// File: @openzeppelin/contracts/security/ReentrancyGuard.sol


// OpenZeppelin Contracts v4.4.1 (security/ReentrancyGuard.sol)

pragma solidity ^0.8.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// File: @openzeppelin/contracts/utils/Context.sol


// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// File: @openzeppelin/contracts/access/Ownable.sol


// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;


/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        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 {
        _transferOwnership(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");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// File: @openzeppelin/contracts/utils/math/SafeMath.sol


// OpenZeppelin Contracts (last updated v4.6.0) (utils/math/SafeMath.sol)

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
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) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            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) {
        unchecked {
            // 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) {
        unchecked {
            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) {
        unchecked {
            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) {
        return a + b;
    }

    /**
     * @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 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) {
        return a * b;
    }

    /**
     * @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.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        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) {
        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) {
        unchecked {
            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.
     *
     * 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) {
        unchecked {
            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) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

// File: @openzeppelin/contracts/utils/Address.sol


// OpenZeppelin Contracts (last updated v4.7.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @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
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal 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
                /// @solidity memory-safe-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin/contracts/token/ERC20/extensions/draft-IERC20Permit.sol


// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/draft-IERC20Permit.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol


// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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);

    /**
     * @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 `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, 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 `from` to `to` 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 from,
        address to,
        uint256 amount
    ) external returns (bool);
}

// File: @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol


// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;




/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    function safePermit(
        IERC20Permit token,
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        uint256 nonceBefore = token.nonces(owner);
        token.permit(owner, spender, value, deadline, v, r, s);
        uint256 nonceAfter = token.nonces(owner);
        require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// File: Staking.sol


pragma solidity ^0.8.0;





contract Staking is Ownable, ReentrancyGuard {

    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    // Whether it is initialized
    bool public isInitialized;
    uint256 public duration;

    uint256 public slot;

    // Whether a limit is set for users
    bool public hasUserLimit;
    // The pool limit (0 if none)
    uint256 public poolLimitPerUser;

    // The block number when staking starts.
    uint256 public startBlock;
    // The block number when staking ends.
    uint256 public bonusEndBlock;

    address public walletA;

    uint256 private constant  MIN_SLOT = 1;
    uint256 private constant  MAX_SLOT = 60 * 60 * 24;
    uint256 private constant  DAY_LENGTH = 60 * 60 * 24;
    uint256 private constant  MAX_INT = type(uint256).max;

    // The staked token
    address stakingToken;

    uint256 private totalEarnedTokenDeposed;

    struct Lockup {
        uint8 stakeType;
        uint256 duration;
        uint256 depositFee;
        uint256 withdrawFee;
        uint256 rate;
        uint256 lastRewardBlock;
        uint256 totalStaked;
        uint256 totalEarned;
        uint256 totalCompounded;
        uint256 totalWithdrawn;
        bool depositFeeReverse;
        bool withdrawFeeReverse;
    }

    struct UserInfo {
        uint256 lastRewardBlock;
        uint256 totalStaked;
        uint256 totalEarned;
        uint256 totalCompounded;
        uint256 totalWithdrawn;
    }

    struct Stake {
        uint8 stakeType;
        uint256 duration;
        uint256 end;
        uint256 lastRewardBlock;
        uint256 staked;
        uint256 earned;
        uint256 compounded;
        uint256 withdrawn;
    }

    uint256 constant MAX_STAKES = 2048;

