ETH Price: $2,505.21 (+2.43%)

Transaction Decoder

Block:
15349425 at Aug-16-2022 01:19:09 AM +UTC
Transaction Fee:
0.0012354 ETH $3.09
Gas Used:
102,950 Gas / 12 Gwei

Emitted Events:

Account State Difference:

  Address   Before After State Difference Code
0x49EE64Bc...3806ab325 46.875 Eth46.9 Eth0.025
0x874902E9...97bC3465a
0.0310139 Eth
Nonce: 15
0.0047785 Eth
Nonce: 16
0.0262354
(Ethermine)
954.65464091356924604 Eth954.65476625701697579 Eth0.00012534344772975

Execution Trace

ETH 0.025 KaijuLegends.privateSaleMint( quantity_=1, signature_=0x3C891BB80B03913EDF324C75BB87E729FE696DBEE551C81B4E8F5D4FBEF67060320F5DA0F1A5CFC89EB03D2A271C1ED7DD278D3F48DE3BBBA765BD03FE6DE4A81B )
  • Null: 0x000...001.7d82e0dd( )
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    import "@openzeppelin/contracts/access/Ownable.sol";
    import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
    import "@openzeppelin/contracts/security/Pausable.sol";
    import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
    import "@openzeppelin/contracts/utils/Strings.sol";
    import "erc721a/contracts/ERC721A.sol";
    contract KaijuLegends is Ownable, ERC721A, ReentrancyGuard, Pausable {
        /* ======== LIBRARIES ======== */
        using ECDSA for bytes32;
        /* ======== ENUMS ======== */
        enum BatchMintType {
            CRYPTODOTCOM, // 0
            GIVEAWAYS, // 1
            TEAM_TOKENS, // 2
            FREE_MINTS // 3
        }
        /* ======== EVENTS ======== */
        event UpdateSales(bool privateSaleActive, bool partnerSaleActive);
        event UpdateBurn(bool active);
        event UpdateMaxMint(uint256 maxMintPerTx, uint256 maxMintPerWallet);
        event UpdatePartnerMaxMint(uint256 partnerMaxMintPerTx, uint256 partnerMaxMintPerWallet);
        event UpdateTreasury(address treasury);
        event UpdateWhitelistSigner(address whitelistSigner);
        event UpdateBaseURI(string baseURI);
        event UpdatePlaceholderURI(string placeholderURI);
        event UpdatePrivateSalePrice(uint256 privateSalePrice);
        event UpdateCryptoDotComSupply(uint256 supply);
        event UpdateFreeMintsSupply(uint256 supply);
        event UpdateGiveawaySupply(uint256 supply);
        event UpdateTeamTokensSupply(uint256 supply);
        event UpdateMaxSupply(
            uint256 cryptoDotComMaxSupply,
            uint256 privateSaleMaxSupply_,
            uint256 partnerMaxSupply_
        );
        event UpdatePartnerMintContract(address partnerMintContract);
        /* ======== VARIABLES ======== */
        bool public privateSaleActive = true;
        bool public partnerSaleActive = false;
        bool public enableBurn = false;
        uint256 public constant COLLECTION_SUPPLY = 7777;
        uint256 public partnerMaxMintPerTx = 5;
        uint256 public partnerMaxMintPerWallet = 5;
        uint256 public maxMintPerTx = 3;
        uint256 public maxMintPerWallet = 6;
        uint256 public privateSalePrice = .15 ether;
        uint256 public partnerMaxSupply = 200;
        uint256 public cryptoDotComMaxSupply = 2000;
        uint256 public privateSaleMaxSupply = 5577;
        uint256 public cryptoDotComSupply;
        uint256 public giveawaySupply;
        uint256 public teamTokensSupply;
        uint256 public freeMintsSupply;
        uint256 public partnerSupply;
        uint256 public privateSaleSupply;
        address public treasury;
        address public whitelistSigner;
        address public partnerMintContract;
        string public baseURI;
        string public placeholderURI;
        bytes32 public DOMAIN_SEPARATOR;
        bytes32 public constant PRESALE_TYPEHASH =
            keccak256("PrivateSale(address buyer)");
        /* ======== CONSTRUCTOR ======== */
        constructor() ERC721A("Kaiju Legends", "KAIJU") {
            _pause();
            uint256 chainId;
            assembly {
                chainId := chainid()
            }
            DOMAIN_SEPARATOR = keccak256(
                abi.encode(
                    keccak256(
                        "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
                    ),
                    keccak256(bytes("KAIJU")),
                    keccak256(bytes("1")),
                    chainId,
                    address(this)
                )
            );
            whitelistSigner = owner();
        }
        /* ======== MODIFIERS ======== */
        /*
         * @notice: Checks if the msg.sender is the owner or the treasury address
         */
        modifier onlyTreasuryOrOwner() {
            require(
                treasury == _msgSender() || owner() == _msgSender(),
                "Caller is not the owner or treasury"
            );
            _;
        }
        /*
         * @notice: Checks if the msg.sender is the partnerMintContract
         */
        modifier onlyPartner() {
            require(partnerMintContract == _msgSender(), "Caller is not partner");
            _;
        }
        /* ======== SETTERS ======== */
        /*
         * @notice: Pause the smart contract
         * @param: paused_: A boolean to pause or unpause the contract
         */
        function setPaused(bool paused_) external onlyTreasuryOrOwner {
            if (paused_) _pause();
            else _unpause();
        }
        /*
         * @notice: Set the private sale enabled or enabled
         * @param: privateSaleActive_: A boolean to pause or unpause the private sale
         */
        function setSales(bool privateSaleActive_, bool partnerSaleActive_)
            external
            onlyTreasuryOrOwner
        {
            privateSaleActive = privateSaleActive_;
            partnerSaleActive = partnerSaleActive_;
            emit UpdateSales(privateSaleActive_, partnerSaleActive_);
        }
        /*
         * @notice: Set the private sale price
         * @param: privateSalePrice_: The new price for the private sale in WEI
         */
        function setPrivateSalePrice(uint256 privateSalePrice_)
            external
            onlyTreasuryOrOwner
        {
            privateSalePrice = privateSalePrice_;
            emit UpdatePrivateSalePrice(privateSalePrice_);
        }
        /*
         * @notice: Set the max mint per transaction for private sale
         * @param: maxMintPerTx_: The new max mint per transaction
         * @param: maxMintPerWallet_: The new max mint per wallet
         */
        function setPrivateSaleMaxMint(uint256 maxMintPerTx_, uint256 maxMintPerWallet_)
            external
            onlyTreasuryOrOwner
        {
            maxMintPerTx = maxMintPerTx_;
            maxMintPerWallet = maxMintPerWallet_;
            emit UpdateMaxMint(maxMintPerTx_, maxMintPerWallet_);
        }
        /*
         * @notice: Set the new base URI
         * @param: baseURI_: The string of the new base uri
         */
        function setBaseURI(string memory baseURI_) external onlyTreasuryOrOwner {
            baseURI = baseURI_;
            emit UpdateBaseURI(baseURI_);
        }
        /*
         * @notice: Set the new placeholder URI
         * @param: placeholderURI_: The string of the new placeholder URI
         */
        function setPlaceholderURI(string memory placeholderURI_)
            external
            onlyTreasuryOrOwner
        {
            placeholderURI = placeholderURI_;
            emit UpdatePlaceholderURI(placeholderURI_);
        }
        /*
         * @notice: Set the new treasury address
         * @param: treasury_: The new treasury address
         */
        function setTreasury(address treasury_) external onlyTreasuryOrOwner {
            treasury = treasury_;
            emit UpdateTreasury(treasury_);
        }
        /*
         * @notice: Set the new whitelist signer
         * @param: whitelistSigner_: The address of the new whitelist signer for the private sale
         */
        function setWhitelistSigner(address whitelistSigner_)
            external
            onlyTreasuryOrOwner
        {
            whitelistSigner = whitelistSigner_;
            emit UpdateWhitelistSigner(whitelistSigner_);
        }
        /*
         * @notice: Set the new max supply for partner
         * @param: maxMintPerWallet_: The max supply for partner
         */
        function setMaxSupply(
            uint256 cryptoDotComMaxSupply_,
            uint256 privateSaleMaxSupply_,
            uint256 partnerMaxSupply_
        ) external onlyTreasuryOrOwner {
            cryptoDotComMaxSupply = cryptoDotComMaxSupply_;
            privateSaleMaxSupply = privateSaleMaxSupply_;
            partnerMaxSupply = partnerMaxSupply_;
            emit UpdateMaxSupply(
                cryptoDotComMaxSupply_,
                privateSaleMaxSupply_,
                partnerMaxSupply_
            );
        }
        /*
         * @notice: Set the new partnerMintContract address
