{"54nft_erc721_v2.sol":{"content":"// SPDX-License-Identifier: MIT\r\npragma solidity ^0.8.0;\r\n\r\nimport \"./basicERC20.sol\";\r\nimport \"./ERC721URIStorage.sol\";\r\nimport \"./verifySignature.sol\";\r\n\r\ncontract s54nftERC721v2 is ERC721URIStorage, VerifySignature {\r\n    \r\n    address moderator;\r\n    address creator;\r\n\r\n    uint256 public modFirstRoyalties = 200; //it\u0027s cuz has 2 decimal = 2.00\r\n    uint256 public modRoyalties      = 200;\r\n    uint256 public creRoyalties      = 200;\r\n    \r\n    uint256 public cost       = 0.001 ether;\r\n    uint256 public maxSupply  = 0;\r\n    uint256 public supply     = 0;\r\n\r\n    uint256 public lastNonce  = 0;\r\n\r\n    uint256 public modTime    = 7 days;\r\n    \r\n    mapping(uint256 =\u003e uint8) internal usedNonce;\r\n    mapping(uint256 =\u003e uint256) internal lastTransact;\r\n    \r\n    event nftMinted(address to, uint256 count, address payToken, uint256 payAmount, uint256[] tokenIds);\r\n\r\n    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);\r\n\r\n    constructor(string memory name, string memory symbol, address setCreator, address setModerator, uint256 setModFirstRoyalties, uint256 setModRoyalties, uint256 setCreRoyalties , uint256 setCost, uint256 setMaxSuplly) ERC721(name, symbol) {\r\n        moderator           = setModerator;\r\n        modFirstRoyalties   = setModFirstRoyalties;\r\n        modRoyalties        = setModRoyalties;\r\n        creRoyalties        = setCreRoyalties;\r\n        creator             = setCreator;\r\n        cost                = setCost;\r\n        maxSupply           = setMaxSuplly;\r\n    }\r\n    \r\n    function modifModRoyalties(uint256 royalties) public onlyModerator {\r\n        modRoyalties = royalties;\r\n    }\r\n    \r\n    function modifCreRoyalties(uint256 royalties) public onlyCreator {\r\n        creRoyalties = royalties;\r\n    }\r\n    \r\n    function modifCost(uint256 setCost) public onlyCreator {\r\n        cost = setCost;\r\n    }\r\n    \r\n    function _setBaseURI(string memory _uri) public onlyModerator {\r\n        _baseURIstr = _uri;\r\n    }\r\n\r\n    function calcShares(address tokenOwner, uint256 amount) private view returns(uint256 [] memory) {\r\n        \r\n        uint256 svalue = amount;\r\n        uint256[] memory shares = new uint256[](3);\r\n\r\n        if(amount \u003c 10000){\r\n            svalue = svalue * 10000;\r\n        }\r\n\r\n        if(tokenOwner == creator){\r\n           \r\n            shares[0] = svalue / 10000 * (10000 - modFirstRoyalties); //creator share\r\n            shares[1] = svalue - shares[0]; //moderator share\r\n            //shares[1] = svalue / 10000 * modFirstRoyalties; //moderator share\r\n\r\n            if(amount \u003c 10000){\r\n                shares[0] = shares[0] / 10000;\r\n                shares[1] = amount - shares[0];\r\n                //shares[1] = shares[1] / 10000;\r\n            }\r\n\r\n            return shares;  \r\n\r\n        } else {\r\n            \r\n            uint256 totShares = creRoyalties + modRoyalties;\r\n            \r\n            uint256 shareable =  svalue / 10000 * totShares;\r\n            \r\n            shares[0] = shareable / totShares * creRoyalties; //creator share\r\n            shares[1] = shareable / totShares * modRoyalties; //moderator share\r\n            \r\n            shares[2] = amount - shareable; // seller share\r\n\r\n            if(amount \u003c 10000){\r\n                shares[0] = shares[0] / 10000;\r\n                shares[1] = shares[1] / 10000;\r\n                shares[2] = shares[2] / 10000;\r\n            }\r\n\r\n            return shares; \r\n            \r\n        }\r\n    }\r\n    \r\n    function distribShares(address tokenOwner, address payToken, uint256 amount) internal {\r\n        //require(msg.value \u003e= cost, \"Amount send not enough\");\r\n\r\n        if(amount \u003e 0){\r\n\r\n            uint256[] memory _shares = calcShares(tokenOwner, amount);\r\n            \r\n            if(payToken == address(0)){\r\n                \r\n                if(tokenOwner != creator \u0026\u0026 _shares[2] \u003e 0){\r\n                    //payable(tokenOwner).transfer(shares[2]);\r\n                    require(payable(tokenOwner).send(_shares[2]));\r\n                }\r\n                if(_shares[0] \u003e 0){\r\n                    //payable(creator).transfer( _shares[0]);\r\n                    require(payable(creator).send(_shares[0]));\r\n                }\r\n                if(_shares[1] \u003e 0){\r\n                    //payable(moderator).transfer(_shares[1]);\r\n                    require(payable(moderator).send(_shares[1]));\r\n                }\r\n                \r\n            } else {\r\n\r\n                ERC20 t = ERC20(payToken);\r\n                \r\n                require(t.transferFrom(msg.sender, address(this), amount));\r\n                                \r\n                if(tokenOwner != creator  \u0026\u0026 _shares[2] \u003e 0){\r\n                    require(t.transfer(tokenOwner, _shares[2]));\r\n                }\r\n                if(_shares[0] \u003e 0){\r\n                    require(t.transfer(creator, _shares[0]));\r\n                }\r\n                if(_shares[1] \u003e 0){\r\n                    require(t.transfer(moderator, _shares[1]));\r\n                }\r\n                \r\n            }\r\n\r\n        }\r\n\r\n    }\r\n    \r\n    function mintToken(address reciver, string[] memory tokenURI, uint256[] memory optionalId, address payToken,\r\n                        uint256 payAmount, uint256 nonce, bytes memory data)\r\n        public\r\n        payable\r\n        returns (uint256[] memory)\r\n    {\r\n        \r\n        uint256 count = tokenURI.length;\r\n        uint256[] memory tokenIds = new uint256[](count);\r\n\r\n        if(maxSupply != 0){\r\n            require(supply + (count - 1) \u003c maxSupply, \"Max supply reached\");\r\n        }\r\n\r\n        if(msg.value \u003e 0 \u0026\u0026 payToken == address(0)){\r\n            payAmount = msg.value;\r\n        }\r\n\r\n        if(msg.sender != moderator \u0026\u0026 msg.sender != creator){\r\n            lognonce(nonce);\r\n            require(verifyMint(moderator, reciver, payToken, payAmount, tokenURI, optionalId, nonce, data), \"Not allowed\");\r\n        }\r\n        \r\n        distribShares(creator, payToken, payAmount);\r\n\r\n        