    Lockup[] public lockups;
    mapping(address => Stake[]) public userStakes;
    mapping(address => mapping(uint8 => UserInfo)) public userStaked;

    event Deposit(address indexed user, uint256 stakeType, uint256 amount, uint256 depositFee, bool depositFeeReverse, uint256 fee);
    event Withdraw(address indexed user, uint256 stakeType, uint256 amount, uint256 depositFee, bool depositFeeReverse, uint256 fee);
    event EmergencyWithdraw(address indexed user, uint256 amount);
    event AdminTokenRecovered(address tokenRecovered, uint256 amount);

    event NewStartAndEndBlocks(uint256 startBlock, uint256 endBlock);
    event LockupUpdated(uint8 _type, uint256 _duration, uint256 _fee0, uint256 _fee1, uint256 _rate, bool _depositFeeReverse, bool _withdrawFeeReverse);
    event NewPoolLimit(bool hasUserLimit, uint256 poolLimitPerUser);
    event RewardsStop(uint256 blockNumber);
    event DurationUpdated(uint256 duration);

    event SetSettings(
        address _walletA
    );

    /* +++
     * @notice Initialize the contract
     * @param _stakingToken: staked token address
     */
    function initialize(
        address _stakingToken,
        uint256 _slot,
        uint256 _duration
    ) external onlyOwner {
        require(!isInitialized, "Already initialized");
        require(_slot >= MIN_SLOT && _slot <= MAX_SLOT, "Incorrect slot!");
        require((DAY_LENGTH / _slot) * _slot == DAY_LENGTH, "Incorrect slot!");
        require(_duration > 0, "Incorrect duration!");

        slot = _slot;
        duration = _duration;

        // Make this contract initialized
        isInitialized = true;
        stakingToken = _stakingToken;
        walletA = msg.sender;

        lockups.push(Lockup(0, 0, 0, 200, 1500, 0, 0, 0, 0, 0, false, false));
        lockups.push(Lockup(1, 30 * 24 * 60 * 60, 0, 0, 2500, 0, 0, 0, 0, 0, false, false));
        lockups.push(Lockup(2, 90 * 24 * 60 * 60, 0, 0, 4000, 0, 0, 0, 0, 0, false, false));
        lockups.push(Lockup(3, 180 * 24 * 60 * 60, 0, 0, 5000, 0, 0, 0, 0, 0, false, false));
        lockups.push(Lockup(4, 360 * 24 * 60 * 60, 0, 0, 6000, 0, 0, 0, 0, 0, false, false));

    }

    /* +++
     * @notice Deposit staked tokens
     */
    function deposit(uint256 _amount, uint8 _stakeType) external nonReentrant {
        require(isInitialized, "Not initialized");
        require(startBlock > 0, "Pool not started");
        require(_amount > 0, "Amount should be greater than 0");
        require(_stakeType < lockups.length, "Invalid stake type");

        UserInfo storage user = userStaked[msg.sender][_stakeType];
        Lockup storage lockup = lockups[_stakeType];

        //calc user and lockup reward
        _calcUserLockupReward(_stakeType);

        uint256 beforeAmount = IERC20(stakingToken).balanceOf(address(this));
        IERC20(stakingToken).safeTransferFrom(
            address(msg.sender),
            address(this),
            _amount
        );
        uint256 afterAmount = IERC20(stakingToken).balanceOf(address(this));
        uint256 realAmount = afterAmount.sub(beforeAmount);

        if (hasUserLimit) {
            require(
                realAmount.add(user.totalStaked) <= poolLimitPerUser,
                "User amount above limit"
            );
        }
        uint256 fee;
        if (lockup.depositFee > 0) {
            fee = realAmount.mul(lockup.depositFee).div(10000);
            if (fee > 0) {
                if(lockup.depositFeeReverse == false){
                    IERC20(stakingToken).safeTransfer(walletA, fee);
                    realAmount = realAmount.sub(fee);
                } else {
                    realAmount = realAmount.add(fee);
                }
            }
        }

        _addStake(_stakeType, msg.sender, lockup.duration, realAmount);

        user.totalStaked = user.totalStaked.add(realAmount);
        lockup.totalStaked = lockup.totalStaked.add(realAmount);

        emit Deposit(msg.sender, _stakeType, realAmount, lockup.depositFee, lockup.depositFeeReverse, fee);
    }

