// File: Address.sol



// SPDX-License-Identifier: MIT
// 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: AdminControl.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/// @author: manifold.xyz

import "./ERC165.sol";
import "./EnumerableSet.sol";
import "./Ownable.sol";
import "./IAdminControl.sol";

abstract contract AdminControl is Ownable, IAdminControl, ERC165 {
    using EnumerableSet for EnumerableSet.AddressSet;

    // Track registered admins
    EnumerableSet.AddressSet private _admins;

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

    /**
     * @dev Only allows approved admins to call the specified function
     */
    modifier adminRequired() {
        require(owner() == msg.sender || _admins.contains(msg.sender), "AdminControl: Must be owner or admin");
        _;
    }   

    /**
     * @dev See {IAdminControl-getAdmins}.
     */
    function getAdmins() external view override returns (address[] memory admins) {
        admins = new address[](_admins.length());
        for (uint i = 0; i < _admins.length(); i++) {
            admins[i] = _admins.at(i);
        }
        return admins;
    }

    /**
     * @dev See {IAdminControl-approveAdmin}.
     */
    function approveAdmin(address admin) external override onlyOwner {
        if (!_admins.contains(admin)) {
            emit AdminApproved(admin, msg.sender);
            _admins.add(admin);
        }
    }

    /**
     * @dev See {IAdminControl-revokeAdmin}.
     */
    function revokeAdmin(address admin) external override onlyOwner {
        if (_admins.contains(admin)) {
            emit AdminRevoked(admin, msg.sender);
            _admins.remove(admin);
        }
    }

    /**
     * @dev See {IAdminControl-isAdmin}.
     */
    function isAdmin(address admin) public override view returns (bool) {
        return (owner() == admin || _admins.contains(admin));
    }

}
// File: base64.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0;

/// @title Base64
/// @author Brecht Devos - <brecht@loopring.org>
/// @notice Provides functions for encoding/decoding base64
library Base64 {
    string internal constant TABLE_ENCODE = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
    bytes  internal constant TABLE_DECODE = hex"0000000000000000000000000000000000000000000000000000000000000000"
                                            hex"00000000000000000000003e0000003f3435363738393a3b3c3d000000000000"
                                            hex"00000102030405060708090a0b0c0d0e0f101112131415161718190000000000"
                                            hex"001a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132330000000000";

    function encode(bytes memory data) internal pure returns (string memory) {
        if (data.length == 0) return '';

        // load the table into memory
        string memory table = TABLE_ENCODE;

        // multiply by 4/3 rounded up
        uint256 encodedLen = 4 * ((data.length + 2) / 3);

        // add some extra buffer at the end required for the writing
        string memory result = new string(encodedLen + 32);

        assembly {
            // set the actual output length
            mstore(result, encodedLen)

            // prepare the lookup table
            let tablePtr := add(table, 1)

            // input ptr
            let dataPtr := data
            let endPtr := add(dataPtr, mload(data))

            // result ptr, jump over length
            let resultPtr := add(result, 32)

            // run over the input, 3 bytes at a time
            for {} lt(dataPtr, endPtr) {}
            {
                // read 3 bytes
                dataPtr := add(dataPtr, 3)
                let input := mload(dataPtr)

                // write 4 characters
                mstore8(resultPtr, mload(add(tablePtr, and(shr(18, input), 0x3F))))
                resultPtr := add(resultPtr, 1)
                mstore8(resultPtr, mload(add(tablePtr, and(shr(12, input), 0x3F))))
                resultPtr := add(resultPtr, 1)
                mstore8(resultPtr, mload(add(tablePtr, and(shr( 6, input), 0x3F))))
                resultPtr := add(resultPtr, 1)
                mstore8(resultPtr, mload(add(tablePtr, and(        input,  0x3F))))
                resultPtr := add(resultPtr, 1)
            }

            // padding with '='
            switch mod(mload(data), 3)
            case 1 { mstore(sub(resultPtr, 2), shl(240, 0x3d3d)) }
            case 2 { mstore(sub(resultPtr, 1), shl(248, 0x3d)) }
        }

        return result;
    }

    function decode(string memory _data) internal pure returns (bytes memory) {
        bytes memory data = bytes(_data);

        if (data.length == 0) return new bytes(0);
        require(data.length % 4 == 0, "invalid base64 decoder input");

