// File: swap.sol



// SPDX-License-Identifier: MIT

/* solhint-disable var-name-mixedcase */
pragma solidity 0.8.17;

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

/**
 * @title TradeOffer.fi forked and modified from Airswap under MIT
 * @notice https://www.tradeoffer.fi | https://airswap.com
 * 
 */
contract Swap is ISwap, Ownable {
  using SafeERC20 for IERC20;

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

  bytes32 public constant ORDER_TYPEHASH =
    keccak256(
      "Order(uint256 nonce,uint256 expiry,address signerWallet,address signerToken,uint256 signerAmount,uint256 protocolFee,address senderWallet,address senderToken,uint256 senderAmount)"
    );

  bytes32 public constant DOMAIN_NAME = keccak256("TROF");
  bytes32 public constant DOMAIN_VERSION = keccak256("1");
  bytes32 public immutable DOMAIN_SEPARATOR;

  uint32 public immutable DOMAIN_CHAIN_ID;
  uint32 internal constant MAX_ERROR_COUNT = 6;
  uint32 public constant FEE_DIVISOR = 10000;

  /**
   * @notice Double mapping of signers to nonce groups to nonce states
   * @dev The nonce group is computed as nonce / 256, so each group of 256 sequential nonces uses the same key
   * @dev The nonce states are encoded as 256 bits, for each nonce in the group 0 means available and 1 means used
   */
  mapping(address => mapping(uint256 => uint256)) internal _nonceGroups;
  mapping(address => address) public override authorized;

  uint256 public protocolFee;
  address public protocolFeeWallet;

  constructor(
    uint256 _protocolFee,
    address _protocolFeeWallet
  ) {
    require(_protocolFee < FEE_DIVISOR, "INVALID_FEE");
    require(_protocolFeeWallet != address(0), "INVALID_FEE_WALLET");

    uint32 currentChainId = getChainId();
    DOMAIN_CHAIN_ID = currentChainId;
    DOMAIN_SEPARATOR = keccak256(
      abi.encode(
        DOMAIN_TYPEHASH,
        DOMAIN_NAME,
        DOMAIN_VERSION,
        currentChainId,
        this
      )
    );
    protocolFee = _protocolFee;
    protocolFeeWallet = _protocolFeeWallet;
  }

  /**
   * @notice Atomic ERC20 Swap for Any Sender
   * @param recipient address Wallet to receive sender proceeds
   * @param nonce uint256 Unique and should be sequential
   * @param expiry uint256 Expiry in seconds since 1 January 1970
   * @param signerWallet address Wallet of the signer
   * @param signerToken address ERC20 token transferred from the signer
   * @param signerAmount uint256 Amount transferred from the signer
   * @param senderToken address ERC20 token transferred from the sender
   * @param senderAmount uint256 Amount transferred from the sender
   * @param v uint8 "v" value of the ECDSA signature
   * @param r bytes32 "r" value of the ECDSA signature
   * @param s bytes32 "s" value of the ECDSA signature
   */
  function swapAnySender(
    address recipient,
    uint256 nonce,
    uint256 expiry,
    address signerWallet,
    address signerToken,
    uint256 signerAmount,
    address senderToken,
    uint256 senderAmount,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) external override {
    // Ensure the order is valid
    _checkValidOrder(
      nonce,
      expiry,
      signerWallet,
      signerToken,
      signerAmount,
      address(0),
      senderToken,
      senderAmount,
      v,
      r,
      s
    );

    // Transfer token from sender to signer
    IERC20(senderToken).safeTransferFrom(
      msg.sender,
      signerWallet,
      senderAmount
    );

    // Transfer token from signer to recipient
    IERC20(signerToken).safeTransferFrom(signerWallet, recipient, signerAmount);

    // Calculate and transfer protocol fee and any rebate
    // _transferProtocolFee(signerToken, signerWallet, signerAmount);
    IERC20(signerToken).safeTransferFrom(
      signerWallet,
      protocolFeeWallet,
      (signerAmount * protocolFee) / FEE_DIVISOR
    );