    /* +++ */
    function _addStake(uint8 _stakeType, address _account, uint256 _duration, uint256 _amount) internal {
        Stake[] storage stakes = userStakes[_account];

        // uint256 end = _getSlot().add(_duration.mul(DAY_LENGTH / slot));
        uint256 end = block.timestamp.add(_duration).div(slot);

        uint256 i = stakes.length;
        require(i < MAX_STAKES, "Max stakes");

        stakes.push();

        // insert the stake
        Stake storage newStake = stakes[i];
        newStake.stakeType = _stakeType;
        newStake.duration = _duration;
        newStake.end = end;
        newStake.staked = _amount;
        newStake.lastRewardBlock = _getSlot();

    }

    /* +++
     * @notice Withdraw staked tokens and collect reward tokens
     * @param _amount: amount to withdraw (in earnedToken)
     */
    function withdraw(uint256 _amount, uint8 _stakeType) external nonReentrant {
        require(isInitialized, "Not initialized");
        require(startBlock > 0, "Pool not started");
        require(_amount > 0, "Amount should be greator than 0");
        require(_stakeType < lockups.length, "Invalid stake type");

        UserInfo storage user = userStaked[msg.sender][_stakeType];
        Stake[] storage stakes = userStakes[msg.sender];
        Lockup storage lockup = lockups[_stakeType];

        uint256 remained = _amount;
        uint256 rewardAmount = _claimReward(_stakeType, _amount);
        if (rewardAmount >= remained) {
            remained = 0;
        } else {
            remained = remained.sub(rewardAmount);
        }

        uint256 pending = 0;

        for (uint256 j = 0; j < stakes.length; j++) {
            Stake storage stake = stakes[j];
            if (stake.stakeType != _stakeType) continue;
            if (stake.staked == 0) continue;
            if (_getSlot() <= stake.end) continue;
            if (remained == 0) break;

            uint256 _pending = stake.staked;
            if (_pending > remained) {
                _pending = remained;
            }

            stake.staked = stake.staked.sub(_pending);
            remained = remained.sub(_pending);
            pending = pending.add(_pending);
        }

        if (pending > 0) {
            require(availableRewardTokens() >= pending, "Insufficient reward tokens");

            lockup.totalStaked = lockup.totalStaked.sub(pending);
            user.totalStaked = user.totalStaked.sub(pending);

            uint256 fee;
            if (lockup.withdrawFee > 0) {
                fee = pending.mul(lockup.withdrawFee).div(10000);
                if(fee > 0){
                    if(lockup.withdrawFeeReverse == false){
                        IERC20(stakingToken).safeTransfer(walletA, fee);
                        pending = pending.sub(fee);
                    } else {
                        pending = pending.add(fee);
                    }
                }
            }

            IERC20(stakingToken).safeTransfer(address(msg.sender), pending);
            emit Withdraw(msg.sender, _stakeType, pending, lockup.withdrawFee, lockup.withdrawFeeReverse, fee);

        }

    }


    /* +++ */
    function _claimReward(uint8 _stakeType, uint256 _amount) internal returns (uint256){
        require(isInitialized, "Not initialized");
        require(startBlock > 0, "Pool not started");
        require(_amount > 0, "Amount should be greator than 0");
        require(_stakeType < lockups.length, "Invalid stake type");

        UserInfo storage user = userStaked[msg.sender][_stakeType];
        Stake[] storage stakes = userStakes[msg.sender];
        Lockup storage lockup = lockups[_stakeType];