for (uint256 i = 0; i \u003c count; i++) {\r\n            \r\n            supply += 1;\r\n\r\n            uint256 tmpid = supply; // supply as item id\r\n\r\n            if( optionalId[i] \u003e 0 ){                \r\n                tmpid = optionalId[i];\r\n            }\r\n\r\n            if(_exists(tmpid) == false){\r\n                tokenIds[i] = tmpid;\r\n                _mint(reciver, tmpid); \r\n                _setTokenURI(tmpid, tokenURI[i]);\r\n                lastTransact[tmpid]=block.timestamp;\r\n            } else {\r\n                revert(\"TokenId Used\");\r\n            }\r\n\r\n        }\r\n\r\n        emit nftMinted(reciver, count, payToken, payAmount, tokenIds);\r\n        return tokenIds;\r\n\r\n    }\r\n\r\n    function buy(\r\n        address from,\r\n        uint256 tokenid,\r\n        address reciver,\r\n        address payToken,\r\n        uint256 payAmount,\r\n        uint256 nonce,\r\n        bytes memory data\r\n    ) public payable {\r\n\r\n        if(msg.value \u003e 0 \u0026\u0026 payToken == address(0)){\r\n            payAmount = msg.value;\r\n        }\r\n\r\n        if(msg.sender != moderator){\r\n            lognonce(nonce);\r\n            require(verifyBuy(moderator, from, tokenid, reciver, payToken, payAmount, nonce, data), \"Not allowed\");\r\n        }\r\n\r\n        distribShares(from, payToken, payAmount);\r\n\r\n        _transfer(from, reciver, tokenid);\r\n\r\n        lastTransact[tokenid]=block.timestamp;\r\n\r\n    }\r\n    \r\n    function transferFrom(\r\n        address from,\r\n        address to,\r\n        uint256 tokenid\r\n    ) public payable virtual override {\r\n\r\n        ifAllOk(tokenid);\r\n        \r\n        distribShares(ownerOf(tokenid), address(0), msg.value);\r\n        \r\n        _transfer(from, to, tokenid);\r\n\r\n        lastTransact[tokenid] = block.timestamp;\r\n\r\n    }\r\n    \r\n    function safeTransferFrom(\r\n        address from,\r\n        address to,\r\n        uint256 tokenId\r\n    ) public payable virtual override {\r\n        safeTransferFrom(from, to, tokenId, \"\");\r\n    }\r\n    \r\n    function safeTransferFrom(\r\n        address from,\r\n        address to,\r\n        uint256 tokenid,\r\n        bytes memory _data\r\n    ) public payable virtual override {\r\n\r\n        ifAllOk(tokenid);\r\n        \r\n        distribShares(from, address(0), msg.value);\r\n\r\n        _safeTransfer(from, to, tokenid, _data);\r\n\r\n        lastTransact[tokenid]=block.timestamp;\r\n        \r\n    }\r\n\r\n    function burn(uint256 tokenid) public virtual {\r\n        ifAllOk(tokenid);\r\n        _burn(tokenid);\r\n    }\r\n\r\n    // function ownerOf(uint256 tokenId) public view virtual override returns (address) {\r\n    //     address owner = _owners[tokenId];\r\n    //     return owner;\r\n    // }\r\n\r\n    function totalSupply() public view returns (uint256) {\r\n        return maxSupply;\r\n    }\r\n\r\n    function approveSpendERC20(address token, address spender, uint256 value)\r\n        public onlyModerator returns (bool)\r\n    {\r\n        ERC20 t = ERC20(token);\r\n        return t.approve(spender, value);\r\n    }\r\n    \r\n    function withdraw() public payable onlyModerator {\r\n        require(payable(msg.sender).send(address(this).balance));\r\n    }\r\n\r\n    /**\r\n     * @dev Returns the address of the current owner.\r\n     */\r\n    function owner() public view virtual returns (address) {\r\n        return creator;\r\n    }\r\n\r\n    /**\r\n     * @dev Transfers ownership of the contract to a new account (`newOwner`).\r\n     * Can only be called by the current owner.\r\n     */\r\n    function transferOwnership(address newOwner) public virtual onlyCreator {\r\n        require(newOwner != address(0), \"Ownable: new owner is the zero address\");\r\n        _setOwner(newOwner);\r\n    }\r\n\r\n    function _setOwner(address newOwner) private {\r\n        address oldOwner = creator;\r\n        creator = newOwner;\r\n        emit OwnershipTransferred(oldOwner, newOwner);\r\n    }\r\n\r\n    modifier onlyCreator {\r\n        require(msg.sender == creator, \"Only owner function\");\r\n        _;\r\n    }\r\n    \r\n    modifier onlyModerator {\r\n        require(msg.sender == moderator, \"Only Moderator Function\");\r\n        _;\r\n    }\r\n    function ifAprovedOrOwner(uint256 tokenid) private view {\r\n        require(_isApprovedOrOwner(_msgSender(), tokenid), \"ERC721: caller is not owner nor approved\");\r\n    }\r\n\r\n    function ifcanModerate(uint256 tokenid) private view {\r\n        require(lastTransact[tokenid] + modTime \u003e block.timestamp, \"Moderation time over\");\r\n    }\r\n\r\n    function ifAllOk(uint256 tokenid) internal view {\r\n        if(msg.sender != moderator ){\r\n            ifAprovedOrOwner(tokenid);\r\n            //require(_isApprovedOrOwner(_msgSender(), tokenId), \"ERC721Burnable: caller is not owner nor approved\");\r\n        } else {\r\n            ifcanModerate(tokenid);\r\n            //require(lastTransact[tokenId] + modTime \u003e block.timestamp, \"Moderation time over\");\r\n        }\r\n    }\r\n\r\n    function lognonce(uint256 nonce) internal {\r\n        require(usedNonce[nonce] != 1, \"Nonce already Used\");\r\n        if(nonce \u003e lastNonce){\r\n            lastNonce = nonce;\r\n        }\r\n        usedNonce[nonce] = 1;\r\n    }\r\n    \r\n}"},"Address.sol":{"content":"// SPDX-License-Identifier: MIT\r\n\r\npragma solidity ^0.8.0;\r\n\r\n/**\r\n * @dev Collection of functions related to the address type\r\n */\r\nlibrary Address {\r\n    /**\r\n     * @dev Returns true if `account` is a contract.\r\n     *\r\n     * [IMPORTANT]\r\n     * ====\r\n     * It is unsafe to assume that an address for which this function returns\r\n     * false is an externally-owned account (EOA) and not a contract.\r\n     *\r\n     * Among others, `isContract` will return false for the following\r\n     * types of addresses:\r\n     *\r\n     *  - an externally-owned account\r\n     *  - a contract in construction\r\n     *  - an address where a contract will be created\r\n     *  - an address where a contract lived, but was destroyed\r\n     * ====\r\n     */\r\n    function isContract(address account) internal view returns (bool) {\r\n        // This method relies on extcodesize, which returns 0 for contracts in\r\n        // construction, since the code is only stored at the end of the\r\n        // constructor execution.