Contract Address Details

// SPDX-License-Identifier: GPL-3.0-only
pragma solidity ^0.8.0;

import "./interface/IERC20.sol";
import "./interface/IERC1271.sol";
import "./interface/IWETH.sol";
import "./interface/ISwitchRouter.sol";
import "./interface/ISwitchLimitOrder.sol";
import "./lib/SafeERC20.sol";
import "./lib/Maintainable.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
/**
 * @title SwitchPLSFlow
 * @notice Enables native PLS limit orders on SwitchLimitOrder.
 *
 *         Users send PLS in a single transaction. This contract:
 *           1. Wraps PLS → WPLS
 *           2. Approves SwitchLimitOrder + SwitchRouter for WPLS
 *           3. Stores the order so it can be filled by SwitchLimitOrder
 *           4. Implements ERC-1271 so SwitchLimitOrder can validate this
 *              contract as the "maker" of the order
 *
 *         This contract becomes the `maker` in the EIP-712 order struct.
 *         The user's address is stored as `originalMaker` and set as the
 *         `recipient` so output tokens always go to the user.
 *
 *         Cancellation: only the originalMaker can cancel, which unwraps
 *         WPLS → PLS and returns it.
 *
 *         The EIP-712 domain MUST match SwitchLimitOrder's domain exactly:
 *           { name: "SwitchLimitOrder", version: "2", chainId, verifyingContract }
 *         where verifyingContract = address of the SwitchLimitOrder contract
 *         (NOT address(this)). We compute the domain separator manually to
 *         ensure the digest matches what SwitchLimitOrder computes.
 */
contract SwitchPLSFlow is IERC1271, Maintainable, ReentrancyGuard {
    using SafeERC20 for IERC20;

    // ═══════════════════════════════════════════════════════════════════════════
    // CONSTANTS
    // ═══════════════════════════════════════════════════════════════════════════

    bytes4 private constant ERC1271_MAGIC = 0x1626ba7e;

    bytes32 private constant EIP712_DOMAIN_TYPEHASH = keccak256(
        "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
    );

    bytes32 public constant LIMIT_ORDER_TYPEHASH = keccak256(
        "LimitOrder(address maker,address tokenIn,address tokenOut,uint256 amountIn,uint256 minAmountOut,uint256 deadline,uint256 nonce,bool feeOnOutput,address recipient,bool unwrapOutput,address partnerAddress)"
    );

    // ═══════════════════════════════════════════════════════════════════════════
    // IMMUTABLES
    // ═══════════════════════════════════════════════════════════════════════════

    address public immutable SWITCH_LIMIT_ORDER;
    address public immutable SWITCH_ROUTER;
    address public immutable WNATIVE;

    /// @notice EIP-712 domain separator matching SwitchLimitOrder's domain
    ///         Uses SWITCH_LIMIT_ORDER as verifyingContract (not address(this))
    bytes32 public immutable LIMIT_ORDER_DOMAIN_SEPARATOR;

    // ═══════════════════════════════════════════════════════════════════════════
    // STATE
    // ═══════════════════════════════════════════════════════════════════════════

    /// @notice Order data stored for ERC-1271 validation and cancellation
    struct PLSOrder {
        address originalMaker;  // The user who deposited PLS
        address tokenOut;       // Output token
        uint256 amountIn;       // WPLS amount (= PLS deposited)
        uint256 minAmountOut;   // Minimum output for the user
        uint256 deadline;       // Order expiry (0 = never)
        bool    feeOnOutput;    // Fee placement preference
        bool    unwrapOutput;   // Whether to unwrap output WPLS → PLS
        bool    active;         // false = cancelled or filled
        address partnerAddress; // Partner to receive 50% of fees (address(0) = no partner)
    }

    /// @notice nonce → order details
    mapping(uint256 => PLSOrder) public orders;

    /// @notice Tracks valid order digests for ERC-1271 validation
    mapping(bytes32 => bool) public validOrderDigests;

    /// @notice Global auto-incrementing nonce counter (prevents collisions in orders[] mapping)
    uint256 public globalNonceCounter;

    // ═══════════════════════════════════════════════════════════════════════════
    // EVENTS
    // ═══════════════════════════════════════════════════════════════════════════

    event PLSOrderCreated(
        address indexed originalMaker,
        uint256 indexed nonce,
        address tokenOut,
        uint256 amountIn,
        uint256 minAmountOut,
        uint256 deadline
    );

    event PLSOrderCancelled(
        address indexed originalMaker,
        uint256 indexed nonce,
        uint256 refundAmount
    );