        //calc user and lockup reward
        _calcUserLockupReward(_stakeType);
        //calc stake reward
        _calcStakeReward(_stakeType);

        uint256 remained = _amount;
        uint256 pending = 0;

        for (uint256 j = 0; j < stakes.length; j++) {
            Stake storage stake = stakes[j];
            if (stake.stakeType != _stakeType) continue;
            // if (stake.amount == 0) continue;
            if (_getSlot() <= stake.end) continue;

            uint256 _pending = stake.earned.sub(stake.compounded).sub(stake.withdrawn);

            if (_pending > remained) {
                _pending = remained;
            }

            remained = remained.sub(_pending);

            pending = pending.add(_pending);
            stake.withdrawn = stake.withdrawn + _pending;

            if (remained == 0) {
                break;
            }

        }

        if (pending > 0) {
            require(availableRewardTokens() >= pending, "Insufficient reward tokens");
            IERC20(stakingToken).safeTransfer(address(msg.sender), pending);

            lockup.totalWithdrawn = lockup.totalWithdrawn + pending;
            user.totalWithdrawn = user.totalWithdrawn + pending;

            emit Withdraw(msg.sender, _stakeType, pending, lockup.withdrawFee, lockup.withdrawFeeReverse, 0);

        }

        return pending;
    }


    /* +++ */
    function claimReward(uint8 _stakeType) external payable nonReentrant {
        require(isInitialized, "Not initialized");
        require(startBlock > 0, "Pool not started");
        require(_stakeType < lockups.length, "Invalid stake type");

        _claimReward(_stakeType, MAX_INT);
    }

    /* +++ */
    function claimReward(uint8 _stakeType, uint256 _amount) external payable nonReentrant {
        require(isInitialized, "Not initialized");
        require(startBlock > 0, "Pool not started");
        require(_stakeType < lockups.length, "Invalid stake type");

        _claimReward(_stakeType, _amount);
    }

    /* +++ */
    function compoundReward(uint8 _stakeType) external payable nonReentrant {
        require(isInitialized, "Not initialized");
        require(startBlock > 0, "Pool not started");
        require(_stakeType < lockups.length, "Invalid stake type");

        UserInfo storage user = userStaked[msg.sender][_stakeType];
        Stake[] storage stakes = userStakes[msg.sender];
        Lockup storage lockup = lockups[_stakeType];

        //calc user and lockup reward
        _calcUserLockupReward(_stakeType);
        //calc stake reward
        _calcStakeReward(_stakeType);

        uint256 pending = 0;
        for (uint256 j = 0; j < stakes.length; j++) {
            Stake storage stake = stakes[j];
            if (stake.stakeType != _stakeType) continue;
            // if (stake.staked == 0) continue;

            uint256 _pending = stake.earned.sub(stake.compounded).sub(stake.withdrawn);
            pending = pending.add(_pending);

            stake.staked = stake.staked.add(_pending);
            stake.compounded = stake.compounded.add(_pending);
        }

        if (pending > 0) {

            user.totalStaked = user.totalStaked.add(pending);
            user.totalCompounded = user.totalCompounded.add(pending);
            lockup.totalStaked = lockup.totalStaked.add(pending);
            lockup.totalCompounded = lockup.totalCompounded.add(pending);

            emit Deposit(msg.sender, _stakeType, pending, lockup.depositFee, lockup.depositFeeReverse, 0);
        }
    }

    /* +++ */
    function _calcUserLockupReward(uint8 _stakeType) internal {
        require(isInitialized, "Not initialized");
        require(startBlock > 0, "Pool not started");
        require(_stakeType < lockups.length, "Invalid stake type");

        Lockup storage lockup = lockups[_stakeType];
        UserInfo storage user = userStaked[msg.sender][_stakeType];
        uint256 currentSlot = _getSlot();
        uint256 rate;
        uint256 pending;

        rate = _getRate(lockup.rate).mul(_getMultiplier(lockup.lastRewardBlock, currentSlot));
        pending = lockup.totalStaked.mul(rate).div(10 ** 24);
        lockup.totalEarned = lockup.totalEarned + pending;
        lockup.lastRewardBlock = currentSlot;

        rate = _getRate(lockup.rate).mul(_getMultiplier(user.lastRewardBlock, currentSlot));
        pending = user.totalStaked.mul(rate).div(10 ** 24);
        user.totalEarned = user.totalEarned + pending;
        user.lastRewardBlock = currentSlot;