        // load the table into memory
        bytes memory table = TABLE_DECODE;

        // every 4 characters represent 3 bytes
        uint256 decodedLen = (data.length / 4) * 3;

        // add some extra buffer at the end required for the writing
        bytes memory result = new bytes(decodedLen + 32);

        assembly {
            // padding with '='
            let lastBytes := mload(add(data, mload(data)))
            if eq(and(lastBytes, 0xFF), 0x3d) {
                decodedLen := sub(decodedLen, 1)
                if eq(and(lastBytes, 0xFFFF), 0x3d3d) {
                    decodedLen := sub(decodedLen, 1)
                }
            }

            // set the actual output length
            mstore(result, decodedLen)

            // prepare the lookup table
            let tablePtr := add(table, 1)

            // input ptr
            let dataPtr := data
            let endPtr := add(dataPtr, mload(data))

            // result ptr, jump over length
            let resultPtr := add(result, 32)

            // run over the input, 4 characters at a time
            for {} lt(dataPtr, endPtr) {}
            {
               // read 4 characters
               dataPtr := add(dataPtr, 4)
               let input := mload(dataPtr)

               // write 3 bytes
               let output := add(
                   add(
                       shl(18, and(mload(add(tablePtr, and(shr(24, input), 0xFF))), 0xFF)),
                       shl(12, and(mload(add(tablePtr, and(shr(16, input), 0xFF))), 0xFF))),
                   add(
                       shl( 6, and(mload(add(tablePtr, and(shr( 8, input), 0xFF))), 0xFF)),
                               and(mload(add(tablePtr, and(        input , 0xFF))), 0xFF)
                    )
                )
                mstore(resultPtr, shl(232, output))
                resultPtr := add(resultPtr, 3)
            }
        }

        return result;
    }
}

// File: Clock.sol



// SPDX-License-Identifier: MIT

pragma solidity >= 0.8.13;

import "./ERC721.sol";
import "./IERC20.sol";
import "./IEIP2981.sol";
import "./AdminControl.sol";
import "./Strings.sol";
import './base64.sol';
import "./ClockURI.sol";


contract Clock is ERC721, AdminControl {
    
    uint256 private _royaltyAmount; //in % 
    uint256 public _tokenId;
    uint256 public _maxSupply = 200;

    mapping(uint => string) _modes;
    mapping(uint => string) _wallColors;
    mapping(uint => uint) _chronos;
    mapping(uint => uint) _timers;
    mapping(uint => uint) _alarms;
    mapping(uint => string) _opacities;
    mapping(uint => string) _clockFills;
    mapping(uint => string) _clockFrames;
    mapping(uint => string) _clockScreen;
    mapping(uint => string) _ledColors;
    mapping(uint => string) _shadows;

    address payable private _royalties_recipient;
    address _clockURIAddress;

    string[] public _colorOptions;
    string[] public _opacitiesOptions;
    string[] public _clockOutlinesOptions;
    string[] public _clockFillsOptions;
    string[] public _screenColorsOptions;
    string[] public _ledColorsOptions;
    string[] public _shadowsOptions;

    bool _clocksHacked;
    bool _publicMintOpened;
    
    struct Hack{
        string value;
        string mode;
        uint256 chrono;
        uint256 timer;
        uint256 alarm;
    }

    Hack _hack;

    constructor () ERC721("ETH Clock", "ETH Clock") {
        _royalties_recipient = payable(msg.sender);
        _royaltyAmount = 10;
        _tokenId = 0;
        _clockURIAddress = 0xeEAb674E788cC7Da0624bc555bC5aEfEf9F2881B;
        _colorOptions = ['ffd097', 'f8a7a7', 'c3d5fc', 'a0e3a1', 'f0eb5b', 'a3a3a3'];
        _opacitiesOptions = ['0', '3', '6'];
        _clockOutlinesOptions = ['fff', '000'];
        _clockFillsOptions = ['752125', 'c90000', '00a331', '7202b3'];
        _screenColorsOptions = ['cccccc', 'fff', '1e1e1e'];
        _ledColorsOptions = ['ff000c', '008700', '0074b8','ffa200'];
        _shadowsOptions = ['0','1','2','3'];
    } 

