            buybackAndNotify(_buybackPrinciple, _buybackAmount);
        } 

        IERC20(want).safeTransfer(_vault, _amount.sub(_feeDev).sub(_feeTreasury));
    }
	
    // buyback MM and notify MasterChef
    function buybackAndNotify(address _buybackPrinciple, uint256 _buybackAmount) internal {
        if (buybackEnabled == true && _buybackAmount > 0) {
            _swapUniswap(_buybackPrinciple, mmToken, _buybackAmount);
            uint256 _mmBought = IERC20(mmToken).balanceOf(address(this));
            IERC20(mmToken).safeTransfer(masterChef, _mmBought);
            IMasterchef(masterChef).notifyBuybackReward(_mmBought);
        }
    }
	
    // Migration for emergency, used in underlying strategy stuck case. Be careful
    bool public emergencyExit;
    function setEmergencyExit(bool _enable) external {
        require(msg.sender == governance, "!governance");
        emergencyExit = _enable;
    }

    // Withdraw all funds, normally used when migrating strategies
    function withdrawAll() external returns (uint256 balance) {
        require(msg.sender == controller, "!controller");
        if (!emergencyExit) {
            _withdrawAll();
        }

        balance = IERC20(want).balanceOf(address(this));

        address _vault = IController(controller).vaults(address(want));
        require(_vault != address(0), "!vault"); // additional protection so we don't burn the funds
        IERC20(want).safeTransfer(_vault, balance);
    }

    function _withdrawAll() internal {
        _withdrawSome(balanceOfPool());
    }

    function _withdrawSome(uint256 _amount) internal virtual returns (uint256);	
	
    // convert LP to buyback principle token
    function _convertWantToBuyback(uint256 _lpAmount) internal virtual returns (address, uint256);

    // each harvest need to update `lastHarvestBlock=block.number` and `lastHarvestInWant=yield profit converted to want for re-invest`
    // add modifier onlyBenignCallers
    function harvest() public virtual;

    // **** Emergency functions ****

    // **** Internal functions ****
	
    function figureOutPath(address _from, address _to, uint256 _amount) public view returns (bool useSushi, address[] memory swapPath){
        address[] memory path;
        address[] memory sushipath;

        path = new address[](2);
        path[0] = _from;
        path[1] = _to;

        sushipath = new address[](2);
        sushipath[0] = _from;
        sushipath[1] = _to;

        uint256 _sushiOut = sushipath.length > 0? UniswapRouterV2(sushiRouter).getAmountsOut(_amount, sushipath)[sushipath.length - 1] : 0;
        uint256 _uniOut = sushipath.length > 0? UniswapRouterV2(univ2Router2).getAmountsOut(_amount, path)[path.length - 1] : 1;

        bool useSushi = _sushiOut > _uniOut? true : false;		
        address[] memory swapPath = useSushi ? sushipath : path;
		
        return (useSushi, swapPath);
    }
	
    function _swapUniswap(
        address _from,
        address _to,
        uint256 _amount
    ) internal {
        (bool useSushi, address[] memory swapPath) = figureOutPath(_from, _to, _amount);
        address _router = useSushi? sushiRouter : univ2Router2;
		
        _swapUniswapWithDetailConfig(_from, _to, _amount, 1, swapPath, _router);
    }
	
    function _swapUniswapWithDetailConfig(
        address _from,
        address _to,
        uint256 _amount,
        uint256 _amountOutMin,
        address[] memory _swapPath,
        address _router
    ) internal {
        require(_to != address(0), '!invalidOutToken');
        require(_router != address(0), '!swapRouter');
        require(IERC20(_from).balanceOf(address(this)) >= _amount, '!notEnoughtAmountIn');

        if (_amount > 0){			
            IERC20(_from).safeApprove(_router, 0);
            IERC20(_from).safeApprove(_router, _amount);

