// File: https://raw.githubusercontent.com/sharedStake-dev/badger-system/master/deps/%40openzeppelin/contracts/GSN/Context.sol

pragma solidity ^0.6.0;

/*
 * @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: https://raw.githubusercontent.com/sharedStake-dev/badger-system/master/deps/%40openzeppelin/contracts/access/Ownable.sol


pragma solidity ^0.6.0;

/**
 * @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.
 */
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 () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view 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 {
        emit OwnershipTransferred(_owner, address(0));
        _owner = 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");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: https://raw.githubusercontent.com/sharedStake-dev/badger-system/master/deps/%40openzeppelin/contracts/utils/Address.sol


pragma solidity ^0.6.2;

/**
 * @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 in 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");
        return _functionCallWithValue(target, data, value, 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);
            }
        }
    }
}

// File: https://raw.githubusercontent.com/sharedStake-dev/badger-system/master/deps/%40openzeppelin/contracts/math/SafeMath.sol


pragma solidity ^0.6.0;

/**
 * @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, 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;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts 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) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message 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, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: https://raw.githubusercontent.com/sharedStake-dev/badger-system/master/deps/%40openzeppelin/contracts/token/ERC20/SafeERC20.sol


pragma solidity ^0.6.0;




/**
 * @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: https://raw.githubusercontent.com/sharedStake-dev/badger-system/master/deps/%40openzeppelin/contracts/utils/ReentrancyGuard.sol


pragma solidity ^0.6.0;

/**
 * @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].
 */
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: https://raw.githubusercontent.com/sharedStake-dev/badger-system/master/deps/%40openzeppelin/contracts/token/ERC20/IERC20.sol


pragma solidity ^0.6.0;

/**
 * @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: https://raw.githubusercontent.com/sharedStake-dev/badger-system/master/contracts/badger-timelock/Executor.sol

pragma solidity >=0.5.0 <0.7.0;

/*
    Gnosis Safe Executor - library wrapping low level calls
    https://github.com/gnosis/safe-contracts/blob/development/contracts/base/Executor.sol

    Ability to execute delegateCall has been removed for security
*/

/// @title Executor - A contract that can execute transactions
/// @author Richard Meissner - <richard@gnosis.pm>

contract Executor {
    function execute(
        address to,
        uint256 value,
        bytes memory data,
        uint256 txGas
    ) internal returns (bool success) {
        success = executeCall(to, value, data, txGas);
    }

    function executeCall(
        address to,
        uint256 value,
        bytes memory data,
        uint256 txGas
    ) internal returns (bool success) {
        // solium-disable-next-line security/no-inline-assembly
        assembly {
            success := call(
                txGas,
                to,
                value,
                add(data, 0x20),
                mload(data),
                0,
                0
            )
        }
    }
}

// File: browser/smartVesting.sol

pragma solidity 0.6.9;

/**
 * SharedStake vesting contract
 * Fork of badger SmartVesting
 * */







/**
 * @title SingleTokenVesting
 * @dev A token holder contract that can release its token balance gradually like a
 * typical vesting scheme, with a cliff and vesting period. Optionally revocable by the
 * owner. Only tracks vesting for a single token, rather than all ERC20s.
 */
abstract contract SingleTokenVestingNonRevocable is Ownable {
    // The vesting schedule is time-based (i.e. using block timestamps as opposed to e.g. block numbers), and is
    // therefore sensitive to timestamp manipulation (which is something miners can do, to a certain degree). Therefore,
    // it is recommended to avoid using short time durations (less than a minute). Typical vesting schemes, with a
    // cliff period of a year and a duration of four years, are safe to use.
    // solhint-disable not-rely-on-time

    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    event TokensReleased(address token, uint256 amount);

    IERC20 internal _token;
    // beneficiary of tokens after they are released
    address private _beneficiary;

