// File: contracts/SaleFcfs.sol



//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "./interfaces/IVoters.sol";
import "./interfaces/IERC677Receiver.sol";

interface IStaking {
    function deposit(uint amount, address to) external;
}

interface ITiers {
    function userInfos(address user) external view returns (uint256, uint256, uint256);
    function userInfoTotal(address user) external view returns (uint256, uint256);
}

contract SaleFcfs is IERC677Receiver, Ownable, ReentrancyGuard {
    using SafeERC20 for IERC20;

    // Represents a sale participant
    struct UserInfo {
        // Amount of payment token deposited / purchased
        uint amount;
        // Wether they already claimed their tokens
        bool claimed;
    }

    uint public constant PRECISION = 1e8;
    // Time alloted to claim tiers allocations
    uint public constant ALLOCATION_DURATION = 7200; // 2 hours
    // The raising token
    IERC20 public immutable paymentToken;
    // The offering token
    IERC20 public immutable offeringToken;
    // The vXRUNE Token
    IERC20 public immutable vxrune;
    // The time (unix seconds) when sale starts
    uint public immutable startTime;
    // The time (unix security) when sale ends
    uint public immutable endTime;
    // Total amount of offering tokens that will be offered
    uint public offeringAmount;
    // Total amount of raising tokens that need to be raised
    uint public raisingAmount;
    // Total amount of raising tokens that can be raised from tiers
    uint public raisingAmountTiers;
    // Maximum a user can contribute
    uint public immutable perUserCap;
    // Wether deposits are paused
    bool public paused;
    // Wether the sale is finalized
    bool public finalized;
    // Total amount of raising tokens that have already been raised
    uint public totalAmount;
    // User's participation info
    mapping(address => UserInfo) public userInfo;
    // Participants list
    address[] public addressList;
    // SingleStaking: Contract
    IStaking public immutable staking;
    // Tiers: Contract
    ITiers public tiers;
    // Tiers: Size of guaranteed allocation
    uint public tiersAllocation;
    // Tiers: levels
    uint[] public tiersLevels;
    // Tiers: multipliers
    uint[] public tiersMultipliers;

    event PausedToggled(bool paused);
    event TiersConfigured(address tiersContract, uint allocation, uint[] levels, uint[] multipliers);
    event RaisingAmountSet(uint amount);
    event AmountsSet(uint offering, uint raising, uint raisingTiers);
    event Deposit(address indexed user, uint amount);
    event Harvest(address indexed user, uint amount);

    constructor(
        address _paymentToken,
        address _offeringToken,
        address _vxrune,
        uint _startTime,
        uint _endTime,
        uint _offeringAmount,
        uint _raisingAmount,
        uint _raisingAmountTiers,
        uint _perUserCap,
        address _staking
    ) Ownable() {
        paymentToken = IERC20(_paymentToken);
        offeringToken = IERC20(_offeringToken);
        vxrune = IERC20(_vxrune);
        startTime = _startTime;
        endTime = _endTime;
        offeringAmount = _offeringAmount;
        raisingAmount = _raisingAmount;
        raisingAmountTiers = _raisingAmountTiers;
        perUserCap = _perUserCap;
        staking = IStaking(_staking);
        require(_paymentToken != address(0) && _offeringToken != address(0), "!zero");
        require(_paymentToken != _offeringToken, "payment != offering");
        require(_offeringAmount > 0, "offering > 0");
        require(_raisingAmount > 0, "raising > 0");
        require(_startTime > block.timestamp, "start > now");
        require(_startTime + ALLOCATION_DURATION < _endTime, "start < end");
        require(_startTime < 1e10, "start time not unix");
        require(_endTime < 1e10, "start time not unix");
    }

    function configureTiers(
        address tiersContract,
        uint allocation,
        uint[] calldata levels,
        uint[] calldata multipliers
    ) external onlyOwner {
        tiers = ITiers(tiersContract);
        tiersAllocation = allocation;
        tiersLevels = levels;
        tiersMultipliers = multipliers;
        emit TiersConfigured(tiersContract, allocation, levels, multipliers);
    }

    function setRaisingAmount(uint amount) external onlyOwner {
      require(block.timestamp < startTime && totalAmount == 0, "sale started");
      raisingAmount = amount;
      emit RaisingAmountSet(amount);
    }

    function setAmounts(uint offering, uint raising, uint raisingTiers) external onlyOwner {
      require(block.timestamp < startTime && totalAmount == 0, "sale started");
      offeringAmount = offering;
      raisingAmount = raising;
      raisingAmountTiers = raisingTiers;
      emit AmountsSet(offering, raising, raisingTiers);
    }

    function togglePaused() external onlyOwner {
        paused = !paused;
        emit PausedToggled(paused);
    }

    function finalize() external {
        require(msg.sender == owner() || block.timestamp > endTime + 30 days, "not allowed");
        finalized = true;
    }

    function getAddressListLength() external view returns (uint) {
        return addressList.length;
    }