    // ═══════════════════════════════════════════════════════════════════════════
    // ERRORS
    // ═══════════════════════════════════════════════════════════════════════════

    error ZeroAmount();
    error InvalidToken();
    error OrderNotActive();
    error NotOrderOwner();
    error TransferFailed();

    // ═══════════════════════════════════════════════════════════════════════════
    // CONSTRUCTOR
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @param _switchLimitOrder Address of the SwitchLimitOrder contract
     * @param _switchRouter     Address of the SwitchRouter contract
     * @param _wnative          Address of WPLS
     *
     * @dev We compute the EIP-712 domain separator manually using
     *      SWITCH_LIMIT_ORDER as verifyingContract so that the digests
     *      stored here match exactly what SwitchLimitOrder computes.
     *      (OpenZeppelin's EIP712 base would use address(this) instead,
     *      which would cause a domain mismatch.)
     */
    constructor(
        address _switchLimitOrder,
        address _switchRouter,
        address _wnative
    ) {
        require(_switchLimitOrder != address(0), "Invalid limit order");
        require(_switchRouter != address(0), "Invalid router");
        require(_wnative != address(0), "Invalid WNATIVE");

        SWITCH_LIMIT_ORDER = _switchLimitOrder;
        SWITCH_ROUTER = _switchRouter;
        WNATIVE = _wnative;

        // Build the domain separator using SwitchLimitOrder's address
        // so digests match what SwitchLimitOrder.sol computes
        LIMIT_ORDER_DOMAIN_SEPARATOR = keccak256(abi.encode(
            EIP712_DOMAIN_TYPEHASH,
            keccak256(bytes("SwitchLimitOrder")),
            keccak256(bytes("2")),
            block.chainid,
            _switchLimitOrder   // verifyingContract = SwitchLimitOrder, NOT address(this)
        ));

        // Pre-approve WPLS for SwitchLimitOrder (pulls during feeOnInput fills)
        IERC20(_wnative).approve(_switchLimitOrder, type(uint256).max);
        // Pre-approve WPLS for SwitchRouter (pulls during feeOnOutput fills via goSwitchFrom)
        IERC20(_wnative).approve(_switchRouter, type(uint256).max);
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // CREATE ORDER
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @notice Create a native PLS limit order in a single transaction.
     *         Wraps PLS → WPLS and stores the order for filling.
     *
     * @param tokenOut      The token the user wants to receive
     * @param minAmountOut  Minimum amount of tokenOut the user accepts
     * @param deadline      Unix timestamp expiry (0 = no expiry)
     * @param feeOnOutput   Whether protocol fee is taken from output
     * @param unwrapOutput  Whether to unwrap WPLS → PLS if tokenOut is WPLS
     * @return nonce        The nonce assigned to this order
     */
    function createOrder(
        address tokenOut,
        uint256 minAmountOut,
        uint256 deadline,
        bool feeOnOutput,
        bool unwrapOutput,
        address partnerAddress
    ) external payable nonReentrant returns (uint256 nonce) {
        if (msg.value == 0) revert ZeroAmount();
        if (tokenOut == address(0) || tokenOut == WNATIVE && !unwrapOutput) {
            // tokenOut can be WNATIVE only if unwrapOutput is true (user wants PLS back)
            // Otherwise this would be WPLS→WPLS which makes no sense
            if (tokenOut == WNATIVE && !unwrapOutput) revert InvalidToken();
        }

        // Wrap PLS → WPLS
        IWETH(WNATIVE).deposit{value: msg.value}();

        // Assign nonce (global to prevent storage collisions between users)
        nonce = globalNonceCounter++;

        // The order recipient is always the original user
        address recipient = msg.sender;

        // Store order
        orders[nonce] = PLSOrder({
            originalMaker: msg.sender,
            tokenOut: tokenOut,
            amountIn: msg.value,
            minAmountOut: minAmountOut,
            deadline: deadline,
            feeOnOutput: feeOnOutput,
            unwrapOutput: unwrapOutput,
            active: true,
            partnerAddress: partnerAddress
        });

        // Compute and store the EIP-712 digest for ERC-1271 validation
        bytes32 structHash = keccak256(abi.encode(
            LIMIT_ORDER_TYPEHASH,
            address(this),   // maker = this contract
            WNATIVE,         // tokenIn = WPLS
            tokenOut,
            msg.value,       // amountIn
            minAmountOut,
            deadline,
            nonce,
            feeOnOutput,
            recipient,
            unwrapOutput,
            partnerAddress
        ));
        bytes32 digest = keccak256(abi.encodePacked(
            "\x19\x01", LIMIT_ORDER_DOMAIN_SEPARATOR, structHash
        ));
        validOrderDigests[digest] = true;

