PerkVault

{{
  "language": "Solidity",
  "sources": {
    "PerkVault.sol": {
      "content": "// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import "@openzeppelin/contracts/utils/Pausable.sol";
import "@openzeppelin/contracts/utils/Strings.sol";

/**
 * @title PerkVault
 * @dev Enhanced ERC-721 contract with payment integration support
 */
contract PerkVault is ERC721, Ownable, ReentrancyGuard, Pausable {
    using SafeERC20 for IERC20;
    using Strings for uint256;

    // State variables
    uint256 private _tokenIdCounter = 1;
    uint256 public maxSupply;
    
    IERC20 public immutable USDC;
    
    // Metadata
    string private _baseTokenURI;
    string private _contractName;
    string private _contractSymbol;
    
    // Whitelist for authorized minter addresses
    mapping(address => bool) public authorizedMinters;
    
    // Constants
    uint256 public constant MAX_MINT_PER_TX = 100;
    
    // Events
    event NFTMinted(address indexed recipient, uint256 indexed tokenId, uint256 quantity);
    event NFTBurned(address indexed burner, uint256 indexed tokenId);
    event MinterAuthorized(address indexed minter, bool authorized);
    event USDCWithdrawn(address indexed to, uint256 amount);
    event ContractPaused();
    event ContractUnpaused();
    event BaseURIUpdated(string newBaseURI);
    event MaxSupplyUpdated(uint256 newMaxSupply);
    event NameUpdated(string newName);
    event SymbolUpdated(string newSymbol);
    
    // Errors
    error UnauthorizedCaller();
    error InvalidRecipient();
    error InvalidQuantity();
    error MaxSupplyReached();
    error MaxSupplyExceeded();
    error QuantityTooHigh();

    /**
     * @dev Constructor for Ethereum Mainnet deployment
     * @param _name Token name 
     * @param _symbol Token symbol 
     * @param _owner Contract owner address
     * @param _maxSupply Maximum number of NFTs that can be minted
     * @param _initialBaseURI Initial base URI for token metadata
     */
    constructor(
        string memory _name,
        string memory _symbol,
        address _owner,
        uint256 _maxSupply,
        string memory _initialBaseURI
    ) ERC721(_name, _symbol) Ownable(_owner) {
        require(_owner != address(0), "Invalid owner address");
        
        // Ethereum Mainnet USDC address (6 decimals)
        USDC = IERC20(0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48);
        
        maxSupply = _maxSupply;
        _baseTokenURI = _initialBaseURI;
        _contractName = _name;
        _contractSymbol = _symbol;
    }

    /**
     * @dev Main mint function that authorized minters
     * @param _to Address to receive the NFT
     * @param _quantity Number of NFTs to mint
     * @param _usdcAmount Amount of USDC to pull from the caller (in USDC units - 6 decimals)
     */
    function mintNFT(address _to, uint256 _quantity, uint256 _usdcAmount) external nonReentrant whenNotPaused {
        // Only authorized minters can call this function
        if (!authorizedMinters[msg.sender]) {
            revert UnauthorizedCaller();
        }
        
        // Pull USDC from the caller - they must have approved this amount first
        if (_usdcAmount > 0) {
            USDC.safeTransferFrom(msg.sender, address(this), _usdcAmount);
        }
        
        // Mint the NFT(s)
        _mintInternal(_to, _quantity);
    }

    /**
     * @dev Owner mint function - allows contract owner to mint NFTs 
     * @param _to Address to receive the NFT
     * @param _quantity Number of NFTs to mint
     */
    function ownerMint(address _to, uint256 _quantity) external onlyOwner {
        _mintInternal(_to, _quantity);
    }

    /**
     * @dev Internal mint logic with all validations
     */
    function _mintInternal(address _to, uint256 _quantity) private {
        if (_to == address(0)) revert InvalidRecipient();
        if (_quantity == 0) revert InvalidQuantity();
        if (_quantity > MAX_MINT_PER_TX) revert QuantityTooHigh();
        
        // Check max supply if set (0 means unlimited)
        if (maxSupply > 0) {
            if (_tokenIdCounter > maxSupply) revert MaxSupplyReached();
            if (_tokenIdCounter + _quantity - 1 > maxSupply) revert MaxSupplyExceeded();
        }
        
        uint256 startTokenId = _tokenIdCounter;
        
        // Mint NFTs
        for (uint256 i = 0; i < _quantity; i++) {
            uint256 tokenId = _tokenIdCounter;
            _tokenIdCounter++;
            _safeMint(_to, tokenId);
        }
        
        emit NFTMinted(_to, startTokenId, _quantity);
    }

    /**
     * @dev Authorize or revoke a minter address
     * @param _minter Minter address to authorize/revoke
     * @param _authorized True to authorize, false to revoke
     */
    function setMinterAuthorization(address _minter, bool _authorized) external onlyOwner {
        authorizedMinters[_minter] = _authorized;
        emit MinterAuthorized(_minter, _authorized);
    }

    /**
     * @dev Batch authorize or revoke multiple minter addresses
     * @param _minters Array of minter addresses
     * @param _authorized True to authorize, false to revoke
     */
    function batchSetMinterAuthorization(address[] calldata _minters, bool _authorized) external onlyOwner {
        for (uint256 i = 0; i < _minters.length; i++) {
            authorizedMinters[_minters[i]] = _authorized;
            emit MinterAuthorized(_minters[i], _authorized);
        }
    }

    /**
     * @dev Set base URI for token metadata
     * @param baseURI_ New base URI
     */
    function setBaseURI(string memory baseURI_) external onlyOwner {
        _baseTokenURI = baseURI_;
        emit BaseURIUpdated(baseURI_);
    }

