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

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

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

// 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;
    }
}

// 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
// OpenZeppelin Contracts v4.4.1 (token/ERC721/ERC721.sol)

pragma solidity ^0.8.0;

import "./IERC721.sol";
import "./IERC721Receiver.sol";
import "./extensions/IERC721Metadata.sol";
import "../../utils/Address.sol";
import "../../utils/Context.sol";
import "../../utils/Strings.sol";
import "../../utils/introspection/ERC165.sol";

/**
 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
 * the Metadata extension, but not including the Enumerable extension, which is available separately as
 * {ERC721Enumerable}.
 */
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
    using Address for address;
    using Strings for uint256;

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    // Mapping from token ID to owner address
    mapping(uint256 => address) private _owners;

    // Mapping owner address to token count
    mapping(address => uint256) private _balances;

    // Mapping from token ID to approved address
    mapping(uint256 => address) private _tokenApprovals;

    // Mapping from owner to operator approvals
    mapping(address => mapping(address => bool)) private _operatorApprovals;

    /**
     * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
        return
            interfaceId == type(IERC721).interfaceId ||
            interfaceId == type(IERC721Metadata).interfaceId ||
            super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC721-balanceOf}.
     */
    function balanceOf(address owner) public view virtual override returns (uint256) {
        require(owner != address(0), "ERC721: balance query for the zero address");
        return _balances[owner];
    }

    /**
     * @dev See {IERC721-ownerOf}.
     */
    function ownerOf(uint256 tokenId) public view virtual override returns (address) {
        address owner = _owners[tokenId];
        require(owner != address(0), "ERC721: owner query for nonexistent token");
        return owner;
    }

    /**
     * @dev See {IERC721Metadata-name}.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev See {IERC721Metadata-symbol}.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev See {IERC721Metadata-tokenURI}.
     */
    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");

        string memory baseURI = _baseURI();
        return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
    }

    /**
     * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
     * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
     * by default, can be overriden in child contracts.
     */
    function _baseURI() internal view virtual returns (string memory) {
        return "";
    }

    /**
     * @dev See {IERC721-approve}.
     */
    function approve(address to, uint256 tokenId) public virtual override {
        address owner = ERC721.ownerOf(tokenId);
        require(to != owner, "ERC721: approval to current owner");

        require(
            _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
            "ERC721: approve caller is not owner nor approved for all"
        );

        _approve(to, tokenId);
    }

    /**
     * @dev See {IERC721-getApproved}.
     */
    function getApproved(uint256 tokenId) public view virtual override returns (address) {
        require(_exists(tokenId), "ERC721: approved query for nonexistent token");

        return _tokenApprovals[tokenId];
    }

    /**
     * @dev See {IERC721-setApprovalForAll}.
     */
    function setApprovalForAll(address operator, bool approved) public virtual override {
        _setApprovalForAll(_msgSender(), operator, approved);
    }

    /**
     * @dev See {IERC721-isApprovedForAll}.
     */
    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
        return _operatorApprovals[owner][operator];
    }

    /**
     * @dev See {IERC721-transferFrom}.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");

        _transfer(from, to, tokenId);
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        safeTransferFrom(from, to, tokenId, "");
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
        _safeTransfer(from, to, tokenId, _data);
    }

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * `_data` is additional data, it has no specified format and it is sent in call to `to`.
     *
     * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
     * implement alternative mechanisms to perform token transfer, such as signature-based.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeTransfer(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) internal virtual {
        _transfer(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Returns whether `tokenId` exists.
     *
     * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
     *
     * Tokens start existing when they are minted (`_mint`),
     * and stop existing when they are burned (`_burn`).
     */
    function _exists(uint256 tokenId) internal view virtual returns (bool) {
        return _owners[tokenId] != address(0);
    }

    /**
     * @dev Returns whether `spender` is allowed to manage `tokenId`.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
        require(_exists(tokenId), "ERC721: operator query for nonexistent token");
        address owner = ERC721.ownerOf(tokenId);
        return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
    }

    /**
     * @dev Safely mints `tokenId` and transfers it to `to`.
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeMint(address to, uint256 tokenId) internal virtual {
        _safeMint(to, tokenId, "");
    }

    /**
     * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
     * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
     */
    function _safeMint(
        address to,
        uint256 tokenId,
        bytes memory _data
    ) internal virtual {
        _mint(to, tokenId);
        require(
            _checkOnERC721Received(address(0), to, tokenId, _data),
            "ERC721: transfer to non ERC721Receiver implementer"
        );
    }