        // Announce on the LimitOrder contract so the backend indexes it
        ISwitchLimitOrder(SWITCH_LIMIT_ORDER).placeOrder(
            ISwitchLimitOrder.LimitOrder({
                maker: address(this),
                tokenIn: WNATIVE,
                tokenOut: tokenOut,
                amountIn: msg.value,
                minAmountOut: minAmountOut,
                deadline: deadline,
                nonce: nonce,
                feeOnOutput: feeOnOutput,
                recipient: recipient,
                unwrapOutput: unwrapOutput,
                partnerAddress: partnerAddress
            }),
            ""  // No ECDSA signature — PLSFlow uses ERC-1271
        );

        emit PLSOrderCreated(msg.sender, nonce, tokenOut, msg.value, minAmountOut, deadline);
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // CANCEL ORDER
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @notice Cancel a PLS order and reclaim funds.
     *         Unwraps WPLS → PLS and sends back to the original maker.
     *         Also invalidates the nonce on SwitchLimitOrder to prevent filling.
     *
     * @param nonce The nonce of the order to cancel
     */
    function cancelOrder(uint256 nonce) external nonReentrant {
        PLSOrder storage order = orders[nonce];
        if (!order.active) revert OrderNotActive();
        if (order.originalMaker != msg.sender) revert NotOrderOwner();

        order.active = false;

        // Invalidate digest for ERC-1271
        bytes32 structHash = keccak256(abi.encode(
            LIMIT_ORDER_TYPEHASH,
            address(this),
            WNATIVE,
            order.tokenOut,
            order.amountIn,
            order.minAmountOut,
            order.deadline,
            nonce,
            order.feeOnOutput,
            msg.sender,       // recipient = originalMaker
            order.unwrapOutput,
            order.partnerAddress
        ));
        bytes32 digest = keccak256(abi.encodePacked(
            "\x19\x01", LIMIT_ORDER_DOMAIN_SEPARATOR, structHash
        ));
        validOrderDigests[digest] = false;

        // Refund: unwrap WPLS → PLS and send to user
        uint256 refundAmount = order.amountIn;

        // Check we still have the WPLS (it may have been partially or fully filled)
        uint256 wplsBal = IERC20(WNATIVE).balanceOf(address(this));
        if (refundAmount > wplsBal) {
            refundAmount = wplsBal;
        }

        if (refundAmount > 0) {
            IWETH(WNATIVE).withdraw(refundAmount);
            (bool ok, ) = payable(msg.sender).call{value: refundAmount}("");
            if (!ok) revert TransferFailed();
        }

        emit PLSOrderCancelled(msg.sender, nonce, refundAmount);
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // ERC-1271: SIGNATURE VALIDATION
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @notice Validates a signature for ERC-1271.
     *         SwitchLimitOrder calls this when the order's maker is a contract.
     *         We check that the digest matches a stored valid order.
     *
     * @param hash       The EIP-712 typed data hash
     * @param signature  Unused (we validate via stored digests, not signatures)
     * @return magicValue ERC-1271 magic value if valid, 0x00000000 if not
     */
    function isValidSignature(
        bytes32 hash,
        bytes calldata signature
    ) external view override returns (bytes4) {
        // Silence unused variable warning
        signature;

        if (validOrderDigests[hash]) {
            return ERC1271_MAGIC;
        }
        return bytes4(0);
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // VIEW FUNCTIONS
    // ═══════════════════════════════════════════════════════════════════════════

    function getOrder(uint256 nonce) external view returns (PLSOrder memory) {
        return orders[nonce];
    }

    function getGlobalNonce() external view returns (uint256) {
        return globalNonceCounter;
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // EMERGENCY
    // ═══════════════════════════════════════════════════════════════════════════

    function recoverTokens(address _token, uint256 _amount) external onlyMaintainer {
        IERC20(_token).safeTransfer(msg.sender, _amount);
    }

    function recoverNative(uint256 _amount) external onlyMaintainer {
        (bool ok, ) = payable(msg.sender).call{value: _amount}("");
        require(ok, "Native transfer failed");
    }

    receive() external payable {}
}
        

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}
          

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/access/AccessControl.sol";