    /**
     * @dev Update the collection name
     * @param newName New collection name
     */
    function updateName(string memory newName) external onlyOwner {
        _contractName = newName;
        emit NameUpdated(newName);
    }

    /**
     * @dev Update the collection symbol
     * @param newSymbol New collection symbol
     */
    function updateSymbol(string memory newSymbol) external onlyOwner {
        _contractSymbol = newSymbol;
        emit SymbolUpdated(newSymbol);
    }

    /**
     * @dev Update max supply (can only decrease or set if currently unlimited)
     * @param _newMaxSupply New maximum supply (must be >= current supply)
     */
    function setMaxSupply(uint256 _newMaxSupply) external onlyOwner {
        require(_newMaxSupply >= _tokenIdCounter - 1, "Max supply below current supply");
        require(maxSupply == 0 || _newMaxSupply <= maxSupply, "Can only decrease max supply");
        
        maxSupply = _newMaxSupply;
        emit MaxSupplyUpdated(_newMaxSupply);
    }

    /**
     * @dev Pause the contract - stops authorized minting but allows owner functions
     */
    function pauseContract() external onlyOwner {
        _pause();
        emit ContractPaused();
    }

    /**
     * @dev Unpause the contract - allows authorized minting again
     */
    function unpauseContract() external onlyOwner {
        _unpause();
        emit ContractUnpaused();
    }

    /**
     * @dev Withdraw all USDC from the contract to owner
     */
    function withdrawAllUSDC() external onlyOwner {
        uint256 balance = USDC.balanceOf(address(this));
        require(balance > 0, "No USDC to withdraw");
        
        USDC.safeTransfer(owner(), balance);
        emit USDCWithdrawn(owner(), balance);
    }

    /**
     * @dev Withdraw specific amount of USDC from the contract to owner
     * @param _amount Amount of USDC to withdraw (in USDC's smallest unit - 6 decimals)
     */
    function withdrawUSDC(uint256 _amount) external onlyOwner {
        require(_amount > 0, "Amount must be greater than 0");
        require(USDC.balanceOf(address(this)) >= _amount, "Insufficient USDC balance");
        
        USDC.safeTransfer(owner(), _amount);
        emit USDCWithdrawn(owner(), _amount);
    }

    /**
     * @dev Withdraw USDC to a specific address
     * @param _to Address to send USDC to
     * @param _amount Amount of USDC to withdraw
     */
    function withdrawUSDCTo(address _to, uint256 _amount) external onlyOwner {
        require(_to != address(0), "Invalid recipient address");
        require(_amount > 0, "Amount must be greater than 0");
        require(USDC.balanceOf(address(this)) >= _amount, "Insufficient USDC balance");
        
        USDC.safeTransfer(_to, _amount);
        emit USDCWithdrawn(_to, _amount);
    }

    // View functions
    
    /**
     * @dev Override to return custom base URI
     */
    function _baseURI() internal view override returns (string memory) {
        return _baseTokenURI;
    }

    /**
     * @dev Returns the token URI for a given token ID
     * @param tokenId Token ID to get URI for
     */
    function tokenURI(uint256 tokenId) public view override returns (string memory) {
        _requireOwned(tokenId);
        
        string memory baseURI = _baseURI();
        return bytes(baseURI).length > 0 
            ? string(abi.encodePacked(baseURI, tokenId.toString(), ".json"))
            : "";
    }

    /**
     * @dev Override name() to return updatable name
     */
    function name() public view override returns (string memory) {
        return _contractName;
    }

    /**
     * @dev Override symbol() to return updatable symbol
     */
    function symbol() public view override returns (string memory) {
        return _contractSymbol;
    }

    /**
     * @dev Get current USDC balance of the contract
     */
    function getUSDCBalance() external view returns (uint256) {
        return USDC.balanceOf(address(this));
    }

    /**
     * @dev Get total number of NFTs minted
     */
    function totalSupply() external view returns (uint256) {
        return _tokenIdCounter - 1;
    }

    /**
     * @dev Get next token ID that will be minted
     */
    function nextTokenId() external view returns (uint256) {
        return _tokenIdCounter;
    }

    /**
     * @dev Check if an address is an authorized minter
     */
    function isMinterAuthorized(address _minter) external view returns (bool) {
        return authorizedMinters[_minter];
    }

    /**
     * @dev Get the current base URI
     */
    function baseURI() external view returns (string memory) {
        return _baseTokenURI;
    }

    /**
     * @dev Check how many more NFTs can be minted (returns max uint256 if unlimited)
     */
    function remainingSupply() external view returns (uint256) {
        if (maxSupply == 0) return type(uint256).max; // Unlimited
        uint256 minted = _tokenIdCounter - 1;
        if (minted >= maxSupply) return 0;
        return maxSupply - minted;
    }

    /**
     * @dev Get contract version and network info
     */
    function getContractInfo() external pure returns (
        string memory version,
        string memory network,
        address usdcAddress
    ) {
        return (
            "1.0.0",
            "Ethereum Mainnet",
            0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48
        );
    }
}"
    },
    "@openzeppelin/contracts/utils/Strings.sol": {
      "content": "// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.3.0) (utils/Strings.sol)

pragma solidity ^0.8.20;

import {Math} from "./math/Math.sol";
import {SafeCast} from "./math/SafeCast.sol";
import {SignedMath} from "./math/SignedMath.sol";

/**
 * @dev String operations.
 */
library Strings {
    using SafeCast for *;

    bytes16 private constant HEX_DIGITS = "0123456789abcdef";
    uint8 private constant ADDRESS_LENGTH = 20;
    uint256 private constant SPECIAL_CHARS_LOOKUP =
        (1 << 0x08) | // backspace
            (1 << 0x09) | // tab
            (1 << 0x0a) | // newline
            (1 << 0x0c) | // form feed
            (1 << 0x0d) | // carriage return
            (1 << 0x22) | // double quote
            (1 << 0x5c); // backslash