    /**
     * @dev Mints `tokenId` and transfers it to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - `to` cannot be the zero address.
     *
     * Emits a {Transfer} event.
     */
    function _mint(address to, uint256 tokenId) internal virtual {
        require(to != address(0), "ERC721: mint to the zero address");
        require(!_exists(tokenId), "ERC721: token already minted");

        _beforeTokenTransfer(address(0), to, tokenId);

        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(address(0), to, tokenId);
    }

    /**
     * @dev Destroys `tokenId`.
     * The approval is cleared when the token is burned.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     *
     * Emits a {Transfer} event.
     */
    function _burn(uint256 tokenId) internal virtual {
        address owner = ERC721.ownerOf(tokenId);

        _beforeTokenTransfer(owner, address(0), tokenId);

        // Clear approvals
        _approve(address(0), tokenId);

        _balances[owner] -= 1;
        delete _owners[tokenId];

        emit Transfer(owner, address(0), tokenId);
    }

    /**
     * @dev Transfers `tokenId` from `from` to `to`.
     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     *
     * Emits a {Transfer} event.
     */
    function _transfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {
        require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer of token that is not own");
        require(to != address(0), "ERC721: transfer to the zero address");

        _beforeTokenTransfer(from, to, tokenId);

        // Clear approvals from the previous owner
        _approve(address(0), tokenId);

        _balances[from] -= 1;
        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(from, to, tokenId);
    }

    /**
     * @dev Approve `to` to operate on `tokenId`
     *
     * Emits a {Approval} event.
     */
    function _approve(address to, uint256 tokenId) internal virtual {
        _tokenApprovals[tokenId] = to;
        emit Approval(ERC721.ownerOf(tokenId), to, tokenId);
    }

    /**
     * @dev Approve `operator` to operate on all of `owner` tokens
     *
     * Emits a {ApprovalForAll} event.
     */
    function _setApprovalForAll(
        address owner,
        address operator,
        bool approved
    ) internal virtual {
        require(owner != operator, "ERC721: approve to caller");
        _operatorApprovals[owner][operator] = approved;
        emit ApprovalForAll(owner, operator, approved);
    }

    /**
     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
     * The call is not executed if the target address is not a contract.
     *
     * @param from address representing the previous owner of the given token ID
     * @param to target address that will receive the tokens
     * @param tokenId uint256 ID of the token to be transferred
     * @param _data bytes optional data to send along with the call
     * @return bool whether the call correctly returned the expected magic value
     */
    function _checkOnERC721Received(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) private returns (bool) {
        if (to.isContract()) {
            try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
                return retval == IERC721Receiver.onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert("ERC721: transfer to non ERC721Receiver implementer");
                } else {
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        } else {
            return true;
        }
    }

    /**
     * @dev Hook that is called before any token transfer. This includes minting
     * and burning.
     *
     * Calling conditions:
     *
     * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
     * transferred to `to`.
     * - When `from` is zero, `tokenId` will be minted for `to`.
     * - When `to` is zero, ``from``'s `tokenId` will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {}
}

// 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 (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;

import "../../utils/introspection/IERC165.sol";

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes calldata data
    ) external;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/IERC721Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC721.sol";

/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Metadata is IERC721 {
    /**
     * @dev Returns the token collection name.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the token collection symbol.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
     */
    function tokenURI(uint256 tokenId) external view returns (string memory);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/IERC721Receiver.sol)

pragma solidity ^0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
    /**
     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
     *
     * The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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 SetProtocolFeeLight(uint256 protocolFeeLight);

  event SetProtocolFeeWallet(address indexed feeWallet);

  event SetRebateScale(uint256 rebateScale);

  event SetRebateMax(uint256 rebateMax);

  event SetStaking(address indexed staking);

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

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

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

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

  function swapNFTs(
    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);

  function calculateProtocolFee(address, uint256)
    external
    view
    returns (uint256);
}

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

pragma solidity ^0.8.0;

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

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

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

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

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

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

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

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

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

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

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

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @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] = _HEX_SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }
}

// SPDX-License-Identifier: MIT

/* solhint-disable var-name-mixedcase */
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "./interfaces/ISwap.sol";

/**
 * @title AirSwap: Atomic Token Swap
 * @notice https://www.airswap.io/
 */
contract Swap is ISwap, Ownable {
  using SafeERC20 for IERC20;

