// Sources flattened with hardhat v2.7.0 https://hardhat.org

// File @openzeppelin/contracts/utils/Address.sol@v4.7.0


// OpenZeppelin Contracts (last updated v4.7.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly
                /// @solidity memory-safe-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}


// File @openzeppelin/contracts/utils/introspection/IERC165.sol@v4.7.0


// 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);
}


// File @openzeppelin/contracts/token/ERC721/IERC721.sol@v4.7.0


// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;

/**
 * @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`.
     *
     * 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;

    /**
     * @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 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 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 the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @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);
}


// File @openzeppelin/contracts/token/ERC721/IERC721Receiver.sol@v4.7.0


// OpenZeppelin Contracts (last updated v4.6.0) (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 `IERC721Receiver.onERC721Received.selector`.
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}


// File @openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol@v4.7.0


// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/IERC721Metadata.sol)

pragma solidity ^0.8.0;

/**
 * @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);
}


// File @openzeppelin/contracts/utils/Context.sol@v4.7.0


// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}


// File @openzeppelin/contracts/utils/Strings.sol@v4.7.0


// OpenZeppelin Contracts (last updated v4.7.0) (utils/Strings.sol)

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";
    uint8 private constant _ADDRESS_LENGTH = 20;

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // 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);
    }

    /**
     * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
     */
    function toHexString(address addr) internal pure returns (string memory) {
        return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
    }
}


// File @openzeppelin/contracts/utils/introspection/ERC165.sol@v4.7.0


// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)

pragma solidity ^0.8.0;

/**
 * @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;
    }
}


// File @openzeppelin/contracts/token/ERC721/ERC721.sol@v4.7.0


// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC721/ERC721.sol)

pragma solidity ^0.8.0;







/**
 * @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: address zero is not a valid owner");
        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: invalid token ID");
        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) {
        _requireMinted(tokenId);

        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 overridden 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 token owner nor approved for all"
        );

        _approve(to, tokenId);
    }

    /**
     * @dev See {IERC721-getApproved}.
     */
    function getApproved(uint256 tokenId) public view virtual override returns (address) {
        _requireMinted(tokenId);

        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: caller is not token 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: caller is not token 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) {
        address owner = ERC721.ownerOf(tokenId);
        return (spender == owner || isApprovedForAll(owner, spender) || getApproved(tokenId) == 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);

        _afterTokenTransfer(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);

        _afterTokenTransfer(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 from incorrect owner");
        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);

        _afterTokenTransfer(from, to, tokenId);
    }

    /**
     * @dev Approve `to` to operate on `tokenId`
     *
     * Emits an {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 an {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 Reverts if the `tokenId` has not been minted yet.
     */
    function _requireMinted(uint256 tokenId) internal view virtual {
        require(_exists(tokenId), "ERC721: invalid token ID");
    }

    /**
     * @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 {
                    /// @solidity memory-safe-assembly
                    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 {}

    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {}
}


// File @openzeppelin/contracts/token/ERC721/extensions/IERC721Enumerable.sol@v4.7.0


// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC721/extensions/IERC721Enumerable.sol)

pragma solidity ^0.8.0;

/**
 * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Enumerable is IERC721 {
    /**
     * @dev Returns the total amount of tokens stored by the contract.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns a token ID owned by `owner` at a given `index` of its token list.
     * Use along with {balanceOf} to enumerate all of ``owner``'s tokens.
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256);

    /**
     * @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
     * Use along with {totalSupply} to enumerate all tokens.
     */
    function tokenByIndex(uint256 index) external view returns (uint256);
}


// File @openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol@v4.7.0


// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/ERC721Enumerable.sol)

pragma solidity ^0.8.0;


/**
 * @dev This implements an optional extension of {ERC721} defined in the EIP that adds
 * enumerability of all the token ids in the contract as well as all token ids owned by each
 * account.
 */
abstract contract ERC721Enumerable is ERC721, IERC721Enumerable {
    // Mapping from owner to list of owned token IDs
    mapping(address => mapping(uint256 => uint256)) private _ownedTokens;

    // Mapping from token ID to index of the owner tokens list
    mapping(uint256 => uint256) private _ownedTokensIndex;

    // Array with all token ids, used for enumeration
    uint256[] private _allTokens;

    // Mapping from token id to position in the allTokens array
    mapping(uint256 => uint256) private _allTokensIndex;

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(IERC165, ERC721) returns (bool) {
        return interfaceId == type(IERC721Enumerable).interfaceId || super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC721Enumerable-tokenOfOwnerByIndex}.
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) public view virtual override returns (uint256) {
        require(index < ERC721.balanceOf(owner), "ERC721Enumerable: owner index out of bounds");
        return _ownedTokens[owner][index];
    }

    /**
     * @dev See {IERC721Enumerable-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _allTokens.length;
    }

    /**
     * @dev See {IERC721Enumerable-tokenByIndex}.
     */
    function tokenByIndex(uint256 index) public view virtual override returns (uint256) {
        require(index < ERC721Enumerable.totalSupply(), "ERC721Enumerable: global index out of bounds");
        return _allTokens[index];
    }

    /**
     * @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` cannot be the zero address.
     * - `to` cannot be the zero address.
     *
     * 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 override {
        super._beforeTokenTransfer(from, to, tokenId);

        if (from == address(0)) {
            _addTokenToAllTokensEnumeration(tokenId);
        } else if (from != to) {
            _removeTokenFromOwnerEnumeration(from, tokenId);
        }
        if (to == address(0)) {
            _removeTokenFromAllTokensEnumeration(tokenId);
        } else if (to != from) {
            _addTokenToOwnerEnumeration(to, tokenId);
        }
    }

    /**
     * @dev Private function to add a token to this extension's ownership-tracking data structures.
     * @param to address representing the new owner of the given token ID
     * @param tokenId uint256 ID of the token to be added to the tokens list of the given address
     */
    function _addTokenToOwnerEnumeration(address to, uint256 tokenId) private {
        uint256 length = ERC721.balanceOf(to);
        _ownedTokens[to][length] = tokenId;
        _ownedTokensIndex[tokenId] = length;
    }

    /**
     * @dev Private function to add a token to this extension's token tracking data structures.
     * @param tokenId uint256 ID of the token to be added to the tokens list
     */
    function _addTokenToAllTokensEnumeration(uint256 tokenId) private {
        _allTokensIndex[tokenId] = _allTokens.length;
        _allTokens.push(tokenId);
    }

    /**
     * @dev Private function to remove a token from this extension's ownership-tracking data structures. Note that
     * while the token is not assigned a new owner, the `_ownedTokensIndex` mapping is _not_ updated: this allows for
     * gas optimizations e.g. when performing a transfer operation (avoiding double writes).
     * This has O(1) time complexity, but alters the order of the _ownedTokens array.
     * @param from address representing the previous owner of the given token ID
     * @param tokenId uint256 ID of the token to be removed from the tokens list of the given address
     */
    function _removeTokenFromOwnerEnumeration(address from, uint256 tokenId) private {
        // To prevent a gap in from's tokens array, we store the last token in the index of the token to delete, and
        // then delete the last slot (swap and pop).