\r\n\r\n        uint256 size;\r\n        assembly {\r\n            size := extcodesize(account)\r\n        }\r\n        return size \u003e 0;\r\n    }\r\n\r\n    /**\r\n     * @dev Replacement for Solidity\u0027s `transfer`: sends `amount` wei to\r\n     * `recipient`, forwarding all available gas and reverting on errors.\r\n     *\r\n     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost\r\n     * of certain opcodes, possibly making contracts go over the 2300 gas limit\r\n     * imposed by `transfer`, making them unable to receive funds via\r\n     * `transfer`. {sendValue} removes this limitation.\r\n     *\r\n     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].\r\n     *\r\n     * IMPORTANT: because control is transferred to `recipient`, care must be\r\n     * taken to not create reentrancy vulnerabilities. Consider using\r\n     * {ReentrancyGuard} or the\r\n     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].\r\n     */\r\n    function sendValue(address payable recipient, uint256 amount) internal {\r\n        require(address(this).balance \u003e= amount, \"Address: insufficient balance\");\r\n\r\n        (bool success, ) = recipient.call{value: amount}(\"\");\r\n        require(success, \"Address: unable to send value, recipient may have reverted\");\r\n    }\r\n\r\n    /**\r\n     * @dev Performs a Solidity function call using a low level `call`. A\r\n     * plain `call` is an unsafe replacement for a function call: use this\r\n     * function instead.\r\n     *\r\n     * If `target` reverts with a revert reason, it is bubbled up by this\r\n     * function (like regular Solidity function calls).\r\n     *\r\n     * Returns the raw returned data. To convert to the expected return value,\r\n     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - `target` must be a contract.\r\n     * - calling `target` with `data` must not revert.\r\n     *\r\n     * _Available since v3.1._\r\n     */\r\n    function functionCall(address target, bytes memory data) internal returns (bytes memory) {\r\n        return functionCall(target, data, \"Address: low-level call failed\");\r\n    }\r\n\r\n    /**\r\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with\r\n     * `errorMessage` as a fallback revert reason when `target` reverts.\r\n     *\r\n     * _Available since v3.1._\r\n     */\r\n    function functionCall(\r\n        address target,\r\n        bytes memory data,\r\n        string memory errorMessage\r\n    ) internal returns (bytes memory) {\r\n        return functionCallWithValue(target, data, 0, errorMessage);\r\n    }\r\n\r\n    /**\r\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\r\n     * but also transferring `value` wei to `target`.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - the calling contract must have an ETH balance of at least `value`.\r\n     * - the called Solidity function must be `payable`.\r\n     *\r\n     * _Available since v3.1._\r\n     */\r\n    function functionCallWithValue(\r\n        address target,\r\n        bytes memory data,\r\n        uint256 value\r\n    ) internal returns (bytes memory) {\r\n        return functionCallWithValue(target, data, value, \"Address: low-level call with value failed\");\r\n    }\r\n\r\n    /**\r\n     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but\r\n     * with `errorMessage` as a fallback revert reason when `target` reverts.\r\n     *\r\n     * _Available since v3.1._\r\n     */\r\n    function functionCallWithValue(\r\n        address target,\r\n        bytes memory data,\r\n        uint256 value,\r\n        string memory errorMessage\r\n    ) internal returns (bytes memory) {\r\n        require(address(this).balance \u003e= value, \"Address: insufficient balance for call\");\r\n        require(isContract(target), \"Address: call to non-contract\");\r\n\r\n        (bool success, bytes memory returndata) = target.call{value: value}(data);\r\n        return verifyCallResult(success, returndata, errorMessage);\r\n    }\r\n\r\n    /**\r\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\r\n     * but performing a static call.\r\n     *\r\n     * _Available since v3.3._\r\n     */\r\n    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {\r\n        return functionStaticCall(target, data, \"Address: low-level static call failed\");\r\n    }\r\n\r\n    /**\r\n     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],\r\n     * but performing a static call.\r\n     *\r\n     * _Available since v3.3._\r\n     */\r\n    function functionStaticCall(\r\n        address target,\r\n        bytes memory data,\r\n        string memory errorMessage\r\n    ) internal view returns (bytes memory) {\r\n        require(isContract(target), \"Address: static call to non-contract\");\r\n\r\n        (bool success, bytes memory returndata) = target.staticcall(data);\r\n        return verifyCallResult(success, returndata, errorMessage);\r\n    }\r\n\r\n    /**\r\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\r\n     * but performing a delegate call.\r\n     *\r\n     * _Available since v3.4._\r\n     */\r\n    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {\r\n        return functionDelegateCall(target, data, \"Address: low-level delegate call failed\");\r\n    }\r\n\r\n    /**\r\n     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],\r\n     * but performing a delegate call.\r\n     *\r\n     * _Available since v3.4._\r\n     */\r\n    function functionDelegateCall(\r\n        address target,\r\n        bytes memory data,\r\n        string memory errorMessage\r\n    ) internal returns (bytes memory) {\r\n        require(isContract(target), \"Address: delegate call to non-contract\");\r\n\r\n        (bool success, bytes memory returndata) = target.delegatecall(data);\r\n        return verifyCallResult(success, returndata, errorMessage);\r\n    }\r\n\r\n    /**\r\n     * @dev Tool to verifies that a low level call was successful, and revert if it wasn\u0027t, either by bubbling the\r\n     * revert reason using the provided one.