    function supportsInterface(bytes4 interfaceId)
        public
        view
        virtual
        override(ERC721, AdminControl)
        returns (bool)
    {
        return
        AdminControl.supportsInterface(interfaceId) ||
        ERC721.supportsInterface(interfaceId) ||
        interfaceId == type(IEIP2981).interfaceId ||
        super.supportsInterface(interfaceId);
    }

    function adminMint(
        address account
    ) external adminRequired{
        require(_tokenId + 1 < _maxSupply);
        _mint(account, _tokenId);
        _modes[_tokenId] = 'Clock';
        _wallColors[_tokenId] = _colorOptions[getPseudoRndNum(_colorOptions.length, account)];
        _opacities[_tokenId] = _opacitiesOptions[getPseudoRndNum(_opacitiesOptions.length, account)];
        _clockFills[_tokenId] = _clockFillsOptions[getPseudoRndNum(_clockFillsOptions.length, account)];
        _clockFrames[_tokenId] = _clockOutlinesOptions[getPseudoRndNum(_clockOutlinesOptions.length, account)];
        _clockScreen[_tokenId] = _screenColorsOptions[getPseudoRndNum(_screenColorsOptions.length, account)];
        _ledColors[_tokenId] = _ledColorsOptions[getPseudoRndNum(_ledColorsOptions.length, account)];
        _shadows[_tokenId] = _shadowsOptions[getPseudoRndNum(_shadowsOptions.length, account)];
        _tokenId += 1;
    }

    function getPseudoRndNum(uint256 length, address account) public view returns (uint256){    
        uint256 rnd = uint256(keccak256(abi.encodePacked(block.difficulty, block.timestamp, _tokenId, length, msg.sender, account))) % length;
        return rnd;   
    }

    function setTimer(uint256 tokenId, uint256 blocks) external {
        require(msg.sender == ownerOf(tokenId));
        require(blocks > 0, "The block number needs to be positive");
        _modes[tokenId] = 'Timer';
        _timers[tokenId] = block.number + blocks;
    }

    function setAlarm(uint256 tokenId, uint256 targetBlock) external {
        require(msg.sender == ownerOf(tokenId));
        require(targetBlock > block.number, "An alarm needs to be in the future");
        _modes[tokenId] = 'Alarm';
        _alarms[tokenId] = targetBlock;
    }

    function setChrono(uint256 tokenId) external {
        require(msg.sender == ownerOf(tokenId));
        _modes[tokenId] = 'Chrono';
        _chronos[tokenId] = block.number;
    }

    function resetClock(uint256 tokenId) external {
        require(msg.sender == ownerOf(tokenId));
        _modes[tokenId] ='Clock';
    }

    function setClockURIAddress(address clockURIAddress) external adminRequired{
        _clockURIAddress = clockURIAddress;
    }

    function hackClocks(
        string calldata value,
        string calldata mode,
        uint256 timer,
        uint256 alarm
    )external adminRequired{
        require(alarm > block.number);
        require(timer > 0);
        _clocksHacked = true;
        _hack.value = value;
        _hack.mode = mode;
        _hack.chrono = block.number;
        _hack.timer =  block.number + timer;
        _hack.alarm = alarm;
    }

    function restoreClocks()external adminRequired{
        _clocksHacked = false;
    }
    
    function getClockValue(uint256 tokenId) internal view returns(string memory value){
        string memory clockValue = Strings.toString(block.number);
        string memory mode = _clocksHacked ? _hack.mode : _modes[tokenId];
        if(keccak256(bytes(mode)) == keccak256("Timer")){
            uint256 timer = _clocksHacked ? _hack.timer : _timers[tokenId];
            if(block.number >= timer){
                clockValue =  _clocksHacked ? _hack.value : "0000000000";
            }else{
                clockValue = Strings.toString(timer - block.number);
            }
        }else if(keccak256(bytes(mode)) == keccak256('Chrono')) {
            uint256 chrono = _clocksHacked ? _hack.chrono : _chronos[tokenId];
            clockValue = Strings.toString(block.number - chrono);
        }

        uint256 clockValueLength = bytes(clockValue).length;
        if(clockValueLength<10 && keccak256(bytes(clockValue)) != keccak256(bytes(_hack.value))){
            for(uint256 i=0;i<(10-clockValueLength); i++){
                clockValue = string.concat("0", clockValue) ;
            }
        }
        return clockValue;
    }