    /**
     * @dev The `value` string doesn't fit in the specified `length`.
     */
    error StringsInsufficientHexLength(uint256 value, uint256 length);

    /**
     * @dev The string being parsed contains characters that are not in scope of the given base.
     */
    error StringsInvalidChar();

    /**
     * @dev The string being parsed is not a properly formatted address.
     */
    error StringsInvalidAddressFormat();

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        unchecked {
            uint256 length = Math.log10(value) + 1;
            string memory buffer = new string(length);
            uint256 ptr;
            assembly ("memory-safe") {
                ptr := add(buffer, add(32, length))
            }
            while (true) {
                ptr--;
                assembly ("memory-safe") {
                    mstore8(ptr, byte(mod(value, 10), HEX_DIGITS))
                }
                value /= 10;
                if (value == 0) break;
            }
            return buffer;
        }
    }

    /**
     * @dev Converts a `int256` to its ASCII `string` decimal representation.
     */
    function toStringSigned(int256 value) internal pure returns (string memory) {
        return string.concat(value < 0 ? "-" : "", toString(SignedMath.abs(value)));
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        unchecked {
            return toHexString(value, Math.log256(value) + 1);
        }
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        uint256 localValue = value;
        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_DIGITS[localValue & 0xf];
            localValue >>= 4;
        }
        if (localValue != 0) {
            revert StringsInsufficientHexLength(value, length);
        }
        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);
    }

    /**
     * @dev Converts an `address` with fixed length of 20 bytes to its checksummed ASCII `string` hexadecimal
     * representation, according to EIP-55.
     */
    function toChecksumHexString(address addr) internal pure returns (string memory) {
        bytes memory buffer = bytes(toHexString(addr));

        // hash the hex part of buffer (skip length + 2 bytes, length 40)
        uint256 hashValue;
        assembly ("memory-safe") {
            hashValue := shr(96, keccak256(add(buffer, 0x22), 40))
        }

        for (uint256 i = 41; i > 1; --i) {
            // possible values for buffer[i] are 48 (0) to 57 (9) and 97 (a) to 102 (f)
            if (hashValue & 0xf > 7 && uint8(buffer[i]) > 96) {
                // case shift by xoring with 0x20
                buffer[i] ^= 0x20;
            }
            hashValue >>= 4;
        }
        return string(buffer);
    }

    /**
     * @dev Returns true if the two strings are equal.
     */
    function equal(string memory a, string memory b) internal pure returns (bool) {
        return bytes(a).length == bytes(b).length && keccak256(bytes(a)) == keccak256(bytes(b));
    }

    /**
     * @dev Parse a decimal string and returns the value as a `uint256`.
     *
     * Requirements:
     * - The string must be formatted as `[0-9]*`
     * - The result must fit into an `uint256` type
     */
    function parseUint(string memory input) internal pure returns (uint256) {
        return parseUint(input, 0, bytes(input).length);
    }

    /**
     * @dev Variant of {parseUint-string} that parses a substring of `input` located between position `begin` (included) and
     * `end` (excluded).
     *
     * Requirements:
     * - The substring must be formatted as `[0-9]*`
     * - The result must fit into an `uint256` type
     */
    function parseUint(string memory input, uint256 begin, uint256 end) internal pure returns (uint256) {
        (bool success, uint256 value) = tryParseUint(input, begin, end);
        if (!success) revert StringsInvalidChar();
        return value;
    }

    /**
     * @dev Variant of {parseUint-string} that returns false if the parsing fails because of an invalid character.
     *
     * NOTE: This function will revert if the result does not fit in a `uint256`.
     */
    function tryParseUint(string memory input) internal pure returns (bool success, uint256 value) {
        return _tryParseUintUncheckedBounds(input, 0, bytes(input).length);
    }

    /**
     * @dev Variant of {parseUint-string-uint256-uint256} that returns false if the parsing fails because of an invalid
     * character.
     *
     * NOTE: This function will revert if the result does not fit in a `uint256`.
     */
    function tryParseUint(
        string memory input,
        uint256 begin,
        uint256 end
    ) internal pure returns (bool success, uint256 value) {
        if (end > bytes(input).length || begin > end) return (false, 0);
        return _tryParseUintUncheckedBounds(input, begin, end);
    }

    /**
     * @dev Implementation of {tryParseUint-string-uint256-uint256} that does not check bounds. Caller should make sure that
     * `begin <= end <= input.length`. Other inputs would result in undefined behavior.
     */
    function _tryParseUintUncheckedBounds(
        string memory input,
        uint256 begin,
        uint256 end
    ) private pure returns (bool success, uint256 value) {
        bytes memory buffer = bytes(input);

        uint256 result = 0;
        for (uint256 i = begin; i < end; ++i) {
            uint8 chr = _tryParseChr(bytes1(_unsafeReadBytesOffset(buffer, i)));
            if (chr > 9) return (false, 0);
            result *= 10;
            result += chr;
        }
        return (true, result);
    }

    /**
     * @dev Parse a decimal string and returns the value as a `int256`.
     *
     * Requirements:
     * - The string must be formatted as `[-+]?[0-9]*`
     * - The result must fit in an `int256` type.
     */
    function parseInt(string memory input) internal pure returns (int256) {
        return parseInt(input, 0, bytes(input).length);
    }

