// File: contracts/FXIProofStaking.sol



// SPDX-License-Identifier: None
pragma solidity ^0.8.19;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

import "./interfaces/IFXIStaking.sol";

contract FXIStaking is Ownable, IFXIStaking {
    using SafeERC20 for IERC20;

    mapping(address => UserInfo) public userInfo;
    mapping(address => uint256) public rewardDebt;
    mapping(address => uint256) public totalRewardDeposits;

    uint256 public totalStakedAmount;
    uint256 public unstakeDuration = 2 days;
    uint256 public unallocatedETH;
    uint256 public accRewardsPerShare;
    uint256 public ethDebt;
    uint256 public globalETHCollected;

    address[] userList;
    address[] depositorList;

    IERC20 public immutable stakingToken;

    event Stake(address indexed user, uint256 amount);
    event Unstake(address indexed user, uint256 amount);
    event Withdraw(address indexed user, uint256 amount);
    event Claim(address indexed user, uint256 amount);

    constructor(address _stakingToken) {
        stakingToken = IERC20(_stakingToken);
    }

    function stake(uint256 _amount) external override {
        UserInfo storage user = userInfo[msg.sender];
        uint256 pending;
        if (_amount == 0) {
            revert("cant stake 0");
        }

        if (!user.existingStaker) {
            user.existingStaker = true;
            userList.push(msg.sender);
        }

        if (user.stakedAmount > 0) {
            pending =
                ((user.stakedAmount * accRewardsPerShare) / 1e24) -
                user.rewardDebt;
        }

        uint256 pendingUnstake = user.pendingUnstakeAmount;
        if (pendingUnstake >= _amount) {
            user.pendingUnstakeAmount -= _amount;
        } else {
            uint256 tokensNeeded = _amount - pendingUnstake;
            user.pendingUnstakeAmount = 0;
            stakingToken.safeTransferFrom(
                msg.sender,
                address(this),
                tokensNeeded
            );
        }

        user.stakedAmount += _amount;
        user.rewardDebt = (user.stakedAmount * accRewardsPerShare) / 1e24;
        totalStakedAmount += _amount;

        if (pending > 0) {
            user.claimableRewards += pending;
        }

        emit Stake(msg.sender, _amount);
    }

    function unstake(uint256 _amount) external override {
        UserInfo storage user = userInfo[msg.sender];
        if (_amount == 0) {
            revert("cant unstake 0");
        }
        if (user.stakedAmount < _amount) {
            revert("not enough staked");
        }
        uint256 pending = ((user.stakedAmount * accRewardsPerShare) / 1e24) -
            user.rewardDebt;
        user.stakedAmount -= _amount;
        user.lastUnstakeTime = block.timestamp;
        user.pendingUnstakeAmount += _amount;
        user.rewardDebt = (user.stakedAmount * accRewardsPerShare) / 1e24;
        totalStakedAmount -= _amount;

        if (pending > 0) {
            user.claimableRewards += pending;
        }

        emit Unstake(msg.sender, _amount);
    }

    function restakeTokens() external override {
        UserInfo storage user = userInfo[msg.sender];
        uint256 pending;
        uint256 amountToRestake = user.pendingUnstakeAmount;
        if (amountToRestake == 0) {
            revert("No pending unstakes");
        }

        if (user.stakedAmount > 0) {
            pending =
                ((user.stakedAmount * accRewardsPerShare) / 1e24) -
                user.rewardDebt;
        }

        user.pendingUnstakeAmount = 0;
        user.stakedAmount += amountToRestake;
        user.rewardDebt = (user.stakedAmount * accRewardsPerShare) / 1e24;
        totalStakedAmount += amountToRestake;

        if (pending > 0) {
            user.claimableRewards += pending;
        }
    }

    function claimUnstakedToken() external override {
        UserInfo storage user = userInfo[msg.sender];
        uint256 toWithdraw = user.pendingUnstakeAmount;
        if (toWithdraw == 0) {
            revert("No pending unstakes");
        }
        if (block.timestamp < user.lastUnstakeTime + unstakeDuration) {
            revert("unstake not ready");
        }
        user.pendingUnstakeAmount = 0;
        stakingToken.safeTransfer(msg.sender, toWithdraw);
        emit Withdraw(msg.sender, toWithdraw);
    }

    function claimRewards() public override {
        UserInfo storage user = userInfo[msg.sender];
        user.claimableRewards +=
            ((user.stakedAmount * accRewardsPerShare) / 1e24) -
            user.rewardDebt;
        uint256 claimable = user.claimableRewards;
        if (claimable == 0) {
            revert("no rewards to claim");
        }
        user.rewardDebt = (user.stakedAmount * accRewardsPerShare) / 1e24;
        uint256 amount = address(this).balance > claimable
            ? claimable
            : address(this).balance;
        user.claimableRewards -= amount;
        user.claimedAmount += amount; //for analytics only
        (bool sent, ) = msg.sender.call{value: amount}("");
        if (!sent) {
            revert("sending ETH failed");
        }
        emit Claim(msg.sender, amount);
    }