        uint256 lastTokenIndex = ERC721.balanceOf(from) - 1;
        uint256 tokenIndex = _ownedTokensIndex[tokenId];

        // When the token to delete is the last token, the swap operation is unnecessary
        if (tokenIndex != lastTokenIndex) {
            uint256 lastTokenId = _ownedTokens[from][lastTokenIndex];

            _ownedTokens[from][tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
            _ownedTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
        }

        // This also deletes the contents at the last position of the array
        delete _ownedTokensIndex[tokenId];
        delete _ownedTokens[from][lastTokenIndex];
    }

    /**
     * @dev Private function to remove a token from this extension's token tracking data structures.
     * This has O(1) time complexity, but alters the order of the _allTokens array.
     * @param tokenId uint256 ID of the token to be removed from the tokens list
     */
    function _removeTokenFromAllTokensEnumeration(uint256 tokenId) private {
        // To prevent a gap in the tokens array, we store the last token in the index of the token to delete, and
        // then delete the last slot (swap and pop).

        uint256 lastTokenIndex = _allTokens.length - 1;
        uint256 tokenIndex = _allTokensIndex[tokenId];

        // When the token to delete is the last token, the swap operation is unnecessary. However, since this occurs so
        // rarely (when the last minted token is burnt) that we still do the swap here to avoid the gas cost of adding
        // an 'if' statement (like in _removeTokenFromOwnerEnumeration)
        uint256 lastTokenId = _allTokens[lastTokenIndex];

        _allTokens[tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
        _allTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index

        // This also deletes the contents at the last position of the array
        delete _allTokensIndex[tokenId];
        _allTokens.pop();
    }
}


// File @openzeppelin/contracts/token/ERC721/extensions/ERC721Burnable.sol@v4.7.0


// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC721/extensions/ERC721Burnable.sol)

pragma solidity ^0.8.0;


/**
 * @title ERC721 Burnable Token
 * @dev ERC721 Token that can be burned (destroyed).
 */
abstract contract ERC721Burnable is Context, ERC721 {
    /**
     * @dev Burns `tokenId`. See {ERC721-_burn}.
     *
     * Requirements:
     *
     * - The caller must own `tokenId` or be an approved operator.
     */
    function burn(uint256 tokenId) public virtual {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: caller is not token owner nor approved");
        _burn(tokenId);
    }
}


// File @openzeppelin/contracts/interfaces/IERC2981.sol@v4.7.0


// OpenZeppelin Contracts (last updated v4.6.0) (interfaces/IERC2981.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface for the NFT Royalty Standard.
 *
 * A standardized way to retrieve royalty payment information for non-fungible tokens (NFTs) to enable universal
 * support for royalty payments across all NFT marketplaces and ecosystem participants.
 *
 * _Available since v4.5._
 */
interface IERC2981 is IERC165 {
    /**
     * @dev Returns how much royalty is owed and to whom, based on a sale price that may be denominated in any unit of
     * exchange. The royalty amount is denominated and should be paid in that same unit of exchange.
     */
    function royaltyInfo(uint256 tokenId, uint256 salePrice)
        external
        view
        returns (address receiver, uint256 royaltyAmount);
}


// File @openzeppelin/contracts/token/common/ERC2981.sol@v4.7.0


// OpenZeppelin Contracts (last updated v4.7.0) (token/common/ERC2981.sol)

pragma solidity ^0.8.0;


/**
 * @dev Implementation of the NFT Royalty Standard, a standardized way to retrieve royalty payment information.
 *
 * Royalty information can be specified globally for all token ids via {_setDefaultRoyalty}, and/or individually for
 * specific token ids via {_setTokenRoyalty}. The latter takes precedence over the first.
 *
 * Royalty is specified as a fraction of sale price. {_feeDenominator} is overridable but defaults to 10000, meaning the
 * fee is specified in basis points by default.
 *
 * IMPORTANT: ERC-2981 only specifies a way to signal royalty information and does not enforce its payment. See
 * https://eips.ethereum.org/EIPS/eip-2981#optional-royalty-payments[Rationale] in the EIP. Marketplaces are expected to
 * voluntarily pay royalties together with sales, but note that this standard is not yet widely supported.
 *
 * _Available since v4.5._
 */
abstract contract ERC2981 is IERC2981, ERC165 {
    struct RoyaltyInfo {
        address receiver;
        uint96 royaltyFraction;
    }

    RoyaltyInfo private _defaultRoyaltyInfo;
    mapping(uint256 => RoyaltyInfo) private _tokenRoyaltyInfo;

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(IERC165, ERC165) returns (bool) {
        return interfaceId == type(IERC2981).interfaceId || super.supportsInterface(interfaceId);
    }

    /**
     * @inheritdoc IERC2981
     */
    function royaltyInfo(uint256 _tokenId, uint256 _salePrice) public view virtual override returns (address, uint256) {
        RoyaltyInfo memory royalty = _tokenRoyaltyInfo[_tokenId];

        if (royalty.receiver == address(0)) {
            royalty = _defaultRoyaltyInfo;
        }

        uint256 royaltyAmount = (_salePrice * royalty.royaltyFraction) / _feeDenominator();

        return (royalty.receiver, royaltyAmount);
    }

    /**
     * @dev The denominator with which to interpret the fee set in {_setTokenRoyalty} and {_setDefaultRoyalty} as a
     * fraction of the sale price. Defaults to 10000 so fees are expressed in basis points, but may be customized by an
     * override.
     */
    function _feeDenominator() internal pure virtual returns (uint96) {
        return 10000;
    }

    /**
     * @dev Sets the royalty information that all ids in this contract will default to.
     *
     * Requirements:
     *
     * - `receiver` cannot be the zero address.
     * - `feeNumerator` cannot be greater than the fee denominator.
     */
    function _setDefaultRoyalty(address receiver, uint96 feeNumerator) internal virtual {
        require(feeNumerator <= _feeDenominator(), "ERC2981: royalty fee will exceed salePrice");
        require(receiver != address(0), "ERC2981: invalid receiver");

        _defaultRoyaltyInfo = RoyaltyInfo(receiver, feeNumerator);
    }

    /**
     * @dev Removes default royalty information.
     */
    function _deleteDefaultRoyalty() internal virtual {
        delete _defaultRoyaltyInfo;
    }

    /**
     * @dev Sets the royalty information for a specific token id, overriding the global default.
     *
     * Requirements:
     *
     * - `receiver` cannot be the zero address.
     * - `feeNumerator` cannot be greater than the fee denominator.
     */
    function _setTokenRoyalty(
        uint256 tokenId,
        address receiver,
        uint96 feeNumerator
    ) internal virtual {
        require(feeNumerator <= _feeDenominator(), "ERC2981: royalty fee will exceed salePrice");
        require(receiver != address(0), "ERC2981: Invalid parameters");