            UniswapRouterV2(_router).swapExactTokensForTokens(
                _amount,
                _amountOutMin,
                _swapPath,
                address(this),
                now
            );
        }
    }

}

interface AggregatorV3Interface {
  
  function latestRoundData() external view returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
  );

}

interface ManagerLike {
    function ilks(uint256) external view returns (bytes32);
    function owns(uint256) external view returns (address);
    function urns(uint256) external view returns (address);
    function vat() external view returns (address);
    function open(bytes32, address) external returns (uint256);
    function give(uint256, address) external;
    function frob(uint256, int256, int256) external;
    function flux(uint256, address, uint256) external;
    function move(uint256, address, uint256) external;
    function exit(address, uint256, address, uint256) external;
    function quit(uint256, address) external;
    function enter(address, uint256) external;
}

interface VatLike {
    function can(address, address) external view returns (uint256);
    function ilks(bytes32) external view returns (uint256, uint256, uint256, uint256, uint256);
    function dai(address) external view returns (uint256);
    function urns(bytes32, address) external view returns (uint256, uint256);
    function frob(bytes32, address, address, address, int256, int256) external;
    function hope(address) external;
    function move(address, address, uint256) external;
}

interface GemJoinLike {
    function dec() external returns (uint256);
    function join(address, uint256) external payable;
    function exit(address, uint256) external;
}

interface DaiJoinLike {
    function join(address, uint256) external payable;
    function exit(address, uint256) external;
}

interface JugLike {
    function drip(bytes32) external returns (uint256);
}


// Base contract for MakerDAO based DAI-minting strategies
abstract contract StrategyMakerBase is StrategyBase {
    // MakerDAO modules
    address public constant dssCdpManager = 0x5ef30b9986345249bc32d8928B7ee64DE9435E39;
    address public constant daiJoin = 0x9759A6Ac90977b93B58547b4A71c78317f391A28;
    address public constant jug = 0x19c0976f590D67707E62397C87829d896Dc0f1F1;
    address public constant vat = 0x35D1b3F3D7966A1DFe207aa4514C12a259A0492B;
    address public constant debtToken = 0x6B175474E89094C44Da98b954EedeAC495271d0F;
    uint256 public minDebt = 30001000000000000000000;
    address public constant eth_usd = 0x5f4eC3Df9cbd43714FE2740f5E3616155c5b8419;

    // sub-strategy related constants
    address public collateral;
    uint256 public collateralDecimal = 1e18;
    address public gemJoin;
    address public collateralOracle;
    bytes32 public collateralIlk;
    AggregatorV3Interface internal priceFeed;
    uint256 public collateralPriceDecimal = 1;
    bool public collateralPriceEth = false;
	
    // singleton CDP for this strategy
    uint256 public cdpId = 0;
	
    // configurable minimum collateralization percent this strategy would hold for CDP
    uint256 public minRatio = 155;
    // collateralization percent buffer in CDP debt actions
    uint256 public ratioBuff = 500;
    uint256 public constant ratioBuffMax = 10000;
    uint256 constant RAY = 10 ** 27;

    constructor(
        address _collateralJoin,
        bytes32 _collateralIlk,
        address _collateral,
        uint256 _collateralDecimal,
        address _collateralOracle,
        uint256 _collateralPriceDecimal,
        bool _collateralPriceEth,
        address _want,
        address _governance,
        address _strategist,
        address _controller,
        address _timelock
    )
        public
        StrategyBase(_want, _governance, _strategist, _controller, _timelock)
    {
        require(_want == _collateral, '!mismatchWant');
		
        gemJoin = _collateralJoin;
        collateralIlk = _collateralIlk;		    
        collateral = _collateral;   
        collateralDecimal = _collateralDecimal;
        collateralOracle = _collateralOracle;
        priceFeed = AggregatorV3Interface(collateralOracle);
        collateralPriceDecimal = _collateralPriceDecimal;
        collateralPriceEth = _collateralPriceEth;
    }