         * @param: partnerMintContract_: The address of the new partner minting contract
         */
        function setPartnerMintContract(address partnerMintContract_)
            external
            onlyTreasuryOrOwner
        {
            partnerMintContract = partnerMintContract_;
            emit UpdatePartnerMintContract(partnerMintContract_);
        }
         /*
         * @notice: Set the max mint per transaction for partner
         * @param: partnerMaxMintPerTx: The new max mint per transaction
         * @param: partnerMaxMintPerWallet: The new max mint per wallet
         */
        function setPartnerSaleMaxMint(uint256 partnerMaxMintPerTx_, uint256 partnerMaxMintPerWallet_)
            external
            onlyTreasuryOrOwner
        {
            partnerMaxMintPerTx = partnerMaxMintPerTx_;
            partnerMaxMintPerWallet = partnerMaxMintPerWallet_;
            emit UpdatePartnerMaxMint(partnerMaxMintPerTx_, partnerMaxMintPerWallet_);
        }
        /*
         * @notice: If `enableBurn` = true burning will be enabled for people to burn else it will disabled
         * @param: enableBurn_: Enable or disable
         */
        function setEnableBurn(bool enableBurn_)
            external
            onlyTreasuryOrOwner
        {
            enableBurn = enableBurn_;
            emit UpdateBurn(enableBurn_);
        }
        /* ======== INTERNAL ======== */
        /*
         * @notice: Validations of the mint process
         */
        function _validateMint(
            address receiver_,
            uint256 quantity_,
            uint256 saleSupply_,
            uint256 saleMaxSupply_,
            uint256 saleMaxMintPerTx_,
            uint256 saleMaxMintPerWallet_,
            bool saleIsActive_
        ) private {
            require(
                saleIsActive_,
                "KaijuLegends: Sale has not begun yet"
            );
            require(
                (totalSupply() + quantity_) <= COLLECTION_SUPPLY,
                "KaijuLegends: Reached max supply"
            );
            require(
                (saleSupply_ + quantity_) <= saleMaxSupply_,
                "KaijuLegends: Reached max supply"
            );
            require(
                quantity_ > 0 && quantity_ <= saleMaxMintPerTx_,
                "KaijuLegends: Reached max mint per tx"
            );
            require(
                (_numberMinted(receiver_) + quantity_) <= saleMaxMintPerWallet_,
                "KaijuLegends: Reached max mint per wallet"
            );
            _refundIfOver(privateSalePrice * quantity_);
        }
        /*
         * @notice: Recovering the hash and checking if the signer is equal to the `whitelistSigner`
         */
        function _validatePrivateSaleSignature(bytes memory signature_)
            private
            view
        {
            // Verify EIP-712 signature
            bytes32 digest = keccak256(
                abi.encodePacked(
                    "\\x19\\x01",
                    DOMAIN_SEPARATOR,
                    keccak256(abi.encode(PRESALE_TYPEHASH, _msgSender()))
                )
            );
            address recoveredAddress = digest.recover(signature_);
            require(
                recoveredAddress != address(0) &&
                    recoveredAddress == address(whitelistSigner),
                "KaijuLegends: Invalid signature"
            );
        }
        /*
         * @notice: If a user sends more ETH than the actuall mint price than the exceeded amount will be send back
         * @param: price_: The total price for the mint
         */
        function _refundIfOver(uint256 price_) private {
            require(msg.value >= price_, "Need to send more ETH.");
            if (msg.value > price_) {
                payable(_msgSender()).transfer(msg.value - price_);
            }
        }
        /* ======== EXTERNAL ======== */
        /*
         * @notice: The private sale mint
         * @param: quantity_: The mint amount
         * @param: signature_: The signature hash that will be used to verify the user has been whitelisted
         */
        function privateSaleMint(uint256 quantity_, bytes memory signature_)
            external
            payable
            whenNotPaused
        {
            _validateMint(_msgSender(), quantity_, privateSaleSupply, privateSaleMaxSupply, maxMintPerTx, maxMintPerWallet, privateSaleActive);
            _validatePrivateSaleSignature(signature_);
            _safeMint(_msgSender(), quantity_);
            privateSaleSupply += quantity_;
        }
        /*
         * The partner partner sale
         * @param receiver_: The address that will receive the token
         * @param quantity_: The mint amount
         */
        function partnerSale(address receiver_, uint256 quantity_)
            external
            payable
            onlyPartner
        {
            require(
                partnerMintContract != address(0),
                "KaijuLegends: partnerMintContract is the zero address"
            );
            _validateMint(receiver_, quantity_, partnerSupply, partnerMaxSupply, partnerMaxMintPerTx, partnerMaxMintPerWallet, partnerSaleActive);
            _safeMint(receiver_, quantity_);
            partnerSupply += quantity_;
        }
        /*
         * @notice: This batch mint is meant for the CRYPTO.COM sale / Giveaways / Collaborations. Only the `treasury / owner` can mint them to a wallet
         * @param: to_: The address that will receive the token ids
         * @param: quantity_: The mint amount
         */
        function batchMint(
            address to_,
            uint256 quantity_,
            BatchMintType type_
        ) external onlyTreasuryOrOwner {
            require(quantity_ > 0, "KaijuLegends: Quantity must be higher than 0");
            require(
                (totalSupply() + quantity_) <= COLLECTION_SUPPLY,
                "KaijuLegends: Reached max supply"
            );
            _safeMint(to_, quantity_);
            if (type_ == BatchMintType.CRYPTODOTCOM) {
                require(
                    (cryptoDotComSupply + quantity_) <= cryptoDotComMaxSupply,
                    "KaijuLegends: Reached the max supply for cryptoDotCom"
                );
                // 0
                cryptoDotComSupply += quantity_;
                emit UpdateCryptoDotComSupply(cryptoDotComSupply);
            } else if (type_ == BatchMintType.GIVEAWAYS) {
                // 1
                giveawaySupply += quantity_;
                emit UpdateGiveawaySupply(giveawaySupply);
            } else if (type_ == BatchMintType.TEAM_TOKENS) {
                // 2
                teamTokensSupply += quantity_;
                emit UpdateTeamTokensSupply(teamTokensSupply);
            } else if (type_ == BatchMintType.FREE_MINTS) {
                // 3
                freeMintsSupply += quantity_;
                emit UpdateFreeMintsSupply(freeMintsSupply);
            }
        }
        /*
         * @notice: Withdraw the ETH from the contract to the treasury address
         */
        function withdrawEth() external onlyTreasuryOrOwner nonReentrant {
            payable(address(treasury)).transfer(address(this).balance);
        }
        /*
         * @notice: Burn a token id to reduce the token supply
         */
        function burn(uint256 tokenId) external {
            require(enableBurn, 'KaijuLegends: Not possible to burn');
            _burn(tokenId);
        }
        /* ======== OVERRIDES ======== */
        /*
         * @notice: returns the baseURI for the token metadata
         */
        function _baseURI() internal view virtual override returns (string memory) {
            return baseURI;
        }
        /*
         * @notice: returns a URI for the tokenId
         * @param: tokenId_: the minted token id
         */
        function tokenURI(uint256 tokenId_)
            public
            view
            override
            returns (string memory)
        {
            require(_exists(tokenId_), "URI query for nonexistent token");
            if (bytes(baseURI).length <= 0) {
                return placeholderURI;
            }
            string memory uri = _baseURI();
            return string(abi.encodePacked(uri, Strings.toString(tokenId_)));
        }
        /*
         * @notice: returns the number of tokens the address has minted
         * @param: owner: address that owns token ids
         */
        function numberMinted(address owner) external view returns (uint256) {
            return _numberMinted(owner);
        }
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    import "../utils/Context.sol";
    /**
     * @dev Contract module which provides a basic access control mechanism, where
     * there is an account (an owner) that can be granted exclusive access to
     * specific functions.