/**
 * @dev Contract module which extends the basic access control mechanism of Ownable
 * to include many maintainers, whom only the owner (DEFAULT_ADMIN_ROLE) may add and
 * remove.
 *
 * 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 this modifier:
 * `onlyMaintainer`, which can be applied to your functions to restrict their use to
 * the accounts with the role of maintainer.
 */

abstract contract Maintainable is Context, AccessControl {
    bytes32 public constant MAINTAINER_ROLE = keccak256("MAINTAINER_ROLE");

    constructor() {
        address msgSender = _msgSender();
        // members of the DEFAULT_ADMIN_ROLE alone may revoke and grant role membership
        _setupRole(DEFAULT_ADMIN_ROLE, msgSender);
        _setupRole(MAINTAINER_ROLE, msgSender);
    }

    function addMaintainer(address addedMaintainer) public virtual {
        grantRole(MAINTAINER_ROLE, addedMaintainer);
    }

    function removeMaintainer(address removedMaintainer) public virtual {
        revokeRole(MAINTAINER_ROLE, removedMaintainer);
    }

    function renounceRole(bytes32 role) public virtual {
        address msgSender = _msgSender();
        renounceRole(role, msgSender);
    }

    function transferOwnership(address newOwner) public virtual {
        address msgSender = _msgSender();
        grantRole(DEFAULT_ADMIN_ROLE, newOwner);
        renounceRole(DEFAULT_ADMIN_ROLE, msgSender);
    }

    modifier onlyMaintainer() {
        address msgSender = _msgSender();
        require(hasRole(MAINTAINER_ROLE, msgSender), "Maintainable: Caller is not a maintainer");
        _;
    }
}
          

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

import "./IERC20.sol";

interface IWETH is IERC20 {
    function withdraw(uint256 amount) external;

    function deposit() external payable;
}
          

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


struct Query {
    address adapter;
    address tokenIn;
    address tokenOut;
    uint256 amountOut;
}
struct Offer {
    bytes amounts;
    bytes adapters;
    bytes path;
    uint256 gasEstimate;
}
struct FormattedOffer {
    uint256[] amounts;
    address[] adapters;
    address[] path;
    uint256 gasEstimate;
}
struct Trade {
    uint256 amountIn;
    uint256 amountOut;
    address[] path;
    address[] adapters;
}

struct HopAdapterAllocation {
    address adapter;
    uint256 amountIn;
}

struct HopAllocation {
    address tokenIn;
    address tokenOut;
    HopAdapterAllocation[] legs;
}

struct RouteAllocation {
    uint256 amountIn;
    HopAllocation[] hops;
}

interface ISwitchRouter {

    event UpdatedAdapters(address[] _newAdapters);
    event UpdatedMinFee(uint256 _oldMinFee, uint256 _newMinFee);
    event UpdatedFeeClaimer(address _oldFeeClaimer, address _newFeeClaimer);
    event Switched(address indexed _tokenIn, address indexed _tokenOut, uint256 _amountIn, uint256 _amountOut, address _partnerAddress);
    event UpdatedFeeExempt(address indexed account, bool exempt);

    // admin
    function setAdapters(address[] memory _adapters) external;
    function setFeeClaimer(address _claimer) external;
    function setMinFee(uint256 _fee) external;
    function setFeeExempt(address account, bool exempt) external;
    function setMinFeeExempt(address account, bool exempt) external;
    function setFeeExemptBatch(address[] calldata accounts, bool[] calldata flags) external;
    function adaptersCount() external view returns (uint256);
    function ADAPTERS(uint256 index) external view returns (address);
    function MIN_FEE() external view returns (uint256);
    function MIN_FEE_EXEMPT(address account) external view returns (bool);
    function FEE_CLAIMER() external view returns (address);
    function FEE_EXEMPT(address account) external view returns (bool);

    // query

    function queryAdapter(
        uint256 _amountIn,
        address _tokenIn,
        address _tokenOut,
        uint8 _index
    ) external returns (uint256);

    function queryNoSplit(
        uint256 _amountIn,
        address _tokenIn,
        address _tokenOut,
        uint8[] calldata _options
    ) external view returns (Query memory);

    function queryNoSplit(
        uint256 _amountIn,
        address _tokenIn,
        address _tokenOut
    ) external view returns (Query memory);

    function findBestPathWithGas(
        uint256 _amountIn,
        address _tokenIn,
        address _tokenOut,
        uint256 _maxSteps,
        uint256 _gasPrice
    ) external view returns (FormattedOffer memory);

    function findBestPath(
        uint256 _amountIn,
        address _tokenIn,
        address _tokenOut,
        uint256 _maxSteps
    ) external view returns (FormattedOffer memory);

    function findBestPathRange(
        uint256 _amountIn,
        address _tokenIn,
        address _tokenOut,
        uint256 _maxSteps,
        uint256 _trustedStart,
        uint256 _trustedCount
    ) external view returns (FormattedOffer memory);