    // **** Modifiers **** //
	
    modifier onlyCDPInUse {
        uint256 collateralAmt = getCollateralBalance();
        require(collateralAmt > 0, '!zeroCollateral');
		
        uint256 debtAmt = getDebtBalance();
        require(debtAmt > 0, '!zeroDebt');		
        _;
    }
	
    modifier onlyCDPInitiated {        
        require(cdpId > 0, '!noCDP');	
        _;
    }
    
    modifier onlyAboveMinDebt(uint256 _daiAmt) {  
        uint256 debtAmt = getDebtBalance();   
        require((_daiAmt < debtAmt && (debtAmt.sub(_daiAmt) >= minDebt)) || debtAmt <= _daiAmt, '!minDebt');
        _;
    }
	
    function getCollateralBalance() public view returns (uint256) {
        (uint256 ink, ) = VatLike(vat).urns(collateralIlk, ManagerLike(dssCdpManager).urns(cdpId));
        return ink.mul(collateralDecimal).div(1e18);
    }
	
    function getDebtBalance() public view returns (uint256) {
        address urnHandler = ManagerLike(dssCdpManager).urns(cdpId);
        (, uint256 art) = VatLike(vat).urns(collateralIlk, urnHandler);
        (, uint256 rate, , , ) = VatLike(vat).ilks(collateralIlk);
        uint rad = mul(art, rate);
        if (rad == 0) {
            return 0;
        }
        uint256 wad = rad / RAY;
        return mul(wad, RAY) < rad ? wad + 1 : wad;
    }	
    
    function ilkDebts() public view returns(uint256, uint256, bool){
        (uint256 Art, uint256 rate,,uint256 line,) = VatLike(vat).ilks(collateralIlk);
        uint256 currentDebt = Art.mul(rate).div(RAY);
        uint256 maxDebt = line.div(RAY);
        return (currentDebt, maxDebt, maxDebt > currentDebt);
    }

    // **** Getters ****
	
    function balanceOfPool() public override view returns (uint256){
        return getCollateralBalance();
    }

    function collateralValue(uint256 collateralAmt) public view returns (uint256){
        uint256 collateralPrice = getLatestCollateralPrice();
        return collateralAmt.mul(collateralPrice).mul(1e18).div(collateralDecimal).div(collateralPriceDecimal);
    }

    function currentRatio() public view returns (uint256) {	
        uint256 _collateral = cdpId > 0? getCollateralBalance() : 0;
        if (_collateral > 0){
            uint256 collateralAmt = collateralValue(_collateral).mul(100);
            uint256 debtAmt = getDebtBalance();		
            return collateralAmt.div(debtAmt);
        }else{
            return 0;
        }
    } 
    
    // if borrow is true (for lockAndDraw): return (maxDebt - currentDebt) if positive value, otherwise return 0
    // if borrow is false (for redeemAndFree): return (currentDebt - maxDebt) if positive value, otherwise return 0
    function calculateDebtFor(uint256 collateralAmt, bool borrow) public view returns (uint256) {
        uint256 maxDebt = collateralAmt > 0? collateralValue(collateralAmt).mul(ratioBuffMax).div(_getBufferedMinRatio(ratioBuffMax)) : 0;
		
        uint256 debtAmt = getDebtBalance();
		
        uint256 debt = 0;
        
        if (borrow && maxDebt >= debtAmt){
            debt = maxDebt.sub(debtAmt);
        } else if (!borrow && debtAmt >= maxDebt){
            debt = debtAmt.sub(maxDebt);
        }
        
        return (debt > 0)? debt : 0;
    }
	
    function _getBufferedMinRatio(uint256 _multiplier) internal view returns (uint256){
        return _multiplier.mul(minRatio).mul(ratioBuffMax.add(ratioBuff)).div(ratioBuffMax).div(100);
    }

    function borrowableDebt() public view returns (uint256) {
        uint256 collateralAmt = getCollateralBalance();
        return calculateDebtFor(collateralAmt, true);
    }

    function requiredPaidDebt(uint256 _redeemCollateralAmt) public view returns (uint256) {
        uint256 totalCollateral = getCollateralBalance();
        uint256 collateralAmt = _redeemCollateralAmt >= totalCollateral? 0 : totalCollateral.sub(_redeemCollateralAmt);
        return calculateDebtFor(collateralAmt, false);
    }