    /**
     * @dev Variant of {parseInt-string} that parses a substring of `input` located between position `begin` (included) and
     * `end` (excluded).
     *
     * Requirements:
     * - The substring must be formatted as `[-+]?[0-9]*`
     * - The result must fit in an `int256` type.
     */
    function parseInt(string memory input, uint256 begin, uint256 end) internal pure returns (int256) {
        (bool success, int256 value) = tryParseInt(input, begin, end);
        if (!success) revert StringsInvalidChar();
        return value;
    }

    /**
     * @dev Variant of {parseInt-string} that returns false if the parsing fails because of an invalid character or if
     * the result does not fit in a `int256`.
     *
     * NOTE: This function will revert if the absolute value of the result does not fit in a `uint256`.
     */
    function tryParseInt(string memory input) internal pure returns (bool success, int256 value) {
        return _tryParseIntUncheckedBounds(input, 0, bytes(input).length);
    }

    uint256 private constant ABS_MIN_INT256 = 2 ** 255;

    /**
     * @dev Variant of {parseInt-string-uint256-uint256} that returns false if the parsing fails because of an invalid
     * character or if the result does not fit in a `int256`.
     *
     * NOTE: This function will revert if the absolute value of the result does not fit in a `uint256`.
     */
    function tryParseInt(
        string memory input,
        uint256 begin,
        uint256 end
    ) internal pure returns (bool success, int256 value) {
        if (end > bytes(input).length || begin > end) return (false, 0);
        return _tryParseIntUncheckedBounds(input, begin, end);
    }

    /**
     * @dev Implementation of {tryParseInt-string-uint256-uint256} that does not check bounds. Caller should make sure that
     * `begin <= end <= input.length`. Other inputs would result in undefined behavior.
     */
    function _tryParseIntUncheckedBounds(
        string memory input,
        uint256 begin,
        uint256 end
    ) private pure returns (bool success, int256 value) {
        bytes memory buffer = bytes(input);

        // Check presence of a negative sign.
        bytes1 sign = begin == end ? bytes1(0) : bytes1(_unsafeReadBytesOffset(buffer, begin)); // don't do out-of-bound (possibly unsafe) read if sub-string is empty
        bool positiveSign = sign == bytes1("+");
        bool negativeSign = sign == bytes1("-");
        uint256 offset = (positiveSign || negativeSign).toUint();

        (bool absSuccess, uint256 absValue) = tryParseUint(input, begin + offset, end);

        if (absSuccess && absValue < ABS_MIN_INT256) {
            return (true, negativeSign ? -int256(absValue) : int256(absValue));
        } else if (absSuccess && negativeSign && absValue == ABS_MIN_INT256) {
            return (true, type(int256).min);
        } else return (false, 0);
    }

    /**
     * @dev Parse a hexadecimal string (with or without "0x" prefix), and returns the value as a `uint256`.
     *
     * Requirements:
     * - The string must be formatted as `(0x)?[0-9a-fA-F]*`
     * - The result must fit in an `uint256` type.
     */
    function parseHexUint(string memory input) internal pure returns (uint256) {
        return parseHexUint(input, 0, bytes(input).length);
    }

    /**
     * @dev Variant of {parseHexUint-string} that parses a substring of `input` located between position `begin` (included) and
     * `end` (excluded).
     *
     * Requirements:
     * - The substring must be formatted as `(0x)?[0-9a-fA-F]*`
     * - The result must fit in an `uint256` type.
     */
    function parseHexUint(string memory input, uint256 begin, uint256 end) internal pure returns (uint256) {
        (bool success, uint256 value) = tryParseHexUint(input, begin, end);
        if (!success) revert StringsInvalidChar();
        return value;
    }

    /**
     * @dev Variant of {parseHexUint-string} that returns false if the parsing fails because of an invalid character.
     *
     * NOTE: This function will revert if the result does not fit in a `uint256`.
     */
    function tryParseHexUint(string memory input) internal pure returns (bool success, uint256 value) {
        return _tryParseHexUintUncheckedBounds(input, 0, bytes(input).length);
    }

    /**
     * @dev Variant of {parseHexUint-string-uint256-uint256} that returns false if the parsing fails because of an
     * invalid character.
     *
     * NOTE: This function will revert if the result does not fit in a `uint256`.
     */
    function tryParseHexUint(
        string memory input,
        uint256 begin,
        uint256 end
    ) internal pure returns (bool success, uint256 value) {
        if (end > bytes(input).length || begin > end) return (false, 0);
        return _tryParseHexUintUncheckedBounds(input, begin, end);
    }

    /**
     * @dev Implementation of {tryParseHexUint-string-uint256-uint256} that does not check bounds. Caller should make sure that
     * `begin <= end <= input.length`. Other inputs would result in undefined behavior.
     */
    function _tryParseHexUintUncheckedBounds(
        string memory input,
        uint256 begin,
        uint256 end
    ) private pure returns (bool success, uint256 value) {
        bytes memory buffer = bytes(input);

        // skip 0x prefix if present
        bool hasPrefix = (end > begin + 1) && bytes2(_unsafeReadBytesOffset(buffer, begin)) == bytes2("0x"); // don't do out-of-bound (possibly unsafe) read if sub-string is empty
        uint256 offset = hasPrefix.toUint() * 2;

        uint256 result = 0;
        for (uint256 i = begin + offset; i < end; ++i) {
            uint8 chr = _tryParseChr(bytes1(_unsafeReadBytesOffset(buffer, i)));
            if (chr > 15) return (false, 0);
            result *= 16;
            unchecked {
                // Multiplying by 16 is equivalent to a shift of 4 bits (with additional overflow check).
                // This guarantees that adding a value < 16 will not cause an overflow, hence the unchecked.
                result += chr;
            }
        }
        return (true, result);
    }