        _tokenRoyaltyInfo[tokenId] = RoyaltyInfo(receiver, feeNumerator);
    }

    /**
     * @dev Resets royalty information for the token id back to the global default.
     */
    function _resetTokenRoyalty(uint256 tokenId) internal virtual {
        delete _tokenRoyaltyInfo[tokenId];
    }
}


// File contracts/token/IERC4907.sol

pragma solidity 0.8.4;

interface IERC4907 {
  /// Logged when the user of a token assigns a new user or updates expires
  /// @notice Emitted when the `user` of an NFT or the `expires` of the `user` is changed
  /// The zero address for user indicates that there is no user address
  event UpdateUser(uint256 indexed tokenId, address indexed user, uint64 expires);

  /// @notice set the user and expires of a NFT
  /// @dev The zero address indicates there is no user 
  /// Throws if `tokenId` is not valid NFT
  /// @param user  The new user of the NFT
  /// @param expires  UNIX timestamp, The new user could use the NFT before expires
  function setUser(uint256 tokenId, address user, uint64 expires) external;

  /// @notice Get the user address of an NFT
  /// @dev The zero address indicates that there is no user or the user is expired
  /// @param tokenId The NFT to get the user address for
  /// @return The user address for this NFT
  function userOf(uint256 tokenId) external view returns(address);

  /// @notice Get the user expires of an NFT
  /// @dev The zero value indicates that there is no user 
  /// @param tokenId The NFT to get the user expires for
  /// @return The user expires for this NFT
  function userExpires(uint256 tokenId) external view returns(uint256);
}


// File contracts/Error.sol


pragma solidity 0.8.4;

error Unauthorized();

error InvalidNFTId();

error InvalidAddress();

error InvalidSignature();

error InvalidAmount();

error InvalidMaxMintPerTx();

error InvalidMaxMintPerAddress();

error NFTNotLocked();

error Blacklisted();

error NoChangeToTheState();

error ArrayLengthMismatch();

error BlacklistedTransfer();

error NotERC721();

error NotERC1155();

error NotAcceptedERC20();

error NotAcceptedERC721();

error NotAcceptedERC1155();

error NotContract();

error NoBridge();

error NoMinterRole();

error ExceedMinterAllowance();

error MathOverflow();

error NoOperatorRole();

error SaleNotEnded();

error NFTSoldOut();

error SaleNotGoing();

error ExceedMaxMintable();

error InsufficientEth();

error ExceedCap();

error ExceedMaxMintPerTx();

error ExceedMaxMintPerAddress();

error EthReceived();

error InvalidMintingCap();

error NoWhitelist();

error NotOwnerNorApproved();


// File contracts/token/ERC4907.sol

pragma solidity 0.8.4; 



contract ERC4907 is ERC721, IERC4907 {
  struct UserInfo {
    address user;   // address of user role
    uint64 expires; // unix timestamp, user expires
  }

  mapping(uint256 => UserInfo) internal _users;

  constructor(
    string memory name_, 
    string memory symbol_
  ) ERC721(name_, symbol_) { }
  
  /// @notice set the user and expires of a NFT
  /// @dev The zero address indicates there is no user 
  /// Throws if `tokenId` is not valid NFT
  /// @param user  The new user of the NFT
  /// @param expires  UNIX timestamp, The new user could use the NFT before expires
  function setUser(uint256 tokenId, address user, uint64 expires) public virtual override {
    if (!_isApprovedOrOwner(msg.sender, tokenId)) revert NotOwnerNorApproved();
    
    UserInfo storage info = _users[tokenId];
    info.user = user;
    info.expires = expires;
    emit UpdateUser(tokenId, user, expires);
  }

  /// @notice Get the user address of an NFT
  /// @dev The zero address indicates that there is no user or the user is expired
  /// @param tokenId The NFT to get the user address for
  /// @return The user address for this NFT
  function userOf(uint256 tokenId) public view virtual override returns (address) {
    if (uint256(_users[tokenId].expires) >= block.timestamp) {
      return _users[tokenId].user; 
    } else {
      return address(0);
    }
  }

  /// @notice Get the user expires of an NFT
  /// @dev The zero value indicates that there is no user 
  /// @param tokenId The NFT to get the user expires for
  /// @return The user expires for this NFT
  function userExpires(uint256 tokenId) public view virtual override returns (uint256) {
    return _users[tokenId].expires;
  }

  /// @dev See {IERC165-supportsInterface}.
  function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
    return interfaceId == type(IERC4907).interfaceId || super.supportsInterface(interfaceId);
  }

  function _beforeTokenTransfer(
    address from,
    address to,
    uint256 tokenId
  ) internal virtual override{
    super._beforeTokenTransfer(from, to, tokenId);

    if (from != to && _users[tokenId].user != address(0)) {
      delete _users[tokenId];
      emit UpdateUser(tokenId, address(0), 0);
    }
  }
}


// File @openzeppelin/contracts/access/Ownable.sol@v4.7.0


// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

/**
 * @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 contracts/lib/Blacklist.sol


pragma solidity 0.8.4;

contract Blacklist is Ownable {
  // wallet address => blacklisted status
  mapping(address => bool) public blacklist;

  event LogBlacklistAdded(address indexed account);
  event LogBlacklistRemoved(address indexed account);

  /**
    * @dev Add wallet to blacklist
    * `_account` must not be zero address
    */
  function addBlacklist(address[] calldata _accounts) external onlyOwner {
    for (uint256 i = 0; i < _accounts.length; i++) {
      blacklist[_accounts[i]] = true;

      emit LogBlacklistAdded(_accounts[i]);
    }
  }

  /**
    * @dev Remove wallet from blacklist
    */
  function removeBlacklist(address[] calldata _accounts) external onlyOwner {
    for (uint256 i = 0; i < _accounts.length; i++) {
      delete blacklist[_accounts[i]];

      emit LogBlacklistRemoved(_accounts[i]);
    }
  }
}


// File contracts/token/ERC721Blacklisted.sol


pragma solidity 0.8.4;


abstract contract ERC721Blacklisted is ERC721, Blacklist {
  /**
   * @dev Override {ERC721-_beforeTokenTransfer}
   * Disable token transfer for blacklisted wallets
   */
  function _beforeTokenTransfer(
    address _from,
    address _to,
    uint256
  ) internal virtual override {
    require(!blacklist[_from] && !blacklist[_to], "ERC721Blacklisted: TOKEN_TRANSFER_DISABLED");
  }
}


// File @openzeppelin/contracts/security/Pausable.sol@v4.7.0


// OpenZeppelin Contracts (last updated v4.7.0) (security/Pausable.sol)

pragma solidity ^0.8.0;