\r\n     *\r\n     * _Available since v4.3._\r\n     */\r\n    function verifyCallResult(\r\n        bool success,\r\n        bytes memory returndata,\r\n        string memory errorMessage\r\n    ) internal pure returns (bytes memory) {\r\n        if (success) {\r\n            return returndata;\r\n        } else {\r\n            // Look for revert reason and bubble it up if present\r\n            if (returndata.length \u003e 0) {\r\n                // The easiest way to bubble the revert reason is using memory via assembly\r\n\r\n                assembly {\r\n                    let returndata_size := mload(returndata)\r\n                    revert(add(32, returndata), returndata_size)\r\n                }\r\n            } else {\r\n                revert(errorMessage);\r\n            }\r\n        }\r\n    }\r\n}\r\n"},"basicERC20.sol":{"content":"// SPDX-License-Identifier: MIT\r\npragma solidity ^0.8.0;\r\n\r\nabstract contract ERC20Basic {\r\n  function totalSupply() public virtual view returns (uint256);\r\n  function balanceOf(address who) public virtual view returns (uint256);\r\n  function transfer(address to, uint256 value) public virtual returns (bool);\r\n  event Transfer(address indexed from, address indexed to, uint256 value);\r\n}\r\n\r\nabstract contract ERC20 is ERC20Basic {\r\n  function allowance(address owner, address spender)\r\n    public virtual view returns (uint256);\r\n\r\n  function transferFrom(address from, address to, uint256 value)\r\n    public virtual returns (bool);\r\n\r\n  function approve(address spender, uint256 value) public virtual returns (bool);\r\n  event Approval(\r\n    address indexed owner,\r\n    address indexed spender,\r\n    uint256 value\r\n  );\r\n}\r\n"},"Context.sol":{"content":"// SPDX-License-Identifier: MIT\r\n\r\npragma solidity ^0.8.0;\r\n\r\n/**\r\n * @dev Provides information about the current execution context, including the\r\n * sender of the transaction and its data. While these are generally available\r\n * via msg.sender and msg.data, they should not be accessed in such a direct\r\n * manner, since when dealing with meta-transactions the account sending and\r\n * paying for execution may not be the actual sender (as far as an application\r\n * is concerned).\r\n *\r\n * This contract is only required for intermediate, library-like contracts.\r\n */\r\nabstract contract Context {\r\n    function _msgSender() internal view virtual returns (address) {\r\n        return msg.sender;\r\n    }\r\n\r\n    function _msgData() internal view virtual returns (bytes calldata) {\r\n        return msg.data;\r\n    }\r\n}\r\n"},"ERC165.sol":{"content":"// SPDX-License-Identifier: MIT\r\n\r\npragma solidity ^0.8.0;\r\n\r\nimport \"./IERC165.sol\";\r\n\r\n/**\r\n * @dev Implementation of the {IERC165} interface.\r\n *\r\n * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check\r\n * for the additional interface id that will be supported. For example:\r\n *\r\n * ```solidity\r\n * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {\r\n *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);\r\n * }\r\n * ```\r\n *\r\n * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.\r\n */\r\nabstract contract ERC165 is IERC165 {\r\n    /**\r\n     * @dev See {IERC165-supportsInterface}.\r\n     */\r\n    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {\r\n        return interfaceId == type(IERC165).interfaceId;\r\n    }\r\n}\r\n"},"ERC721.sol":{"content":"// SPDX-License-Identifier: MIT\r\n\r\npragma solidity ^0.8.0;\r\n\r\nimport \"./IERC721.sol\";\r\nimport \"./IERC721Metadata.sol\";\r\nimport \"./Address.sol\";\r\nimport \"./Context.sol\";\r\nimport \"./Strings.sol\";\r\nimport \"./ERC165.sol\";\r\nimport \"./IERC721Receiver.sol\";\r\n\r\n/**\r\n * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including\r\n * the Metadata extension, but not including the Enumerable extension, which is available separately as\r\n * {ERC721Enumerable}.\r\n */\r\nabstract contract ERC721 is Context, ERC165, IERC721 {\r\n    using Address for address;\r\n    using Strings for uint256;\r\n\r\n    // Token name\r\n    string private _name;\r\n\r\n    // Token symbol\r\n    string private _symbol;\r\n\r\n    string internal _baseURIstr = \"https://ipfs.io/ipfs/\";\r\n\r\n    // Mapping from token ID to owner address\r\n    mapping(uint256 =\u003e address) internal _owners;\r\n\r\n    // Mapping owner address to token count\r\n    mapping(address =\u003e uint256) private _balances;\r\n\r\n    // Mapping from token ID to approved address\r\n    mapping(uint256 =\u003e address) private _tokenApprovals;\r\n\r\n    // Mapping from owner to operator approvals\r\n    mapping(address =\u003e mapping(address =\u003e bool)) private _operatorApprovals;\r\n\r\n    /**\r\n     * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.\r\n     */\r\n    constructor(string memory name_, string memory symbol_) {\r\n        _name = name_;\r\n        _symbol = symbol_;\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC165-supportsInterface}.\r\n     */\r\n    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {\r\n        return\r\n            interfaceId == type(IERC721).interfaceId ||\r\n            interfaceId == type(IERC721Metadata).interfaceId ||\r\n            super.supportsInterface(interfaceId);\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC721-balanceOf}.\r\n     */\r\n    function balanceOf(address owner) public view virtual override returns (uint256) {\r\n        require(owner != address(0), \"ERC721: balance query for the zero address\");\r\n        return _balances[owner];\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC721-ownerOf}.\r\n     */\r\n    function ownerOf(uint256 tokenId) public view virtual override returns (address) {\r\n        address owner = _owners[tokenId];\r\n        require(owner != address(0), \"ERC721: owner query for nonexistent token\");\r\n        return owner;\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC721Metadata-name}.\r\n     */\r\n    function name() public view virtual returns (string memory) {\r\n        return _name;\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC721Metadata-symbol}.\r\n     */\r\n    function symbol() public view virtual returns (string memory) {\r\n        return _symbol;\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC721Metadata-tokenURI}.\r\n     */\r\n    function tokenURI(uint256 tokenId) public view virtual returns (string memory) {\r\n        require(_exists(tokenId), \"ERC721Metadata: URI query for nonexistent token\");\r\n\r\n        string memory baseURI = _baseURI();\r\n        return bytes(baseURI).length \u003e 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : \"\";\r\n    }\r\n\r\n    /**\r\n     * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each\r\n     * token will be the concatenation of the `baseURI` and the `tokenId`. Empty\r\n     * by default, can be overriden in child contracts.