     *
     * By default, the owner account will be the one that deploys the contract. This
     * can later be changed with {transferOwnership}.
     *
     * This module is used through inheritance. It will make available the modifier
     * `onlyOwner`, which can be applied to your functions to restrict their use to
     * the owner.
     */
    abstract contract Ownable is Context {
        address private _owner;
        event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
        /**
         * @dev Initializes the contract setting the deployer as the initial owner.
         */
        constructor() {
            _setOwner(_msgSender());
        }
        /**
         * @dev Returns the address of the current owner.
         */
        function owner() public view virtual returns (address) {
            return _owner;
        }
        /**
         * @dev Throws if called by any account other than the owner.
         */
        modifier onlyOwner() {
            require(owner() == _msgSender(), "Ownable: caller is not the owner");
            _;
        }
        /**
         * @dev Leaves the contract without owner. It will not be possible to call
         * `onlyOwner` functions anymore. Can only be called by the current owner.
         *
         * NOTE: Renouncing ownership will leave the contract without an owner,
         * thereby removing any functionality that is only available to the owner.
         */
        function renounceOwnership() public virtual onlyOwner {
            _setOwner(address(0));
        }
        /**
         * @dev Transfers ownership of the contract to a new account (`newOwner`).
         * Can only be called by the current owner.
         */
        function transferOwnership(address newOwner) public virtual onlyOwner {
            require(newOwner != address(0), "Ownable: new owner is the zero address");
            _setOwner(newOwner);
        }
        function _setOwner(address newOwner) private {
            address oldOwner = _owner;
            _owner = newOwner;
            emit OwnershipTransferred(oldOwner, newOwner);
        }
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    /**
     * @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 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;
        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 make it call a
         * `private` function that does the actual work.
         */
        modifier nonReentrant() {
            // On the first call to nonReentrant, _notEntered will be true
            require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
            // Any calls to nonReentrant after this point will fail
            _status = _ENTERED;
            _;
            // By storing the original value once again, a refund is triggered (see
            // https://eips.ethereum.org/EIPS/eip-2200)
            _status = _NOT_ENTERED;
        }
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    import "../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 {
        /**
         * @dev Emitted when the pause is triggered by `account`.
         */
        event Paused(address account);
        /**
         * @dev Emitted when the pause is lifted by `account`.
         */
        event Unpaused(address account);
        bool private _paused;
        /**
         * @dev Initializes the contract in unpaused state.
         */
        constructor() {
            _paused = false;
        }
        /**
         * @dev Returns true if the contract is paused, and false otherwise.
         */
        function paused() public view virtual returns (bool) {
            return _paused;
        }
        /**
         * @dev Modifier to make a function callable only when the contract is not paused.
         *
         * Requirements:
         *
         * - The contract must not be paused.
         */
        modifier whenNotPaused() {
            require(!paused(), "Pausable: paused");
            _;
        }
        /**
         * @dev Modifier to make a function callable only when the contract is paused.
         *
         * Requirements:
         *
         * - The contract must be paused.
         */
        modifier whenPaused() {
            require(paused(), "Pausable: not paused");
            _;
        }
        /**
         * @dev Triggers stopped state.
         *
         * Requirements:
         *
         * - The contract must not be paused.
         */
        function _pause() internal virtual whenNotPaused {
            _paused = true;
            emit Paused(_msgSender());
        }
        /**
         * @dev Returns to normal state.
         *
         * Requirements:
         *
         * - The contract must be paused.
         */
        function _unpause() internal virtual whenPaused {
            _paused = false;
            emit Unpaused(_msgSender());
        }
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    /**
     * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
     *
     * These functions can be used to verify that a message was signed by the holder
     * of the private keys of a given address.
     */
    library ECDSA {
        enum RecoverError {
            NoError,
            InvalidSignature,
            InvalidSignatureLength,
            InvalidSignatureS,
            InvalidSignatureV
        }
        function _throwError(RecoverError error) private pure {
            if (error == RecoverError.NoError) {
                return; // no error: do nothing
            } else if (error == RecoverError.InvalidSignature) {
                revert("ECDSA: invalid signature");
            } else if (error == RecoverError.InvalidSignatureLength) {
                revert("ECDSA: invalid signature length");
            } else if (error == RecoverError.InvalidSignatureS) {
                revert("ECDSA: invalid signature 's' value");
            } else if (error == RecoverError.InvalidSignatureV) {
                revert("ECDSA: invalid signature 'v' value");
            }
        }
        /**
         * @dev Returns the address that signed a hashed message (`hash`) with
         * `signature` or error string. This address can then be used for verification purposes.
         *
         * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
         * this function rejects them by requiring the `s` value to be in the lower
         * half order, and the `v` value to be either 27 or 28.
         *
         * IMPORTANT: `hash` _must_ be the result of a hash operation for the
         * verification to be secure: it is possible to craft signatures that
         * recover to arbitrary addresses for non-hashed data. A safe way to ensure
         * this is by receiving a hash of the original message (which may otherwise
         * be too long), and then calling {toEthSignedMessageHash} on it.