    }

    /* +++ */
    function _calcStakeReward(uint8 _stakeType) internal {
        require(isInitialized, "Not initialized");
        require(startBlock > 0, "Pool not started");
        require(_stakeType < lockups.length, "Invalid stake type");

        Stake[] storage stakes = userStakes[msg.sender];
        Lockup storage lockup = lockups[_stakeType];

        uint256 currentSlot = _getSlot();
        uint256 rate;
        uint256 pending;

        for (uint256 j = 0; j < stakes.length; j++) {
            Stake storage stake = stakes[j];
            if (stake.stakeType != _stakeType) continue;
            if (stake.staked == 0) continue;

            rate = _getRate(lockup.rate).mul(_getMultiplier(stake.lastRewardBlock, currentSlot));

            pending = stake.staked.mul(rate).div(10 ** 24);
            stake.earned = stake.earned.add(pending);
            stake.lastRewardBlock = currentSlot;
        }

    }

    /* +++
     * @notice Withdraw staked tokens without caring about rewards
     * @dev Needs to be for emergency.
     */
    function emergencyWithdraw(uint8 _stakeType) external nonReentrant {
        require(isInitialized, "Not initialized");
        require(startBlock > 0, "Pool not started");
        require(_stakeType < lockups.length, "Invalid stake type");

        UserInfo storage user = userStaked[msg.sender][_stakeType];
        Stake[] storage stakes = userStakes[msg.sender];
        Lockup storage lockup = lockups[_stakeType];

        //calc user and lockup reward
        _calcUserLockupReward(_stakeType);
        //calc stake reward
        _calcStakeReward(_stakeType);

        uint256 amountToTransfer = 0;
        uint256 totalStaked = 0;
        uint256 totalCompounded = 0;
        uint256 totalEarned = 0;

        for (uint256 j = 0; j < stakes.length; j++) {
            Stake storage stake = stakes[j];
            if (stake.stakeType != _stakeType) continue;
            if (stake.staked == 0) continue;
            if (_getSlot() > stake.end) continue;


            amountToTransfer = amountToTransfer.add(stake.staked).sub(stake.compounded);
            totalStaked = totalStaked.add(stake.staked);
            totalCompounded = totalCompounded.add(stake.compounded);
            totalEarned = totalEarned.add(stake.earned);

            stake.staked = 0;
            stake.earned = 0;
            stake.withdrawn = 0;
            stake.compounded = 0;
        }

        if (amountToTransfer > 0) {

            lockup.totalStaked = lockup.totalStaked.sub(totalStaked);
            lockup.totalEarned = lockup.totalEarned.sub(totalEarned);
            lockup.totalCompounded = lockup.totalCompounded.sub(totalCompounded);

            user.totalStaked = user.totalStaked.sub(totalStaked);
            user.totalEarned = user.totalEarned.sub(totalEarned);
            user.totalCompounded = user.totalCompounded.sub(totalCompounded);

            IERC20(stakingToken).safeTransfer(address(msg.sender), amountToTransfer);

        }

        emit EmergencyWithdraw(msg.sender, amountToTransfer);
    }

    /* +++ */
    function rewardPerStakeType(uint8 _stakeType) public view returns (uint256) {
        if (_stakeType >= lockups.length) return 0;

        return lockups[_stakeType].rate;
    }

    /** +++
     * @notice Available amount of reward token
     */
    function availableRewardTokens() public view returns (uint256) {

        uint256 _amount = IERC20(stakingToken).balanceOf(address(this));

        uint256 reserved;
        //        for (uint256 j = 0; j < lockups.length; j++) {
        //            Lockup storage lockup = lockups[j];
        //            reserved = reserved.add(lockup.totalStaked + lockup.totalEarned - lockup.totalCompounded - lockup.totalWithdrawn);
        //        }

        if (_amount > reserved)
            return _amount.sub(reserved);
        else
            return 0;
    }