    // **** sub-strategy implementation ****
    function _convertWantToBuyback(uint256 _lpAmount) internal virtual override returns (address, uint256);
	
    function _depositDAI(uint256 _daiAmt) internal virtual;
	
    function _withdrawDAI(uint256 _daiAmt) internal virtual;
    
    function _swapDebtToWant(uint256 _swapIn) internal virtual returns(uint256);
	
    // **** Oracle (using chainlink) ****
	
    function getLatestCollateralPrice() public view returns (uint256){
        require(collateralOracle != address(0), '!_collateralOracle');	
        (
            uint80 roundID, 
            int price,
            uint startedAt,
            uint timeStamp,
            uint80 answeredInRound
        ) = priceFeed.latestRoundData();
		
        if (price > 0){		
            int ethPrice = 1;
            if (collateralPriceEth){
               (,ethPrice,,,) = AggregatorV3Interface(eth_usd).latestRoundData();			
            }
            return uint256(price).mul(collateralPriceDecimal).mul(uint256(ethPrice)).div(1e8).div(collateralPriceEth? 1e18 : 1);
        } else{
            return 0;
        }
    }

    // **** Setters ****
 
    function setMinDebt(uint256 _minDebt) external onlyBenevolent {
        minDebt = _minDebt;
    }	
 
    function setMinRatio(uint256 _minRatio) external onlyBenevolent {
        minRatio = _minRatio;
    }	
	
    function setRatioBuff(uint256 _ratioBuff) external onlyBenevolent {
        ratioBuff = _ratioBuff;
    }
	
    // **** MakerDAO CDP actions ****

    function mul(uint256 x, uint256 y) internal pure returns (uint256 z) {
        require(y == 0 || (z = x * y) / y == x, "mul-overflow");
    }
	
    function toRad(uint256 wad) internal pure returns (uint256 rad) {
        rad = mul(wad, RAY);
    }
	
    function sub(uint256 x, uint256 y) internal pure returns (uint256 z) {
        require((z = x - y) <= x, "sub-overflow");
    }
	
    function toInt(uint256 x) internal pure returns (int256 y) {
        y = int256(x);
        require(y >= 0, "int-overflow");
    }
	
    function convertTo18(address gemJoin, uint256 amt) internal returns (uint256 wad) {
        wad = mul(amt, 10 ** (18 - GemJoinLike(gemJoin).dec()));
    }
	
    function _getDrawDart(address vat, address jug, address urn, bytes32 ilk, uint wad) internal returns (int256 dart) {
        uint256 rate = JugLike(jug).drip(ilk);
        uint256 dai = VatLike(vat).dai(urn);
        if (dai < toRad(wad)) {
            dart = toInt(sub(toRad(wad), dai).div(rate));
            dart = mul(uint256(dart), rate) < toRad(wad) ? dart + 1 : dart;
        }
    }
	
    function _getWipeDart(address vat, uint dai, address urn, bytes32 ilk) internal view returns (int256 dart) {
        (, uint256 rate,,,) = VatLike(vat).ilks(ilk);
        (, uint256 art) = VatLike(vat).urns(ilk, urn);
        dart = toInt(dai.div(rate));
        dart = uint256(dart) <= art ? - dart : - toInt(art);
    }
	
    function openCDP() external onlyBenevolent{
        require(cdpId <= 0, "!cdpAlreadyOpened");
		
        cdpId = ManagerLike(dssCdpManager).open(collateralIlk, address(this));		
		