    function findBestPathRangeWithGas(
        uint256 _amountIn,
        address _tokenIn,
        address _tokenOut,
        uint256 _maxSteps,
        uint256 _gasPrice,
        uint256 _trustedStart,
        uint256 _trustedCount
    ) external view returns (FormattedOffer memory);

    function queryAdaptersRange(
        uint256 _amountIn,
        address _tokenIn,
        address _tokenOut,
        uint256 _start,
        uint256 _count
    ) external view returns (Query[] memory results);

    function quoteSplit(Trade[] calldata _trades) external view returns (uint256 totalOut);

    // Unified swap function
    function goSwitch(
        RouteAllocation[] calldata _routes,
        address _to,
        uint256 _minTotalAmountOut,
        uint256 _fee,
        bool _feeOnOutput,
        bool _unwrapOutput,
        address _partnerAddress
    ) external payable;

    // Pull-from-payer swap (only callable by the limit order contract)
    function goSwitchFrom(
        address _payer,
        RouteAllocation[] calldata _routes,
        address _to,
        uint256 _minTotalAmountOut,
        bool _unwrapOutput
    ) external;

    // Pull tokens from a payer to a recipient (only callable by the limit order contract)
    function pullTokens(
        address _token,
        address _from,
        address _to,
        uint256 _amount
    ) external;

    function LIMIT_ORDER_CONTRACT() external view returns (address);
}
          

// SPDX-License-Identifier: GPL-3.0-only
pragma solidity ^0.8.0;

interface ISwitchLimitOrder {
    struct LimitOrder {
        address maker;
        address tokenIn;
        address tokenOut;
        uint256 amountIn;
        uint256 minAmountOut;
        uint256 deadline;
        uint256 nonce;
        bool feeOnOutput;
        address recipient;
        bool unwrapOutput;
        address partnerAddress;
    }

    function placeOrder(LimitOrder calldata order, bytes calldata signature) external;
}
          

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

interface IERC20 {
    event Approval(address, address, uint256);
    event Transfer(address, address, uint256);

    function name() external view returns (string memory);

    function decimals() external view returns (uint8);

    function transferFrom(
        address,
        address,
        uint256
    ) external returns (bool);

    function allowance(address, address) external view returns (uint256);

    function approve(address, uint256) external returns (bool);

    function transfer(address, uint256) external returns (bool);

    function balanceOf(address) external view returns (uint256);

    function nonces(address) external view returns (uint256); // Only tokens that support permit

    function permit(
        address,
        address,
        uint256,
        uint256,
        uint8,
        bytes32,
        bytes32
    ) external; // Only tokens that support permit

    function swap(address, uint256) external; // Only Avalanche bridge tokens

    function swapSupply(address) external view returns (uint256); // Only Avalanche bridge tokens

    function totalSupply() external view returns (uint256);
}
          

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

/**
 * @dev Interface for ERC-1271: Standard Signature Validation Method for Contracts.
 *      See https://eips.ethereum.org/EIPS/eip-1271
 */
interface IERC1271 {
    /**
     * @dev Returns `0x1626ba7e` if the signature is valid for the given hash.
     */
    function isValidSignature(
        bytes32 hash,
        bytes calldata signature
    ) external view returns (bytes4);
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/SignedMath.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard signed math utilities missing in the Solidity language.
 */
library SignedMath {
    /**
     * @dev Returns the largest of two signed numbers.
     */
    function max(int256 a, int256 b) internal pure returns (int256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two signed numbers.
     */
    function min(int256 a, int256 b) internal pure returns (int256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two signed numbers without overflow.
     * The result is rounded towards zero.
     */
    function average(int256 a, int256 b) internal pure returns (int256) {
        // Formula from the book "Hacker's Delight"
        int256 x = (a & b) + ((a ^ b) >> 1);
        return x + (int256(uint256(x) >> 255) & (a ^ b));
    }

    /**
     * @dev Returns the absolute unsigned value of a signed value.
     */
    function abs(int256 n) internal pure returns (uint256) {
        unchecked {
            // must be unchecked in order to support `n = type(int256).min`
            return uint256(n >= 0 ? n : -n);
        }
    }
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/math/Math.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    enum Rounding {
        Down, // Toward negative infinity
        Up, // Toward infinity
        Zero // Toward zero
    }

    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow.
        return (a & b) + (a ^ b) / 2;
    }