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor() {
        _paused = false;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        _requireNotPaused();
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        _requirePaused();
        _;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Throws if the contract is paused.
     */
    function _requireNotPaused() internal view virtual {
        require(!paused(), "Pausable: paused");
    }

    /**
     * @dev Throws if the contract is not paused.
     */
    function _requirePaused() internal view virtual {
        require(paused(), "Pausable: not paused");
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}


// File contracts/lib/PausableOwned.sol


pragma solidity 0.8.4;


contract PausableOwned is Ownable, Pausable {
  /**
   * @dev Pause the contract
   * Only `owner` can call
   */
  function pause() public onlyOwner {
    super._pause();
  }

  /**
   * @dev Unpause the contract
   * Only `owner` can call
   */
  function unpause() public onlyOwner {
    super._unpause();
  }
}


// File @openzeppelin/contracts/access/IAccessControl.sol@v4.7.0


// OpenZeppelin Contracts v4.4.1 (access/IAccessControl.sol)

pragma solidity ^0.8.0;

/**
 * @dev External interface of AccessControl declared to support ERC165 detection.
 */
interface IAccessControl {
    /**
     * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
     *
     * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
     * {RoleAdminChanged} not being emitted signaling this.
     *
     * _Available since v3.1._
     */
    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);

    /**
     * @dev Emitted when `account` is granted `role`.
     *
     * `sender` is the account that originated the contract call, an admin role
     * bearer except when using {AccessControl-_setupRole}.
     */
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Emitted when `account` is revoked `role`.
     *
     * `sender` is the account that originated the contract call:
     *   - if using `revokeRole`, it is the admin role bearer
     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
     */
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) external view returns (bool);

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {AccessControl-_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) external view returns (bytes32);

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) external;

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) external;

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) external;
}


// File @openzeppelin/contracts/access/AccessControl.sol@v4.7.0


// OpenZeppelin Contracts (last updated v4.7.0) (access/AccessControl.sol)

pragma solidity ^0.8.0;




/**
 * @dev Contract module that allows children to implement role-based access
 * control mechanisms. This is a lightweight version that doesn't allow enumerating role
 * members except through off-chain means by accessing the contract event logs. Some
 * applications may benefit from on-chain enumerability, for those cases see
 * {AccessControlEnumerable}.
 *
 * Roles are referred to by their `bytes32` identifier. These should be exposed
 * in the external API and be unique. The best way to achieve this is by
 * using `public constant` hash digests:
 *
 * ```
 * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
 * ```
 *
 * Roles can be used to represent a set of permissions. To restrict access to a
 * function call, use {hasRole}:
 *
 * ```
 * function foo() public {
 *     require(hasRole(MY_ROLE, msg.sender));
 *     ...
 * }
 * ```
 *
 * Roles can be granted and revoked dynamically via the {grantRole} and
 * {revokeRole} functions. Each role has an associated admin role, and only
 * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
 *
 * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
 * that only accounts with this role will be able to grant or revoke other
 * roles. More complex role relationships can be created by using
 * {_setRoleAdmin}.
 *
 * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
 * grant and revoke this role. Extra precautions should be taken to secure
 * accounts that have been granted it.
 */
abstract contract AccessControl is Context, IAccessControl, ERC165 {
    struct RoleData {
        mapping(address => bool) members;
        bytes32 adminRole;
    }

    mapping(bytes32 => RoleData) private _roles;

    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;

    /**
     * @dev Modifier that checks that an account has a specific role. Reverts
     * with a standardized message including the required role.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
     *
     * _Available since v4.1._
     */
    modifier onlyRole(bytes32 role) {
        _checkRole(role);
        _;
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IAccessControl).interfaceId || super.supportsInterface(interfaceId);
    }

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) public view virtual override returns (bool) {
        return _roles[role].members[account];
    }

    /**
     * @dev Revert with a standard message if `_msgSender()` is missing `role`.
     * Overriding this function changes the behavior of the {onlyRole} modifier.
     *
     * Format of the revert message is described in {_checkRole}.
     *
     * _Available since v4.6._
     */
    function _checkRole(bytes32 role) internal view virtual {
        _checkRole(role, _msgSender());
    }

    /**
     * @dev Revert with a standard message if `account` is missing `role`.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
     */
    function _checkRole(bytes32 role, address account) internal view virtual {
        if (!hasRole(role, account)) {
            revert(
                string(
                    abi.encodePacked(
                        "AccessControl: account ",
                        Strings.toHexString(uint160(account), 20),
                        " is missing role ",
                        Strings.toHexString(uint256(role), 32)
                    )
                )
            );
        }
    }

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) public view virtual override returns (bytes32) {
        return _roles[role].adminRole;
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     *
     * May emit a {RoleGranted} event.
     */
    function grantRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _grantRole(role, account);
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     *
     * May emit a {RoleRevoked} event.
     */
    function revokeRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _revokeRole(role, account);
    }

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been revoked `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     *
     * May emit a {RoleRevoked} event.
     */
    function renounceRole(bytes32 role, address account) public virtual override {
        require(account == _msgSender(), "AccessControl: can only renounce roles for self");

        _revokeRole(role, account);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event. Note that unlike {grantRole}, this function doesn't perform any
     * checks on the calling account.
     *
     * May emit a {RoleGranted} event.
     *
     * [WARNING]
     * ====
     * This function should only be called from the constructor when setting
     * up the initial roles for the system.
     *
     * Using this function in any other way is effectively circumventing the admin
     * system imposed by {AccessControl}.
     * ====
     *
     * NOTE: This function is deprecated in favor of {_grantRole}.
     */
    function _setupRole(bytes32 role, address account) internal virtual {
        _grantRole(role, account);
    }

    /**
     * @dev Sets `adminRole` as ``role``'s admin role.
     *
     * Emits a {RoleAdminChanged} event.
     */
    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
        bytes32 previousAdminRole = getRoleAdmin(role);
        _roles[role].adminRole = adminRole;
        emit RoleAdminChanged(role, previousAdminRole, adminRole);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * Internal function without access restriction.
     *
     * May emit a {RoleGranted} event.
     */
    function _grantRole(bytes32 role, address account) internal virtual {
        if (!hasRole(role, account)) {
            _roles[role].members[account] = true;
            emit RoleGranted(role, account, _msgSender());
        }
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * Internal function without access restriction.
     *
     * May emit a {RoleRevoked} event.
     */
    function _revokeRole(bytes32 role, address account) internal virtual {
        if (hasRole(role, account)) {
            _roles[role].members[account] = false;
            emit RoleRevoked(role, account, _msgSender());
        }
    }
}


// File contracts/lib/Minterable.sol


pragma solidity 0.8.4;



contract Minterable is AccessControl, Ownable {
  bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");