    // Emit a Swap event
    emit Swap(
      nonce,
      block.timestamp,
      signerWallet,
      signerToken,
      signerAmount,
      protocolFee,
      msg.sender,
      senderToken,
      senderAmount
    );
  }

  /**
   * @notice Atomic ERC20 Swap for Whitelisted Sender 
   * @param nonce uint256 Unique and should be sequential
   * @param expiry uint256 Expiry in seconds since 1 January 1970
   * @param signerWallet address Wallet of the signer
   * @param signerToken address ERC20 token transferred from the signer
   * @param signerAmount uint256 Amount transferred from the signer
   * @param senderToken address ERC20 token transferred from the sender
   * @param senderAmount uint256 Amount transferred from the sender
   * @param v uint8 "v" value of the ECDSA signature
   * @param r bytes32 "r" value of the ECDSA signature
   * @param s bytes32 "s" value of the ECDSA signature
   */
  function swapWithRecipient(
    uint256 nonce,
    uint256 expiry,
    address signerWallet,
    address signerToken,
    uint256 signerAmount,
    address senderToken,
    uint256 senderAmount,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) external override {
    require(DOMAIN_CHAIN_ID == getChainId(), "CHAIN_ID_CHANGED");

    // Ensure the expiry is not passed
    require(expiry > block.timestamp, "EXPIRY_PASSED");

    // Recover the signatory from the hash and signature
    address signatory = ecrecover(
      keccak256(
        abi.encodePacked(
          "\x19\x01",
          DOMAIN_SEPARATOR,
          keccak256(
            abi.encode(
              ORDER_TYPEHASH,
              nonce,
              expiry,
              signerWallet,
              signerToken,
              signerAmount,
              protocolFee,
              msg.sender,
              senderToken,
              senderAmount
            )
          )
        )
      ),
      v,
      r,
      s
    );

    // Ensure the signatory is not null
    require(signatory != address(0), "SIGNATURE_INVALID");

    // Ensure the nonce is not yet used and if not mark it used
    require(_markNonceAsUsed(signatory, nonce), "NONCE_ALREADY_USED");

    // Ensure the signatory is authorized by the signer wallet
    if (signerWallet != signatory) {
      require(authorized[signerWallet] == signatory, "UNAUTHORIZED");
    }

    // Transfer token from sender to signer
    IERC20(senderToken).safeTransferFrom(
      msg.sender,
      signerWallet,
      senderAmount
    );

    // Transfer token from signer to recipient
    IERC20(signerToken).safeTransferFrom(
      signerWallet,
      msg.sender,
      signerAmount
    );

    // Transfer fee from signer to feeWallet
    IERC20(signerToken).safeTransferFrom(
      signerWallet,
      protocolFeeWallet,
      (signerAmount * protocolFee) / FEE_DIVISOR
    );

    // Emit a Swap event
    emit Swap(
      nonce,
      block.timestamp,
      signerWallet,
      signerToken,
      signerAmount,
      protocolFee,
      msg.sender,
      senderToken,
      senderAmount
    );
  }

  /**
   * @notice Set the fee
   * @param _protocolFee uint256 Value of the fee in basis points
   */
  function setProtocolFee(uint256 _protocolFee) external onlyOwner {
    // Ensure the fee is less than divisor
    require(_protocolFee < FEE_DIVISOR, "INVALID_FEE");
    protocolFee = _protocolFee;
    emit SetProtocolFee(_protocolFee);
  }

  /**
   * @notice Set the fee wallet
   * @param _protocolFeeWallet address Wallet to transfer fee to
   */
  function setProtocolFeeWallet(address _protocolFeeWallet) external onlyOwner {
    // Ensure the new fee wallet is not null
    require(_protocolFeeWallet != address(0), "INVALID_FEE_WALLET");
    protocolFeeWallet = _protocolFeeWallet;
    emit SetProtocolFeeWallet(_protocolFeeWallet);
  }