        IERC20(collateral).approve(gemJoin, uint256(-1));
        IERC20(debtToken).approve(daiJoin, uint256(-1));
    }
	
    function getUrnVatIlk() internal returns (address, address, bytes32){
        return (ManagerLike(dssCdpManager).urns(cdpId), ManagerLike(dssCdpManager).vat(), ManagerLike(dssCdpManager).ilks(cdpId));
    }
	
    function addCollateralAndBorrow(uint256 _collateralAmt, uint256 _daiAmt) internal onlyCDPInitiated {   
        require(_daiAmt.add(getDebtBalance()) >= minDebt, '!minDebt');
        (address urn, address vat, bytes32 ilk) = getUrnVatIlk();		
		GemJoinLike(gemJoin).join(urn, _collateralAmt);  
		ManagerLike(dssCdpManager).frob(cdpId, toInt(convertTo18(gemJoin, _collateralAmt)), _getDrawDart(vat, jug, urn, ilk, _daiAmt));
		ManagerLike(dssCdpManager).move(cdpId, address(this), toRad(_daiAmt));
        if (VatLike(vat).can(address(this), address(daiJoin)) == 0) {
            VatLike(vat).hope(daiJoin);
        }
        DaiJoinLike(daiJoin).exit(address(this), _daiAmt);
    } 
	
    function repayAndRedeemCollateral(uint256 _collateralAmt, uint _daiAmt) internal onlyCDPInitiated onlyAboveMinDebt(_daiAmt) { 
        (address urn, address vat, bytes32 ilk) = getUrnVatIlk();
        if (_daiAmt > 0){
            DaiJoinLike(daiJoin).join(urn, _daiAmt);
        }
        uint256 wad18 = _collateralAmt > 0? convertTo18(gemJoin, _collateralAmt) : 0;
        ManagerLike(dssCdpManager).frob(cdpId, -toInt(wad18),  _getWipeDart(vat, VatLike(vat).dai(urn), urn, ilk));
        if (_collateralAmt > 0){
            ManagerLike(dssCdpManager).flux(cdpId, address(this), wad18);
            GemJoinLike(gemJoin).exit(address(this), _collateralAmt);
        }
    } 

    // **** State Mutation functions ****
	
    function keepMinRatio() external onlyCDPInUse onlyBenignCallers {		
        uint256 requiredPaidback = requiredPaidDebt(0);
        if (requiredPaidback > 0){
            _withdrawDAI(requiredPaidback);
            uint256 wad = IERC20(debtToken).balanceOf(address(this));
            require(wad >= requiredPaidback, '!keepMinRatioRedeem');
			
            repayAndRedeemCollateral(0, requiredPaidback);
            uint256 goodRatio = currentRatio();
            require(goodRatio >= minRatio.sub(1), '!stillBelowMinRatio');
        }
    }
	
    function deposit() public override {
        uint256 _want = balanceOfWant();
        (,,bool roomForNewMint) = ilkDebts();
        if (_want > 0 && roomForNewMint) {	
            uint256 _newDebt = calculateDebtFor(_want.add(getCollateralBalance()), true);
            if(_newDebt > 0 && _newDebt.add(getDebtBalance()) >= minDebt){
               addCollateralAndBorrow(_want, _newDebt);
               uint256 wad = IERC20(debtToken).balanceOf(address(this));
               _depositDAI(_newDebt > wad? wad : _newDebt);
            }
        }
    }

    function _withdrawSome(uint256 _amount) internal override returns (uint256) {
        bool _full = _amount >= getCollateralBalance();
        uint256 requiredPaidback = requiredPaidDebt(_amount);
        
        if (requiredPaidback > 0){
            _withdrawDAI(requiredPaidback);
            require(IERC20(debtToken).balanceOf(address(this)) >= requiredPaidback, '!mismatchAfterWithdraw');
        }
		
        repayAndRedeemCollateral(_amount, requiredPaidback);
        