    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        require(_exists(tokenId));
        string memory clockValue = getClockValue(tokenId);
        string memory wallColor = _clocksHacked ? '000' : _wallColors[tokenId];
        string memory mode = _clocksHacked ? _hack.mode : _modes[tokenId];
        uint256 timer = _clocksHacked ? _hack.timer : _timers[tokenId];
        uint256 alarm = _clocksHacked ? _hack.alarm : _alarms[tokenId];
        string[9] memory clockCustomization = [
            clockValue, 
            mode,
            wallColor, 
            _opacities[tokenId], 
            _clockFills[tokenId], 
            _clockFrames[tokenId], 
            _clockScreen[tokenId], 
            _ledColors[tokenId],
            _shadows[tokenId]];

        string memory uri = ClockURI(_clockURIAddress).buildURI(
            clockCustomization,
            timer,
            alarm
        );
        return uri;
    }

    function burn(uint256 tokenId) public {
        require(ownerOf(tokenId)== msg.sender, "You can only burn your own tokens");
        _burn(tokenId);
    }

    function setRoyalties(address payable _recipient, uint256 _royaltyPerCent) external adminRequired {
        _royalties_recipient = _recipient;
        _royaltyAmount = _royaltyPerCent;
    }

    function royaltyInfo(uint256 salePrice) external view returns (address, uint256) {
        if(_royalties_recipient != address(0)){
            return (_royalties_recipient, (salePrice * _royaltyAmount) / 100 );
        }
        return (address(0), 0);
    }

    function withdraw(address recipient) external adminRequired {
        payable(recipient).transfer(address(this).balance);
    }

}   
// File: ClockMintFrame.sol



// SPDX-License-Identifier: MIT

pragma solidity >= 0.8.13;

import "./IERC721.sol";
import "./Clock.sol";

contract ClockMint{

    // Congratulations! You found the final contract. 
    // This contract will allow you to mint one Block Clock for free (I mean, you still have to pay gas).
    // I hope you'll enjoy it!
    // The rest of the scavenger hunt was on Rinkeby to save your hard earn ETH. 
    // But this is the real deal. Don't forget to switch back your wallet to Mainnet.
    // If you got here and all the clocks are gone, you can still mint one here: https://block-clock.xyz

    address public _clockAddress;

    bool public _publicMintOpened;

    uint256 public _supply;

    mapping(address => bool) public _isAdmin;
    mapping(address => bool) public _hasAlreadyMinted;

    constructor(){
        _isAdmin[msg.sender]=true;
    }
    

    function setClockAddress(address clockAddress) external{
        require(_isAdmin[msg.sender], "Only Admins can set ClockAddress");
        _clockAddress = clockAddress;
    }

    function togglePublicMintOpened() external{
        require(_isAdmin[msg.sender], "Only Admins can toggle mint");
        _publicMintOpened = !_publicMintOpened;
    }


    function mint(
    ) external {
        require(_publicMintOpened, "Mint closed");
        require(_supply <=5, "No more free Block-Clocks available..." );
        require(!_hasAlreadyMinted[msg.sender],"Leave some for the others...");
        Clock(_clockAddress).adminMint(msg.sender);
        _supply += 1;
        _hasAlreadyMinted[msg.sender] = true;
    }


