// File: contracts\interfaces\IRewardStaking.sol

// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;

interface IRewardStaking {
    function stakeFor(address, uint256) external;
    function stake( uint256) external;
    function withdraw(uint256 amount, bool claim) external;
    function withdrawAndUnwrap(uint256 amount, bool claim) external;
    function earned(address account) external view returns (uint256);
    function getReward() external;
    function getReward(address _account, bool _claimExtras) external;
    function extraRewardsLength() external view returns (uint256);
    function extraRewards(uint256 _pid) external view returns (address);
    function rewardToken() external view returns (address);
    function balanceOf(address _account) external view returns (uint256);
    function rewardRate() external view returns(uint256);
    function totalSupply() external view returns(uint256);
}

// File: contracts\interfaces\IConvexDeposits.sol

pragma solidity 0.6.12;

interface IConvexDeposits {
    function deposit(uint256 _pid, uint256 _amount, bool _stake) external returns(bool);
    function deposit(uint256 _amount, bool _lock, address _stakeAddress) external;
}

// File: contracts\interfaces\IRewardHook.sol


pragma solidity 0.6.12;

interface IRewardHook {
    function onRewardClaim() external;
}

// File: @openzeppelin\contracts\math\SafeMath.sol


pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, 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 (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @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) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @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) {
        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, reverting 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) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. 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 mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * 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);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * 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);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. 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 mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin\contracts\token\ERC20\IERC20.sol


pragma solidity >=0.6.0 <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


pragma solidity >=0.6.2 <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;
        // solhint-disable-next-line no-inline-assembly
        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");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (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

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin\contracts\token\ERC20\SafeERC20.sol


pragma solidity >=0.6.0 <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 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");
        }
    }
}

// File: @openzeppelin\contracts\utils\Context.sol


pragma solidity >=0.6.0 <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 GSN 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 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;
    }
}

// File: @openzeppelin\contracts\token\ERC20\ERC20.sol


pragma solidity >=0.6.0 <0.8.0;



/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20 {
    using SafeMath for uint256;

    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 virtual returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual 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 virtual returns (uint8) {
        return _decimals;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual 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 Sets {decimals} to a value other than the default one of 18.
     *
     * WARNING: This function should only be called from the constructor. Most
     * applications that interact with token contracts will not expect
     * {decimals} to ever change, and may work incorrectly if it does.
     */
    function _setupDecimals(uint8 decimals_) internal virtual {
        _decimals = decimals_;
    }

    /**
     * @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 { }
}

// File: @openzeppelin\contracts\utils\ReentrancyGuard.sol


pragma solidity >=0.6.0 <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 () internal {
        _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: contracts\wrappers\CvxCrvStakingWrapper.sol

pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;
//Wrapper for staked cvxcrv that allows other incentives and user reward weighting

//Based on Curve.fi's gauge wrapper implementations at https://github.com/curvefi/curve-dao-contracts/tree/master/contracts/gauges/wrappers
contract CvxCrvStakingWrapper is ERC20, ReentrancyGuard {
    using SafeERC20
    for IERC20;
    using SafeMath
    for uint256;

    struct EarnedData {
        address token;
        uint256 amount;
    }

    struct RewardType {
        address reward_token;
        uint8 reward_group;
        uint128 reward_integral;
        uint128 reward_remaining;
        mapping(address => uint256) reward_integral_for;
        mapping(address => uint256) claimable_reward;
    }

    //constants/immutables
    address public constant crvDepositor = address(0x8014595F2AB54cD7c604B00E9fb932176fDc86Ae);
    address public constant cvxCrvStaking = address(0x3Fe65692bfCD0e6CF84cB1E7d24108E434A7587e);
    address public constant crv = address(0xD533a949740bb3306d119CC777fa900bA034cd52);
    address public constant cvx = address(0x4e3FBD56CD56c3e72c1403e103b45Db9da5B9D2B);
    address public constant cvxCrv = address(0x62B9c7356A2Dc64a1969e19C23e4f579F9810Aa7);
    address public constant threeCrv = address(0x6c3F90f043a72FA612cbac8115EE7e52BDe6E490);
    address public constant treasury = address(0x1389388d01708118b497f59521f6943Be2541bb7);
    uint256 private constant WEIGHT_PRECISION = 10000;
    uint256 private constant MAX_REWARD_COUNT = 10;