    function getParams() external view returns (uint, uint, uint, uint, uint, uint, uint, bool, bool) {
        return (startTime, endTime, raisingAmount, offeringAmount, raisingAmountTiers, perUserCap, totalAmount, paused, finalized);
    }

    function getTiersParams() external view returns (uint, uint[] memory, uint[] memory) {
        return (tiersAllocation, tiersLevels, tiersMultipliers);
    }

    function getOfferingAmount(address _user) public view returns (uint) {
        return (userInfo[_user].amount * offeringAmount) / raisingAmount;
    }

    function getUserAllocation(address user) public view returns (uint, uint) {
        // Allocation is zero if user just joined / changed tiers, or is not in tiers
        (, uint lastDeposit,) = tiers.userInfos(user);
        if (lastDeposit >= startTime || lastDeposit == 0) {
          return (0, 0);
        }

        // Find the highest tiers and use that allocation amount
        uint allocation = 0;
        (, uint tiersTotal) = tiers.userInfoTotal(user);
        for (uint i = 0; i < tiersLevels.length; i++) {
            if (tiersTotal >= tiersLevels[i]) {
                allocation = (tiersAllocation * tiersMultipliers[i]) / PRECISION;
            }
        }
        return (allocation, tiersTotal);
    }

    function _deposit(address user, uint amount) private nonReentrant {
        require(!paused, "paused");
        require(block.timestamp >= startTime && block.timestamp <= endTime, "sale not active");
        require(amount > 0, "need amount > 0");
        require(totalAmount < raisingAmount, "sold out");

        if (userInfo[user].amount == 0) {
            addressList.push(address(user));
        }

        // Check tiers and cap purchase to allocation
        (uint allocation, uint tiersTotal) = getUserAllocation(user);
        if (block.timestamp < startTime + ALLOCATION_DURATION) {
            require(userInfo[user].amount + amount <= allocation, "over allocation size");
            require(totalAmount + amount <= raisingAmountTiers, "reached phase 1 total cap");
        } else {
            require(perUserCap == 0 || userInfo[user].amount + amount <= allocation + perUserCap, "over per user cap");
            require(vxrune.balanceOf(user) >= 100 || tiersTotal >= 100, "minimum 100 vXRUNE or staked to participate");
        }

        // Refund any payment amount that would bring up over the raising amount
        if (totalAmount + amount > raisingAmount) {
            paymentToken.safeTransfer(user, (totalAmount + amount) - raisingAmount);
            amount = raisingAmount - totalAmount;
        }

        userInfo[user].amount = userInfo[user].amount + amount;
        totalAmount = totalAmount + amount;
        emit Deposit(user, amount);
    }

    function deposit(uint amount) external {
        _transferFrom(msg.sender, amount);
        _deposit(msg.sender, amount);
    }

    function onTokenTransfer(address user, uint amount, bytes calldata _data) external override {
        require(msg.sender == address(paymentToken), "onTokenTransfer: not paymentToken");
        _deposit(user, amount);
    }

    function harvest(bool stake) external nonReentrant {
        require(!paused, "paused");
        require(block.timestamp > endTime, "sale not ended");
        require(finalized, "not finalized");
        require(userInfo[msg.sender].amount > 0, "have you participated?");
        require(!userInfo[msg.sender].claimed, "nothing to harvest");
        userInfo[msg.sender].claimed = true;
        uint amount = getOfferingAmount(msg.sender);

        if (stake) {
            require(address(staking) != address(0), "no staking available");
            offeringToken.approve(address(staking), amount);
            staking.deposit(amount, msg.sender);
        } else {
            offeringToken.safeTransfer(address(msg.sender), amount);
        }

        emit Harvest(msg.sender, amount);
    }

    function withdrawToken(address token, uint amount) external onlyOwner {
        IERC20(token).safeTransfer(msg.sender, amount);
    }

    function _transferFrom(address from, uint amount) private {
        uint balanceBefore = paymentToken.balanceOf(address(this));
        paymentToken.safeTransferFrom(from, address(this), amount);
        uint balanceAfter = paymentToken.balanceOf(address(this));
        require(balanceAfter - balanceBefore == amount, "_transferFrom: balance change does not match amount");
    }
}

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



// SPDX-License-Identifier: MIT

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() {
        _setOwner(_msgSender());
    }

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

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

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

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

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

// File: @openzeppelin/contracts/security/ReentrancyGuard.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

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

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

        _;

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

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

// File: @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT

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/IVoters.sol



//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface IVoters {
  function snapshot() external returns (uint);
  function totalSupplyAt(uint snapshotId) external view returns (uint);
  function votesAt(address account, uint snapshotId) external view returns (uint);
  function balanceOf(address account) external view returns (uint);
  function balanceOfAt(address account, uint snapshotId) external view returns (uint);
  function donate(uint amount) external;
}

// File: contracts/interfaces/IERC677Receiver.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface IERC677Receiver {
  function onTokenTransfer(address _sender, uint _value, bytes calldata _data) external;
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

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

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

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

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

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

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

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

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

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

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

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

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

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

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

    /**
     * @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);
            }
        }
    }
}