         *
         * Documentation for signature generation:
         * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
         * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
         *
         * _Available since v4.3._
         */
        function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
            // Check the signature length
            // - case 65: r,s,v signature (standard)
            // - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098) _Available since v4.1._
            if (signature.length == 65) {
                bytes32 r;
                bytes32 s;
                uint8 v;
                // ecrecover takes the signature parameters, and the only way to get them
                // currently is to use assembly.
                assembly {
                    r := mload(add(signature, 0x20))
                    s := mload(add(signature, 0x40))
                    v := byte(0, mload(add(signature, 0x60)))
                }
                return tryRecover(hash, v, r, s);
            } else if (signature.length == 64) {
                bytes32 r;
                bytes32 vs;
                // ecrecover takes the signature parameters, and the only way to get them
                // currently is to use assembly.
                assembly {
                    r := mload(add(signature, 0x20))
                    vs := mload(add(signature, 0x40))
                }
                return tryRecover(hash, r, vs);
            } else {
                return (address(0), RecoverError.InvalidSignatureLength);
            }
        }
        /**
         * @dev Returns the address that signed a hashed message (`hash`) with
         * `signature`. This address can then be used for verification purposes.
         *
         * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
         * this function rejects them by requiring the `s` value to be in the lower
         * half order, and the `v` value to be either 27 or 28.
         *
         * IMPORTANT: `hash` _must_ be the result of a hash operation for the
         * verification to be secure: it is possible to craft signatures that
         * recover to arbitrary addresses for non-hashed data. A safe way to ensure
         * this is by receiving a hash of the original message (which may otherwise
         * be too long), and then calling {toEthSignedMessageHash} on it.
         */
        function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
            (address recovered, RecoverError error) = tryRecover(hash, signature);
            _throwError(error);
            return recovered;
        }
        /**
         * @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
         *
         * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
         *
         * _Available since v4.3._
         */
        function tryRecover(
            bytes32 hash,
            bytes32 r,
            bytes32 vs
        ) internal pure returns (address, RecoverError) {
            bytes32 s;
            uint8 v;
            assembly {
                s := and(vs, 0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff)
                v := add(shr(255, vs), 27)
            }
            return tryRecover(hash, v, r, s);
        }
        /**
         * @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
         *
         * _Available since v4.2._
         */
        function recover(
            bytes32 hash,
            bytes32 r,
            bytes32 vs
        ) internal pure returns (address) {
            (address recovered, RecoverError error) = tryRecover(hash, r, vs);
            _throwError(error);
            return recovered;
        }
        /**
         * @dev Overload of {ECDSA-tryRecover} that receives the `v`,
         * `r` and `s` signature fields separately.
         *
         * _Available since v4.3._
         */
        function tryRecover(
            bytes32 hash,
            uint8 v,
            bytes32 r,
            bytes32 s
        ) internal pure returns (address, RecoverError) {
            // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
            // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
            // the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
            // signatures from current libraries generate a unique signature with an s-value in the lower half order.
            //
            // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
            // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
            // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
            // these malleable signatures as well.
            if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
                return (address(0), RecoverError.InvalidSignatureS);
            }
            if (v != 27 && v != 28) {
                return (address(0), RecoverError.InvalidSignatureV);
            }
            // If the signature is valid (and not malleable), return the signer address
            address signer = ecrecover(hash, v, r, s);
            if (signer == address(0)) {
                return (address(0), RecoverError.InvalidSignature);
            }
            return (signer, RecoverError.NoError);
        }
        /**
         * @dev Overload of {ECDSA-recover} that receives the `v`,
         * `r` and `s` signature fields separately.
         */
        function recover(
            bytes32 hash,
            uint8 v,
            bytes32 r,
            bytes32 s
        ) internal pure returns (address) {
            (address recovered, RecoverError error) = tryRecover(hash, v, r, s);
            _throwError(error);
            return recovered;
        }
        /**
         * @dev Returns an Ethereum Signed Message, created from a `hash`. This
         * produces hash corresponding to the one signed with the
         * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
         * JSON-RPC method as part of EIP-191.
         *
         * See {recover}.
         */
        function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
            // 32 is the length in bytes of hash,
            // enforced by the type signature above
            return keccak256(abi.encodePacked("\\x19Ethereum Signed Message:\
    32", hash));
        }
        /**
         * @dev Returns an Ethereum Signed Typed Data, created from a
         * `domainSeparator` and a `structHash`. This produces hash corresponding
         * to the one signed with the
         * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
         * JSON-RPC method as part of EIP-712.
         *
         * See {recover}.
         */
        function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
            return keccak256(abi.encodePacked("\\x19\\x01", domainSeparator, structHash));
        }
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    /**
     * @dev String operations.
     */
    library Strings {
        bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";
        /**
         * @dev Converts a `uint256` to its ASCII `string` decimal representation.
         */
        function toString(uint256 value) internal pure returns (string memory) {
            // Inspired by OraclizeAPI's implementation - MIT licence
            // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol
            if (value == 0) {
                return "0";
            }
            uint256 temp = value;
            uint256 digits;
            while (temp != 0) {
                digits++;
                temp /= 10;
            }
            bytes memory buffer = new bytes(digits);
            while (value != 0) {
                digits -= 1;
                buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
                value /= 10;
            }
            return string(buffer);
        }
        /**
         * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
         */
        function toHexString(uint256 value) internal pure returns (string memory) {
            if (value == 0) {
                return "0x00";
            }
            uint256 temp = value;
            uint256 length = 0;
            while (temp != 0) {
                length++;
                temp >>= 8;
            }
            return toHexString(value, length);
        }
        /**
         * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
         */
        function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
            bytes memory buffer = new bytes(2 * length + 2);
            buffer[0] = "0";
            buffer[1] = "x";
            for (uint256 i = 2 * length + 1; i > 1; --i) {
                buffer[i] = _HEX_SYMBOLS[value & 0xf];
                value >>= 4;
            }
            require(value == 0, "Strings: hex length insufficient");
            return string(buffer);
        }
    }
    // SPDX-License-Identifier: MIT
    // Creator: Chiru Labs
    pragma solidity ^0.8.4;
    import '@openzeppelin/contracts/token/ERC721/IERC721.sol';
    import '@openzeppelin/contracts/token/ERC721/IERC721Receiver.sol';
    import '@openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol';
    import '@openzeppelin/contracts/token/ERC721/extensions/IERC721Enumerable.sol';
    import '@openzeppelin/contracts/utils/Address.sol';
    import '@openzeppelin/contracts/utils/Context.sol';
    import '@openzeppelin/contracts/utils/Strings.sol';
    import '@openzeppelin/contracts/utils/introspection/ERC165.sol';
    error ApprovalCallerNotOwnerNorApproved();
    error ApprovalQueryForNonexistentToken();
    error ApproveToCaller();
    error ApprovalToCurrentOwner();
    error BalanceQueryForZeroAddress();
    error MintedQueryForZeroAddress();
    error BurnedQueryForZeroAddress();
    error AuxQueryForZeroAddress();
    error MintToZeroAddress();
    error MintZeroQuantity();
    error OwnerIndexOutOfBounds();
    error OwnerQueryForNonexistentToken();
    error TokenIndexOutOfBounds();
    error TransferCallerNotOwnerNorApproved();
    error TransferFromIncorrectOwner();
    error TransferToNonERC721ReceiverImplementer();
    error TransferToZeroAddress();
    error URIQueryForNonexistentToken();
    /**
     * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
     * the Metadata extension. Built to optimize for lower gas during batch mints.