    //rewards
    RewardType[] public rewards;
    mapping(address => uint256) public registeredRewards;
    address public rewardHook;
    mapping (address => uint256) public userRewardWeight;
    uint256 public supplyWeight;

    //management
    bool public isShutdown;
    address public owner;

    event Deposited(address indexed _user, address indexed _account, uint256 _amount, bool _isCrv);
    event Withdrawn(address indexed _user, uint256 _amount);
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
    event RewardInvalidated(address _rewardToken);
    event RewardGroupSet(address _rewardToken, uint256 _rewardGroup);
    event HookSet(address _rewardToken);
    event IsShutdown();
    event RewardPaid(address indexed _user, address indexed _token, uint256 _amount, address _receiver);

    constructor() public
        ERC20(
            "Staked CvxCrv",
            "stkCvxCrv"
        ){

        owner = address(0xa3C5A1e09150B75ff251c1a7815A07182c3de2FB); //default to convex multisig
        emit OwnershipTransferred(address(0), owner);

        addRewards();
        setApprovals();

        //preset hook
        rewardHook = address(0x723f9Aa67FDD9B0e375eF8553eB2AFC28eCD4a96);
        emit HookSet(rewardHook);
    }


    function decimals() public view override returns (uint8) {
        return 18;
    }

     modifier onlyOwner() {
        require(owner == msg.sender, "Ownable: caller is not the owner");
        _;
    }

    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(owner, newOwner);
        owner = newOwner;
    }

    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(owner, address(0));
        owner = address(0);
    }

    function shutdown() external onlyOwner nonReentrant{
        isShutdown = true;
        emit IsShutdown();
    }

    function reclaim() external onlyOwner nonReentrant{
        require(isShutdown,"!shutdown");

        //reclaim extra staked cvxcrv tokens and return to treasury if this wrapper is shutdown
        //in order that the extra staking weight can be migrated
        uint256 extraTokens = IRewardStaking(cvxCrvStaking).balanceOf(address(this)) - totalSupply();
        IRewardStaking(cvxCrvStaking).withdraw(extraTokens, false);
        IERC20(cvxCrv).safeTransfer(treasury, extraTokens);
    }

    function setApprovals() public {
        IERC20(crv).safeApprove(crvDepositor, 0);
        IERC20(crv).safeApprove(crvDepositor, uint256(-1));
        IERC20(cvxCrv).safeApprove(cvxCrvStaking, 0);
        IERC20(cvxCrv).safeApprove(cvxCrvStaking, uint256(-1));
    }

    function addRewards() internal {

        if (rewards.length == 0) {
            rewards.push(
                RewardType({
                    reward_token: crv,
                    reward_integral: 0,
                    reward_remaining: 0,
                    reward_group: 0
                })
            );
            rewards.push(
                RewardType({
                    reward_token: cvx,
                    reward_integral: 0,
                    reward_remaining: 0,
                    reward_group: 0
                })
            );
            rewards.push(
                RewardType({
                    reward_token: threeCrv,
                    reward_integral: 0,
                    reward_remaining: 0,
                    reward_group: 1
                })
            );
            registeredRewards[crv] = 1; //mark registered at index+1
            registeredRewards[cvx] = 2; //mark registered at index+1
            registeredRewards[threeCrv] = 3; //mark registered at index+1
            //send to self to warmup state
            IERC20(crv).transfer(address(this),0);
            //send to self to warmup state
            IERC20(cvx).transfer(address(this),0);
            //send to self to warmup state
            IERC20(threeCrv).transfer(address(this),0);

            emit RewardGroupSet(crv, 0);
            emit RewardGroupSet(cvx, 0);
            emit RewardGroupSet(threeCrv, 1);
        }
    }

    function addTokenReward(address _token, uint256 _rewardGroup) public onlyOwner nonReentrant{
        require(_token != address(0) && _token != cvxCrvStaking && _token != address(this) && _token != cvxCrv,"invalid address");

