Izlude.sol

// File @openzeppelin/contracts/utils/Context.sol@v4.2.0

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}


// File @openzeppelin/contracts/access/Ownable.sol@v4.2.0

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _setOwner(_msgSender());
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _setOwner(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _setOwner(newOwner);
    }

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}


// File @openzeppelin/contracts/security/ReentrancyGuard.sol@v4.2.0

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}


// File @openzeppelin/contracts/token/ERC20/IERC20.sol@v4.2.0

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}


// File @openzeppelin/contracts/utils/Address.sol@v4.2.0

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
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) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @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);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) private pure returns (bytes memory) {
        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

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}


// File @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol@v4.2.0

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;


/**
 * @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 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'
        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) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _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
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}


// File contracts/interfaces/IByalanIsland.sol

//SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

interface IByalanIsland {
    function izlude() external view returns (address);
}


// File contracts/interfaces/ISailor.sol

//SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

interface ISailor {
    function MAX_FEE() external view returns (uint256);

    function totalFee() external view returns (uint256);

    function callFee() external view returns (uint256);

    function kswFee() external view returns (uint256);
}


// File contracts/interfaces/IByalan.sol

//SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;
interface IByalan is IByalanIsland, ISailor {
    function want() external view returns (address);

    function beforeDeposit() external;

    function deposit() external;

    function withdraw(uint256) external;

    function balanceOf() external view returns (uint256);

    function balanceOfWant() external view returns (uint256);

    function balanceOfPool() external view returns (uint256);

    function balanceOfMasterChef() external view returns (uint256);

    function pendingReward() external view returns (uint256);

    function harvest() external;

    function retireStrategy() external;

    function panic() external;

    function pause() external;

    function unpause() external;

    function paused() external view returns (bool);
}


// File contracts/interfaces/IFeeKafra.sol

//SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

interface IFeeKafra {
    function MAX_FEE() external view returns (uint256);

    function depositFee() external view returns (uint256);

    function withdrawFee() external view returns (uint256);

    function treasuryFeeDeposit() external view returns (uint256);

    function kswFeeDeposit() external view returns (uint256);

    function treasuryFeeWithdraw() external view returns (uint256);

    function kswFeeWithdraw() external view returns (uint256);

    function calculateDepositFee(uint256 _wantAmount, address _user) external view returns (uint256);

    function calculateWithdrawFee(uint256 _wantAmount, address _user) external view returns (uint256);

    function distributeDepositFee(IERC20 _token, address _fromUser) external;

    function distributeWithdrawFee(IERC20 _token, address _fromUser) external;
}


// File contracts/interfaces/IAllocKafra.sol

//SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

interface IAllocKafra {
    function MAX_ALLOCATION() external view returns (uint16);

    function limitAllocation() external view returns (uint16);

    function canAllocate(
        uint256 _amount,
        uint256 _balanceOfWant,
        uint256 _balanceOfMasterChef,
        address _user
    ) external view returns (bool);
}


// File contracts/Izlude.sol

//SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;





contract Izlude is Ownable, ReentrancyGuard {
    using SafeERC20 for IERC20;

    mapping(address => uint256) private _balances;
    uint256 private _totalSupply;

    struct ByalanCandidate {
        address implementation;
        uint256 proposedTime;
    }

    // The last proposed byalan to switch to.
    ByalanCandidate public byalanCandidate;
    // The byalan currently in use by the izlude.
    IByalan public byalan;
    // The minimum time it has to pass before a strat candidate can be approved.
    uint256 public immutable approvalDelay;

    address public morroc;
    IFeeKafra public feeKafra;
    IAllocKafra public allocKafra;

    event NewStrategyCandidate(address implementation);
    event UpgradeStrategy(address implementation);

    constructor(IByalan _byalan, uint256 _approvalDelay) {
        byalan = _byalan;
        approvalDelay = _approvalDelay;
    }

    modifier onlyMorroc() {
        require(_msgSender() == morroc, "!morroc");
        _;
    }

    function setMorroc(address _morroc) external onlyOwner {
        morroc = _morroc;
    }

    function setFeeKafra(IFeeKafra _feeKafra) external onlyOwner {
        feeKafra = _feeKafra;
    }

    function setAllocKafra(IAllocKafra _allocKafra) external onlyOwner {
        allocKafra = _allocKafra;
    }

    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address _account) public view returns (uint256) {
        return _balances[_account];
    }

    function _mint(address _account, uint256 _jellopy) private {
        require(_account != address(0), "mint to the zero address");

        _totalSupply += _jellopy;
        _balances[_account] += _jellopy;
    }

    // burn jellopy from account
    function _burn(address _account, uint256 _jellopy) private {
        require(_account != address(0), "burn from the zero address");

        uint256 accountBalance = _balances[_account];
        require(accountBalance >= _jellopy, "burn amount exceeds balance");
        _balances[_account] = accountBalance - _jellopy;
        _totalSupply -= _jellopy;
    }

    function want() public view returns (IERC20) {
        return IERC20(byalan.want());
    }

    /**
     * @dev It calculates the total underlying value of {token} held by the system.
     * It takes into account the izlude contract balance, the strategy contract balance
     *  and the balance deployed in other contracts as part of the strategy.
     */
    function balance() public view returns (uint256) {
        return want().balanceOf(address(this)) + byalan.balanceOf();
    }