  /**
   * @notice Authorize a signer
   * @param signer address Wallet of the signer to authorize
   * @dev Emits an Authorize event
   */
  function authorize(address signer) external override {
    require(signer != address(0), "SIGNER_INVALID");
    authorized[msg.sender] = signer;
    emit Authorize(signer, msg.sender);
  }

  /**
   * @notice Revoke the signer
   * @dev Emits a Revoke event
   */
  function revoke() external override {
    address tmp = authorized[msg.sender];
    delete authorized[msg.sender];
    emit Revoke(tmp, msg.sender);
  }

  /**
   * @notice Cancel one or more nonces
   * @dev Cancelled nonces are marked as used
   * @dev Emits a Cancel event
   * @dev Out of gas may occur in arrays of length > 400
   * @param nonces uint256[] List of nonces to cancel
   */
  function cancel(uint256[] calldata nonces) external override {
    for (uint256 i = 0; i < nonces.length; i++) {
      uint256 nonce = nonces[i];
      if (_markNonceAsUsed(msg.sender, nonce)) {
        emit Cancel(nonce, msg.sender);
      }
    }
  }

  /**
   * @notice Validates Swap Order for any potential errors
   * @param senderWallet address Wallet that would send the order
   * @param nonce uint256 Unique and should be sequential
   * @param expiry uint256 Expiry in seconds since 1 January 1970
   * @param signerWallet address Wallet of the signer
   * @param signerToken address ERC20 token transferred from the signer
   * @param signerAmount uint256 Amount transferred from the signer
   * @param senderToken address ERC20 token transferred from the sender
   * @param senderAmount uint256 Amount transferred from the sender
   * @param v uint8 "v" value of the ECDSA signature
   * @param r bytes32 "r" value of the ECDSA signature
   * @param s bytes32 "s" value of the ECDSA signature
   * @return tuple of error count and bytes32[] memory array of error messages
   */
  function check(
    address senderWallet,
    uint256 nonce,
    uint256 expiry,
    address signerWallet,
    address signerToken,
    uint256 signerAmount,
    address senderToken,
    uint256 senderAmount,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) public view returns (uint256, bytes32[] memory) {
    bytes32[] memory errors = new bytes32[](MAX_ERROR_COUNT);
    Order memory order;
    uint256 errCount;
    order.nonce = nonce;
    order.expiry = expiry;
    order.signerWallet = signerWallet;
    order.signerToken = signerToken;
    order.signerAmount = signerAmount;
    order.senderToken = senderToken;
    order.senderAmount = senderAmount;
    order.v = v;
    order.r = r;
    order.s = s;
    order.senderWallet = senderWallet;
    bytes32 hashed = _getOrderHash(
      order.nonce,
      order.expiry,
      order.signerWallet,
      order.signerToken,
      order.signerAmount,
      order.senderWallet,
      order.senderToken,
      order.senderAmount
    );
    address signatory = _getSignatory(hashed, order.v, order.r, order.s);

    if (signatory == address(0)) {
      errors[errCount] = "SIGNATURE_INVALID";
      errCount++;
    }

    if (order.expiry < block.timestamp) {
      errors[errCount] = "EXPIRY_PASSED";
      errCount++;
    }

    if (
      order.signerWallet != signatory &&
      authorized[order.signerWallet] != signatory
    ) {
      errors[errCount] = "UNAUTHORIZED";
      errCount++;
    } else {
      if (nonceUsed(signatory, order.nonce)) {
        errors[errCount] = "NONCE_ALREADY_USED";
        errCount++;
      }
    }

    if (order.senderWallet != address(0)) {
      uint256 senderBalance = IERC20(order.senderToken).balanceOf(
        order.senderWallet
      );

      uint256 senderAllowance = IERC20(order.senderToken).allowance(
        order.senderWallet,
        address(this)
      );

      if (senderAllowance < order.senderAmount) {
        errors[errCount] = "SENDER_ALLOWANCE_LOW";
        errCount++;
      }