        //check if already registered
        if(registeredRewards[_token] == 0){
            //limit reward count
            require(rewards.length < MAX_REWARD_COUNT, "max rewards");
            //new token, add token to list
            rewards.push(
                RewardType({
                    reward_token: _token,
                    reward_integral: 0,
                    reward_remaining: 0,
                    reward_group: _rewardGroup > 0 ? uint8(1) : uint8(0)
                })
            );
            //add to registered map
            registeredRewards[_token] = rewards.length; //mark registered at index+1
            //send to self to warmup state
            IERC20(_token).transfer(address(this),0);   

            emit RewardGroupSet(_token, _rewardGroup);
        }else{
            //get previous used index of given token
            //this ensures that reviving can only be done on the previous used slot
            uint256 index = registeredRewards[_token];
            if(index > 0){
                //index is registeredRewards minus one
                RewardType storage reward = rewards[index-1];
                //check if it was invalidated
                if(reward.reward_token == address(0)){
                    //revive
                    reward.reward_token = _token;
                }
            }
        }
    }

    //allow invalidating a reward if the token causes trouble in calcRewardIntegral
    function invalidateReward(address _token) public onlyOwner {
        uint256 index = registeredRewards[_token];
        if(index > 0){
            //index is registered rewards minus one
            RewardType storage reward = rewards[index-1];
            require(reward.reward_token == _token, "!mismatch");
            //set reward token address to 0, integral calc will now skip
            reward.reward_token = address(0);
            emit RewardInvalidated(_token);
        }
    }

    //set reward group
    function setRewardGroup(address _token, uint256 _rewardGroup) public onlyOwner {
        //checkpoint
        _checkpoint([address(msg.sender),address(0)]);

        uint256 index = registeredRewards[_token];
        if(index > 0){
            //index is registered rewards minus one
            RewardType storage reward = rewards[index-1];
            reward.reward_group = _rewardGroup > 0 ? uint8(1) : uint8(0);
            emit RewardGroupSet(_token, _rewardGroup);
        }
    }

    function setHook(address _hook) external onlyOwner{
        rewardHook = _hook;
        emit HookSet(_hook);
    }

    function rewardLength() external view returns(uint256) {
        return rewards.length;
    }


    function _calcRewardIntegral(uint256 _index, address[2] memory _accounts, uint256[2] memory _balances, uint256 _supply, bool _isClaim) internal{
         RewardType storage reward = rewards[_index];
         //skip invalidated rewards
         //if a reward token starts throwing an error, calcRewardIntegral needs a way to exit
         if(reward.reward_token == address(0)){
            return;
         }

        //get difference in balance and remaining rewards
        //getReward is unguarded so we use reward_remaining to keep track of how much was actually claimed
        uint256 bal = IERC20(reward.reward_token).balanceOf(address(this));
        

        if (bal.sub(reward.reward_remaining) > 0) {
            //adjust supply based on reward group
            if(reward.reward_group == 0){
                //use inverse (supplyWeight can never be more than _supply)
                _supply = (_supply - supplyWeight);
            }else{
                //use supplyWeight
                _supply = supplyWeight;
            }

            if(_supply > 0){
                reward.reward_integral = reward.reward_integral + uint128(bal.sub(reward.reward_remaining).mul(1e20).div(_supply));
            }
        }

        //update user integrals
        for (uint256 u = 0; u < _accounts.length; u++) {
            //do not give rewards to address 0
            if (_accounts[u] == address(0)) continue;
            if(_isClaim && u != 0) continue; //if claiming, only update/claim for first address and use second as forwarding

            //adjust user balance based on reward group
            uint256 userb = _balances[u];
            if(reward.reward_group == 0){
                //use userRewardWeight inverse: weight of 0 should be full reward group 0
                userb = userb * (WEIGHT_PRECISION - userRewardWeight[_accounts[u]]) / WEIGHT_PRECISION;
            }else{
                //use userRewardWeight: weight of 10,000 should be full reward group 1
                userb = userb * userRewardWeight[_accounts[u]] / WEIGHT_PRECISION;
            }