    /**
     * @dev Parse a hexadecimal string (with or without "0x" prefix), and returns the value as an `address`.
     *
     * Requirements:
     * - The string must be formatted as `(0x)?[0-9a-fA-F]{40}`
     */
    function parseAddress(string memory input) internal pure returns (address) {
        return parseAddress(input, 0, bytes(input).length);
    }

    /**
     * @dev Variant of {parseAddress-string} that parses a substring of `input` located between position `begin` (included) and
     * `end` (excluded).
     *
     * Requirements:
     * - The substring must be formatted as `(0x)?[0-9a-fA-F]{40}`
     */
    function parseAddress(string memory input, uint256 begin, uint256 end) internal pure returns (address) {
        (bool success, address value) = tryParseAddress(input, begin, end);
        if (!success) revert StringsInvalidAddressFormat();
        return value;
    }

    /**
     * @dev Variant of {parseAddress-string} that returns false if the parsing fails because the input is not a properly
     * formatted address. See {parseAddress-string} requirements.
     */
    function tryParseAddress(string memory input) internal pure returns (bool success, address value) {
        return tryParseAddress(input, 0, bytes(input).length);
    }

    /**
     * @dev Variant of {parseAddress-string-uint256-uint256} that returns false if the parsing fails because input is not a properly
     * formatted address. See {parseAddress-string-uint256-uint256} requirements.
     */
    function tryParseAddress(
        string memory input,
        uint256 begin,
        uint256 end
    ) internal pure returns (bool success, address value) {
        if (end > bytes(input).length || begin > end) return (false, address(0));

        bool hasPrefix = (end > begin + 1) && bytes2(_unsafeReadBytesOffset(bytes(input), begin)) == bytes2("0x"); // don't do out-of-bound (possibly unsafe) read if sub-string is empty
        uint256 expectedLength = 40 + hasPrefix.toUint() * 2;

        // check that input is the correct length
        if (end - begin == expectedLength) {
            // length guarantees that this does not overflow, and value is at most type(uint160).max
            (bool s, uint256 v) = _tryParseHexUintUncheckedBounds(input, begin, end);
            return (s, address(uint160(v)));
        } else {
            return (false, address(0));
        }
    }

    function _tryParseChr(bytes1 chr) private pure returns (uint8) {
        uint8 value = uint8(chr);

        // Try to parse `chr`:
        // - Case 1: [0-9]
        // - Case 2: [a-f]
        // - Case 3: [A-F]
        // - otherwise not supported
        unchecked {
            if (value > 47 && value < 58) value -= 48;
            else if (value > 96 && value < 103) value -= 87;
            else if (value > 64 && value < 71) value -= 55;
            else return type(uint8).max;
        }

        return value;
    }

    /**
     * @dev Escape special characters in JSON strings. This can be useful to prevent JSON injection in NFT metadata.
     *
     * WARNING: This function should only be used in double quoted JSON strings. Single quotes are not escaped.
     *
     * NOTE: This function escapes all unicode characters, and not just the ones in ranges defined in section 2.5 of
     * RFC-4627 (U+0000 to U+001F, U+0022 and U+005C). ECMAScript's `JSON.parse` does recover escaped unicode
     * characters that are not in this range, but other tooling may provide different results.
     */
    function escapeJSON(string memory input) internal pure returns (string memory) {
        bytes memory buffer = bytes(input);
        bytes memory output = new bytes(2 * buffer.length); // worst case scenario
        uint256 outputLength = 0;

        for (uint256 i; i < buffer.length; ++i) {
            bytes1 char = bytes1(_unsafeReadBytesOffset(buffer, i));
            if (((SPECIAL_CHARS_LOOKUP & (1 << uint8(char))) != 0)) {
                output[outputLength++] = "\\";
                if (char == 0x08) output[outputLength++] = "b";
                else if (char == 0x09) output[outputLength++] = "t";
                else if (char == 0x0a) output[outputLength++] = "n";
                else if (char == 0x0c) output[outputLength++] = "f";
                else if (char == 0x0d) output[outputLength++] = "r";
                else if (char == 0x5c) output[outputLength++] = "\\";
                else if (char == 0x22) {
                    // solhint-disable-next-line quotes
                    output[outputLength++] = '"';
                }
            } else {
                output[outputLength++] = char;
            }
        }
        // write the actual length and deallocate unused memory
        assembly ("memory-safe") {
            mstore(output, outputLength)
            mstore(0x40, add(output, shl(5, shr(5, add(outputLength, 63)))))
        }

        return string(output);
    }

    /**
     * @dev Reads a bytes32 from a bytes array without bounds checking.
     *
     * NOTE: making this function internal would mean it could be used with memory unsafe offset, and marking the
     * assembly block as such would prevent some optimizations.
     */
    function _unsafeReadBytesOffset(bytes memory buffer, uint256 offset) private pure returns (bytes32 value) {
        // This is not memory safe in the general case, but all calls to this private function are within bounds.
        assembly ("memory-safe") {
            value := mload(add(buffer, add(0x20, offset)))
        }
    }
}
"
    },
    "@openzeppelin/contracts/utils/Pausable.sol": {
      "content": "// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.3.0) (utils/Pausable.sol)

pragma solidity ^0.8.20;

import {Context} from "../utils/Context.sol";

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    bool private _paused;

    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    /**
     * @dev The operation failed because the contract is paused.
     */
    error EnforcedPause();

    /**
     * @dev The operation failed because the contract is not paused.
     */
    error ExpectedPause();

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        _requireNotPaused();
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        _requirePaused();
        _;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Throws if the contract is paused.
     */
    function _requireNotPaused() internal view virtual {
        if (paused()) {
            revert EnforcedPause();
        }
    }