}
// File: ClockURI.sol



// SPDX-License-Identifier: MIT

pragma solidity >= 0.8.13;

import './base64.sol';


contract ClockURI{


    bytes[5] private _svgComponents;
    string[] private _uriComponents;

    mapping(string => string) _colorNames;
    mapping(string => string) _opacitiesNames;
    mapping(string => string) _clockOutlinesNames;
    mapping(string => string) _clockFillsNames;
    mapping(string => string) _screenColorsNames;
    mapping(string => string) _ledColorsNames;
    mapping(string => string) _shadowNames;
    mapping(string => string) _shadowValues;

    string [4] _shadows;

     constructor () {
        _uriComponents = [
            'data:application/json;utf8,{"name":"',
            '", "description":"',
            '", "created_by":"Smartcontrart", "image":"data:image/svg+xml;base64,',
            '", "attributes":[',
            ']}'];

        _colorNames['ffd097'] ='Orange'; 
        _colorNames['f8a7a7'] ='Pink'; 
        _colorNames['c3d5fc'] ='Blue'; 
        _colorNames['a0e3a1'] ='Green'; 
        _colorNames['f0eb5b'] = 'Yellow';
        _colorNames['Yellow'] = 'Grey';

        _opacitiesNames['0'] = 'Indoors';
        _opacitiesNames['3'] = 'Cloudy';
        _opacitiesNames['6'] = 'Sunny';

        _clockOutlinesNames['fff'] = 'White';
        _clockOutlinesNames['000'] = 'Black';

        _clockFillsNames['752125'] = 'Brown';
        _clockFillsNames['c90000'] = 'Red';
        _clockFillsNames['00a331'] = 'Green';
        _clockFillsNames['7202b3'] = 'Purple';

        _screenColorsNames['cccccc'] = 'Grey';
        _screenColorsNames['fff'] = 'White';
        _screenColorsNames['1e1e1e'] = 'Black';

        _ledColorsNames['ff000c'] = 'Red';
        _ledColorsNames['008700'] = 'Green';
        _ledColorsNames['0074b8'] = 'Blue';
        _ledColorsNames['ffa200'] = 'Orange';
        
        _shadowValues['0'] = '<polygon class="cls-2" points="873.8 653.64 206.49 426.04 -282.52 915.05 164.93 1362.51 873.8 653.64"/>';
        _shadowValues['1'] = '<polygon class="cls-2" points="206.17 426.36 873.48 653.96 1362.5 164.95 915.04 -282.51 206.17 426.36"/>';
        _shadowValues['2'] = '<polygon class="cls-2" points="873.81 426.35 206.51 653.95 -282.51 164.93 164.95 -282.52 873.81 426.35"/>';
        _shadowValues['3'] = '<polygon class="cls-2" points="206.19 653.62 873.49 426.03 1362.51 915.04 915.05 1362.5 206.19 653.62"/>';

        _shadowNames['0'] = 'Dawn';
        _shadowNames['1'] = 'Afternoon';
        _shadowNames['2'] = 'Morning';
        _shadowNames['3'] = 'Dusk';
    }
    
    function getSVGPart1(
        string calldata wallColor, 
        string calldata opacity,
        string calldata shadow
    ) internal view returns(bytes memory svgPart1) {
        return (
            abi.encodePacked(
                '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1080 1080" width="1080" height="1080"> <defs> <style> .cls-8{fill:#fff;font-family:Helvetica;font-size:22.76px} .cls-9{fill:#000;font-family:Verdana;font-size:80px} .cls-2{opacity:.',
                opacity,
                ';}</style> </defs> <path style="fill:#',
                wallColor,
                '" id="background" d="M0 0h1080v1080H0z"/> <g>',
                _shadowValues[shadow]
            )
        );
    }