  // Minter address => allowed minting amount
  mapping(address => uint256) public minterAllowances;

  event LogMinterAdded(address indexed account);

  event LogMinterRemoved(address indexed account);

  event LogAllowanceIncreased(
    address indexed minter,
    uint256 amount
  );

  event LogAllowanceDecreased(
    address indexed minter,
    uint256 amount
  );

  /**
   * @dev Restricted to members of the `minter` role.
   */
  modifier onlyMinter() {
    if (!super.hasRole(MINTER_ROLE, msg.sender)) revert NoMinterRole();

    _;
  }

  /**
   * @dev Throw if `_account` is zero address or contract owner
   */
  modifier notZeroAndOwner(address _account) {
    if (_account == address(0) || _account == owner()) revert InvalidAddress();

    _;
  }

  /**
   * @dev Throw if `_amount` is zero
   */
  modifier notZero(uint256 _amount) {
    if (_amount == 0) revert InvalidAmount();

    _;
  }

  /**
   * @dev Contract owner is minter
   */
  constructor() {
    super._setupRole(DEFAULT_ADMIN_ROLE, msg.sender);
    super._setupRole(MINTER_ROLE, msg.sender);
  }

  /**
   * @dev Increase minting allowance
   *
   * Requirements:
   * - Only contract owner can call
   * @param _minter minter wallet; must not be zero nor owner address
   * @param _amount increasing allowance amount; must not be zero
   */
  function increaseAllowance(
    address _minter,
    uint256 _amount
  ) external onlyOwner notZeroAndOwner(_minter) notZero(_amount) {
    uint256 allowed = minterAllowances[_minter];
    if (allowed > type(uint256).max - _amount) revert MathOverflow();

    unchecked {
      // we will not overflow because of above check
      minterAllowances[_minter] = allowed + _amount;
      emit LogAllowanceIncreased(_minter, allowed + _amount);
    }
  }

  /**
   * @dev See {_decreaseAllowance}
   *
   * Requirements:
   * - Only contract owner can call
   */
  function decreaseAllowance(
    address _minter,
    uint256 _amount
  ) external onlyOwner {
    _decreaseAllowance(_minter, _amount);
  }

  /**
   * @dev Add a new minter
   *
   * Requirements:
   * - Only contract owner can call
   * @param _account minter address; must not be zero address; must not be minter
   */
  function addMinter(address _account) external onlyOwner {
    if (_account == address(0)) revert InvalidAddress();
    
    super._grantRole(MINTER_ROLE, _account);
    emit LogMinterAdded(_account);
  }

  /**
   * @dev Remove minter
   *
   * Requirements:
   * - Only contract owner can call
   * @param _account minter address; must be minter
   */
  function removeMinter(address _account) external onlyOwner {
    super._revokeRole(MINTER_ROLE, _account);
    emit LogMinterRemoved(_account);
  }

  /**
   * @dev Check minter role ownership
   * @param _account checking account
   */
  function isMinter(address _account) external view returns (bool) {
    return super.hasRole(MINTER_ROLE, _account);
  }  

  /**
   * @dev Override {Ownable-transferOwnership}
   * Super method has `onlyOwner` modifier
   * Revoke default admin role and minter role from old owner and grant to new owner
   * @param _newOwner new owner address; must not be zero address
   */
  function transferOwnership(address _newOwner) public virtual override {
    address oldOwner = owner();
    super._revokeRole(DEFAULT_ADMIN_ROLE, oldOwner);
    super._revokeRole(MINTER_ROLE, oldOwner);
    super._grantRole(DEFAULT_ADMIN_ROLE, _newOwner);
    super._grantRole(MINTER_ROLE, _newOwner);
    super.transferOwnership(_newOwner);
  }

  /**
   * @dev Decrease minting allowance
   * @param _minter minter wallet; must not be zero nor owner address
   * @param _amount increasing allowance amount; must not be zero; must not exceed current allowance
   */
  function _decreaseAllowance(
    address _minter,
    uint256 _amount
  ) internal notZeroAndOwner(_minter) notZero(_amount) {
    uint256 allowed = minterAllowances[_minter];
    if (_amount > allowed) revert ExceedMinterAllowance();

    unchecked {
      // we will not underflow because of above check
      minterAllowances[_minter] = allowed - _amount;
      emit LogAllowanceDecreased(_minter, allowed - _amount);
    }
  }
}


// File contracts/token/Asset.sol


pragma solidity 0.8.4;









contract Asset is ERC721Enumerable, ERC721Burnable, ERC721Blacklisted, ERC2981, ERC4907, PausableOwned, Minterable {
  using Address for address;
  
  // Base token URI
  string public baseTokenURI;

  // Last token ID
  uint256 public tokenId;

  event LogMinted(
    address indexed account, 
    uint256 indexed tokenId
  );

  event LogBurnt(uint256 indexed tokenId);

  event LogBaseTokenURISet(string baseTokenURI);

  /**
   * @dev Throw if minting allowance is exceeded for non owner minter
   * @param _address minter wallet
   * @param _amount minting amount
   */
  modifier decreaseValidAllowance(
    address _address,
    uint256 _amount
  ) {
    if (_address != owner()) super._decreaseAllowance(_address, _amount);

    _;
  }

  constructor(
    string memory _name,
    string memory _symbol,
    string memory _baseTokenURI,
    uint256 _lastTokenId
  ) ERC4907(_name, _symbol) {
    baseTokenURI = _baseTokenURI;
    tokenId = _lastTokenId;
  }

  /**
   * @dev Set base token uri
   *
   * Requirements:
   * - Only `owner` can call
   * @param _baseTokenURI new base token uri string
   */
  function setBaseTokenURI(string memory _baseTokenURI) external onlyOwner {
    if (keccak256(abi.encodePacked(_baseTokenURI)) == keccak256(abi.encodePacked(baseTokenURI))) {
      revert NoChangeToTheState();
    }

    baseTokenURI = _baseTokenURI;
    emit LogBaseTokenURISet(_baseTokenURI);
  }

  /**
   * See {ERC2981-_setDefaultRoyalty}
   *
   * Requirements:
   * - Only `owner` can call
   */
  function setDefaultRoyalty(
    address _receiver, 
    uint96 _feeNumerator
  ) external onlyOwner {
    super._setDefaultRoyalty(_receiver, _feeNumerator);
  }

  /**
   * See {ERC2981-_deleteDefaultRoyalty}
   *
   * Requirements:
   * - Only `owner` can call
   */
  function deleteDefaultRoyalty() external onlyOwner {
    super._deleteDefaultRoyalty();
  }

  /**
   * See {ERC2981-_setTokenRoyalty}
   *
   * Requirements:
   * - Only `owner` can call
   */
  function setTokenRoyalty(
    uint256 _tokenId,
    address _receiver,
    uint96 _feeNumerator
  ) external onlyOwner {
    super._setTokenRoyalty(_tokenId, _receiver, _feeNumerator);
  }