\r\n     */\r\n    function _baseURI() internal view virtual returns (string memory) {\r\n        return _baseURIstr;\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC721-approve}.\r\n     */\r\n    function approve(address to, uint256 tokenId) public virtual override {\r\n        address owner = ERC721.ownerOf(tokenId);\r\n        require(to != owner, \"ERC721: approval to current owner\");\r\n\r\n        require(\r\n            _msgSender() == owner || isApprovedForAll(owner, _msgSender()),\r\n            \"ERC721: approve caller is not owner nor approved for all\"\r\n        );\r\n\r\n        _approve(to, tokenId);\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC721-getApproved}.\r\n     */\r\n    function getApproved(uint256 tokenId) public view virtual override returns (address) {\r\n        require(_exists(tokenId), \"ERC721: approved query for nonexistent token\");\r\n\r\n        return _tokenApprovals[tokenId];\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC721-setApprovalForAll}.\r\n     */\r\n    function setApprovalForAll(address operator, bool approved) public virtual override {\r\n        require(operator != _msgSender(), \"ERC721: approve to caller\");\r\n\r\n        _operatorApprovals[_msgSender()][operator] = approved;\r\n        emit ApprovalForAll(_msgSender(), operator, approved);\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC721-isApprovedForAll}.\r\n     */\r\n    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {\r\n        return _operatorApprovals[owner][operator];\r\n    }\r\n\r\n\r\n    /**\r\n     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients\r\n     * are aware of the ERC721 protocol to prevent tokens from being forever locked.\r\n     *\r\n     * `_data` is additional data, it has no specified format and it is sent in call to `to`.\r\n     *\r\n     * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.\r\n     * implement alternative mechanisms to perform token transfer, such as signature-based.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - `from` cannot be the zero address.\r\n     * - `to` cannot be the zero address.\r\n     * - `tokenId` token must exist and be owned by `from`.\r\n     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.\r\n     *\r\n     * Emits a {Transfer} event.\r\n     */\r\n    function _safeTransfer(\r\n        address from,\r\n        address to,\r\n        uint256 tokenId,\r\n        bytes memory _data\r\n    ) internal virtual {\r\n        _transfer(from, to, tokenId);\r\n        require(_checkOnERC721Received(from, to, tokenId, _data), \"ERC721: transfer to non ERC721Receiver implementer\");\r\n    }\r\n\r\n    /**\r\n     * @dev Returns whether `tokenId` exists.\r\n     *\r\n     * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.\r\n     *\r\n     * Tokens start existing when they are minted (`_mint`),\r\n     * and stop existing when they are burned (`_burn`).\r\n     */\r\n    function _exists(uint256 tokenId) internal view virtual returns (bool) {\r\n        return _owners[tokenId] != address(0);\r\n    }\r\n\r\n    /**\r\n     * @dev Returns whether `spender` is allowed to manage `tokenId`.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - `tokenId` must exist.\r\n     */\r\n    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {\r\n        require(_exists(tokenId), \"ERC721: operator query for nonexistent token\");\r\n        address owner = ERC721.ownerOf(tokenId);\r\n        return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));\r\n    }\r\n\r\n    /**\r\n     * @dev Safely mints `tokenId` and transfers it to `to`.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - `tokenId` must not exist.\r\n     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.\r\n     *\r\n     * Emits a {Transfer} event.\r\n     */\r\n    function _safeMint(address to, uint256 tokenId) internal virtual {\r\n        _safeMint(to, tokenId, \"\");\r\n    }\r\n\r\n    /**\r\n     * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is\r\n     * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.\r\n     */\r\n    function _safeMint(\r\n        address to,\r\n        uint256 tokenId,\r\n        bytes memory _data\r\n    ) internal virtual {\r\n        _mint(to, tokenId);\r\n        require(\r\n            _checkOnERC721Received(address(0), to, tokenId, _data),\r\n            \"ERC721: transfer to non ERC721Receiver implementer\"\r\n        );\r\n    }\r\n\r\n    /**\r\n     * @dev Mints `tokenId` and transfers it to `to`.\r\n     *\r\n     * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - `tokenId` must not exist.\r\n     * - `to` cannot be the zero address.\r\n     *\r\n     * Emits a {Transfer} event.\r\n     */\r\n    function _mint(address to, uint256 tokenId) internal virtual {\r\n        require(to != address(0), \"ERC721: mint to the zero address\");\r\n        require(!_exists(tokenId), \"ERC721: token already minted\");\r\n\r\n        _beforeTokenTransfer(address(0), to, tokenId);\r\n\r\n        _balances[to] += 1;\r\n        _owners[tokenId] = to;\r\n\r\n        emit Transfer(address(0), to, tokenId);\r\n    }\r\n\r\n    /**\r\n     * @dev Destroys `tokenId`.\r\n     * The approval is cleared when the token is burned.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - `tokenId` must exist.\r\n     *\r\n     * Emits a {Transfer} event.\r\n     */\r\n    function _burn(uint256 tokenId) internal virtual {\r\n        address owner = ERC721.ownerOf(tokenId);\r\n\r\n        _beforeTokenTransfer(owner, address(0), tokenId);\r\n\r\n        // Clear approvals\r\n        _approve(address(0), tokenId);\r\n\r\n        _balances[owner] -= 1;\r\n        delete _owners[tokenId];\r\n\r\n        emit Transfer(owner, address(0), tokenId);\r\n    }\r\n\r\n    /**\r\n     * @dev Transfers `tokenId` from `from` to `to`.\r\n     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - `to` cannot be the zero address.\r\n     * - `tokenId` token must be owned by `from`.\r\n     *\r\n     * Emits a {Transfer} event.