    /* +++ */
    function userInfo(uint8 _stakeType, address _account) public view returns (uint256 amount, uint256 available, uint256 locked) {
        Stake[] storage stakes = userStakes[_account];

        for (uint256 i = 0; i < stakes.length; i++) {
            Stake storage stake = stakes[i];

            if (stake.stakeType != _stakeType) continue;
            if (stake.staked == 0) continue;

            amount = amount.add(stake.staked);
            if (_getSlot() > stake.end) {
                available = available.add(stake.staked);
            } else {
                locked = locked.add(stake.staked);
            }
        }
    }

    /* +++
     * @notice View function to see pending reward on frontend.
     * @param _user: user address
     * @return Pending reward for a given user
     */
    function pendingReward(address _account, uint8 _stakeType) external view returns (uint256) {
        if (_stakeType >= lockups.length) return 0;
        if (startBlock == 0) return 0;

        Stake[] storage stakes = userStakes[_account];
        Lockup storage lockup = lockups[_stakeType];

        if (lockup.totalStaked == 0) return 0;

        uint256 pending = 0;
        for (uint256 i = 0; i < stakes.length; i++) {
            Stake storage stake = stakes[i];
            if (stake.stakeType != _stakeType) continue;
            // if (stake.staked == 0) continue;

            pending = pending.add(stake.earned - stake.compounded - stake.withdrawn);
            uint256 rate = _getRate(lockup.rate).mul(_getMultiplier(stake.lastRewardBlock, _getSlot()));
            uint256 reward = stake.staked.mul(rate).div(10 ** 24);
            pending = pending.add(reward);

        }
        return pending;
    }

    /* +++
     * @notice Deposit reward token
     * @dev Only call by owner. Needs to be for deposit of reward token.
     */
    function depositRewards(uint _amount) external onlyOwner nonReentrant {
        require(_amount > 0);

        uint256 beforeAmt = IERC20(stakingToken).balanceOf(address(this));
        IERC20(stakingToken).safeTransferFrom(msg.sender, address(this), _amount);
        uint256 afterAmt = IERC20(stakingToken).balanceOf(address(this));

        totalEarnedTokenDeposed = totalEarnedTokenDeposed.add(afterAmt).sub(beforeAmt);
    }

    /* +++
     * @notice It allows the admin to recover wrong tokens sent to the contract
     */
    function recoverWrongTokens(address _tokenAddress, uint256 _tokenAmount) external onlyOwner {
        uint256 reserved;

        if (_tokenAddress == stakingToken) {
            for (uint256 j = 0; j < lockups.length; j++) {
                Lockup storage lockup = lockups[j];
                reserved = reserved.add(lockup.totalStaked + lockup.totalEarned - lockup.totalCompounded - lockup.totalWithdrawn);
            }
        }

        if (reserved > 0) {
            uint256 tokenBal = IERC20(_tokenAddress).balanceOf(address(this));
            require(_tokenAmount <= tokenBal.sub(reserved), "Insufficient balance");
        }

        if (_tokenAddress == address(0x0)) {
            payable(msg.sender).transfer(_tokenAmount);
        } else {
            IERC20(_tokenAddress).safeTransfer(address(msg.sender), _tokenAmount);
        }

        emit AdminTokenRecovered(_tokenAddress, _tokenAmount);
    }

    /* +++ */
    function startReward() external onlyOwner {
        require(startBlock == 0, "Pool was already started");

        startBlock = _getSlot().add(1);
        bonusEndBlock = startBlock.add(duration.mul(DAY_LENGTH / slot));

        emit NewStartAndEndBlocks(startBlock, bonusEndBlock);
    }

    /* +++ */
    function stopReward() external onlyOwner {
        bonusEndBlock = _getSlot();
    }