    // Durations and timestamps are expressed in UNIX time, the same units as block.timestamp.
    uint256 private _cliff;
    uint256 private _start;
    uint256 private _duration;

    uint256 private _released;

    /**
     * @dev Creates a vesting contract that vests its balance of any ERC20 token to the
     * beneficiary, gradually in a linear fashion until start + duration. By then all
     * of the balance will have vested.
     * @param token address of the token to vest
     * @param beneficiary address of the beneficiary to whom vested tokens are transferred
     * @param cliffDuration duration in seconds of the cliff in which tokens will begin to vest
     * @param start the time (as Unix time) at which point vesting starts
     * @param duration duration in seconds of the period in which the tokens will vest
     */
    constructor(
        IERC20 token,
        address beneficiary,
        uint256 start,
        uint256 cliffDuration,
        uint256 duration
        ) public {
        require(address(token) != address(0), "TokenVesting: token is the zero address");
        require(beneficiary != address(0), "TokenVesting: beneficiary is the zero address");
        // solhint-disable-next-line max-line-length
        require(cliffDuration <= duration, "TokenVesting: cliff is longer than duration");
        require(duration > 0, "TokenVesting: duration is 0");
        // solhint-disable-next-line max-line-length
        require(start.add(duration) > block.timestamp, "TokenVesting: final time is before current time");

        _token = token;
        _beneficiary = beneficiary;
        _duration = duration;
        _cliff = start.add(cliffDuration);
        _start = start;
    }

    /**
     * @return the token being held.
     */
    function token() public view returns (IERC20) {
        return _token;
    }

    /**
     * @return the beneficiary of the tokens.
     */
    function beneficiary() public view returns (address) {
        return _beneficiary;
    }

    /**
     * @return the cliff time of the token vesting.
     */
    function cliff() public view returns (uint256) {
        return _cliff;
    }

    /**
     * @return the start time of the token vesting.
     */
    function start() public view returns (uint256) {
        return _start;
    }

    /**
     * @return the duration of the token vesting.
     */
    function duration() public view returns (uint256) {
        return _duration;
    }

    /**
     * @return the amount of the token released.
     */
    function released() public view returns (uint256) {
        return _released;
    }

    /**
     * @notice Allows the beneficiary to be changed for future multi sig deploys or team structure changes
     */
    function changeBeneficiary(address newBeneficiary) external onlyOwner() {
        _beneficiary = newBeneficiary;
    }

    /**
     * @notice Transfers vested tokens to beneficiary.
     */
    function release() public {
        uint256 unreleased = _releasableAmount();

        require(unreleased > 0, "TokenVesting: no tokens are due");

        _released = _released.add(unreleased);

        _token.safeTransfer(_beneficiary, unreleased);

        emit TokensReleased(address(_token), unreleased);
    }

    function releasableAmount() public view returns (uint256) {
        return _releasableAmount();
    }

    /**
     * @dev Calculates the amount that has already vested but hasn't been released yet.
     */
    function _releasableAmount() private view returns (uint256) {
        return _vestedAmount().sub(_released);
    }

    /**
     * @dev Calculates the amount that has already vested.
     */
    function _vestedAmount() private view returns (uint256) {
        uint256 currentBalance = _token.balanceOf(address(this));
        uint256 totalBalance = currentBalance.add(_released);

        if (block.timestamp < _cliff) {
            return 0;
        } else if (block.timestamp >= _start.add(_duration)) {
            return totalBalance;
        } else {
            return totalBalance.mul(block.timestamp.sub(_start)).div(_duration);
        }
    }
}

/* 
  A token vesting contract that is capable of interacting with other smart contracts.
  This allows the beneficiary to participate in on-chain goverance processes, despite having locked tokens.
  The beneficiary can withdraw the appropriate vested amount at any time.

  Features safety functions to allow beneficiary to claim ETH & ERC20-compliant tokens sent to the timelock contract, accidentially or otherwise.