     *
     * Assumes serials are sequentially minted starting at _startTokenId() (defaults to 0, e.g. 0, 1, 2, 3..).
     *
     * Assumes that an owner cannot have more than 2**64 - 1 (max value of uint64) of supply.
     *
     * Assumes that the maximum token id cannot exceed 2**256 - 1 (max value of uint256).
     */
    contract ERC721A is Context, ERC165, IERC721, IERC721Metadata {
        using Address for address;
        using Strings for uint256;
        // Compiler will pack this into a single 256bit word.
        struct TokenOwnership {
            // The address of the owner.
            address addr;
            // Keeps track of the start time of ownership with minimal overhead for tokenomics.
            uint64 startTimestamp;
            // Whether the token has been burned.
            bool burned;
        }
        // Compiler will pack this into a single 256bit word.
        struct AddressData {
            // Realistically, 2**64-1 is more than enough.
            uint64 balance;
            // Keeps track of mint count with minimal overhead for tokenomics.
            uint64 numberMinted;
            // Keeps track of burn count with minimal overhead for tokenomics.
            uint64 numberBurned;
            // For miscellaneous variable(s) pertaining to the address
            // (e.g. number of whitelist mint slots used).
            // If there are multiple variables, please pack them into a uint64.
            uint64 aux;
        }
        // The tokenId of the next token to be minted.
        uint256 internal _currentIndex;
        // The number of tokens burned.
        uint256 internal _burnCounter;
        // Token name
        string private _name;
        // Token symbol
        string private _symbol;
        // Mapping from token ID to ownership details
        // An empty struct value does not necessarily mean the token is unowned. See ownershipOf implementation for details.
        mapping(uint256 => TokenOwnership) internal _ownerships;
        // Mapping owner address to address data
        mapping(address => AddressData) private _addressData;
        // Mapping from token ID to approved address
        mapping(uint256 => address) private _tokenApprovals;
        // Mapping from owner to operator approvals
        mapping(address => mapping(address => bool)) private _operatorApprovals;
        constructor(string memory name_, string memory symbol_) {
            _name = name_;
            _symbol = symbol_;
            _currentIndex = _startTokenId();
        }
        /**
         * To change the starting tokenId, please override this function.
         */
        function _startTokenId() internal view virtual returns (uint256) {
            return 0;
        }
        /**
         * @dev See {IERC721Enumerable-totalSupply}.
         * @dev Burned tokens are calculated here, use _totalMinted() if you want to count just minted tokens.
         */
        function totalSupply() public view returns (uint256) {
            // Counter underflow is impossible as _burnCounter cannot be incremented
            // more than _currentIndex - _startTokenId() times
            unchecked {
                return _currentIndex - _burnCounter - _startTokenId();
            }
        }
        /**
         * Returns the total amount of tokens minted in the contract.
         */
        function _totalMinted() internal view returns (uint256) {
            // Counter underflow is impossible as _currentIndex does not decrement,
            // and it is initialized to _startTokenId()
            unchecked {
                return _currentIndex - _startTokenId();
            }
        }
        /**
         * @dev See {IERC165-supportsInterface}.
         */
        function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
            return
                interfaceId == type(IERC721).interfaceId ||
                interfaceId == type(IERC721Metadata).interfaceId ||
                super.supportsInterface(interfaceId);
        }
        /**
         * @dev See {IERC721-balanceOf}.
         */
        function balanceOf(address owner) public view override returns (uint256) {
            if (owner == address(0)) revert BalanceQueryForZeroAddress();
            return uint256(_addressData[owner].balance);
        }
        /**
         * Returns the number of tokens minted by `owner`.
         */
        function _numberMinted(address owner) internal view returns (uint256) {
            if (owner == address(0)) revert MintedQueryForZeroAddress();
            return uint256(_addressData[owner].numberMinted);
        }
        /**
         * Returns the number of tokens burned by or on behalf of `owner`.
         */
        function _numberBurned(address owner) internal view returns (uint256) {
            if (owner == address(0)) revert BurnedQueryForZeroAddress();
            return uint256(_addressData[owner].numberBurned);
        }
        /**
         * Returns the auxillary data for `owner`. (e.g. number of whitelist mint slots used).
         */
        function _getAux(address owner) internal view returns (uint64) {
            if (owner == address(0)) revert AuxQueryForZeroAddress();
            return _addressData[owner].aux;
        }
        /**
         * Sets the auxillary data for `owner`. (e.g. number of whitelist mint slots used).
         * If there are multiple variables, please pack them into a uint64.
         */
        function _setAux(address owner, uint64 aux) internal {
            if (owner == address(0)) revert AuxQueryForZeroAddress();
            _addressData[owner].aux = aux;
        }
        /**
         * Gas spent here starts off proportional to the maximum mint batch size.
         * It gradually moves to O(1) as tokens get transferred around in the collection over time.
         */
        function ownershipOf(uint256 tokenId) internal view returns (TokenOwnership memory) {
            uint256 curr = tokenId;
            unchecked {
                if (_startTokenId() <= curr && curr < _currentIndex) {
                    TokenOwnership memory ownership = _ownerships[curr];
                    if (!ownership.burned) {
                        if (ownership.addr != address(0)) {
                            return ownership;
                        }
                        // Invariant:
                        // There will always be an ownership that has an address and is not burned
                        // before an ownership that does not have an address and is not burned.
                        // Hence, curr will not underflow.
                        while (true) {
                            curr--;
                            ownership = _ownerships[curr];
                            if (ownership.addr != address(0)) {
                                return ownership;
                            }
                        }
                    }
                }
            }
            revert OwnerQueryForNonexistentToken();
        }
        /**
         * @dev See {IERC721-ownerOf}.
         */
        function ownerOf(uint256 tokenId) public view override returns (address) {
            return ownershipOf(tokenId).addr;
        }
        /**
         * @dev See {IERC721Metadata-name}.
         */
        function name() public view virtual override returns (string memory) {
            return _name;
        }
        /**
         * @dev See {IERC721Metadata-symbol}.
         */
        function symbol() public view virtual override returns (string memory) {
            return _symbol;
        }
        /**
         * @dev See {IERC721Metadata-tokenURI}.
         */
        function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
            if (!_exists(tokenId)) revert URIQueryForNonexistentToken();
            string memory baseURI = _baseURI();
            return bytes(baseURI).length != 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : '';
        }
        /**
         * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
         * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
         * by default, can be overriden in child contracts.
         */
        function _baseURI() internal view virtual returns (string memory) {
            return '';
        }
        /**
         * @dev See {IERC721-approve}.
         */
        function approve(address to, uint256 tokenId) public override {
            address owner = ERC721A.ownerOf(tokenId);
            if (to == owner) revert ApprovalToCurrentOwner();
            if (_msgSender() != owner && !isApprovedForAll(owner, _msgSender())) {
                revert ApprovalCallerNotOwnerNorApproved();
            }
            _approve(to, tokenId, owner);
        }
        /**
         * @dev See {IERC721-getApproved}.
         */
        function getApproved(uint256 tokenId) public view override returns (address) {
            if (!_exists(tokenId)) revert ApprovalQueryForNonexistentToken();
            return _tokenApprovals[tokenId];
        }
        /**
         * @dev See {IERC721-setApprovalForAll}.