\r\n     */\r\n    function _transfer(\r\n        address from,\r\n        address to,\r\n        uint256 tokenId\r\n    ) internal virtual {\r\n        require(ERC721.ownerOf(tokenId) == from, \"ERC721: transfer of token that is not own\");\r\n        require(to != address(0), \"ERC721: transfer to the zero address\");\r\n\r\n        _beforeTokenTransfer(from, to, tokenId);\r\n\r\n        // Clear approvals from the previous owner\r\n        _approve(address(0), tokenId);\r\n\r\n        _balances[from] -= 1;\r\n        _balances[to] += 1;\r\n        _owners[tokenId] = to;\r\n\r\n        emit Transfer(from, to, tokenId);\r\n    }\r\n\r\n    /**\r\n     * @dev Approve `to` to operate on `tokenId`\r\n     *\r\n     * Emits a {Approval} event.\r\n     */\r\n    function _approve(address to, uint256 tokenId) internal virtual {\r\n        _tokenApprovals[tokenId] = to;\r\n        emit Approval(ERC721.ownerOf(tokenId), to, tokenId);\r\n    }\r\n\r\n    /**\r\n     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.\r\n     * The call is not executed if the target address is not a contract.\r\n     *\r\n     * @param from address representing the previous owner of the given token ID\r\n     * @param to target address that will receive the tokens\r\n     * @param tokenId uint256 ID of the token to be transferred\r\n     * @param _data bytes optional data to send along with the call\r\n     * @return bool whether the call correctly returned the expected magic value\r\n     */\r\n    function _checkOnERC721Received(\r\n        address from,\r\n        address to,\r\n        uint256 tokenId,\r\n        bytes memory _data\r\n    ) private returns (bool) {\r\n        if (to.isContract()) {\r\n            try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {\r\n                return retval == IERC721Receiver.onERC721Received.selector;\r\n            } catch (bytes memory reason) {\r\n                if (reason.length == 0) {\r\n                    revert(\"ERC721: transfer to non ERC721Receiver implementer\");\r\n                } else {\r\n                    assembly {\r\n                        revert(add(32, reason), mload(reason))\r\n                    }\r\n                }\r\n            }\r\n        } else {\r\n            return true;\r\n        }\r\n    }\r\n\r\n    /**\r\n     * @dev Hook that is called before any token transfer. This includes minting\r\n     * and burning.\r\n     *\r\n     * Calling conditions:\r\n     *\r\n     * - When `from` and `to` are both non-zero, ``from``\u0027s `tokenId` will be\r\n     * transferred to `to`.\r\n     * - When `from` is zero, `tokenId` will be minted for `to`.\r\n     * - When `to` is zero, ``from``\u0027s `tokenId` will be burned.\r\n     * - `from` and `to` are never both zero.\r\n     *\r\n     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].\r\n     */\r\n    function _beforeTokenTransfer(\r\n        address from,\r\n        address to,\r\n        uint256 tokenId\r\n    ) internal virtual {}\r\n}"},"ERC721URIStorage.sol":{"content":"// SPDX-License-Identifier: MIT\r\n\r\npragma solidity ^0.8.0;\r\n\r\nimport \"./ERC721.sol\";\r\n\r\n/**\r\n * @dev ERC721 token with storage based token URI management.\r\n */\r\nabstract contract ERC721URIStorage is ERC721 {\r\n    using Strings for uint256;\r\n\r\n    // Optional mapping for token URIs\r\n    mapping(uint256 =\u003e string) private _tokenURIs;\r\n\r\n    /**\r\n     * @dev See {IERC721Metadata-tokenURI}.\r\n     */\r\n    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {\r\n        require(_exists(tokenId), \"ERC721URIStorage: URI query for nonexistent token\");\r\n\r\n        string memory _tokenURI = _tokenURIs[tokenId];\r\n        string memory base = _baseURI();\r\n\r\n        // If there is no base URI, return the token URI.\r\n        if (bytes(base).length == 0) {\r\n            return _tokenURI;\r\n        }\r\n        // If both are set, concatenate the baseURI and tokenURI (via abi.encodePacked).\r\n        if (bytes(_tokenURI).length \u003e 0) {\r\n            return string(abi.encodePacked(base, _tokenURI));\r\n        }\r\n\r\n        return super.tokenURI(tokenId);\r\n    }\r\n\r\n    /**\r\n     * @dev Sets `_tokenURI` as the tokenURI of `tokenId`.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - `tokenId` must exist.\r\n     */\r\n    function _setTokenURI(uint256 tokenId, string memory _tokenURI) internal virtual {\r\n        require(_exists(tokenId), \"ERC721URIStorage: URI set of nonexistent token\");\r\n        _tokenURIs[tokenId] = _tokenURI;\r\n    }\r\n\r\n    /**\r\n     * @dev Destroys `tokenId`.\r\n     * The approval is cleared when the token is burned.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - `tokenId` must exist.\r\n     *\r\n     * Emits a {Transfer} event.\r\n     */\r\n    function _burn(uint256 tokenId) internal virtual override {\r\n        super._burn(tokenId);\r\n\r\n        if (bytes(_tokenURIs[tokenId]).length != 0) {\r\n            delete _tokenURIs[tokenId];\r\n        }\r\n    }\r\n}\r\n"},"IERC165.sol":{"content":"// SPDX-License-Identifier: MIT\r\n\r\npragma solidity ^0.8.0;\r\n\r\n/**\r\n * @dev Interface of the ERC165 standard, as defined in the\r\n * https://eips.ethereum.org/EIPS/eip-165[EIP].\r\n *\r\n * Implementers can declare support of contract interfaces, which can then be\r\n * queried by others ({ERC165Checker}).\r\n *\r\n * For an implementation, see {ERC165}.\r\n */\r\ninterface IERC165 {\r\n    /**\r\n     * @dev Returns true if this contract implements the interface defined by\r\n     * `interfaceId`. See the corresponding\r\n     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]\r\n     * to learn more about how these ids are created.\r\n     *\r\n     * This function call must use less than 30 000 gas.\r\n     */\r\n    function supportsInterface(bytes4 interfaceId) external view returns (bool);\r\n}\r\n"},"IERC721.sol":{"content":"// SPDX-License-Identifier: MIT\r\n\r\npragma solidity ^0.8.0;\r\n\r\nimport \"./IERC165.sol\";\r\n\r\n/**\r\n * @dev Required interface of an ERC721 compliant contract.\r\n */\r\ninterface IERC721 is IERC165 {\r\n    /**\r\n     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.\r\n     */\r\n    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);\r\n\r\n    /**\r\n     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.\r\n     */\r\n    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);\r\n\r\n    /**\r\n     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.