    /**
     * @dev Throws if the contract is not paused.
     */
    function _requirePaused() internal view virtual {
        if (!paused()) {
            revert ExpectedPause();
        }
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}
"
    },
    "@openzeppelin/contracts/utils/ReentrancyGuard.sol": {
      "content": "// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.1.0) (utils/ReentrancyGuard.sol)

pragma solidity ^0.8.20;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If EIP-1153 (transient storage) is available on the chain you're deploying at,
 * consider using {ReentrancyGuardTransient} instead.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant NOT_ENTERED = 1;
    uint256 private constant ENTERED = 2;

    uint256 private _status;

    /**
     * @dev Unauthorized reentrant call.
     */
    error ReentrancyGuardReentrantCall();

    constructor() {
        _status = NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _nonReentrantBefore();
        _;
        _nonReentrantAfter();
    }

    function _nonReentrantBefore() private {
        // On the first call to nonReentrant, _status will be NOT_ENTERED
        if (_status == ENTERED) {
            revert ReentrancyGuardReentrantCall();
        }

        // Any calls to nonReentrant after this point will fail
        _status = ENTERED;
    }

    function _nonReentrantAfter() private {
        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = NOT_ENTERED;
    }

    /**
     * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
     * `nonReentrant` function in the call stack.
     */
    function _reentrancyGuardEntered() internal view returns (bool) {
        return _status == ENTERED;
    }
}
"
    },
    "@openzeppelin/contracts/access/Ownable.sol": {
      "content": "// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (access/Ownable.sol)

pragma solidity ^0.8.20;

import {Context} from "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * The initial owner is set to the address provided by the deployer. 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;

    /**
     * @dev The caller account is not authorized to perform an operation.
     */
    error OwnableUnauthorizedAccount(address account);

    /**
     * @dev The owner is not a valid owner account. (eg. `address(0)`)
     */
    error OwnableInvalidOwner(address owner);

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

    /**
     * @dev Initializes the contract setting the address provided by the deployer as the initial owner.
     */
    constructor(address initialOwner) {
        if (initialOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _transferOwnership(initialOwner);
    }

    /**
     * @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 {
        if (owner() != _msgSender()) {
            revert OwnableUnauthorizedAccount(_msgSender());
        }
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling 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 {
        if (newOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _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);
    }
}
"
    },
    "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol": {
      "content": "// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.3.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.20;

import {IERC20} from "../IERC20.sol";
import {IERC1363} from "../../../interfaces/IERC1363.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC-20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    /**
     * @dev An operation with an ERC-20 token failed.
     */
    error SafeERC20FailedOperation(address token);

    /**
     * @dev Indicates a failed `decreaseAllowance` request.
     */
    error SafeERC20FailedDecreaseAllowance(address spender, uint256 currentAllowance, uint256 requestedDecrease);

    /**
     * @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeCall(token.transfer, (to, value)));
    }

    /**
     * @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the
     * calling contract. If `token` returns no value, non-reverting calls are assumed to be successful.
     */
    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeCall(token.transferFrom, (from, to, value)));
    }

    /**
     * @dev Variant of {safeTransfer} that returns a bool instead of reverting if the operation is not successful.
     */
    function trySafeTransfer(IERC20 token, address to, uint256 value) internal returns (bool) {
        return _callOptionalReturnBool(token, abi.encodeCall(token.transfer, (to, value)));
    }

    /**
     * @dev Variant of {safeTransferFrom} that returns a bool instead of reverting if the operation is not successful.
     */
    function trySafeTransferFrom(IERC20 token, address from, address to, uint256 value) internal returns (bool) {
        return _callOptionalReturnBool(token, abi.encodeCall(token.transferFrom, (from, to, value)));
    }

    /**
     * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     *
     * IMPORTANT: If the token implements ERC-7674 (ERC-20 with temporary allowance), and if the "client"
     * smart contract uses ERC-7674 to set temporary allowances, then the "client" smart contract should avoid using
     * this function. Performing a {safeIncreaseAllowance} or {safeDecreaseAllowance} operation on a token contract
     * that has a non-zero temporary allowance (for that particular owner-spender) will result in unexpected behavior.
     */
    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 oldAllowance = token.allowance(address(this), spender);
        forceApprove(token, spender, oldAllowance + value);
    }

    /**
     * @dev Decrease the calling contract's allowance toward `spender` by `requestedDecrease`. If `token` returns no
     * value, non-reverting calls are assumed to be successful.
     *
     * IMPORTANT: If the token implements ERC-7674 (ERC-20 with temporary allowance), and if the "client"
     * smart contract uses ERC-7674 to set temporary allowances, then the "client" smart contract should avoid using
     * this function. Performing a {safeIncreaseAllowance} or {safeDecreaseAllowance} operation on a token contract
     * that has a non-zero temporary allowance (for that particular owner-spender) will result in unexpected behavior.
     */
    function safeDecreaseAllowance(IERC20 token, address spender, uint256 requestedDecrease) internal {
        unchecked {
            uint256 currentAllowance = token.allowance(address(this), spender);
            if (currentAllowance < requestedDecrease) {
                revert SafeERC20FailedDecreaseAllowance(spender, currentAllowance, requestedDecrease);
            }
            forceApprove(token, spender, currentAllowance - requestedDecrease);
        }
    }

    /**
     * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful. Meant to be used with tokens that require the approval
     * to be set to zero before setting it to a non-zero value, such as USDT.
     *
     * NOTE: If the token implements ERC-7674, this function will not modify any temporary allowance. This function
     * only sets the "standard" allowance. Any temporary allowance will remain active, in addition to the value being
     * set here.
     */
    function forceApprove(IERC20 token, address spender, uint256 value) internal {
        bytes memory approvalCall = abi.encodeCall(token.approve, (spender, value));

        if (!_callOptionalReturnBool(token, approvalCall)) {
            _callOptionalReturn(token, abi.encodeCall(token.approve, (spender, 0)));
            _callOptionalReturn(token, approvalCall);
        }
    }