    /**
     * @dev Returns the ceiling of the division of two numbers.
     *
     * This differs from standard division with `/` in that it rounds up instead
     * of rounding down.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b - 1) / b can overflow on addition, so we distribute.
        return a == 0 ? 0 : (a - 1) / b + 1;
    }

    /**
     * @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or denominator == 0
     * @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv)
     * with further edits by Uniswap Labs also under MIT license.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator) internal pure returns (uint256 result) {
        unchecked {
            // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
            // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
            // variables such that product = prod1 * 2^256 + prod0.
            uint256 prod0; // Least significant 256 bits of the product
            uint256 prod1; // Most significant 256 bits of the product
            assembly {
                let mm := mulmod(x, y, not(0))
                prod0 := mul(x, y)
                prod1 := sub(sub(mm, prod0), lt(mm, prod0))
            }

            // Handle non-overflow cases, 256 by 256 division.
            if (prod1 == 0) {
                // Solidity will revert if denominator == 0, unlike the div opcode on its own.
                // The surrounding unchecked block does not change this fact.
                // See https://docs.soliditylang.org/en/latest/control-structures.html#checked-or-unchecked-arithmetic.
                return prod0 / denominator;
            }

            // Make sure the result is less than 2^256. Also prevents denominator == 0.
            require(denominator > prod1, "Math: mulDiv overflow");

            ///////////////////////////////////////////////
            // 512 by 256 division.
            ///////////////////////////////////////////////

            // Make division exact by subtracting the remainder from [prod1 prod0].
            uint256 remainder;
            assembly {
                // Compute remainder using mulmod.
                remainder := mulmod(x, y, denominator)

                // Subtract 256 bit number from 512 bit number.
                prod1 := sub(prod1, gt(remainder, prod0))
                prod0 := sub(prod0, remainder)
            }

            // Factor powers of two out of denominator and compute largest power of two divisor of denominator. Always >= 1.
            // See https://cs.stackexchange.com/q/138556/92363.

            // Does not overflow because the denominator cannot be zero at this stage in the function.
            uint256 twos = denominator & (~denominator + 1);
            assembly {
                // Divide denominator by twos.
                denominator := div(denominator, twos)

                // Divide [prod1 prod0] by twos.
                prod0 := div(prod0, twos)

                // Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
                twos := add(div(sub(0, twos), twos), 1)
            }

            // Shift in bits from prod1 into prod0.
            prod0 |= prod1 * twos;

            // Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
            // that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
            // four bits. That is, denominator * inv = 1 mod 2^4.
            uint256 inverse = (3 * denominator) ^ 2;

            // Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also works
            // in modular arithmetic, doubling the correct bits in each step.
            inverse *= 2 - denominator * inverse; // inverse mod 2^8
            inverse *= 2 - denominator * inverse; // inverse mod 2^16
            inverse *= 2 - denominator * inverse; // inverse mod 2^32
            inverse *= 2 - denominator * inverse; // inverse mod 2^64
            inverse *= 2 - denominator * inverse; // inverse mod 2^128
            inverse *= 2 - denominator * inverse; // inverse mod 2^256

            // Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
            // This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
            // less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1
            // is no longer required.
            result = prod0 * inverse;
            return result;
        }
    }

    /**
     * @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator, Rounding rounding) internal pure returns (uint256) {
        uint256 result = mulDiv(x, y, denominator);
        if (rounding == Rounding.Up && mulmod(x, y, denominator) > 0) {
            result += 1;
        }
        return result;
    }

    /**
     * @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded down.
     *
     * Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
     */
    function sqrt(uint256 a) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        // For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
        //
        // We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
        // `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
        //
        // This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
        // → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
        // → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
        //
        // Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
        uint256 result = 1 << (log2(a) >> 1);

        // At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
        // since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at
        // every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
        // into the expected uint128 result.
        unchecked {
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            return min(result, a / result);
        }
    }