            uint userI = reward.reward_integral_for[_accounts[u]];
            if(_isClaim || userI < reward.reward_integral){
                if(_isClaim){
                    uint256 receiveable = reward.claimable_reward[_accounts[u]].add(userb.mul( uint256(reward.reward_integral).sub(userI)).div(1e20));
                    if(receiveable > 0){
                        reward.claimable_reward[_accounts[u]] = 0;
                        //cheat for gas savings by transfering to the second index in accounts list
                        //if claiming only the 0 index will update so 1 index can hold forwarding info
                        //guaranteed to have an address in u+1 so no need to check
                        IERC20(reward.reward_token).safeTransfer(_accounts[u+1], receiveable);
                        emit RewardPaid(_accounts[u], reward.reward_token, receiveable, _accounts[u+1]);
                        bal = bal.sub(receiveable);
                    }
                }else{
                    reward.claimable_reward[_accounts[u]] = reward.claimable_reward[_accounts[u]].add(userb.mul( uint256(reward.reward_integral).sub(userI)).div(1e20));
                }
                reward.reward_integral_for[_accounts[u]] = reward.reward_integral;
            }
        }

        //update remaining reward here since balance could have changed if claiming
        if(bal != reward.reward_remaining){
            reward.reward_remaining = uint128(bal);
        }
    }

    function _checkpoint(address[2] memory _accounts) internal nonReentrant{

        uint256 supply = totalSupply();
        uint256[2] memory depositedBalance;
        depositedBalance[0] = balanceOf(_accounts[0]);
        depositedBalance[1] = balanceOf(_accounts[1]);
        
        //claim normal cvxcrv staking rewards
        IRewardStaking(cvxCrvStaking).getReward(address(this), true);
        //claim outside staking rewards
        _claimExtras();

        uint256 rewardCount = rewards.length;
        for (uint256 i = 0; i < rewardCount; i++) {
           _calcRewardIntegral(i,_accounts,depositedBalance,supply,false);
        }
    }

    function _checkpointAndClaim(address[2] memory _accounts) internal nonReentrant{

        uint256 supply = totalSupply();
        uint256[2] memory depositedBalance;
        depositedBalance[0] = balanceOf(_accounts[0]); //only do first slot
        
        //claim normal cvxcrv staking rewards
        IRewardStaking(cvxCrvStaking).getReward(address(this), true);
        //claim outside staking rewards
        _claimExtras();

        uint256 rewardCount = rewards.length;
        for (uint256 i = 0; i < rewardCount; i++) {
           _calcRewardIntegral(i,_accounts,depositedBalance,supply,true);
        }
    }

    //claim any rewards not part of the convex pool
    function _claimExtras() internal {
        //claim via hook if exists
        if(rewardHook != address(0)){
            try IRewardHook(rewardHook).onRewardClaim(){
            }catch{}
        }
    }

    function user_checkpoint(address _account) external returns(bool) {
        _checkpoint([_account, address(0)]);
        return true;
    }

    //run earned as a mutable function to claim everything before calculating earned rewards
    function earned(address _account) external returns(EarnedData[] memory claimable) {
        _checkpoint([_account, address(0)]);
        return _earned(_account);
    }

    //because we are doing a mutative earned(), we can just simulate checkpointing a user and looking at recorded claimables
    //thus no need to look at each reward contract's claimable tokens or cvx minting equations etc
    function _earned(address _account) internal view returns(EarnedData[] memory claimable) {
        
        uint256 rewardCount = rewards.length;
        claimable = new EarnedData[](rewardCount);

        for (uint256 i = 0; i < rewardCount; i++) {
            RewardType storage reward = rewards[i];

            //skip invalidated rewards
            if(reward.reward_token == address(0)){
                continue;
            }
    
            claimable[i].amount = reward.claimable_reward[_account];
            claimable[i].token = reward.reward_token;
        }
        return claimable;
    }

    //set a user's reward weight to determine how much of each reward group to receive
    function setRewardWeight(uint256 _weight) public{
        require(_weight <= WEIGHT_PRECISION, "!invalid");

        //checkpoint user
         _checkpoint([address(msg.sender), address(0)]);

        //set user weight and new supply weight
        //supply weight defined as amount of weight for reward group 1
        //..which means reward group 0 will be the inverse (real supply - weight)
        uint256 sweight = supplyWeight;
        //remove old user weight
        sweight -= balanceOf(msg.sender) * userRewardWeight[msg.sender] / WEIGHT_PRECISION;
        //add new user weight
        sweight += balanceOf(msg.sender) * _weight / WEIGHT_PRECISION;
        //store
        supplyWeight = sweight;
        userRewardWeight[msg.sender] = _weight;
    }