        // sweep left debt to want
        if (_full){
           _swapDebtToWant(IERC20(debtToken).balanceOf(address(this)));
        }
        
        return _amount;
    }
    
}

contract CarefulMath {

    /**
     * @dev Possible error codes that we can return
     */
    enum MathError {
        NO_ERROR,
        DIVISION_BY_ZERO,
        INTEGER_OVERFLOW,
        INTEGER_UNDERFLOW
    }

    /**
    * @dev Multiplies two numbers, returns an error on overflow.
    */
    function mulUInt(uint a, uint b) internal pure returns (MathError, uint) {
        if (a == 0) {
            return (MathError.NO_ERROR, 0);
        }

        uint c = a * b;

        if (c / a != b) {
            return (MathError.INTEGER_OVERFLOW, 0);
        } else {
            return (MathError.NO_ERROR, c);
        }
    }

    /**
    * @dev Adds two numbers, returns an error on overflow.
    */
    function addUInt(uint a, uint b) internal pure returns (MathError, uint) {
        uint c = a + b;

        if (c >= a) {
            return (MathError.NO_ERROR, c);
        } else {
            return (MathError.INTEGER_OVERFLOW, 0);
        }
    }
}

contract Exponential is CarefulMath {
    uint constant expScale = 1e18;
    uint constant doubleScale = 1e36;
    uint constant halfExpScale = expScale/2;
    uint constant mantissaOne = expScale;

    struct Exp {
        uint mantissa;
    }

    struct Double {
        uint mantissa;
    }
    
    /**
     * @dev Multiply an Exp by a scalar, then truncate to return an unsigned integer.
     */
    function mulScalarTruncate(Exp memory a, uint scalar) pure internal returns (MathError, uint) {
        (MathError err, Exp memory product) = mulScalar(a, scalar);
        if (err != MathError.NO_ERROR) {
            return (err, 0);
        }

        return (MathError.NO_ERROR, truncate(product));
    }

    /**
     * @dev Multiply an Exp by a scalar, truncate, then add an to an unsigned integer, returning an unsigned integer.
     */
    function mulScalarTruncateAddUInt(Exp memory a, uint scalar, uint addend) pure internal returns (MathError, uint) {
        (MathError err, Exp memory product) = mulScalar(a, scalar);
        if (err != MathError.NO_ERROR) {
            return (err, 0);
        }

        return addUInt(truncate(product), addend);
    }

    /**
     * @dev Multiply an Exp by a scalar, returning a new Exp.
     */
    function mulScalar(Exp memory a, uint scalar) pure internal returns (MathError, Exp memory) {
        (MathError err0, uint scaledMantissa) = mulUInt(a.mantissa, scalar);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        return (MathError.NO_ERROR, Exp({mantissa: scaledMantissa}));
    }

    /**
     * @dev Truncates the given exp to a whole number value.
     *      For example, truncate(Exp{mantissa: 15 * expScale}) = 15
     */
    function truncate(Exp memory exp) pure internal returns (uint) {
        // Note: We are not using careful math here as we're performing a division that cannot fail
        return exp.mantissa / expScale;
    }
}

interface IFuseToken {
    function mint(uint mintAmount) external returns (uint);
    function redeem(uint redeemTokens) external returns (uint);
    function redeemUnderlying(uint redeemAmount) external returns (uint);
    function exchangeRateCurrent() external returns (uint);
    function exchangeRateStored() external view returns (uint);
    function supplyRatePerBlock() external view returns (uint);
    function balanceOfUnderlying(address account) external returns (uint);
}

interface ICurveFi_3 {
    function exchange(int128 from, int128 to, uint256 _from_amount, uint256 _min_to_amount) external;
}