    /**
     * @notice Calculates sqrt(a), following the selected rounding direction.
     */
    function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = sqrt(a);
            return result + (rounding == Rounding.Up && result * result < a ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 2, rounded down, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 128;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 64;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 32;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 16;
            }
            if (value >> 8 > 0) {
                value >>= 8;
                result += 8;
            }
            if (value >> 4 > 0) {
                value >>= 4;
                result += 4;
            }
            if (value >> 2 > 0) {
                value >>= 2;
                result += 2;
            }
            if (value >> 1 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 2, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log2(value);
            return result + (rounding == Rounding.Up && 1 << result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 10, rounded down, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >= 10 ** 64) {
                value /= 10 ** 64;
                result += 64;
            }
            if (value >= 10 ** 32) {
                value /= 10 ** 32;
                result += 32;
            }
            if (value >= 10 ** 16) {
                value /= 10 ** 16;
                result += 16;
            }
            if (value >= 10 ** 8) {
                value /= 10 ** 8;
                result += 8;
            }
            if (value >= 10 ** 4) {
                value /= 10 ** 4;
                result += 4;
            }
            if (value >= 10 ** 2) {
                value /= 10 ** 2;
                result += 2;
            }
            if (value >= 10 ** 1) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log10(value);
            return result + (rounding == Rounding.Up && 10 ** result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 256, rounded down, of a positive value.
     * Returns 0 if given 0.
     *
     * Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
     */
    function log256(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 16;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 8;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 4;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 2;
            }
            if (value >> 8 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 256, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log256(value);
            return result + (rounding == Rounding.Up && 1 << (result << 3) < value ? 1 : 0);
        }
    }
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/Strings.sol)

pragma solidity ^0.8.0;

import "./math/Math.sol";
import "./math/SignedMath.sol";

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _SYMBOLS = "0123456789abcdef";
    uint8 private constant _ADDRESS_LENGTH = 20;

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        unchecked {
            uint256 length = Math.log10(value) + 1;
            string memory buffer = new string(length);
            uint256 ptr;
            /// @solidity memory-safe-assembly
            assembly {
                ptr := add(buffer, add(32, length))
            }
            while (true) {
                ptr--;
                /// @solidity memory-safe-assembly
                assembly {
                    mstore8(ptr, byte(mod(value, 10), _SYMBOLS))
                }
                value /= 10;
                if (value == 0) break;
            }
            return buffer;
        }
    }

    /**
     * @dev Converts a `int256` to its ASCII `string` decimal representation.
     */
    function toString(int256 value) internal pure returns (string memory) {
        return string(abi.encodePacked(value < 0 ? "-" : "", toString(SignedMath.abs(value))));
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        unchecked {
            return toHexString(value, Math.log256(value) + 1);
        }
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }

    /**
     * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
     */
    function toHexString(address addr) internal pure returns (string memory) {
        return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
    }

    /**
     * @dev Returns true if the two strings are equal.
     */
    function equal(string memory a, string memory b) internal pure returns (bool) {
        return keccak256(bytes(a)) == keccak256(bytes(b));
    }
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.4) (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;
    }

    function _contextSuffixLength() internal view virtual returns (uint256) {
        return 0;
    }
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (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() {
        _nonReentrantBefore();
        _;
        _nonReentrantAfter();
    }

    function _nonReentrantBefore() private {
        // On the first call to nonReentrant, _status will be _NOT_ENTERED
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

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

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

    /**
     * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
     * `nonReentrant` function in the call stack.
     */
    function _reentrancyGuardEntered() internal view returns (bool) {
        return _status == _ENTERED;
    }
}
          

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

pragma solidity ^0.8.0;

/**
 * @dev External interface of AccessControl declared to support ERC165 detection.
 */
interface IAccessControl {
    /**
     * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
     *
     * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
     * {RoleAdminChanged} not being emitted signaling this.
     *
     * _Available since v3.1._
     */
    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);

    /**
     * @dev Emitted when `account` is granted `role`.
     *
     * `sender` is the account that originated the contract call, an admin role
     * bearer except when using {AccessControl-_setupRole}.
     */
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Emitted when `account` is revoked `role`.
     *
     * `sender` is the account that originated the contract call:
     *   - if using `revokeRole`, it is the admin role bearer
     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
     */
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) external view returns (bool);

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {AccessControl-_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) external view returns (bytes32);

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) external;

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) external;

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) external;
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (access/AccessControl.sol)

pragma solidity ^0.8.0;

import "./IAccessControl.sol";
import "../utils/Context.sol";
import "../utils/Strings.sol";
import "../utils/introspection/ERC165.sol";

/**
 * @dev Contract module that allows children to implement role-based access
 * control mechanisms. This is a lightweight version that doesn't allow enumerating role
 * members except through off-chain means by accessing the contract event logs. Some
 * applications may benefit from on-chain enumerability, for those cases see
 * {AccessControlEnumerable}.
 *
 * Roles are referred to by their `bytes32` identifier. These should be exposed
 * in the external API and be unique. The best way to achieve this is by
 * using `public constant` hash digests:
 *
 * ```solidity
 * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
 * ```
 *
 * Roles can be used to represent a set of permissions. To restrict access to a
 * function call, use {hasRole}:
 *
 * ```solidity
 * function foo() public {
 *     require(hasRole(MY_ROLE, msg.sender));
 *     ...
 * }
 * ```
 *
 * Roles can be granted and revoked dynamically via the {grantRole} and
 * {revokeRole} functions. Each role has an associated admin role, and only
 * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
 *
 * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
 * that only accounts with this role will be able to grant or revoke other
 * roles. More complex role relationships can be created by using
 * {_setRoleAdmin}.
 *
 * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
 * grant and revoke this role. Extra precautions should be taken to secure
 * accounts that have been granted it. We recommend using {AccessControlDefaultAdminRules}
 * to enforce additional security measures for this role.
 */
abstract contract AccessControl is Context, IAccessControl, ERC165 {
    struct RoleData {
        mapping(address => bool) members;
        bytes32 adminRole;
    }