    /**
     * @dev Performs an {ERC1363} transferAndCall, with a fallback to the simple {ERC20} transfer if the target has no
     * code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
     * targeting contracts.
     *
     * Reverts if the returned value is other than `true`.
     */
    function transferAndCallRelaxed(IERC1363 token, address to, uint256 value, bytes memory data) internal {
        if (to.code.length == 0) {
            safeTransfer(token, to, value);
        } else if (!token.transferAndCall(to, value, data)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Performs an {ERC1363} transferFromAndCall, with a fallback to the simple {ERC20} transferFrom if the target
     * has no code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
     * targeting contracts.
     *
     * Reverts if the returned value is other than `true`.
     */
    function transferFromAndCallRelaxed(
        IERC1363 token,
        address from,
        address to,
        uint256 value,
        bytes memory data
    ) internal {
        if (to.code.length == 0) {
            safeTransferFrom(token, from, to, value);
        } else if (!token.transferFromAndCall(from, to, value, data)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Performs an {ERC1363} approveAndCall, with a fallback to the simple {ERC20} approve if the target has no
     * code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
     * targeting contracts.
     *
     * NOTE: When the recipient address (`to`) has no code (i.e. is an EOA), this function behaves as {forceApprove}.
     * Opposedly, when the recipient address (`to`) has code, this function only attempts to call {ERC1363-approveAndCall}
     * once without retrying, and relies on the returned value to be true.
     *
     * Reverts if the returned value is other than `true`.
     */
    function approveAndCallRelaxed(IERC1363 token, address to, uint256 value, bytes memory data) internal {
        if (to.code.length == 0) {
            forceApprove(token, to, value);
        } else if (!token.approveAndCall(to, value, data)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     *
     * This is a variant of {_callOptionalReturnBool} that reverts if call fails to meet the requirements.
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        uint256 returnSize;
        uint256 returnValue;
        assembly ("memory-safe") {
            let success := call(gas(), token, 0, add(data, 0x20), mload(data), 0, 0x20)
            // bubble errors
            if iszero(success) {
                let ptr := mload(0x40)
                returndatacopy(ptr, 0, returndatasize())
                revert(ptr, returndatasize())
            }
            returnSize := returndatasize()
            returnValue := mload(0)
        }

        if (returnSize == 0 ? address(token).code.length == 0 : returnValue != 1) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     *
     * This is a variant of {_callOptionalReturn} that silently catches all reverts and returns a bool instead.
     */
    function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) {
        bool success;
        uint256 returnSize;
        uint256 returnValue;
        assembly ("memory-safe") {
            success := call(gas(), token, 0, add(data, 0x20), mload(data), 0, 0x20)
            returnSize := returndatasize()
            returnValue := mload(0)
        }
        return success && (returnSize == 0 ? address(token).code.length > 0 : returnValue == 1);
    }
}
"
    },
    "@openzeppelin/contracts/token/ERC20/IERC20.sol": {
      "content": "// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.4.0) (token/ERC20/IERC20.sol)

pragma solidity >=0.4.16;

/**
 * @dev Interface of the ERC-20 standard as defined in the ERC.
 */
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 value of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

    /**
     * @dev Moves a `value` amount of 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 value) 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 a `value` amount of tokens 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 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the
     * allowance mechanism. `value` 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 value) external returns (bool);
}
"
    },
    "@openzeppelin/contracts/token/ERC721/ERC721.sol": {
      "content": "// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.4.0) (token/ERC721/ERC721.sol)

pragma solidity ^0.8.20;

import {IERC721} from "./IERC721.sol";
import {IERC721Metadata} from "./extensions/IERC721Metadata.sol";
import {ERC721Utils} from "./utils/ERC721Utils.sol";
import {Context} from "../../utils/Context.sol";
import {Strings} from "../../utils/Strings.sol";
import {IERC165, ERC165} from "../../utils/introspection/ERC165.sol";
import {IERC721Errors} from "../../interfaces/draft-IERC6093.sol";

/**
 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC-721] Non-Fungible Token Standard, including
 * the Metadata extension, but not including the Enumerable extension, which is available separately as
 * {ERC721Enumerable}.
 */
abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Errors {
    using Strings for uint256;

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    mapping(uint256 tokenId => address) private _owners;

    mapping(address owner => uint256) private _balances;

    mapping(uint256 tokenId => address) private _tokenApprovals;

    mapping(address owner => mapping(address operator => 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_;
    }

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

    /// @inheritdoc IERC721
    function balanceOf(address owner) public view virtual returns (uint256) {
        if (owner == address(0)) {
            revert ERC721InvalidOwner(address(0));
        }
        return _balances[owner];
    }

    /// @inheritdoc IERC721
    function ownerOf(uint256 tokenId) public view virtual returns (address) {
        return _requireOwned(tokenId);
    }

    /// @inheritdoc IERC721Metadata
    function name() public view virtual returns (string memory) {
        return _name;
    }

    /// @inheritdoc IERC721Metadata
    function symbol() public view virtual returns (string memory) {
        return _symbol;
    }

    /// @inheritdoc IERC721Metadata
    function tokenURI(uint256 tokenId) public view virtual returns (string memory) {
        _requireOwned(tokenId);

        string memory baseURI = _baseURI();
        return bytes(baseURI).length > 0 ? string.concat(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 "";
    }

    /// @inheritdoc IERC721
    function approve(address to, uint256 tokenId) public virtual {
        _approve(to, tokenId, _msgSender());
    }