         */
        function setApprovalForAll(address operator, bool approved) public override {
            if (operator == _msgSender()) revert ApproveToCaller();
            _operatorApprovals[_msgSender()][operator] = approved;
            emit ApprovalForAll(_msgSender(), operator, approved);
        }
        /**
         * @dev See {IERC721-isApprovedForAll}.
         */
        function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
            return _operatorApprovals[owner][operator];
        }
        /**
         * @dev See {IERC721-transferFrom}.
         */
        function transferFrom(
            address from,
            address to,
            uint256 tokenId
        ) public virtual override {
            _transfer(from, to, tokenId);
        }
        /**
         * @dev See {IERC721-safeTransferFrom}.
         */
        function safeTransferFrom(
            address from,
            address to,
            uint256 tokenId
        ) public virtual override {
            safeTransferFrom(from, to, tokenId, '');
        }
        /**
         * @dev See {IERC721-safeTransferFrom}.
         */
        function safeTransferFrom(
            address from,
            address to,
            uint256 tokenId,
            bytes memory _data
        ) public virtual override {
            _transfer(from, to, tokenId);
            if (to.isContract() && !_checkContractOnERC721Received(from, to, tokenId, _data)) {
                revert TransferToNonERC721ReceiverImplementer();
            }
        }
        /**
         * @dev Returns whether `tokenId` exists.
         *
         * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
         *
         * Tokens start existing when they are minted (`_mint`),
         */
        function _exists(uint256 tokenId) internal view returns (bool) {
            return _startTokenId() <= tokenId && tokenId < _currentIndex &&
                !_ownerships[tokenId].burned;
        }
        function _safeMint(address to, uint256 quantity) internal {
            _safeMint(to, quantity, '');
        }
        /**
         * @dev Safely mints `quantity` tokens and transfers them to `to`.
         *
         * Requirements:
         *
         * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called for each safe transfer.
         * - `quantity` must be greater than 0.
         *
         * Emits a {Transfer} event.
         */
        function _safeMint(
            address to,
            uint256 quantity,
            bytes memory _data
        ) internal {
            _mint(to, quantity, _data, true);
        }
        /**
         * @dev Mints `quantity` tokens and transfers them to `to`.
         *
         * Requirements:
         *
         * - `to` cannot be the zero address.
         * - `quantity` must be greater than 0.
         *
         * Emits a {Transfer} event.
         */
        function _mint(
            address to,
            uint256 quantity,
            bytes memory _data,
            bool safe
        ) internal {
            uint256 startTokenId = _currentIndex;
            if (to == address(0)) revert MintToZeroAddress();
            if (quantity == 0) revert MintZeroQuantity();
            _beforeTokenTransfers(address(0), to, startTokenId, quantity);
            // Overflows are incredibly unrealistic.
            // balance or numberMinted overflow if current value of either + quantity > 1.8e19 (2**64) - 1
            // updatedIndex overflows if _currentIndex + quantity > 1.2e77 (2**256) - 1
            unchecked {
                _addressData[to].balance += uint64(quantity);
                _addressData[to].numberMinted += uint64(quantity);
                _ownerships[startTokenId].addr = to;
                _ownerships[startTokenId].startTimestamp = uint64(block.timestamp);
                uint256 updatedIndex = startTokenId;
                uint256 end = updatedIndex + quantity;
                if (safe && to.isContract()) {
                    do {
                        emit Transfer(address(0), to, updatedIndex);
                        if (!_checkContractOnERC721Received(address(0), to, updatedIndex++, _data)) {
                            revert TransferToNonERC721ReceiverImplementer();
                        }
                    } while (updatedIndex != end);
                    // Reentrancy protection
                    if (_currentIndex != startTokenId) revert();
                } else {
                    do {
                        emit Transfer(address(0), to, updatedIndex++);
                    } while (updatedIndex != end);
                }
                _currentIndex = updatedIndex;
            }
            _afterTokenTransfers(address(0), to, startTokenId, quantity);
        }
        /**
         * @dev Transfers `tokenId` from `from` to `to`.
         *
         * Requirements:
         *
         * - `to` cannot be the zero address.
         * - `tokenId` token must be owned by `from`.
         *
         * Emits a {Transfer} event.
         */
        function _transfer(
            address from,
            address to,
            uint256 tokenId
        ) private {
            TokenOwnership memory prevOwnership = ownershipOf(tokenId);
            bool isApprovedOrOwner = (_msgSender() == prevOwnership.addr ||
                isApprovedForAll(prevOwnership.addr, _msgSender()) ||
                getApproved(tokenId) == _msgSender());
            if (!isApprovedOrOwner) revert TransferCallerNotOwnerNorApproved();
            if (prevOwnership.addr != from) revert TransferFromIncorrectOwner();
            if (to == address(0)) revert TransferToZeroAddress();
            _beforeTokenTransfers(from, to, tokenId, 1);
            // Clear approvals from the previous owner
            _approve(address(0), tokenId, prevOwnership.addr);
            // Underflow of the sender's balance is impossible because we check for
            // ownership above and the recipient's balance can't realistically overflow.
            // Counter overflow is incredibly unrealistic as tokenId would have to be 2**256.
            unchecked {
                _addressData[from].balance -= 1;
                _addressData[to].balance += 1;
                _ownerships[tokenId].addr = to;
                _ownerships[tokenId].startTimestamp = uint64(block.timestamp);
                // If the ownership slot of tokenId+1 is not explicitly set, that means the transfer initiator owns it.
                // Set the slot of tokenId+1 explicitly in storage to maintain correctness for ownerOf(tokenId+1) calls.
                uint256 nextTokenId = tokenId + 1;
                if (_ownerships[nextTokenId].addr == address(0)) {
                    // This will suffice for checking _exists(nextTokenId),
                    // as a burned slot cannot contain the zero address.
                    if (nextTokenId < _currentIndex) {
                        _ownerships[nextTokenId].addr = prevOwnership.addr;
                        _ownerships[nextTokenId].startTimestamp = prevOwnership.startTimestamp;
                    }
                }
            }
            emit Transfer(from, to, tokenId);
            _afterTokenTransfers(from, to, tokenId, 1);
        }
        /**
         * @dev Destroys `tokenId`.
         * The approval is cleared when the token is burned.
         *
         * Requirements:
         *
         * - `tokenId` must exist.
         *
         * Emits a {Transfer} event.
         */
        function _burn(uint256 tokenId) internal virtual {
            TokenOwnership memory prevOwnership = ownershipOf(tokenId);
            _beforeTokenTransfers(prevOwnership.addr, address(0), tokenId, 1);
            // Clear approvals from the previous owner
            _approve(address(0), tokenId, prevOwnership.addr);
            // Underflow of the sender's balance is impossible because we check for
            // ownership above and the recipient's balance can't realistically overflow.
            // Counter overflow is incredibly unrealistic as tokenId would have to be 2**256.
            unchecked {
                _addressData[prevOwnership.addr].balance -= 1;
                _addressData[prevOwnership.addr].numberBurned += 1;
                // Keep track of who burned the token, and the timestamp of burning.
                _ownerships[tokenId].addr = prevOwnership.addr;
                _ownerships[tokenId].startTimestamp = uint64(block.timestamp);
                _ownerships[tokenId].burned = true;
                // If the ownership slot of tokenId+1 is not explicitly set, that means the burn initiator owns it.