    function getSVGPart2(        
        string calldata clockFill, 
        string calldata clockFrame, 
        string calldata clockScreen
    ) internal view returns(bytes memory svgPart2){
        return(
            abi.encodePacked(
                '<path x="203" y="422" width="673" height="236" rx="31" ry="31" style="fill:#',
                clockFill,
                '" d="M234 421.82H845.55A31.14 31.14 0 0 1 877 452.96V627.05A31.14 31 0 0 1 845.55 658.19H234.46A31.14 31.14 0 0 1 203.32 627.05V452.96A31.14 31.14 0 0 1 234.46 421.82z"/> <path x="203" y="423" width="674" height="235" rx="26" ry="26" style="stroke-miterlimit:10;fill:none;stroke:#',
                clockFrame,
                ';stroke-width:8.44px" d="M229.48 422.55H850.51A26.39 26.39 0 0 1 876.9 448.94V631.06A26.39 26.39 0 0 1 850.51 657.45H229.48A26.39 26.39 0 0 1 203.09 631.06V448.94A26.39 26.39 0 0 1 229.48 422.55z"/> <path x="250" y="460" width="579" height="127" rx="15" ry="15" style="fill:#',
                clockScreen,
                '" d="M265.54 459.66H814.47A15.17 15.17 0 0 1 829.64 474.83V571.7A15.17 15.17 0 0 1 814.47 586.87H265.54A15.17 15.17 0 0 1 250.37 571.7V474.83A15.17 15.17 0 0 1 265.54 459.66z"/> <text transform="translate(285 555)"> <tspan class="cls-9" style="fill:#',
                keccak256(bytes(_screenColorsNames[clockScreen])) == keccak256('Black')  ? 'a4be44' : '000',
                '" x="0" y="0">'
            )
        );
    }

    function getSVGPart3(        
        string calldata value, 
        string calldata mode,
        string calldata clockScreen,
        string calldata ledColor,
        uint timer
    ) internal view returns(bytes memory svgPart3){
        return(
            abi.encodePacked(
                value,
                keccak256(bytes(mode)) == keccak256('Timer') && block.number >= timer ? abi.encodePacked('<animate attributeName="fill" values="#', keccak256(bytes(_screenColorsNames[clockScreen])) == keccak256('Black')  ? 'a4be44' : '000',';transparent" begin="0s" dur="2s" calcMode="discrete" repeatCount="indefinite"/>') :abi.encodePacked(''),
                '</tspan> </text> <text class="cls-8" transform="translate(278 626)"> <tspan x="0" y="0">Clock</tspan> </text> <circle cx="259" cy="618" r="8.5" fill="#',
                keccak256(bytes(mode)) == keccak256('Clock') ? ledColor : '000'
            )
        );
    }

    function getSVGPart4(        
        string calldata mode,
        string calldata ledColor
    ) internal pure returns(bytes memory svgPart4){
        return(
            abi.encodePacked(
                '" stroke="#dafff4" stroke-width="1.5px"/> <text class="cls-8" transform="translate(425 626)"> <tspan x="0" y="0">Chrono</tspan> </text> <circle cx="408" cy="618" r="8.5" fill="#',
                keccak256(bytes(mode)) == keccak256('Chrono') ? ledColor : '000',
                '" stroke="#dafff4" stroke-width="1.5px"/> <text class="cls-8" transform="translate(590 626)"> <tspan x="0" y="0">Timer</tspan> </text> <circle cx="570" cy="618" r="8.5" fill="#',
                keccak256(bytes(mode)) == keccak256('Timer') ? ledColor : '000'
            )
        );
    }

    function getSVGPart5(        
        string calldata mode,
        string calldata ledColor,
        uint alarm
    ) internal view returns(bytes memory svgPart5){
        return(
            abi.encodePacked(
                '" stroke="#dafff4" stroke-width="1.5px"/> <text class="cls-8" transform="translate(758 626)"> <tspan x="0" y="0">Alarm</tspan> </text> <circle cx="739" cy="618" r="8.5" stroke="#dafff4" stroke-width="1.5px"> <animate attributeName="fill" values="',
                keccak256(bytes(mode)) == keccak256('Alarm') ? block.number >= alarm ? string(abi.encodePacked('#',ledColor,';#000')) : string(abi.encodePacked('#', ledColor,';#', ledColor)) : '#000;#000',
                '" begin="0s" dur="2s" calcMode="discrete" repeatCount="indefinite"/> </circle> </g> </svg>  '
            )
        );
    }

    function buildSVG(
        string [9] calldata clockCustomization,
        uint timer,
        uint alarm
    ) internal view returns(string memory svg){
        svg = assembleSVGComponents(
            getSVGPart1(clockCustomization[2], clockCustomization[3], clockCustomization[8]),
            getSVGPart2(clockCustomization[4], clockCustomization[5], clockCustomization[6]),
            getSVGPart3(clockCustomization[0], clockCustomization[1], clockCustomization[6], clockCustomization[7], timer),
            getSVGPart4(clockCustomization[1], clockCustomization[7]),
            getSVGPart5(clockCustomization[1], clockCustomization[7], alarm)
        );
        return svg;
    }
    