  /**
   * See {ERC2981-_resetTokenRoyalty}
   *
   * Requirements:
   * - Only `owner` can call
   */
  function resetTokenRoyalty(uint256 _tokenId) external onlyOwner {
    super._resetTokenRoyalty(_tokenId);
  }
  
  /**
   * @dev Mint a new token
   *
   * Requirements:
   * - Only minter can call (contract owner is minter)
   * - Check minting allowance for non owner minter
   * @param _account receiver wallet
   * @return newTokenId incremented new token id
   */
  function mint(address _account) 
    external 
    onlyMinter 
    decreaseValidAllowance(msg.sender, 1) 
    returns (uint256 newTokenId) 
  {
    unchecked { 
      // we will not overflow on `tokenId` in a lifetime
      newTokenId = ++tokenId;
    }
    
    super._mint(_account, newTokenId);
    emit LogMinted(_account, newTokenId);
  }

  /**
   * @dev Mint a new token for cross-chain transfer
   *
   * Requirements:
   * - Only bridge contract can call (bridge contract is minter)
   * - Check minting allowance for bridge contract
   * @param _account receiver wallet
   * @param _tokenId minting token id
   */
  function mint(
    address _account,
    uint256 _tokenId
  ) external 
    onlyMinter 
    decreaseValidAllowance(msg.sender, 1) 
  {
    super._mint(_account, _tokenId);
    emit LogMinted(_account, _tokenId);
  }

  /**
   * @dev Mint a batch of tokens
   * Zero amount check is done in {Minterable:_decreaseAllowance}
   *
   * Requirements:
   * - Only minter can call (contract owner is minter)
   * - Check minting allowance for non owner minter
   * @param _account receiver wallet
   * @param _amount minting amount; must not be zero
   */
  function mintBatch(
    address _account,
    uint256 _amount
  ) external onlyMinter decreaseValidAllowance(msg.sender, _amount) {
    unchecked { 
      // we are not accepting enough data to overflow on `_amount`
      for (uint256 i = 0; i < _amount; i++) {
        // we will not overflow on `tokenId` in a lifetime
        uint256 newTokenId = ++tokenId; 
        super._mint(_account, newTokenId);
        emit LogMinted(_account, newTokenId);
      }      
    }
  }

  /**
   * @dev Mint a batch of tokens for cross-chain transfer
   *
   * Requirements:
   * - Only bridge contract can call (bridge contract is minter)
   * - Check minting allowance for bridge contract
   * @param _account receiver wallet
   * @param _tokenIds array of minting token id; must not have zero
   */
  function mintBatch(
    address _account,
    uint256[] calldata _tokenIds
  ) external onlyMinter decreaseValidAllowance(msg.sender, _tokenIds.length) {
    unchecked { 
      // we are not accepting enough data to overflow on `_tokenIds`
      for (uint256 i = 0; i < _tokenIds.length; i++) {
        super._mint(_account, _tokenIds[i]);
        emit LogMinted(_account, _tokenIds[i]);
      }      
    }
  }

  /**
   * Override {ERC721Burnable-burn}
   */
  function burn(uint256 _tokenId) public override {
    ERC721Burnable.burn(_tokenId);
    emit LogBurnt(_tokenId);
  }

  /**
   * Override {Minterable-transferOwnership}
   */
  function transferOwnership(address _newOwner) public virtual override(Ownable, Minterable) {
    Minterable.transferOwnership(_newOwner);
  }
  
  /**
   * Override {IERC165-supportsInterface}
   */
  function supportsInterface(bytes4 _interfaceId) 
    public 
    view 
    virtual 
    override(ERC721, ERC721Enumerable, ERC2981, AccessControl, ERC4907)
    returns (bool)
  {
    return super.supportsInterface(_interfaceId);
  }

  /**
   * Disable token transfer:
   * - from/to blacklisted wallets
   * - when paused
   */
  function _beforeTokenTransfer(
    address _from,
    address _to,
    uint256 _tokenId
  ) internal override(ERC721, ERC721Enumerable, ERC721Blacklisted, ERC4907) whenNotPaused {
    ERC721Blacklisted._beforeTokenTransfer(_from, _to, _tokenId);
    ERC721Enumerable._beforeTokenTransfer(_from, _to, _tokenId);
    ERC4907._beforeTokenTransfer(_from, _to, _tokenId);
  }
  
  /**
   * Override {ERC721:_baseURI}
   */
  function _baseURI() internal view override returns (string memory) {
    return baseTokenURI;
  }
}


// File contracts/lib/Operatorable.sol


pragma solidity 0.8.4;



contract Operatorable is AccessControl, Ownable {
  bytes32 public constant OPERATOR_ROLE = keccak256("OPERATOR_ROLE");

  event LogOperatorAdded(address indexed account);

  event LogOperatorRemoved(address indexed account);

  /**
    * @dev Restricted to members of the `operator` role.
    */
  modifier onlyOperator() {
    if (!hasRole(OPERATOR_ROLE, msg.sender)) revert NoOperatorRole();

    _;
  }

  /**
   * @dev Contract owner is operator
   */
  constructor() {
    _setupRole(DEFAULT_ADMIN_ROLE, msg.sender);
    _setupRole(OPERATOR_ROLE, msg.sender);
  }

  /**
   * @dev Add a new operator
   *
   * Requirements:
   * - Only contract owner can call
   * @param _account new operator address; must not be zero address
   */
  function addOperator(address _account) external onlyOwner {
    if (_account == address(0)) revert InvalidAddress();

    super._grantRole(OPERATOR_ROLE, _account);
    emit LogOperatorAdded(_account);
  }

  /**
    * @dev Remove operator
    *
    * Requirements:
    * - Only contract owner can call
    * @param _account removing operator address
    */
  function removeOperator(address _account) external onlyOwner {
    super._revokeRole(OPERATOR_ROLE, _account);
    emit LogOperatorRemoved(_account);
  }

  /**
    * @dev Check operator role ownership
    * @param _account checking account
    */
  function isOperator(address _account) external view returns (bool) {
    return super.hasRole(OPERATOR_ROLE, _account);
  }

  /**
   * @dev Override {Ownable-transferOwnership}
   * Super method has `onlyOwner` modifier
   * Revoke default admin role and operator role from old owner and grant to new owner
   * @param _newOwner new owner address; must not be zero address
   */
  function transferOwnership(address _newOwner) public virtual override {
    address oldOwner = owner();
    super._revokeRole(DEFAULT_ADMIN_ROLE, oldOwner);
    super._revokeRole(OPERATOR_ROLE, oldOwner);
    super._grantRole(DEFAULT_ADMIN_ROLE, _newOwner);
    super._grantRole(OPERATOR_ROLE, _newOwner);
    super.transferOwnership(_newOwner);
  }
}


// File @openzeppelin/contracts/utils/cryptography/ECDSA.sol@v4.7.0


// OpenZeppelin Contracts (last updated v4.7.0) (utils/cryptography/ECDSA.sol)

pragma solidity ^0.8.0;