                // Set the slot of tokenId+1 explicitly in storage to maintain correctness for ownerOf(tokenId+1) calls.
                uint256 nextTokenId = tokenId + 1;
                if (_ownerships[nextTokenId].addr == address(0)) {
                    // This will suffice for checking _exists(nextTokenId),
                    // as a burned slot cannot contain the zero address.
                    if (nextTokenId < _currentIndex) {
                        _ownerships[nextTokenId].addr = prevOwnership.addr;
                        _ownerships[nextTokenId].startTimestamp = prevOwnership.startTimestamp;
                    }
                }
            }
            emit Transfer(prevOwnership.addr, address(0), tokenId);
            _afterTokenTransfers(prevOwnership.addr, address(0), tokenId, 1);
            // Overflow not possible, as _burnCounter cannot be exceed _currentIndex times.
            unchecked {
                _burnCounter++;
            }
        }
        /**
         * @dev Approve `to` to operate on `tokenId`
         *
         * Emits a {Approval} event.
         */
        function _approve(
            address to,
            uint256 tokenId,
            address owner
        ) private {
            _tokenApprovals[tokenId] = to;
            emit Approval(owner, to, tokenId);
        }
        /**
         * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target contract.
         *
         * @param from address representing the previous owner of the given token ID
         * @param to target address that will receive the tokens
         * @param tokenId uint256 ID of the token to be transferred
         * @param _data bytes optional data to send along with the call
         * @return bool whether the call correctly returned the expected magic value
         */
        function _checkContractOnERC721Received(
            address from,
            address to,
            uint256 tokenId,
            bytes memory _data
        ) private returns (bool) {
            try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
                return retval == IERC721Receiver(to).onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert TransferToNonERC721ReceiverImplementer();
                } else {
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        }
        /**
         * @dev Hook that is called before a set of serially-ordered token ids are about to be transferred. This includes minting.
         * And also called before burning one token.
         *
         * startTokenId - the first token id to be transferred
         * quantity - the amount to be transferred
         *
         * Calling conditions:
         *
         * - When `from` and `to` are both non-zero, `from`'s `tokenId` will be
         * transferred to `to`.
         * - When `from` is zero, `tokenId` will be minted for `to`.
         * - When `to` is zero, `tokenId` will be burned by `from`.
         * - `from` and `to` are never both zero.
         */
        function _beforeTokenTransfers(
            address from,
            address to,
            uint256 startTokenId,
            uint256 quantity
        ) internal virtual {}
        /**
         * @dev Hook that is called after a set of serially-ordered token ids have been transferred. This includes
         * minting.
         * And also called after one token has been burned.
         *
         * startTokenId - the first token id to be transferred
         * quantity - the amount to be transferred
         *
         * Calling conditions:
         *
         * - When `from` and `to` are both non-zero, `from`'s `tokenId` has been
         * transferred to `to`.
         * - When `from` is zero, `tokenId` has been minted for `to`.
         * - When `to` is zero, `tokenId` has been burned by `from`.
         * - `from` and `to` are never both zero.
         */
        function _afterTokenTransfers(
            address from,
            address to,
            uint256 startTokenId,
            uint256 quantity
        ) internal virtual {}
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    /**
     * @dev Provides information about the current execution context, including the
     * sender of the transaction and its data. While these are generally available
     * via msg.sender and msg.data, they should not be accessed in such a direct
     * manner, since when dealing with meta-transactions the account sending and
     * paying for execution may not be the actual sender (as far as an application
     * is concerned).
     *
     * This contract is only required for intermediate, library-like contracts.
     */
    abstract contract Context {
        function _msgSender() internal view virtual returns (address) {
            return msg.sender;
        }
        function _msgData() internal view virtual returns (bytes calldata) {
            return msg.data;
        }
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    import "../../utils/introspection/IERC165.sol";
    /**
     * @dev Required interface of an ERC721 compliant contract.
     */
    interface IERC721 is IERC165 {
        /**
         * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
         */
        event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
        /**
         * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
         */
        event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
        /**
         * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
         */
        event ApprovalForAll(address indexed owner, address indexed operator, bool approved);
        /**
         * @dev Returns the number of tokens in ``owner``'s account.
         */
        function balanceOf(address owner) external view returns (uint256 balance);
        /**
         * @dev Returns the owner of the `tokenId` token.
         *
         * Requirements:
         *
         * - `tokenId` must exist.
         */
        function ownerOf(uint256 tokenId) external view returns (address owner);
        /**
         * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
         * are aware of the ERC721 protocol to prevent tokens from being forever locked.
         *
         * Requirements:
         *
         * - `from` cannot be the zero address.
         * - `to` cannot be the zero address.
         * - `tokenId` token must exist and be owned by `from`.
         * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
         * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
         *
         * Emits a {Transfer} event.
         */
        function safeTransferFrom(
            address from,
            address to,
            uint256 tokenId
        ) external;
        /**
         * @dev Transfers `tokenId` token from `from` to `to`.
         *
         * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
         *
         * Requirements:
         *
         * - `from` cannot be the zero address.
         * - `to` cannot be the zero address.
         * - `tokenId` token must be owned by `from`.
         * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
         *
         * Emits a {Transfer} event.
         */
        function transferFrom(
            address from,
            address to,
            uint256 tokenId
        ) external;
        /**
         * @dev Gives permission to `to` to transfer `tokenId` token to another account.
         * The approval is cleared when the token is transferred.
         *
         * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
         *
         * Requirements:
         *
         * - The caller must own the token or be an approved operator.
         * - `tokenId` must exist.
         *
         * Emits an {Approval} event.
         */
        function approve(address to, uint256 tokenId) external;
        /**
         * @dev Returns the account approved for `tokenId` token.
         *
         * Requirements:
         *
         * - `tokenId` must exist.
         */
        function getApproved(uint256 tokenId) external view returns (address operator);
        /**
         * @dev Approve or remove `operator` as an operator for the caller.
         * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
         *
         * Requirements:
         *
         * - The `operator` cannot be the caller.
         *
         * Emits an {ApprovalForAll} event.
         */
        function setApprovalForAll(address operator, bool _approved) external;
        /**
         * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
         *
         * See {setApprovalForAll}
         */
        function isApprovedForAll(address owner, address operator) external view returns (bool);
        /**
         * @dev Safely transfers `tokenId` token from `from` to `to`.
         *
         * Requirements:
         *
         * - `from` cannot be the zero address.
         * - `to` cannot be the zero address.
         * - `tokenId` token must exist and be owned by `from`.
         * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
         * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
         *
         * Emits a {Transfer} event.
         */
        function safeTransferFrom(
            address from,
            address to,
            uint256 tokenId,
            bytes calldata data
        ) external;
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    /**
     * @title ERC721 token receiver interface
     * @dev Interface for any contract that wants to support safeTransfers
     * from ERC721 asset contracts.
     */
    interface IERC721Receiver {
        /**
         * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
         * by `operator` from `from`, this function is called.
         *
         * It must return its Solidity selector to confirm the token transfer.
         * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
         *
         * The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
         */
        function onERC721Received(
            address operator,
            address from,
            uint256 tokenId,
            bytes calldata data
        ) external returns (bytes4);
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    import "../IERC721.sol";
    /**
     * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
     * @dev See https://eips.ethereum.org/EIPS/eip-721
     */
    interface IERC721Metadata is IERC721 {
        /**
         * @dev Returns the token collection name.
         */
        function name() external view returns (string memory);
        /**
         * @dev Returns the token collection symbol.
         */
        function symbol() external view returns (string memory);
        /**
         * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
         */
        function tokenURI(uint256 tokenId) external view returns (string memory);
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    import "../IERC721.sol";
    /**
     * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
     * @dev See https://eips.ethereum.org/EIPS/eip-721
     */
    interface IERC721Enumerable is IERC721 {
        /**
         * @dev Returns the total amount of tokens stored by the contract.
         */
        function totalSupply() external view returns (uint256);
        /**
         * @dev Returns a token ID owned by `owner` at a given `index` of its token list.
         * Use along with {balanceOf} to enumerate all of ``owner``'s tokens.
         */
        function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256 tokenId);
        /**
         * @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
         * Use along with {totalSupply} to enumerate all tokens.
         */
        function tokenByIndex(uint256 index) external view returns (uint256);
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    /**
     * @dev Collection of functions related to the address type
     */
    library Address {
        /**
         * @dev Returns true if `account` is a contract.
         *
         * [IMPORTANT]
         * ====
         * It is unsafe to assume that an address for which this function returns
         * false is an externally-owned account (EOA) and not a contract.
         *
         * Among others, `isContract` will return false for the following
         * types of addresses:
         *
         *  - an externally-owned account
         *  - a contract in construction
         *  - an address where a contract will be created
         *  - an address where a contract lived, but was destroyed
         * ====
         */
        function isContract(address account) internal view returns (bool) {
            // This method relies on extcodesize, which returns 0 for contracts in
            // construction, since the code is only stored at the end of the
            // constructor execution.
            uint256 size;
            assembly {
                size := extcodesize(account)
            }
            return size > 0;
        }
        /**
         * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
         * `recipient`, forwarding all available gas and reverting on errors.
         *
         * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
         * of certain opcodes, possibly making contracts go over the 2300 gas limit
         * imposed by `transfer`, making them unable to receive funds via
         * `transfer`. {sendValue} removes this limitation.
         *
         * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
         *
         * IMPORTANT: because control is transferred to `recipient`, care must be
         * taken to not create reentrancy vulnerabilities. Consider using
         * {ReentrancyGuard} or the
         * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
         */
        function sendValue(address payable recipient, uint256 amount) internal {
            require(address(this).balance >= amount, "Address: insufficient balance");
            (bool success, ) = recipient.call{value: amount}("");
            require(success, "Address: unable to send value, recipient may have reverted");
        }
        /**
         * @dev Performs a Solidity function call using a low level `call`. A
         * plain `call` is an unsafe replacement for a function call: use this
         * function instead.
         *
         * If `target` reverts with a revert reason, it is bubbled up by this
         * function (like regular Solidity function calls).
         *
         * Returns the raw returned data. To convert to the expected return value,
         * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
         *
         * Requirements:
         *
         * - `target` must be a contract.
         * - calling `target` with `data` must not revert.
         *
         * _Available since v3.1._
         */
        function functionCall(address target, bytes memory data) internal returns (bytes memory) {
            return functionCall(target, data, "Address: low-level call failed");
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
         * `errorMessage` as a fallback revert reason when `target` reverts.
         *
         * _Available since v3.1._
         */
        function functionCall(
            address target,
            bytes memory data,
            string memory errorMessage
        ) internal returns (bytes memory) {
            return functionCallWithValue(target, data, 0, errorMessage);
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
         * but also transferring `value` wei to `target`.
         *
         * Requirements:
         *
         * - the calling contract must have an ETH balance of at least `value`.
         * - the called Solidity function must be `payable`.
         *
         * _Available since v3.1._
         */
        function functionCallWithValue(
            address target,
            bytes memory data,
            uint256 value
        ) internal returns (bytes memory) {
            return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
        }
        /**
         * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
         * with `errorMessage` as a fallback revert reason when `target` reverts.
         *
         * _Available since v3.1._
         */
        function functionCallWithValue(
            address target,
            bytes memory data,
            uint256 value,
            string memory errorMessage
        ) internal returns (bytes memory) {
            require(address(this).balance >= value, "Address: insufficient balance for call");
            require(isContract(target), "Address: call to non-contract");
            (bool success, bytes memory returndata) = target.call{value: value}(data);
            return verifyCallResult(success, returndata, errorMessage);
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
         * but performing a static call.
         *
         * _Available since v3.3._
         */
        function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
            return functionStaticCall(target, data, "Address: low-level static call failed");
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
         * but performing a static call.
         *
         * _Available since v3.3._
         */
        function functionStaticCall(
            address target,
            bytes memory data,
            string memory errorMessage
        ) internal view returns (bytes memory) {
            require(isContract(target), "Address: static call to non-contract");
            (bool success, bytes memory returndata) = target.staticcall(data);
            return verifyCallResult(success, returndata, errorMessage);
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
         * but performing a delegate call.
         *
         * _Available since v3.4._
         */
        function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
            return functionDelegateCall(target, data, "Address: low-level delegate call failed");
        }
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
         * but performing a delegate call.
         *
         * _Available since v3.4._
         */
        function functionDelegateCall(
            address target,
            bytes memory data,
            string memory errorMessage
        ) internal returns (bytes memory) {
            require(isContract(target), "Address: delegate call to non-contract");
            (bool success, bytes memory returndata) = target.delegatecall(data);
            return verifyCallResult(success, returndata, errorMessage);
        }
        /**
         * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
         * revert reason using the provided one.
         *
         * _Available since v4.3._
         */
        function verifyCallResult(
            bool success,
            bytes memory returndata,
            string memory errorMessage
        ) internal pure returns (bytes memory) {
            if (success) {
                return returndata;
            } else {
                // Look for revert reason and bubble it up if present
                if (returndata.length > 0) {
                    // The easiest way to bubble the revert reason is using memory via assembly
                    assembly {
                        let returndata_size := mload(returndata)
                        revert(add(32, returndata), returndata_size)
                    }
                } else {
                    revert(errorMessage);
                }
            }
        }
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    import "./IERC165.sol";
    /**
     * @dev Implementation of the {IERC165} interface.
     *
     * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
     * for the additional interface id that will be supported. For example:
     *
     * ```solidity
     * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
     *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
     * }
     * ```
     *
     * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
     */
    abstract contract ERC165 is IERC165 {
        /**
         * @dev See {IERC165-supportsInterface}.
         */
        function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
            return interfaceId == type(IERC165).interfaceId;
        }
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    /**
     * @dev Interface of the ERC165 standard, as defined in the
     * https://eips.ethereum.org/EIPS/eip-165[EIP].
     *
     * Implementers can declare support of contract interfaces, which can then be
     * queried by others ({ERC165Checker}).
     *
     * For an implementation, see {ERC165}.
     */
    interface IERC165 {
        /**
         * @dev Returns true if this contract implements the interface defined by
         * `interfaceId`. See the corresponding
         * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
         * to learn more about how these ids are created.
         *
         * This function call must use less than 30 000 gas.
         */
        function supportsInterface(bytes4 interfaceId) external view returns (bool);
    }