    function assembleSVGComponents(
        bytes memory part1,
        bytes memory part2,
        bytes memory part3,
        bytes memory part4,
        bytes memory part5
    ) internal pure returns(string memory svg){
        return(
            Base64.encode(
                bytes(
                   abi.encodePacked(
                        part1,
                        part2,
                        part3,
                        part4,
                        part5
                   )
                )
            )
        );
    }

    function buildURI( 
        string [9] calldata clockCustomization,
        uint timer,
        uint alarm
    )public view returns (string memory){

        bytes memory byteString = abi.encodePacked(
            abi.encodePacked(_uriComponents[0], "Block Clock"),
            abi.encodePacked(_uriComponents[1], "Ethereum doesn't know time, it knows blocks. This clock represents that. It has 4 modes: clock, chronograph, timer and alarm. A fully onchain project by SmartContrart."),
            abi.encodePacked(_uriComponents[2], buildSVG(
                clockCustomization,
                timer,
                alarm)),
            abi.encodePacked(_uriComponents[3], 
                '{"trait_type": "Wallpaper", "value":"', _colorNames[clockCustomization[2]], '"},',
                '{"trait_type": "Daytime", "value":"', _opacitiesNames[clockCustomization[3]], '"},',
                '{"trait_type": "Frame", "value":"', _clockOutlinesNames[clockCustomization[5]], '"},',
                '{"trait_type": "Clock color", "value":"', _clockFillsNames[clockCustomization[4]], '"},',
                '{"trait_type": "Screen color", "value":"', _screenColorsNames[clockCustomization[6]], '"},',
                '{"trait_type": "Shadow", "value":"', _shadowNames[clockCustomization[8]], '"},',
                '{"trait_type": "LED color", "value":"', _ledColorsNames[clockCustomization[7]], '"}'
            ),
            abi.encodePacked(_uriComponents[4])
        );
        return string(byteString);
    }

}
// File: Context.sol



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

pragma solidity ^0.8.0;

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

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

// File: EnumerableSet.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (utils/structs/EnumerableSet.sol)

pragma solidity ^0.8.0;