    function setUnstakingDuration(
        uint256 newDuration
    ) external override onlyOwner {
        unstakeDuration = newDuration;
    }

    function refreshPool() external override onlyOwner {
        uint256 amountToAdd = unallocatedETH;
        if (amountToAdd == 0) {
            revert("no unallocated ETH");
        }
        if (totalStakedAmount == 0) {
            revert('"no holders');
        }

        unallocatedETH = 0;
        accRewardsPerShare += (amountToAdd * 1e24) / totalStakedAmount; //precision
    }

    receive() external payable {
        uint256 amount = msg.value;
        if (amount == 0) {
            revert("no ETH");
        }
        if (totalRewardDeposits[msg.sender] == 0) {
            depositorList.push(msg.sender);
        }
        totalRewardDeposits[msg.sender] += amount;
        globalETHCollected += amount;
        if (totalStakedAmount == 0) {
            unallocatedETH += amount;
        } else {
            if (ethDebt == 0) {
                accRewardsPerShare += (amount * 1e24) / totalStakedAmount;
            } else if (ethDebt >= amount) {
                ethDebt -= amount;
            } else {
                //amount > ethDebt and we have some ethDebt
                accRewardsPerShare +=
                    ((amount - ethDebt) * 1e24) /
                    totalStakedAmount;
                ethDebt = 0;
            }
        }
    }

    function emergencyWithdrawUnclaimedRewards() external onlyOwner {
        uint256 amount = address(this).balance;
        ethDebt += amount;
        (bool sent, ) = msg.sender.call{value: amount}("");
        if (!sent) {
            revert("sending ETH failed");
        }
    }

    //getters

    function getClaimableRewards(
        address _staker
    ) external view returns (uint256) {
        UserInfo storage user = userInfo[_staker];
        return
            user.claimableRewards +
            ((user.stakedAmount * accRewardsPerShare) / 1e24) -
            user.rewardDebt;
    }

    function getStakers() external view returns (address[] memory) {
        return userList;
    }

    function getDepositors() external view returns (address[] memory) {
        return depositorList;
    }

    function getClaimableUnstakedToken(
        address _staker
    ) external view returns (uint256) {
        UserInfo storage user = userInfo[_staker];
        if (block.timestamp >= user.lastUnstakeTime + unstakeDuration) {
            return user.pendingUnstakeAmount;
        } else {
            return 0;
        }
    }

    function getPendingUnstakeAmount(
        address _staker
    ) external view returns (uint256) {
        return userInfo[_staker].pendingUnstakeAmount;
    }

    function getTotalDepositAmount(
        address user
    ) external view returns (uint256) {
        return totalRewardDeposits[user];
    }
}

// File: @openzeppelin/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

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

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

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _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/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// 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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// File: contracts/interfaces/IFXIStaking.sol



// SPDX-License-Identifier: None
pragma solidity ^0.8.19;

interface IFXIStaking {
    struct UserInfo {
        uint256 stakedAmount;
        uint256 rewardDebt;
        uint256 claimedAmount;
        uint256 claimableRewards;
        uint256 lastUnstakeTime;
        uint256 pendingUnstakeAmount;
        bool existingStaker;
    }

    /// @notice Set unstaking duration.
    /// @dev Only owner can call this function.
    function setUnstakingDuration(uint256 _duration) external;

    /// @notice Deposit accumulated ETH to staking pool again.
    /// @dev Only owner can call this function.
    function refreshPool() external;

    /// @notice Stake amount of staking token.
    function stake(uint256 _amount) external;

    /// @notice Unstake amount of staking token.
    /// @dev unstake amount should be less than staked amount.
    function unstake(uint256 _amount) external;

    /// @notice Restake unstaked token again.
    /// @dev All of the token that before unstake duration will be restaked.
    function restakeTokens() external;

    /// @notice Claimed unstaked token after unstaking period.
    function claimUnstakedToken() external;

    /// @notice Claim rewards.
    /// @dev Rewards are distributed as ETH.
    function claimRewards() external;

    /// @notice Get claimable rewards of the staker.
    function getClaimableRewards(
        address _staker
    ) external view returns (uint256);

    /// @notice Get all stakers address.
    function getStakers() external view returns (address[] memory);

    /// @notice Get claimable unstaked token.
    function getClaimableUnstakedToken(
        address _staker
    ) external view returns (uint256);

    /// @notice Get pending unstake amount by user.
    function getPendingUnstakeAmount(
        address _staker
    ) external view returns (uint256);

    function getTotalDepositAmount(
        address user
    ) external view returns (uint256);

    function getDepositors() external view returns (address[] memory);
}

// File: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT
// 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/utils/Address.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (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

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