    /* +++
     * @notice Update pool
     * @dev Only callable by owner.
     */
    function updatePoolLimitPerUser(bool _hasUserLimit, uint256 _poolLimitPerUser) external onlyOwner {
        hasUserLimit = _hasUserLimit;
        if (_hasUserLimit) {
            poolLimitPerUser = _poolLimitPerUser;
        } else {
            poolLimitPerUser = 0;
        }
        emit NewPoolLimit(hasUserLimit, poolLimitPerUser);
    }

    /* +++ */
    function updateLockup(uint8 _stakeType, uint256 _duration, uint256 _depositFee, uint256 _withdrawFee, uint256 _rate, bool _depositFeeReverse, bool _withdrawFeeReverse) external onlyOwner {
        require(_stakeType < lockups.length, "Lockup Not found");
        require(_depositFee < 2000, "Invalid deposit fee");
        require(_withdrawFee < 2000, "Invalid withdraw fee");

        Lockup storage _lockup = lockups[_stakeType];
        // require(_lockup.totalStaked == 0, "Lockup already staked");

        if(_lockup.totalStaked == 0){
            _lockup.duration = _duration;
            _lockup.rate = _rate;
        }
        
        _lockup.depositFee = _depositFee;
        _lockup.withdrawFee = _withdrawFee;        
        _lockup.depositFeeReverse = _depositFeeReverse;
        _lockup.withdrawFeeReverse = _withdrawFeeReverse;

        emit LockupUpdated(_stakeType, _lockup.duration, _depositFee, _withdrawFee, _lockup.rate, _depositFeeReverse, _withdrawFeeReverse);
    }

    /* +++ */
    function addLockup(uint256 _duration, uint256 _depositFee, uint256 _withdrawFee, uint256 _rate, bool _depositFeeReverse, bool _withdrawFeeReverse) external onlyOwner {
        require(_depositFee < 2000, "Invalid deposit fee");
        require(_withdrawFee < 2000, "Invalid withdraw fee");

        lockups.push();

        Lockup storage _lockup = lockups[lockups.length - 1];
        _lockup.duration = _duration;
        _lockup.depositFee = _depositFee;
        _lockup.withdrawFee = _withdrawFee;
        _lockup.rate = _rate;
        _lockup.depositFeeReverse = _depositFeeReverse;
        _lockup.withdrawFeeReverse = _withdrawFeeReverse;

        emit LockupUpdated(uint8(lockups.length - 1), _duration, _depositFee, _withdrawFee, _rate, _depositFeeReverse, _withdrawFeeReverse);
    }

    /* +++ */
    function setDuration(uint256 _duration) external onlyOwner {
        require(startBlock == 0, "Pool was already started");
        require(_duration >= 30, "lower limit reached");

        duration = _duration;
        emit DurationUpdated(_duration);
    }

    /* +++ */
    function setSettings(
        address _feeAddr
    ) external onlyOwner {
        require(_feeAddr != address(0x0), "Invalid Address");
        walletA = _feeAddr;

        emit SetSettings(_feeAddr);
    }

    /* +++
     * @notice Return reward rate per slot.
     */
    function _getRate(uint256 _rate)
    internal
    view
    returns (uint256)
    {

        uint256 rate = _rate.mul(10 ** 20).div(365).div(DAY_LENGTH / slot);
        return rate;

    }

    /* +++
     * @notice Return reward multiplier over the given _from to _to block.
     */
    function _getMultiplier(uint256 _from, uint256 _to)
    internal
    view
    returns (uint256)
    {
        if (_from >= bonusEndBlock) {
            return 0;
        } else if (_to <= bonusEndBlock) {
            return _to.sub(_from);
        } else {
            return bonusEndBlock.sub(_from);
        }
    }

    /* +++ */
    function _getSlot()
    internal
    view
    returns (uint256 _slot)
    {
        _slot = block.timestamp.div(slot);
    }


receive() external payable {}
}