/**
 * @dev Library for managing
 * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
 * types.
 *
 * Sets have the following properties:
 *
 * - Elements are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Elements are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```
 * contract Example {
 *     // Add the library methods
 *     using EnumerableSet for EnumerableSet.AddressSet;
 *
 *     // Declare a set state variable
 *     EnumerableSet.AddressSet private mySet;
 * }
 * ```
 *
 * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
 * and `uint256` (`UintSet`) are supported.
 *
 * [WARNING]
 * ====
 *  Trying to delete such a structure from storage will likely result in data corruption, rendering the structure unusable.
 *  See https://github.com/ethereum/solidity/pull/11843[ethereum/solidity#11843] for more info.
 *
 *  In order to clean an EnumerableSet, you can either remove all elements one by one or create a fresh instance using an array of EnumerableSet.
 * ====
 */
library EnumerableSet {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Set type with
    // bytes32 values.
    // The Set implementation uses private functions, and user-facing
    // implementations (such as AddressSet) are just wrappers around the
    // underlying Set.
    // This means that we can only create new EnumerableSets for types that fit
    // in bytes32.

    struct Set {
        // Storage of set values
        bytes32[] _values;
        // Position of the value in the `values` array, plus 1 because index 0
        // means a value is not in the set.
        mapping(bytes32 => uint256) _indexes;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            // The value is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function _remove(Set storage set, bytes32 value) private returns (bool) {
        // We read and store the value's index to prevent multiple reads from the same storage slot
        uint256 valueIndex = set._indexes[value];

        if (valueIndex != 0) {
            // Equivalent to contains(set, value)
            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
            // the array, and then remove the last element (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.

            uint256 toDeleteIndex = valueIndex - 1;
            uint256 lastIndex = set._values.length - 1;

            if (lastIndex != toDeleteIndex) {
                bytes32 lastValue = set._values[lastIndex];

                // Move the last value to the index where the value to delete is
                set._values[toDeleteIndex] = lastValue;
                // Update the index for the moved value
                set._indexes[lastValue] = valueIndex; // Replace lastValue's index to valueIndex
            }

            // Delete the slot where the moved value was stored
            set._values.pop();

            // Delete the index for the deleted slot
            delete set._indexes[value];

            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function _contains(Set storage set, bytes32 value) private view returns (bool) {
        return set._indexes[value] != 0;
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function _at(Set storage set, uint256 index) private view returns (bytes32) {
        return set._values[index];
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function _values(Set storage set) private view returns (bytes32[] memory) {
        return set._values;
    }

    // Bytes32Set

    struct Bytes32Set {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _add(set._inner, value);
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _remove(set._inner, value);
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
        return _contains(set._inner, value);
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(Bytes32Set storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
        return _at(set._inner, index);
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(Bytes32Set storage set) internal view returns (bytes32[] memory) {
        return _values(set._inner);
    }

    // AddressSet

    struct AddressSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint160(uint256(_at(set._inner, index))));
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(AddressSet storage set) internal view returns (address[] memory) {
        bytes32[] memory store = _values(set._inner);
        address[] memory result;

        /// @solidity memory-safe-assembly
        assembly {
            result := store
        }

        return result;
    }

    // UintSet

    struct UintSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(UintSet storage set, uint256 value) internal returns (bool) {
        return _remove(set._inner, bytes32(value));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
        return _contains(set._inner, bytes32(value));
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
        return uint256(_at(set._inner, index));
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(UintSet storage set) internal view returns (uint256[] memory) {
        bytes32[] memory store = _values(set._inner);
        uint256[] memory result;

        /// @solidity memory-safe-assembly
        assembly {
            result := store
        }

        return result;
    }
}

// File: ERC165.sol



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

pragma solidity ^0.8.0;

import "./IERC165.sol";

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

// File: ERC721.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC721/ERC721.sol)

pragma solidity ^0.8.0;

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

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

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

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

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

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

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

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

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

    /**
     * @dev See {IERC721-balanceOf}.
     */
    function balanceOf(address owner) public view virtual override returns (uint256) {
        require(owner != address(0), "ERC721: 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: IAdminControl.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/// @author: manifold.xyz

import "./IERC165.sol";

/**
 * @dev Interface for admin control
 */
interface IAdminControl is IERC165 {

    event AdminApproved(address indexed account, address indexed sender);
    event AdminRevoked(address indexed account, address indexed sender);

    /**
     * @dev gets address of all admins
     */
    function getAdmins() external view returns (address[] memory);

    /**
     * @dev add an admin.  Can only be called by contract owner.
     */
    function approveAdmin(address admin) external;

    /**
     * @dev remove an admin.  Can only be called by contract owner.
     */
    function revokeAdmin(address admin) external;

    /**
     * @dev checks whether or not given address is an admin
     * Returns True if they are
     */
    function isAdmin(address admin) external view returns (bool);

}
// File: IEIP2981.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * EIP-2981
 */
interface IEIP2981 {
    /**
     * bytes4(keccak256("royaltyInfo(uint256,uint256)")) == 0x2a55205a
     *
     * => 0x2a55205a = 0x2a55205a
     */
    function royaltyInfo(uint256 tokenId, uint256 value) external view returns (address, uint256);
}
// File: IERC165.sol



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

pragma solidity ^0.8.0;

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

// File: IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

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

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

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

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

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

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

// File: IERC721.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;

import "./IERC165.sol";

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

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

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

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

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

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`.
     *
     * 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: IERC721Metadata.sol



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

pragma solidity ^0.8.0;

import "./IERC721.sol";

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

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

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

// File: IERC721Receiver.sol



// SPDX-License-Identifier: MIT
// 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: Ownable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "./Context.sol";

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

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

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

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

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

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

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

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

// File: Strings.sol



// SPDX-License-Identifier: MIT
// 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);
    }
}