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

  bytes32 public constant ORDER_TYPEHASH =
    keccak256(
      abi.encodePacked(
        "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("SWAP");
  bytes32 public constant DOMAIN_VERSION = keccak256("3");
  uint256 public immutable DOMAIN_CHAIN_ID;
  bytes32 public immutable DOMAIN_SEPARATOR;

  uint256 internal constant MAX_PERCENTAGE = 100;
  uint256 internal constant MAX_SCALE = 77;
  uint256 internal constant MAX_ERROR_COUNT = 6;
  uint256 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;
  uint256 public protocolFeeLight;
  address public protocolFeeWallet;
  uint256 public rebateScale;
  uint256 public rebateMax;
  address public staking;

  constructor(
    uint256 _protocolFee,
    uint256 _protocolFeeLight,
    address _protocolFeeWallet,
    uint256 _rebateScale,
    uint256 _rebateMax,
    address _staking
  ) {
    require(_protocolFee < FEE_DIVISOR, "INVALID_FEE");
    require(_protocolFeeLight < FEE_DIVISOR, "INVALID_FEE");
    require(_protocolFeeWallet != address(0), "INVALID_FEE_WALLET");
    require(_rebateScale <= MAX_SCALE, "SCALE_TOO_HIGH");
    require(_rebateMax <= MAX_PERCENTAGE, "MAX_TOO_HIGH");
    require(_staking != address(0), "INVALID_STAKING");

    uint256 currentChainId = getChainId();
    DOMAIN_CHAIN_ID = currentChainId;
    DOMAIN_SEPARATOR = keccak256(
      abi.encode(
        DOMAIN_TYPEHASH,
        DOMAIN_NAME,
        DOMAIN_VERSION,
        currentChainId,
        this
      )
    );

    protocolFee = _protocolFee;
    protocolFeeLight = _protocolFeeLight;
    protocolFeeWallet = _protocolFeeWallet;
    rebateScale = _rebateScale;
    rebateMax = _rebateMax;
    staking = _staking;
  }

  /**
   * @notice Atomic ERC20 Swap
   * @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 swap(
    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,
      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);

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

  /**
   * @notice Swap Atomic ERC20 Swap (Low Gas Usage)
   * @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 light(
    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,
              protocolFeeLight,
              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 * protocolFeeLight) / FEE_DIVISOR
    );

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

  /**
   * @notice Sender Buys an NFT (ERC721)
   * @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 ERC721 token transferred from the signer
   * @param signerID uint256 Token ID 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 buyNFT(
    uint256 nonce,
    uint256 expiry,
    address signerWallet,
    address signerToken,
    uint256 signerID,
    address senderToken,
    uint256 senderAmount,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) public override {
    _checkValidOrder(
      nonce,
      expiry,
      signerWallet,
      signerToken,
      signerID,
      senderToken,
      senderAmount,
      v,
      r,
      s
    );

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

    // Transfer token from signer to recipient
    IERC721(signerToken).transferFrom(signerWallet, msg.sender, signerID);

    // Calculate and transfer protocol fee and rebate
    _transferProtocolFee(senderToken, msg.sender, senderAmount);

    emit Swap(
      nonce,
      block.timestamp,
      signerWallet,
      signerToken,
      signerID,
      protocolFee,
      msg.sender,
      senderToken,
      senderAmount
    );
  }

  /**
   * @notice Sender Sells an NFT (ERC721)
   * @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 ERC721 token transferred from the sender
   * @param senderID uint256 Token ID 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 sellNFT(
    uint256 nonce,
    uint256 expiry,
    address signerWallet,
    address signerToken,
    uint256 signerAmount,
    address senderToken,
    uint256 senderID,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) public override {
    _checkValidOrder(
      nonce,
      expiry,
      signerWallet,
      signerToken,
      signerAmount,
      senderToken,
      senderID,
      v,
      r,
      s
    );

    // Transfer token from sender to signer
    IERC721(senderToken).transferFrom(msg.sender, signerWallet, senderID);

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

    // Calculate and transfer protocol fee and rebate
    _transferProtocolFee(signerToken, signerWallet, signerAmount);

    emit Swap(
      nonce,
      block.timestamp,
      signerWallet,
      signerToken,
      signerAmount,
      protocolFee,
      msg.sender,
      senderToken,
      senderID
    );
  }

  /**
   * @notice Signer and sender swap NFTs (ERC721)
   * @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 ERC721 token transferred from the signer
   * @param signerID uint256 Token ID transferred from the signer
   * @param senderToken address ERC721 token transferred from the sender
   * @param senderID uint256 Token ID 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 swapNFTs(
    uint256 nonce,
    uint256 expiry,
    address signerWallet,
    address signerToken,
    uint256 signerID,
    address senderToken,
    uint256 senderID,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) public override {
    _checkValidOrder(
      nonce,
      expiry,
      signerWallet,
      signerToken,
      signerID,
      senderToken,
      senderID,
      v,
      r,
      s
    );