/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSA {
    enum RecoverError {
        NoError,
        InvalidSignature,
        InvalidSignatureLength,
        InvalidSignatureS,
        InvalidSignatureV
    }

    function _throwError(RecoverError error) private pure {
        if (error == RecoverError.NoError) {
            return; // no error: do nothing
        } else if (error == RecoverError.InvalidSignature) {
            revert("ECDSA: invalid signature");
        } else if (error == RecoverError.InvalidSignatureLength) {
            revert("ECDSA: invalid signature length");
        } else if (error == RecoverError.InvalidSignatureS) {
            revert("ECDSA: invalid signature 's' value");
        } else if (error == RecoverError.InvalidSignatureV) {
            revert("ECDSA: invalid signature 'v' value");
        }
    }

    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature` or error string. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     *
     * Documentation for signature generation:
     * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
     * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
     *
     * _Available since v4.3._
     */
    function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
        // Check the signature length
        // - case 65: r,s,v signature (standard)
        // - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098) _Available since v4.1._
        if (signature.length == 65) {
            bytes32 r;
            bytes32 s;
            uint8 v;
            // ecrecover takes the signature parameters, and the only way to get them
            // currently is to use assembly.
            /// @solidity memory-safe-assembly
            assembly {
                r := mload(add(signature, 0x20))
                s := mload(add(signature, 0x40))
                v := byte(0, mload(add(signature, 0x60)))
            }
            return tryRecover(hash, v, r, s);
        } else if (signature.length == 64) {
            bytes32 r;
            bytes32 vs;
            // ecrecover takes the signature parameters, and the only way to get them
            // currently is to use assembly.
            /// @solidity memory-safe-assembly
            assembly {
                r := mload(add(signature, 0x20))
                vs := mload(add(signature, 0x40))
            }
            return tryRecover(hash, r, vs);
        } else {
            return (address(0), RecoverError.InvalidSignatureLength);
        }
    }

    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature`. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     */
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, signature);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
     *
     * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address, RecoverError) {
        bytes32 s = vs & bytes32(0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff);
        uint8 v = uint8((uint256(vs) >> 255) + 27);
        return tryRecover(hash, v, r, s);
    }

    /**
     * @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
     *
     * _Available since v4.2._
     */
    function recover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, r, vs);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `v`,
     * `r` and `s` signature fields separately.
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address, RecoverError) {
        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
            return (address(0), RecoverError.InvalidSignatureS);
        }
        if (v != 27 && v != 28) {
            return (address(0), RecoverError.InvalidSignatureV);
        }

        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(hash, v, r, s);
        if (signer == address(0)) {
            return (address(0), RecoverError.InvalidSignature);
        }

        return (signer, RecoverError.NoError);
    }

    /**
     * @dev Overload of {ECDSA-recover} that receives the `v`,
     * `r` and `s` signature fields separately.
     */
    function recover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, v, r, s);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from a `hash`. This
     * produces hash corresponding to the one signed with the
     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
     * JSON-RPC method as part of EIP-191.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
        // 32 is the length in bytes of hash,
        // enforced by the type signature above
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from `s`. This
     * produces hash corresponding to the one signed with the
     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
     * JSON-RPC method as part of EIP-191.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n", Strings.toString(s.length), s));
    }

    /**
     * @dev Returns an Ethereum Signed Typed Data, created from a
     * `domainSeparator` and a `structHash`. This produces hash corresponding
     * to the one signed with the
     * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
     * JSON-RPC method as part of EIP-712.
     *
     * See {recover}.
     */
    function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
    }
}


// File contracts/lib/Signer.sol

pragma solidity 0.8.4;




contract Signer is Ownable {
  using Address for address;
  using ECDSA for bytes32;

  // signer wallet for signature verification
  address public signer;

  // address => nonce starting from 1; against replay attack
  mapping(address => uint256) public nonces;

  event LogSignerSet(address signer);

  /**
   * @param _signer signer wallet
   */
  constructor(address _signer) {
    _setSigner(_signer);
  }

  /**
   * See {_setSigner}
   *
   * Requirements:
   * - Only contract owner can call
   */
  function setSigner(address _signer) external onlyOwner {
    _setSigner(_signer);
  }

  /**
   * @dev Set signer wallet address
   * @param _signer new signer wallet; must not be the same as before; must not be zero address nor contract address
   */
  function _setSigner(address _signer) internal {
    if (signer == _signer) revert NoChangeToTheState();
    if (_signer == address(0) || _signer.isContract()) revert InvalidAddress();

    signer = _signer;
    emit LogSignerSet(_signer);
  }

  /**
   * @dev Verify signature signed off signer wallet
   * @param _hash verifying message hash
   * @param _sig signature
   * @return verified status
   */
  function _verify(
    bytes32 _hash,
    bytes memory _sig
  ) internal view returns (bool) {
    bytes32 h = _hash.toEthSignedMessageHash();
    return h.recover(_sig) == signer;
  }

  /**
   * @dev Return the chain id
   * @return chainId chain id
   */
  function _chainId() internal view returns (uint256 chainId) {
    assembly {
      chainId := chainid()
    }
  }
}


// File contracts/sale/Sale.sol


pragma solidity 0.8.4;





contract Sale is Operatorable, Signer {
  using Address for address;

  enum Step {
    NONE,
    PRESALE,
    SALE
  }

  Step public step;

  // Gaming asset contract
  Asset public immutable asset;

  // Token price in Wei
  uint256 public price;

  // Minting cap in pre-sale and public sale
  uint256 public immutable mintingCap;

  // Maximum mint amount in pre-sale and public sale
  uint256 public maxMintable;

  // Totally minted amount in pre-sale and public sale
  uint256 public totalMinted;

  // Maximum mint amount per one transaction
  uint256 public maxMintPerTx = 3;

  // Maximum mint amount per one wallet
  uint256 public maxMintPerAddress = 3;

  // wallet address => minted amount
  mapping(address => uint256) public minted;

  // whitelist wallet address => minted amount (pre-sale)
  mapping(address => uint256) public mintedPresale;

  event LogMaxMintPerTxSet(uint256 maxMintPerTx);

  event LogMaxMintPerAddressSet(uint256 maxMintPerAddress);

  event LogSaleStarted(address indexed operator);

  event LogPresaleStarted(address indexed operator);

  event LogSaleEnded(address indexed operator);

  event LogAssetSet(Asset indexed asset);

  event LogMintingCapSet(uint256 mintingCap);

  event LogEthSent(
    address indexed account, 
    uint256 amount
  );

  event LogPurchased(
    address indexed account, 
    uint256 amount
  );

  event LogPriceSet(uint256 price);

  event LogMaxMintableSet(uint256 maxMintable);

  event LogUnsoldTokensMinted(
    address indexed account,
    uint256 amount
  );