    /**
     * @dev Custom logic in here for how much the izlude allows to be borrowed.
     * We return 100% of tokens for now. Under certain conditions we might
     * want to keep some of the system funds at hand in the izlude, instead
     * of putting them to work.
     */
    function available() public view returns (uint256) {
        return want().balanceOf(address(this));
    }

    /**
     * @dev Function for various UIs to display the current value of one of our yield tokens.
     * Returns an uint256 with 18 decimals of how much underlying asset one izlude share represents.
     */
    function getPricePerFullShare() external view returns (uint256) {
        return totalSupply() == 0 ? 1e18 : (balance() * 1e18) / totalSupply();
    }

    function calculateDepositFee(uint256 _amount, address _user) public view returns (uint256) {
        if (address(feeKafra) == address(0)) {
            return 0;
        }
        return feeKafra.calculateDepositFee(_amount, _user);
    }

    function calculateWithdrawFee(uint256 _amount, address _user) public view returns (uint256) {
        if (address(feeKafra) == address(0)) {
            return 0;
        }
        return feeKafra.calculateWithdrawFee(_amount, _user);
    }

    function _deposit(uint256 _amount, address _user) private nonReentrant returns (uint256) {
        byalan.beforeDeposit();

        uint256 _pool = balance();
        want().safeTransferFrom(_msgSender(), address(this), _amount);
        uint256 _after = balance();

        _amount = _after - _pool;
        uint256 fee = calculateDepositFee(_amount, _user);
        if (fee > 0) {
            want().safeTransfer(address(feeKafra), fee);
            feeKafra.distributeDepositFee(want(), _user);
        }

        earn();

        _after = balance();
        _amount = _after - _pool; // Additional check for deflationary tokens

        require(
            address(allocKafra) == address(0) ||
                allocKafra.canAllocate(_amount, byalan.balanceOf(), byalan.balanceOfMasterChef(), _user),
            "capacity limit reached"
        );

        uint256 jellopy = 0;
        if (totalSupply() == 0) {
            jellopy = _amount;
        } else {
            jellopy = (_amount * totalSupply()) / _pool;
        }
        _mint(_user, jellopy);
        return jellopy;
    }

    function depositFromMorroc(uint256 _amount, address _user) external onlyMorroc returns (uint256) {
        return _deposit(_amount, _user);
    }

    /**
     * @dev Function to send funds into the strategy and put them to work. It's primarily called
     * by the izlude's deposit() function.
     */
    function earn() public {
        uint256 _bal = available();
        want().safeTransfer(address(byalan), _bal);
        byalan.deposit();
    }

    // burn user jellopy and convert back to want
    // then transfer want to the caller
    // user and caller might not be the same address
    function _withdraw(uint256 _jellopy, address _user) private nonReentrant returns (uint256) {
        uint256 r = (balance() * _jellopy) / totalSupply();
        _burn(_user, _jellopy);

        uint256 b = want().balanceOf(address(this));
        if (b < r) {
            uint256 amount = r - b;
            byalan.withdraw(amount);
            uint256 _after = want().balanceOf(address(this));
            uint256 diff = _after - b;
            if (diff < amount) {
                r = b + diff;
            }
        }

        uint256 fee = calculateWithdrawFee(r, _user);
        if (fee > 0) {
            r -= fee;
            want().safeTransfer(address(feeKafra), fee);
            feeKafra.distributeWithdrawFee(want(), _user);
        }
        want().safeTransfer(_msgSender(), r);
        return r;
    }

    // withdrawFromMorroc jellopy for the user, returns want
    // want will transfer directly to user
    function withdrawFromMorroc(uint256 _jellopy, address _user) external onlyMorroc returns (uint256) {
        return _withdraw(_jellopy, _user);
    }

    /**
     * @dev Sets the candidate for the new strat to use with this izlude.
     * @param _implementation The address of the candidate strategy.
     */
    function proposeStrategy(address _implementation) external onlyOwner {
        require(address(this) == IByalan(_implementation).izlude(), "proposal invalid");
        byalanCandidate = ByalanCandidate({implementation: _implementation, proposedTime: block.timestamp});

        emit NewStrategyCandidate(_implementation);
    }

    /**
     * @dev It switches the active strategy for the strategy candidate. After upgrading, the
     * candidate implementation is set to the 0x00 address, and proposedTime to a time
     * happening in +100 years for safety.
     */
    function upgradeStrategy() external onlyOwner nonReentrant {
        require(byalanCandidate.implementation != address(0), "There is no candidate");
        require(byalanCandidate.proposedTime + approvalDelay < block.timestamp, "Delay has not passed");

        emit UpgradeStrategy(byalanCandidate.implementation);

        byalan.retireStrategy();

        byalan = IByalan(byalanCandidate.implementation);
        byalanCandidate.implementation = address(0);
        byalanCandidate.proposedTime = 5000000000;

        earn();
    }

    /**
     * @dev Rescues random funds stuck that the strat can't handle.
     * @param _token address of the token to rescue.
     */
    function inCaseTokensGetStuck(address _token) external onlyOwner {
        require(_token != address(want()), "!token");

        uint256 amount = IERC20(_token).balanceOf(address(this));
        IERC20(_token).safeTransfer(_msgSender(), amount);
    }
}