      if (senderBalance < order.senderAmount) {
        errors[errCount] = "SENDER_BALANCE_LOW";
        errCount++;
      }
    }

    uint256 signerBalance = IERC20(order.signerToken).balanceOf(
      order.signerWallet
    );

    uint256 signerAllowance = IERC20(order.signerToken).allowance(
      order.signerWallet,
      address(this)
    );

    uint256 signerFeeAmount = (order.signerAmount * protocolFee) / FEE_DIVISOR;

    if (signerAllowance < order.signerAmount + signerFeeAmount) {
      errors[errCount] = "SIGNER_ALLOWANCE_LOW";
      errCount++;
    }

    if (signerBalance < order.signerAmount + signerFeeAmount) {
      errors[errCount] = "SIGNER_BALANCE_LOW";
      errCount++;
    }

    return (errCount, errors);
  }



  /**
   * @notice Returns true if the nonce has been used
   * @param signer address Address of the signer
   * @param nonce uint256 Nonce being checked
   */
  function nonceUsed(address signer, uint256 nonce)
    public
    view
    override
    returns (bool)
  {
    uint256 groupKey = nonce / 256;
    uint256 indexInGroup = nonce % 256;
    return (_nonceGroups[signer][groupKey] >> indexInGroup) & 1 == 1;
  }

  /**
   * @notice Returns the current chainId using the chainid opcode
   * @return id uint256 The chain id
   */
  function getChainId() public view returns (uint32 id) {
    // no-inline-assembly
    assembly {
      id := chainid()
    }
  }

  /**
   * @notice Marks a nonce as used for the given signer
   * @param signer address Address of the signer for which to mark the nonce as used
   * @param nonce uint256 Nonce to be marked as used
   * @return bool True if the nonce was not marked as used already
   */
  function _markNonceAsUsed(address signer, uint256 nonce)
    internal
    returns (bool)
  {
    uint256 groupKey = nonce / 256;
    uint256 indexInGroup = nonce % 256;
    uint256 group = _nonceGroups[signer][groupKey];

    // If it is already used, return false
    if ((group >> indexInGroup) & 1 == 1) {
      return false;
    }

    _nonceGroups[signer][groupKey] = group | (uint256(1) << indexInGroup);

    return true;
  }

  /**
   * @notice Checks Order Expiry, Nonce, Signature
   * @param nonce uint256 Unique and should be sequential
   * @param expiry uint256 Expiry in seconds since 1 January 1970
   * @param signerWallet address Wallet of the signer
   * @param signerToken address ERC20 token transferred from the signer
   * @param signerAmount uint256 Amount transferred from the signer
   * @param senderToken address ERC20 token transferred from the sender
   * @param senderAmount uint256 Amount transferred from the sender
   * @param v uint8 "v" value of the ECDSA signature
   * @param r bytes32 "r" value of the ECDSA signature
   * @param s bytes32 "s" value of the ECDSA signature
   */
  function _checkValidOrder(
    uint256 nonce,
    uint256 expiry,
    address signerWallet,
    address signerToken,
    uint256 signerAmount,
    address senderWallet,
    address senderToken,
    uint256 senderAmount,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) internal {
    require(DOMAIN_CHAIN_ID == getChainId(), "CHAIN_ID_CHANGED");

    // Ensure the expiry is not passed
    require(expiry > block.timestamp, "EXPIRY_PASSED");
  

    bytes32 hashed = _getOrderHash(
      nonce,
      expiry,
      signerWallet,
      signerToken,
      signerAmount,
      senderWallet,
      senderToken,
      senderAmount
    );

    // Recover the signatory from the hash and signature
    address signatory = _getSignatory(hashed, v, r, s);

    // Ensure the signatory is not null
    require(signatory != address(0), "SIGNATURE_INVALID");

    // Ensure the nonce is not yet used and if not mark it used
    require(_markNonceAsUsed(signatory, nonce), "NONCE_ALREADY_USED");