\r\n     */\r\n    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);\r\n\r\n    /**\r\n     * @dev Returns the number of tokens in ``owner``\u0027s account.\r\n     */\r\n    function balanceOf(address owner) external view returns (uint256 balance);\r\n\r\n    /**\r\n     * @dev Returns the owner of the `tokenId` token.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - `tokenId` must exist.\r\n     */\r\n    function ownerOf(uint256 tokenId) external view returns (address owner);\r\n\r\n    /**\r\n     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients\r\n     * are aware of the ERC721 protocol to prevent tokens from being forever locked.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - `from` cannot be the zero address.\r\n     * - `to` cannot be the zero address.\r\n     * - `tokenId` token must exist and be owned by `from`.\r\n     * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.\r\n     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.\r\n     *\r\n     * Emits a {Transfer} event.\r\n     */\r\n    function safeTransferFrom(\r\n        address from,\r\n        address to,\r\n        uint256 tokenId\r\n    ) external payable;\r\n\r\n    /**\r\n     * @dev Transfers `tokenId` token from `from` to `to`.\r\n     *\r\n     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - `from` cannot be the zero address.\r\n     * - `to` cannot be the zero address.\r\n     * - `tokenId` token must be owned by `from`.\r\n     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.\r\n     *\r\n     * Emits a {Transfer} event.\r\n     */\r\n    function transferFrom(\r\n        address from,\r\n        address to,\r\n        uint256 tokenId\r\n    ) external payable;\r\n\r\n    /**\r\n     * @dev Gives permission to `to` to transfer `tokenId` token to another account.\r\n     * The approval is cleared when the token is transferred.\r\n     *\r\n     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - The caller must own the token or be an approved operator.\r\n     * - `tokenId` must exist.\r\n     *\r\n     * Emits an {Approval} event.\r\n     */\r\n    function approve(address to, uint256 tokenId) external;\r\n\r\n    /**\r\n     * @dev Returns the account approved for `tokenId` token.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - `tokenId` must exist.\r\n     */\r\n    function getApproved(uint256 tokenId) external view returns (address operator);\r\n\r\n    /**\r\n     * @dev Approve or remove `operator` as an operator for the caller.\r\n     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - The `operator` cannot be the caller.\r\n     *\r\n     * Emits an {ApprovalForAll} event.\r\n     */\r\n    function setApprovalForAll(address operator, bool _approved) external;\r\n\r\n    /**\r\n     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.\r\n     *\r\n     * See {setApprovalForAll}\r\n     */\r\n    function isApprovedForAll(address owner, address operator) external view returns (bool);\r\n\r\n    /**\r\n     * @dev Safely transfers `tokenId` token from `from` to `to`.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - `from` cannot be the zero address.\r\n     * - `to` cannot be the zero address.\r\n     * - `tokenId` token must exist and be owned by `from`.\r\n     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.\r\n     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.\r\n     *\r\n     * Emits a {Transfer} event.\r\n     */\r\n    function safeTransferFrom(\r\n        address from,\r\n        address to,\r\n        uint256 tokenId,\r\n        bytes calldata data\r\n    ) external payable;\r\n}"},"IERC721Metadata.sol":{"content":"// SPDX-License-Identifier: MIT\r\n\r\npragma solidity ^0.8.0;\r\n\r\nimport \"./IERC721.sol\";\r\n\r\n/**\r\n * @title ERC-721 Non-Fungible Token Standard, optional metadata extension\r\n * @dev See https://eips.ethereum.org/EIPS/eip-721\r\n */\r\ninterface IERC721Metadata is IERC721 {\r\n    /**\r\n     * @dev Returns the token collection name.\r\n     */\r\n    function name() external view returns (string memory);\r\n\r\n    /**\r\n     * @dev Returns the token collection symbol.\r\n     */\r\n    function symbol() external view returns (string memory);\r\n\r\n    /**\r\n     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.\r\n     */\r\n    function tokenURI(uint256 tokenId) external view returns (string memory);\r\n}"},"IERC721Receiver.sol":{"content":"// SPDX-License-Identifier: MIT\r\n\r\npragma solidity ^0.8.0;\r\n\r\n/**\r\n * @title ERC721 token receiver interface\r\n * @dev Interface for any contract that wants to support safeTransfers\r\n * from ERC721 asset contracts.\r\n */\r\ninterface IERC721Receiver {\r\n    /**\r\n     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}\r\n     * by `operator` from `from`, this function is called.\r\n     *\r\n     * It must return its Solidity selector to confirm the token transfer.\r\n     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.\r\n     *\r\n     * The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.\r\n     */\r\n    function onERC721Received(\r\n        address operator,\r\n        address from,\r\n        uint256 tokenId,\r\n        bytes calldata data\r\n    ) external returns (bytes4);\r\n}\r\n"},"Strings.sol":{"content":"// SPDX-License-Identifier: MIT\r\n\r\npragma solidity ^0.8.0;\r\n\r\n/**\r\n * @dev String operations.\r\n */\r\nlibrary Strings {\r\n    bytes16 private constant _HEX_SYMBOLS = \"0123456789abcdef\";\r\n\r\n    /**\r\n     * @dev Converts a `uint256` to its ASCII `string` decimal representation.\r\n     */\r\n    function toString(uint256 value) internal pure returns (string memory) {\r\n        // Inspired by OraclizeAPI\u0027s implementation - MIT licence\r\n        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol\r\n\r\n        if (value == 0) {\r\n            return \"0\";\r\n        }\r\n        uint256 temp = value;\r\n        uint256 digits;\r\n        while (temp != 0) {\r\n            digits++;\r\n            temp /= 10;\r\n        }\r\n        bytes memory buffer = new bytes(digits);\r\n        while (value != 0) {\r\n            digits -= 1;\r\n            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));\r\n            value /= 10;\r\n        }\r\n        return string(buffer);\r\n    }\r\n\r\n    /**\r\n     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.