contract StrategyMakerWBTCV2 is StrategyMakerBase, Exponential {
    // strategy specific: https://github.com/makerdao/mcd-changelog
    address public wbtc_collateral = 0x2260FAC5E5542a773Aa44fBCfeDf7C193bc2C599;
    address public link_btc_usd = 0xF4030086522a5bEEa4988F8cA5B36dbC97BeE88c;
    uint256 public wbtc_collateral_decimal = 1e8;
    bytes32 public wbtc_ilk = "WBTC-A";
    address public wbtc_apt = 0xBF72Da2Bd84c5170618Fbe5914B0ECA9638d5eb5;
    uint256 public constant weth_price_decimal = 1;
    bool public constant wbtc_price_eth = false;
    
    address public constant curve3crvPool = 0xbEbc44782C7dB0a1A60Cb6fe97d0b483032FF1C7;
    address public constant usdcToken = 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48;
		
    // Fuse specific/configurable
    address public fusePool = 0x989273ec41274C4227bCB878C2c26fdd3afbE70d;
    uint256 public fusePoolDecimal = 8;// Tetranode's Locker #6 Pool
    
    uint256 public harvestRatio = 9000; // pencetage taken from claimable during harvest
    uint256 public slippageSwap = 500; // slippage swap during non-curve amm dex
    uint256 public constant DENOMINATOR = 10000;

    constructor(address _governance, address _strategist, address _controller, address _timelock) 
        public StrategyMakerBase(
            wbtc_apt,
            wbtc_ilk,
            wbtc_collateral,
            wbtc_collateral_decimal,			
            link_btc_usd,
            weth_price_decimal,
            wbtc_price_eth,
            wbtc_collateral,
            _governance,
            _strategist,
            _controller,
            _timelock
        )
    {
        // for want exchange
        IERC20(debtToken).safeApprove(curve3crvPool, uint256(-1));
        
        // for fuse pool
        _setupPoolApprovals();  	
    }
	
    // **** Setters ****
    
    function setSlippageSwap(uint256 _slippage) public onlyBenevolent{
        slippageSwap = _slippage;
    }
    
    function setHarvestRatio(uint256 _ratio) public onlyBenevolent{
        harvestRatio = _ratio;
    }
	
    // **** State Mutation functions ****
    
    function _setupPoolApprovals() internal {
        IERC20(debtToken).safeApprove(fusePool, uint256(-1));
        IERC20(fusePool).safeApprove(fusePool, uint256(-1)); 
    }
    
    function migrateFusePool(address _fusePool) public {
        require(msg.sender == timelock, '!timelock');
        
        // withdraw all debt token if needed
        if (IERC20(fusePool).balanceOf(address(this)) > 0){
            _withdrawDAI(IFuseToken(fusePool).balanceOfUnderlying(address(this)));
            require(IFuseToken(fusePool).balanceOfUnderlying(address(this)) == 0, '!stillGotSomeInFuse');
        }
	    
        // migrate to new destination
        fusePool = _fusePool;
        fusePoolDecimal = ERC20(fusePool).decimals();
        
        // setup for new meta pool
        _setupPoolApprovals(); 
        
        // reinvest to new Convex pool
        _depositDAI(IERC20(debtToken).balanceOf(address(this)));
    }
	
    function harvest() public override onlyBenevolent {
        uint256 _claimable = getHarvestable();
        uint256 _wantAmount;
        if (_claimable > 0){
            _withdrawDAI(_claimable);
            _wantAmount = _swapDebtToWant(IERC20(debtToken).balanceOf(address(this)));
        }
		
        if (_wantAmount > 0){
            // Buyback and Reinvest
            uint256 _buybackLpAmount = _wantAmount.mul(performanceFee).div(performanceMax);
            if (buybackEnabled == true && _buybackLpAmount > 0){
                (, uint256 _wethAmt) = _convertWantToBuyback(_buybackLpAmount);
                buybackAndNotify(weth, _wethAmt);
            }
             
            uint256 _wantBal = balanceOfWant();
            if (_wantBal > 0){
                lastHarvestBlock = block.number;
                lastHarvestInWant = _wantBal;
                deposit();
            }
        }
    }
	