    // Ensure the signatory is authorized by the signer wallet
    if (signerWallet != signatory) {
      require(
        authorized[signerWallet] != address(0) &&
          authorized[signerWallet] == signatory,
        "UNAUTHORIZED"
      );
    }
  }

  /**
   * @notice Hash order parameters
   * @param nonce uint256
   * @param expiry uint256
   * @param signerWallet address
   * @param signerToken address
   * @param signerAmount uint256
   * @param senderToken address
   * @param senderAmount uint256
   * @return bytes32
   */
  function _getOrderHash(
    uint256 nonce,
    uint256 expiry,
    address signerWallet,
    address signerToken,
    uint256 signerAmount,
    address senderWallet,
    address senderToken,
    uint256 senderAmount
  ) internal view returns (bytes32) {
    return
      keccak256(
        abi.encode(
          ORDER_TYPEHASH,
          nonce,
          expiry,
          signerWallet,
          signerToken,
          signerAmount,
          protocolFee,
          senderWallet,
          senderToken,
          senderAmount
        )
      );
  }

  /**
   * @notice Recover the signatory from a signature
   * @param hash bytes32
   * @param v uint8
   * @param r bytes32
   * @param s bytes32
   */
  function _getSignatory(
    bytes32 hash,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) internal view returns (address) {
    return
      ecrecover(
        keccak256(abi.encodePacked("\x19\x01", DOMAIN_SEPARATOR, hash)),
        v,
        r,
        s
      );
  }
}
// File: ISwap.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.8.17;

interface ISwap {
  struct Order {
    uint256 nonce;
    uint256 expiry;
    address signerWallet;
    address signerToken;
    uint256 signerAmount;
    address senderWallet;
    address senderToken;
    uint256 senderAmount;
    uint8 v;
    bytes32 r;
    bytes32 s;
  }

  event Swap(
    uint256 indexed nonce,
    uint256 timestamp,
    address indexed signerWallet,
    address signerToken,
    uint256 signerAmount,
    uint256 protocolFee,
    address indexed senderWallet,
    address senderToken,
    uint256 senderAmount
  );

  event Cancel(uint256 indexed nonce, address indexed signerWallet);

  event Authorize(address indexed signer, address indexed signerWallet);

  event Revoke(address indexed signer, address indexed signerWallet);

  event SetProtocolFee(uint256 protocolFee);

  event SetProtocolFeeWallet(address indexed feeWallet);

  function swapAnySender(
    address recipient,
    uint256 nonce,
    uint256 expiry,
    address signerWallet,
    address signerToken,
    uint256 signerAmount,
    address senderToken,
    uint256 senderAmount,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) external;

  function swapWithRecipient(
    uint256 nonce,
    uint256 expiry,
    address signerWallet,
    address signerToken,
    uint256 signerAmount,
    address senderToken,
    uint256 senderAmount,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) external;

  function authorize(address sender) external;

  function revoke() external;

  function cancel(uint256[] calldata nonces) external;

  function nonceUsed(address, uint256) external view returns (bool);

  function authorized(address) external view returns (address);
}
// File: @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../extensions/draft-IERC20Permit.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));
        }
    }

    function safePermit(
        IERC20Permit token,
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        uint256 nonceBefore = token.nonces(owner);
        token.permit(owner, spender, value, deadline, v, r, s);
        uint256 nonceAfter = token.nonces(owner);
        require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
    }

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

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

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (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 Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

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

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

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (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 functionCallWithValue(target, data, 0, "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");
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, 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) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, 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) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or 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 {
            _revert(returndata, errorMessage);
        }
    }

    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // Look for revert reason and bubble it up if present
        if (returndata.length > 0) {
            // The easiest way to bubble the revert reason is using memory via assembly
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert(errorMessage);
        }
    }
}

// File: @openzeppelin/contracts/token/ERC20/extensions/draft-IERC20Permit.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/draft-IERC20Permit.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

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



// 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/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;
    }
}