    // Transfer token from sender to signer
    IERC721(senderToken).transferFrom(msg.sender, signerWallet, senderID);

    // Transfer token from signer to sender
    IERC721(signerToken).transferFrom(signerWallet, msg.sender, signerID);

    emit Swap(
      nonce,
      block.timestamp,
      signerWallet,
      signerToken,
      signerID,
      0,
      msg.sender,
      senderToken,
      senderID
    );
  }

  /**
   * @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 light fee
   * @param _protocolFeeLight uint256 Value of the fee in basis points
   */
  function setProtocolFeeLight(uint256 _protocolFeeLight) external onlyOwner {
    // Ensure the fee is less than divisor
    require(_protocolFeeLight < FEE_DIVISOR, "INVALID_FEE_LIGHT");
    protocolFeeLight = _protocolFeeLight;
    emit SetProtocolFeeLight(_protocolFeeLight);
  }

  /**
   * @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 Set scale
   * @dev Only owner
   * @param _rebateScale uint256
   */
  function setRebateScale(uint256 _rebateScale) external onlyOwner {
    require(_rebateScale <= MAX_SCALE, "SCALE_TOO_HIGH");
    rebateScale = _rebateScale;
    emit SetRebateScale(_rebateScale);
  }

  /**
   * @notice Set max
   * @dev Only owner
   * @param _rebateMax uint256
   */
  function setRebateMax(uint256 _rebateMax) external onlyOwner {
    require(_rebateMax <= MAX_PERCENTAGE, "MAX_TOO_HIGH");
    rebateMax = _rebateMax;
    emit SetRebateMax(_rebateMax);
  }

  /**
   * @notice Set the staking token
   * @param newstaking address Token to check balances on
   */
  function setStaking(address newstaking) external onlyOwner {
    // Ensure the new staking token is not null
    require(newstaking != address(0), "INVALID_STAKING");
    staking = newstaking;
    emit SetStaking(newstaking);
  }

  /**
   * @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++;
      }
    }

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

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

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

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

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

  /**
   * @notice Calculate output amount for an input score
   * @param stakingBalance uint256
   * @param feeAmount uint256
   */
  function calculateDiscount(uint256 stakingBalance, uint256 feeAmount)
    public
    view
    returns (uint256)
  {
    uint256 divisor = (uint256(10)**rebateScale) + stakingBalance;
    return (rebateMax * stakingBalance * feeAmount) / divisor / 100;
  }

  /**
   * @notice Calculates and refers fee amount
   * @param wallet address
   * @param amount uint256
   */
  function calculateProtocolFee(address wallet, uint256 amount)
    public
    view
    override
    returns (uint256)
  {
    // Transfer fee from signer to feeWallet
    uint256 feeAmount = (amount * protocolFee) / FEE_DIVISOR;
    if (feeAmount > 0) {
      uint256 discountAmount = calculateDiscount(
        IERC20(staking).balanceOf(wallet),
        feeAmount
      );
      return feeAmount - discountAmount;
    }
    return feeAmount;
  }

  /**
   * @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 (uint256 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 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,
      msg.sender,
      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] == 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
      );
  }

  /**
   * @notice Calculates and transfers protocol fee and rebate
   * @param sourceToken address
   * @param sourceWallet address
   * @param amount uint256
   */
  function _transferProtocolFee(
    address sourceToken,
    address sourceWallet,
    uint256 amount
  ) internal {
    // Transfer fee from signer to feeWallet
    uint256 feeAmount = (amount * protocolFee) / FEE_DIVISOR;
    if (feeAmount > 0) {
      uint256 discountAmount = calculateDiscount(
        IERC20(staking).balanceOf(msg.sender),
        feeAmount
      );
      if (discountAmount > 0) {
        // Transfer fee from signer to sender
        IERC20(sourceToken).safeTransferFrom(
          sourceWallet,
          msg.sender,
          discountAmount
        );
        // Transfer fee from signer to feeWallet
        IERC20(sourceToken).safeTransferFrom(
          sourceWallet,
          protocolFeeWallet,
          feeAmount - discountAmount
        );
      } else {
        IERC20(sourceToken).safeTransferFrom(
          sourceWallet,
          protocolFeeWallet,
          feeAmount
        );
      }
    }
  }
}

{
  "compilationTarget": {
    "contracts/Swap.sol": "Swap"
  },
  "evmVersion": "london",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 999999
  },
  "remappings": []
}