    function _convertWantToBuyback(uint256 _lpAmount) internal override returns (address, uint256){
        if (_lpAmount <= 0){
            return (weth, 0);
        }
	
        address[] memory _swapPath = new address[](2);
        _swapPath[0] = want;
        _swapPath[1] = weth;
        _swapUniswap(want, weth, _lpAmount);
		
        return (weth, IERC20(weth).balanceOf(address(this)));
    }
	
    function _swapDebtToWant(uint256 _swapIn) internal override returns(uint256){
        uint256 _outMin;
        if (_swapIn > 0){
            uint256 _debtAmt = IERC20(debtToken).balanceOf(address(this));
            uint256 _toSwap = _swapIn > _debtAmt? _debtAmt : _swapIn;
            _outMin = wantFromDebt(_toSwap);
            ICurveFi_3(curve3crvPool).exchange(0, 1, _toSwap, 0);
        }
        
        uint256 _want = balanceOfWant();
        uint256 _usdcAmt = IERC20(usdcToken).balanceOf(address(this));
        if (_usdcAmt > 0){
            address[] memory _swapPath = new address[](3);
            _swapPath[0] = usdcToken;
            _swapPath[1] = weth;
            _swapPath[2] = want;
            _swapUniswapWithDetailConfig(usdcToken, want, _usdcAmt, _outMin, _swapPath, sushiRouter);
        }
        uint256 _wantAfter = balanceOfWant();
        return _wantAfter > _want? _wantAfter.sub(_want) : 0;
    }
	
    function wantFromDebt(uint256 _toSwappedDebt) public view returns (uint256){
        (,int wantPrice,,,) = AggregatorV3Interface(link_btc_usd).latestRoundData();// usd price from chainlink in 1e8 decimal
        uint256 _want = _toSwappedDebt.mul(wbtc_collateral_decimal).div(1e18).mul(1e8).div(uint256(wantPrice));
        return _want.mul(DENOMINATOR.sub(slippageSwap)).div(DENOMINATOR);
    }
	
    function _depositDAI(uint256 _daiAmt) internal override{
        uint256 _debt = IERC20(debtToken).balanceOf(address(this));
        if (_debt == 0){
            return;
        }
        
        require(IFuseToken(fusePool).mint(_debt) == 0, '!mintFuse');
    }
	
    function _withdrawDAI(uint256 _daiAmt) internal override{
        if (_daiAmt == 0){
            return;
        }
	    
        if (_daiAmt >= getDebtBalance()){
            require(IFuseToken(fusePool).redeem(IERC20(fusePool).balanceOf(address(this))) == 0, '!redeemAllFromFuse');
        }else {	
            require(IFuseToken(fusePool).redeemUnderlying(_daiAmt) == 0, '!redeemUnderlyingFromFuse');			
        }
    }

    // Controller only function for creating additional rewards from dust
    function withdraw(IERC20 _asset) external override returns (uint256 balance) {
        require(address(_asset) != fusePool, '!fusePool');
        _withdrawNonWantAsset(_asset);
    }

    // **** Views ****
	
    function balanceOfDebtToken() public view returns (uint256){
        uint exchangeRateStored = IFuseToken(fusePool).exchangeRateStored();
        (, uint256 bal) = mulScalarTruncate(Exp({mantissa: exchangeRateStored}), IERC20(fusePool).balanceOf(address(this)));
        return bal.add(IERC20(debtToken).balanceOf(address(this)));
    }

    // return claimable DAI as supply interest
    function getHarvestable() public returns (uint256) {
        uint256 _bal = IFuseToken(fusePool).balanceOfUnderlying(address(this));
        uint256 _debt = getDebtBalance();
        return _bal > _debt? (_bal.sub(_debt)).mul(harvestRatio).div(DENOMINATOR) : 0;//add some buffer
    }

    function getName() external override pure returns (string memory) {
        return "StrategyMakerWBTCV2";
    }
}