  /**
   * @param _signer signer wallet
   * @param _asset Asset contract address; must be contract address
   * @param _mintingCap minting cap; must not be zero
   */
  constructor(
    address _signer,
    Asset _asset,
    uint256 _mintingCap
  ) Signer(_signer) { 
    if (!address(_asset).isContract()) revert NotContract();
    if (_mintingCap == 0) revert InvalidMintingCap();

    asset = _asset;
    mintingCap = _mintingCap;
    emit LogAssetSet(_asset);
    emit LogMintingCapSet(_mintingCap);
  }

  /**
   * @dev Disable Eth receive with no data
   */
  receive() external payable {
    revert EthReceived();
  }

  /**
   * @dev Start presale step
   *
   * Requirements:
   * - Only operator can call
   */
  function startPresale() external onlyOperator {
    if (step == Step.PRESALE) revert NoChangeToTheState();

    step = Step.PRESALE;
    emit LogPresaleStarted(msg.sender);
  }

  /**
   * @dev End presale/sale
   *
   * Requirements:
   * - Only operator can call
   */
  function endSale() external onlyOperator {
    if (step == Step.NONE) revert NoChangeToTheState();

    step = Step.NONE;
    emit LogSaleEnded(msg.sender);
  }

  /**
   * @dev Start public sale step
   *
   * Requirements:
   * - Only operator can call
   */
  function startSale() external onlyOperator {
    if (step == Step.SALE) revert NoChangeToTheState();

    step = Step.SALE;
    emit LogSaleStarted(msg.sender);
  }

  /**
   * @dev Set NFT price
   *
   * Requirements:
   * - Only operator can call
   * @param _price NFT price; zero possible; must not be same as before
   */
  function setPrice(uint256 _price) external onlyOperator {
    if (_price == price) revert NoChangeToTheState();
    
    price = _price;
    emit LogPriceSet(_price);
  }

  /**
   * @dev Set max mint per tx
   *
   * Requirements:
   * - Only operator can call
   * @param _maxMintPerTx max mint limit per tx; must not be zero; must not be same as before
   */
  function setMaxMintPerTx(uint256 _maxMintPerTx) external onlyOperator {
    if (_maxMintPerTx == 0) revert InvalidMaxMintPerTx();
    if (_maxMintPerTx == maxMintPerTx) revert NoChangeToTheState();

    maxMintPerTx = _maxMintPerTx;
    emit LogMaxMintPerTxSet(_maxMintPerTx);
  }

  /**
   * @dev Set max mint per wallet
   *
   * Requirements:
   * - Only operator can call
   * @param _maxMintPerAddress max mint limit per wallet; must not be zero; must not be same as before
   */
  function setMaxMintPerAddress(uint256 _maxMintPerAddress) external onlyOperator {
    if (_maxMintPerAddress == 0) revert InvalidMaxMintPerAddress();
    if (_maxMintPerAddress == maxMintPerAddress) revert NoChangeToTheState();
    
    maxMintPerAddress = _maxMintPerAddress;
    emit LogMaxMintPerAddressSet(_maxMintPerAddress);
  }

  /**
   * @dev Increase max mint amount
   *
   * Requirements:
   * - Only operator can call
   * - Increased max mint must not exceed cap
   * @param _amount increase amount; must not be zero
   */
  function increaseMaxMintable(uint256 _amount) external onlyOperator {
    if (_amount == 0) revert InvalidAmount();

    uint256 _maxMintableIncreased = maxMintable + _amount;

    if (_maxMintableIncreased > mintingCap) revert ExceedCap();

    maxMintable = _maxMintableIncreased;
    emit LogMaxMintableSet(_maxMintableIncreased);
  }

  /**
   * @dev Mint unsold tokens; amount = total cap - total minted amount
   *
   * Requirements:
   * - Only operator can call
   * - Sale must be ended
   * - NFTs must not be sold out
   * @param _to receiver wallet; must not be zero address
   */
  function mintUnsoldTokens(address _to) external onlyOperator {
    if (step != Step.NONE) revert SaleNotEnded();
    if (totalMinted == mintingCap) revert NFTSoldOut();

    uint256 _amount;

    unchecked {
      // we will not underflow `_amount` because of above check
      _amount = mintingCap - totalMinted;
    }

    asset.mintBatch(_to, _amount);
    totalMinted = mintingCap;
    emit LogUnsoldTokensMinted(_to, _amount);
  }

  /**
   * @dev Withdraw Eth
   *
   * Requirements:
   * - Only `owner` can call
   * @param _to receiver wallet; must not be zero address
   */
  function withdrawEth(address _to) external onlyOwner {
    if (_to == address(0)) revert InvalidAddress();

    uint256 balance = address(this).balance;
    payable(_to).transfer(balance);
    emit LogEthSent(_to, balance);
  }

  /**
   * @dev Purchase tokens
   *
   * Requirements:
   * - Sale must be ongoing
   * - Caller must not be contract address
   * - Enough Eth must be received
   * @param _amount buy amount; must not be zero; must not exceed max mint per tx
   */
  function purchase(
    uint256 _amount,
    bytes calldata _sig
  ) external payable {
    if (msg.sender.isContract()) revert InvalidAddress();
    if (_amount == 0) revert InvalidAmount();
    if (_amount > maxMintPerTx) revert ExceedMaxMintPerTx();

    if (step == Step.PRESALE) {
      bytes32 msgHash = keccak256(abi.encodePacked(
        super._chainId(), 
        address(asset), 
        _amount, 
        msg.sender,
        ++nonces[msg.sender]
      ));

      if (!super._verify(msgHash, _sig)) revert InvalidSignature();

      _updateMintedAmount(mintedPresale, _amount);
    } else if (step == Step.SALE) {
      _updateMintedAmount(minted, _amount);
    } else {
      revert SaleNotGoing();
    }

    uint256 _totalMinted = totalMinted + _amount;
    uint256 totalPrice = _amount * price;

    if (_totalMinted > maxMintable) revert ExceedMaxMintable();
    if (msg.value < totalPrice) revert InsufficientEth();

    asset.mintBatch(msg.sender, _amount);
    totalMinted = _totalMinted;
    uint256 change = msg.value - totalPrice;

    if (change != 0) {
      payable(msg.sender).transfer(change);
    }

    emit LogPurchased(msg.sender, _amount);
  }

  /**
   * Override {Operatorable-transferOwnership}
   */
  function transferOwnership(address _newOwner) public virtual override(Ownable, Operatorable) {
    Operatorable.transferOwnership(_newOwner);
  }

  /**
   * @dev Update minted amount
   * @param _storage mintedPresale or minted
   * @param _amount purchase amount
   */
  function _updateMintedAmount(
    mapping(address => uint256) storage _storage, 
    uint256 _amount
  ) private {
    uint256 _minted = _storage[msg.sender] + _amount;

    if (_minted > maxMintPerAddress) revert ExceedMaxMintPerAddress();

    _storage[msg.sender] = _minted;
  }
}