  An optional 'governor' address has the ability to allow the vesting to send it's tokens to approved destinations. 
  This is intended to allow the token holder to stake their tokens in approved mechanisms.
*/

contract SmartVesting is SingleTokenVestingNonRevocable, Executor, ReentrancyGuard {
    address internal _governor;
    mapping(address => bool) internal _transferAllowed;

    constructor(
        IERC20 token,
        address beneficiary,
        address governor,
        uint256 start,
        uint256 cliffDuration,
        uint256 duration
    ) public SingleTokenVestingNonRevocable(token, beneficiary, start, cliffDuration, duration) {
        _governor = governor;
    }

    event Call(address to, uint256 value, bytes data, bool transfersAllowed);
    event ApproveTransfer(address to);
    event RevokeTransfer(address to);
    event ClaimToken(IERC20 token, uint256 amount);
    event ClaimEther(uint256 amount);

    modifier onlyBeneficiary() {
        require(msg.sender == beneficiary(), "smart-timelock/only-beneficiary");
        _;
    }

    modifier onlyGovernor() {
        require(msg.sender == _governor, "smart-timelock/only-governor");
        _;
    }

    /**
     * @notice Allows the timelock to call arbitrary contracts, as long as it does not reduce it's locked token balance
     * @dev Initialization check is implicitly provided by `voteExists()` as new votes can only be
     *      created via `newVote(),` which requires initialization
     * @param to Contract address to call
     * @param value ETH value to send, if any
     * @param data Encoded data to send
     */
    function call(
        address to,
        uint256 value,
        bytes calldata data
    ) external payable onlyBeneficiary() nonReentrant() returns (bool success) {
        uint256 preAmount = token().balanceOf(address(this));

        success = execute(to, value, data, gasleft());

        if (!_transferAllowed[to]) {
            uint256 postAmount = token().balanceOf(address(this));
            require(postAmount >= preAmount, "smart-vesting/locked-balance-check");
        }

        emit Call(to, value, data, _transferAllowed[to]);
    }

    function approveTransfer(address to) external onlyGovernor() {
        _transferAllowed[to] = true;
        emit ApproveTransfer(to);
    }

    function revokeTransfer(address to) external onlyGovernor() {
        _transferAllowed[to] = false;
        emit RevokeTransfer(to);
    }

    /**
     * @notice Claim ERC20-compliant tokens other than locked token.
     * @param tokenToClaim Token to claim balance of.
     */
    function claimToken(IERC20 tokenToClaim) external onlyBeneficiary() nonReentrant() {
        require(address(tokenToClaim) != address(token()), "smart-timelock/no-locked-token-claim");
        uint256 preAmount = token().balanceOf(address(this));

        uint256 claimableTokenAmount = tokenToClaim.balanceOf(address(this));
        require(claimableTokenAmount > 0, "smart-timelock/no-token-balance-to-claim");

        tokenToClaim.transfer(beneficiary(), claimableTokenAmount);

        uint256 postAmount = token().balanceOf(address(this));
        require(postAmount >= preAmount, "smart-timelock/locked-balance-check");

        emit ClaimToken(tokenToClaim, claimableTokenAmount);
    }

    /**
     * @notice Claim Ether in contract.
     */
    function claimEther() external onlyBeneficiary() nonReentrant() {
        uint256 preAmount = token().balanceOf(address(this));

        uint256 etherToTransfer = address(this).balance;
        require(etherToTransfer > 0, "smart-timelock/no-ether-balance-to-claim");

        payable(beneficiary()).transfer(etherToTransfer);

        uint256 postAmount = token().balanceOf(address(this));
        require(postAmount >= preAmount, "smart-timelock/locked-balance-check");

        emit ClaimEther(etherToTransfer);
    }

    /**
     * @notice Governor address
     */
    function governor() external view returns (address) {
        return _governor;
    }

    /**
     * @notice Allow timelock to receive Ether
     */
    receive() external payable {}
}