    //get user's weighted balance for specified reward group
    function userRewardBalance(address _address, uint256 _rewardGroup) external view returns(uint256){
        uint256 userb = balanceOf(_address);
        if(_rewardGroup == 0){
            //userRewardWeight of 0 should be full weight for reward group 0
            userb = userb * (WEIGHT_PRECISION - userRewardWeight[_address]) / WEIGHT_PRECISION;
        }else{
            // userRewardWeight of 10,000 should be full weight for reward group 1
            userb = userb * userRewardWeight[_address] / WEIGHT_PRECISION;
        }
        return userb;
    }

    //get weighted supply for specified reward group
    function rewardSupply(uint256 _rewardGroup) public view returns(uint256){
        //if group 0, return inverse of supplyWeight
        if(_rewardGroup == 0){
            return (totalSupply() - supplyWeight);
        }

        //else return supplyWeight
        return supplyWeight;
    }

    //claim
    function getReward(address _account) external {
        //claim directly in checkpoint logic to save a bit of gas
        _checkpointAndClaim([_account, _account]);
    }

    //claim and forward
    function getReward(address _account, address _forwardTo) external {
        //if forwarding, require caller is self
        require(msg.sender == _account, "!self");
        //claim directly in checkpoint logic to save a bit of gas
        //pack forwardTo into account array to save gas so that a proxy etc doesnt have to double transfer
        _checkpointAndClaim([_account,_forwardTo]);
    }

    //deposit vanilla crv
    function deposit(uint256 _amount, address _to) public {
        require(!isShutdown, "shutdown");

        //dont need to call checkpoint since _mint() will

        if (_amount > 0) {
            //deposit
            _mint(_to, _amount);
            IERC20(crv).safeTransferFrom(msg.sender, address(this), _amount);
            IConvexDeposits(crvDepositor).deposit(_amount, false, cvxCrvStaking);
        }

        emit Deposited(msg.sender, _to, _amount, true);
    }

    function depositAndSetWeight(uint256 _amount, uint256 _weight) external {
        deposit(_amount, msg.sender);
        setRewardWeight(_weight);
    }

    //stake cvxcrv
    function stake(uint256 _amount, address _to) public {
        require(!isShutdown, "shutdown");

        //dont need to call checkpoint since _mint() will

        if (_amount > 0) {
            //deposit
            _mint(_to, _amount);
            IERC20(cvxCrv).safeTransferFrom(msg.sender, address(this), _amount);
            IRewardStaking(cvxCrvStaking).stake(_amount);
        }

        emit Deposited(msg.sender, _to, _amount, false);
    }

    function stakeAndSetWeight(uint256 _amount, uint256 _weight) external {
        stake(_amount, msg.sender);
        setRewardWeight(_weight);
    }

    //backwards compatibility for other systems (note: amount and address reversed)
    function stakeFor(address _to, uint256 _amount) external {
        stake(_amount, _to);
    }

    //withdraw to convex deposit token
    function withdraw(uint256 _amount) external {
        
        //dont need to call checkpoint since _burn() will

        if (_amount > 0) {
            //withdraw
            _burn(msg.sender, _amount);
            IRewardStaking(cvxCrvStaking).withdraw(_amount, false);
            IERC20(cvxCrv).safeTransfer(msg.sender, _amount);
        }

        emit Withdrawn(msg.sender, _amount);
    }

    function _beforeTokenTransfer(address _from, address _to, uint256 _amount) internal override {
        _checkpoint([_from, _to]);

        if(_from != _to){
            //adjust supply weight assuming post transfer balances
            uint256 sweight = supplyWeight;
            if(_from != address(0)){
                sweight -= balanceOf(_from) * userRewardWeight[_from] / WEIGHT_PRECISION;
                sweight += balanceOf(_from).sub(_amount) * userRewardWeight[_from] / WEIGHT_PRECISION;
            }
            if(_to != address(0)){
                sweight -= balanceOf(_to) * userRewardWeight[_to] / WEIGHT_PRECISION;
                sweight += balanceOf(_to).add(_amount) * userRewardWeight[_to] / WEIGHT_PRECISION;
            }

            //write new supply weight
            supplyWeight = sweight;
        }
    }
}