    mapping(bytes32 => RoleData) private _roles;

    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;

    /**
     * @dev Modifier that checks that an account has a specific role. Reverts
     * with a standardized message including the required role.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
     *
     * _Available since v4.1._
     */
    modifier onlyRole(bytes32 role) {
        _checkRole(role);
        _;
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IAccessControl).interfaceId || super.supportsInterface(interfaceId);
    }

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) public view virtual override returns (bool) {
        return _roles[role].members[account];
    }

    /**
     * @dev Revert with a standard message if `_msgSender()` is missing `role`.
     * Overriding this function changes the behavior of the {onlyRole} modifier.
     *
     * Format of the revert message is described in {_checkRole}.
     *
     * _Available since v4.6._
     */
    function _checkRole(bytes32 role) internal view virtual {
        _checkRole(role, _msgSender());
    }

    /**
     * @dev Revert with a standard message if `account` is missing `role`.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
     */
    function _checkRole(bytes32 role, address account) internal view virtual {
        if (!hasRole(role, account)) {
            revert(
                string(
                    abi.encodePacked(
                        "AccessControl: account ",
                        Strings.toHexString(account),
                        " is missing role ",
                        Strings.toHexString(uint256(role), 32)
                    )
                )
            );
        }
    }

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) public view virtual override returns (bytes32) {
        return _roles[role].adminRole;
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     *
     * May emit a {RoleGranted} event.
     */
    function grantRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _grantRole(role, account);
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     *
     * May emit a {RoleRevoked} event.
     */
    function revokeRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _revokeRole(role, account);
    }

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been revoked `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     *
     * May emit a {RoleRevoked} event.
     */
    function renounceRole(bytes32 role, address account) public virtual override {
        require(account == _msgSender(), "AccessControl: can only renounce roles for self");

        _revokeRole(role, account);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event. Note that unlike {grantRole}, this function doesn't perform any
     * checks on the calling account.
     *
     * May emit a {RoleGranted} event.
     *
     * [WARNING]
     * ====
     * This function should only be called from the constructor when setting
     * up the initial roles for the system.
     *
     * Using this function in any other way is effectively circumventing the admin
     * system imposed by {AccessControl}.
     * ====
     *
     * NOTE: This function is deprecated in favor of {_grantRole}.
     */
    function _setupRole(bytes32 role, address account) internal virtual {
        _grantRole(role, account);
    }

    /**
     * @dev Sets `adminRole` as ``role``'s admin role.
     *
     * Emits a {RoleAdminChanged} event.
     */
    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
        bytes32 previousAdminRole = getRoleAdmin(role);
        _roles[role].adminRole = adminRole;
        emit RoleAdminChanged(role, previousAdminRole, adminRole);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * Internal function without access restriction.
     *
     * May emit a {RoleGranted} event.
     */
    function _grantRole(bytes32 role, address account) internal virtual {
        if (!hasRole(role, account)) {
            _roles[role].members[account] = true;
            emit RoleGranted(role, account, _msgSender());
        }
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * Internal function without access restriction.
     *
     * May emit a {RoleRevoked} event.
     */
    function _revokeRole(bytes32 role, address account) internal virtual {
        if (hasRole(role, account)) {
            _roles[role].members[account] = false;
            emit RoleRevoked(role, account, _msgSender());
        }
    }
}
          

// This is a simplified version of OpenZepplin's SafeERC20 library
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
pragma experimental ABIEncoderV2;

import "../interface/IERC20.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 ERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    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));
    }

    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    /**
     * @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.

        // A Solidity high level call has three parts:
        //  1. The target address is checked to verify it contains contract code
        //  2. The call itself is made, and success asserted
        //  3. The return value is decoded, which in turn checks the size of the returned data.
        // solhint-disable-next-line max-line-length

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "SafeERC20: low-level call failed");

        if (returndata.length > 0) {
            // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}