    /// @inheritdoc IERC721
    function getApproved(uint256 tokenId) public view virtual returns (address) {
        _requireOwned(tokenId);

        return _getApproved(tokenId);
    }

    /// @inheritdoc IERC721
    function setApprovalForAll(address operator, bool approved) public virtual {
        _setApprovalForAll(_msgSender(), operator, approved);
    }

    /// @inheritdoc IERC721
    function isApprovedForAll(address owner, address operator) public view virtual returns (bool) {
        return _operatorApprovals[owner][operator];
    }

    /// @inheritdoc IERC721
    function transferFrom(address from, address to, uint256 tokenId) public virtual {
        if (to == address(0)) {
            revert ERC721InvalidReceiver(address(0));
        }
        // Setting an "auth" arguments enables the `_isAuthorized` check which verifies that the token exists
        // (from != 0). Therefore, it is not needed to verify that the return value is not 0 here.
        address previousOwner = _update(to, tokenId, _msgSender());
        if (previousOwner != from) {
            revert ERC721IncorrectOwner(from, tokenId, previousOwner);
        }
    }

    /// @inheritdoc IERC721
    function safeTransferFrom(address from, address to, uint256 tokenId) public {
        safeTransferFrom(from, to, tokenId, "");
    }

    /// @inheritdoc IERC721
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory data) public virtual {
        transferFrom(from, to, tokenId);
        ERC721Utils.checkOnERC721Received(_msgSender(), from, to, tokenId, data);
    }

    /**
     * @dev Returns the owner of the `tokenId`. Does NOT revert if token doesn't exist
     *
     * IMPORTANT: Any overrides to this function that add ownership of tokens not tracked by the
     * core ERC-721 logic MUST be matched with the use of {_increaseBalance} to keep balances
     * consistent with ownership. The invariant to preserve is that for any address `a` the value returned by
     * `balanceOf(a)` must be equal to the number of tokens such that `_ownerOf(tokenId)` is `a`.
     */
    function _ownerOf(uint256 tokenId) internal view virtual returns (address) {
        return _owners[tokenId];
    }

    /**
     * @dev Returns the approved address for `tokenId`. Returns 0 if `tokenId` is not minted.
     */
    function _getApproved(uint256 tokenId) internal view virtual returns (address) {
        return _tokenApprovals[tokenId];
    }

    /**
     * @dev Returns whether `spender` is allowed to manage `owner`'s tokens, or `tokenId` in
     * particular (ignoring whether it is owned by `owner`).
     *
     * WARNING: This function assumes that `owner` is the actual owner of `tokenId` and does not verify this
     * assumption.
     */
    function _isAuthorized(address owner, address spender, uint256 tokenId) internal view virtual returns (bool) {
        return
            spender != address(0) &&
            (owner == spender || isApprovedForAll(owner, spender) || _getApproved(tokenId) == spender);
    }

    /**
     * @dev Checks if `spender` can operate on `tokenId`, assuming the provided `owner` is the actual owner.
     * Reverts if:
     * - `spender` does not have approval from `owner` for `tokenId`.
     * - `spender` does not have approval to manage all of `owner`'s assets.
     *
     * WARNING: This function assumes that `owner` is the actual owner of `tokenId` and does not verify this
     * assumption.
     */
    function _checkAuthorized(address owner, address spender, uint256 tokenId) internal view virtual {
        if (!_isAuthorized(owner, spender, tokenId)) {
            if (owner == address(0)) {
                revert ERC721NonexistentToken(tokenId);
            } else {
                revert ERC721InsufficientApproval(spender, tokenId);
            }
        }
    }

    /**
     * @dev Unsafe write access to the balances, used by extensions that "mint" tokens using an {ownerOf} override.
     *
     * NOTE: the value is limited to type(uint128).max. This protect against _balance overflow. It is unrealistic that
     * a uint256 would ever overflow from increments when these increments are bounded to uint128 values.
     *
     * WARNING: Increasing an account's balance using this function tends to be paired with an override of the
     * {_ownerOf} function to resolve the ownership of the corresponding tokens so that balances and ownership
     * remain consistent with one another.
     */
    function _increaseBalance(address account, uint128 value) internal virtual {
        unchecked {
            _balances[account] += value;
        }
    }

    /**
     * @dev Transfers `tokenId` from its current owner to `to`, or alternatively mints (or burns) if the current owner
     * (or `to`) is the zero address. Returns the owner of the `tokenId` before the update.
     *
     * The `auth` argument is optional. If the value passed is non 0, then this function will check that
     * `auth` is either the owner of the token, or approved to operate on the token (by the owner).
     *
     * Emits a {Transfer} event.
     *
     * NOTE: If overriding this function in a way that tracks balances, see also {_increaseBalance}.
     */
    function _update(address to, uint256 tokenId, address auth) internal virtual returns (address) {
        address from = _ownerOf(tokenId);

        // Perform (optional) operator check
        if (auth != address(0)) {
            _checkAuthorized(from, auth, tokenId);
        }

        // Execute the update
        if (from != address(0)) {
            // Clear approval. No need to re-authorize or emit the Approval event
            _approve(address(0), tokenId, address(0), false);

            unchecked {
                _balances[from] -= 1;
            }
        }

        if (to != address(0)) {
            unchecked {
                _balances[to] += 1;
            }
        }

        _owners[tokenId] = to;

        emit Transfer(from, to, tokenId);

        return from;
    }

    /**
     * @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 {
        if (to == address(0)) {
            revert ERC721InvalidReceiver(address(0));
        }
        address previousOwner = _update(to, tokenId, address(0));
        if (previousOwner != address(0)) {
            revert ERC721InvalidSender(address(0));
        }
    }

    /**
     * @dev Mints `tokenId`, transfers it to `to` and checks for `to` acceptance.
     *
     * 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 {
        _safeM