\r\n     */\r\n    function toHexString(uint256 value) internal pure returns (string memory) {\r\n        if (value == 0) {\r\n            return \"0x00\";\r\n        }\r\n        uint256 temp = value;\r\n        uint256 length = 0;\r\n        while (temp != 0) {\r\n            length++;\r\n            temp \u003e\u003e= 8;\r\n        }\r\n        return toHexString(value, length);\r\n    }\r\n\r\n    /**\r\n     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.\r\n     */\r\n    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {\r\n        bytes memory buffer = new bytes(2 * length + 2);\r\n        buffer[0] = \"0\";\r\n        buffer[1] = \"x\";\r\n        for (uint256 i = 2 * length + 1; i \u003e 1; --i) {\r\n            buffer[i] = _HEX_SYMBOLS[value \u0026 0xf];\r\n            value \u003e\u003e= 4;\r\n        }\r\n        require(value == 0, \"Strings: hex length insufficient\");\r\n        return string(buffer);\r\n    }\r\n}\r\n"},"verifySignature.sol":{"content":"// SPDX-License-Identifier: MIT\r\npragma solidity ^0.8.3;\r\n\r\n/* Signature Verification\r\n\r\nHow to Sign and Verify\r\n# Signing\r\n1. Create message to sign\r\n2. Hash the message\r\n3. Sign the hash (off chain, keep your private key secret)\r\n\r\n# Verify\r\n1. Recreate hash from the original message\r\n2. Recover signer from signature and hash\r\n3. Compare recovered signer to claimed signer\r\n*/\r\n\r\ncontract VerifySignature {\r\n    /* 1. Unlock MetaMask account\r\n    ethereum.enable()\r\n    */\r\n\r\n    /* 2. Get message hash to sign\r\n    getMessageHash(\r\n        0x14723A09ACff6D2A60DcdF7aA4AFf308FDDC160C,\r\n        123,\r\n        \"coffee and donuts\",\r\n        1\r\n    )\r\n    \r\n\r\n    hash = \"0xcf36ac4f97dc10d91fc2cbb20d718e94a8cbfe0f82eaedc6a4aa38946fb797cd\"\r\n    */\r\n    \r\n    function getBuyMessageHash(\r\n        address from,\r\n        uint256 tokenid,\r\n        address reciver,\r\n        address payToken,\r\n        uint256 payAmount,\r\n        uint256 _nonce\r\n    ) internal pure returns (bytes32) {\r\n        return keccak256(abi.encodePacked(from, tokenid, reciver, payToken, payAmount, _nonce));\r\n    }\r\n    \r\n    function getMintMessageHash(\r\n        address _reciver,\r\n        address _payToken,\r\n        uint256 _value,\r\n        string[] memory _tokenURI,\r\n        uint256[] memory optionalId,\r\n        uint256 _nonce\r\n    ) internal pure returns (bytes32) {\r\n        return keccak256(abi.encodePacked(_reciver, _payToken, _value, abi.encode(_tokenURI), optionalId, _nonce));\r\n    }\r\n\r\n    /* 3. Sign message hash\r\n    # using browser\r\n    account = \"copy paste account of signer here\"\r\n    ethereum.request({ method: \"personal_sign\", params: [account, hash]}).then(console.log)\r\n\r\n    # using web3\r\n    web3.personal.sign(hash, web3.eth.defaultAccount, console.log)\r\n\r\n    Signature will be different for different accounts\r\n    0x993dab3dd91f5c6dc28e17439be475478f5635c92a56e17e82349d3fb2f166196f466c0b4e0c146f285204f0dcb13e5ae67bc33f4b888ec32dfe0a063e8f3f781b\r\n    */\r\n    function getEthSignedMessageHash(bytes32 _messageHash)\r\n        internal\r\n        pure\r\n        returns (bytes32)\r\n    {\r\n        /*\r\n        Signature is produced by signing a keccak256 hash with the following format:\r\n        \"\\x19Ethereum Signed Message\\n\" + len(msg) + msg\r\n        */\r\n        return\r\n            keccak256(\r\n                abi.encodePacked(\"\\x19Ethereum Signed Message:\\n32\", _messageHash)\r\n            );\r\n    }\r\n\r\n    /* 4. Verify signature\r\n    signer = 0xB273216C05A8c0D4F0a4Dd0d7Bae1D2EfFE636dd\r\n    to = 0x14723A09ACff6D2A60DcdF7aA4AFf308FDDC160C\r\n    amount = 123\r\n    message = \"coffee and donuts\"\r\n    nonce = 1\r\n    signature =\r\n        0x993dab3dd91f5c6dc28e17439be475478f5635c92a56e17e82349d3fb2f166196f466c0b4e0c146f285204f0dcb13e5ae67bc33f4b888ec32dfe0a063e8f3f781b\r\n    */\r\n    function verifyBuy(\r\n        address _signer,\r\n        address from,\r\n        uint256 tokenid,\r\n        address reciver,\r\n        address payToken,\r\n        uint256 payAmount,\r\n        uint256 _nonce,\r\n        bytes memory signature\r\n    ) internal pure returns (bool) {\r\n        bytes32 messageHash = getBuyMessageHash(from, tokenid, reciver, payToken, payAmount, _nonce);\r\n        bytes32 ethSignedMessageHash = getEthSignedMessageHash(messageHash);\r\n        return recoverSigner(ethSignedMessageHash, signature) == _signer;\r\n    }\r\n    \r\n    function verifyMint(\r\n        address _signer,\r\n        address _reciver,\r\n        address _payToken,\r\n        uint256 _value,\r\n        string[] memory tokenURI,\r\n        uint256[] memory optionalId,\r\n        uint256 _nonce,\r\n        bytes memory signature\r\n    ) internal pure returns (bool) {\r\n        bytes32 messageHash = getMintMessageHash(_reciver, _payToken, _value, tokenURI, optionalId, _nonce);\r\n        bytes32 ethSignedMessageHash = getEthSignedMessageHash(messageHash);\r\n        return recoverSigner(ethSignedMessageHash, signature) == _signer;\r\n    }\r\n\r\n    function recoverSigner(bytes32 _ethSignedMessageHash, bytes memory _signature)\r\n        internal\r\n        pure\r\n        returns (address)\r\n    {\r\n        (bytes32 r, bytes32 s, uint8 v) = splitSignature(_signature);\r\n\r\n        return ecrecover(_ethSignedMessageHash, v, r, s);\r\n    }\r\n\r\n    function splitSignature(bytes memory sig)\r\n        internal\r\n        pure\r\n        returns (\r\n            bytes32 r,\r\n            bytes32 s,\r\n            uint8 v\r\n        )\r\n    {\r\n        require(sig.length == 65, \"invalid signature length\");\r\n\r\n        assembly {\r\n            /*\r\n            First 32 bytes stores the length of the signature\r\n\r\n            add(sig, 32) = pointer of sig + 32\r\n            effectively, skips first 32 bytes of signature\r\n\r\n            mload(p) loads next 32 bytes starting at the memory address p into memory\r\n            */\r\n\r\n            // first 32 bytes, after the length prefix\r\n            r := mload(add(sig, 32))\r\n            // second 32 bytes\r\n            s := mload(add(sig, 64))\r\n            // final byte (first byte of the next 32 bytes)\r\n            v := byte(0, mload(add(sig, 96)))\r\n        }\r\n\r\n        // implicitly return (r, s, v)\r\n    }\r\n    \r\n}"}}