reCAPTCHACHIBIS

{{
  "language": "Solidity",
  "sources": {
    "output/contracts/reCAPTCHACHIBIS.sol": {
      "content": "// SPDX-License-Identifier: MIT 
pragma solidity ^0.8.28;

import {ERC721A} from "erc721a/contracts/ERC721A.sol";
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
import {ERC2981} from "@openzeppelin/contracts/token/common/ERC2981.sol";
import {BitMaps} from "@openzeppelin/contracts/utils/structs/BitMaps.sol";
import {OperatorFilterer} from "closedsea/src/OperatorFilterer.sol";
import {MerkleProof} from "@openzeppelin/contracts/utils/cryptography/MerkleProof.sol";

error MaxSupplyExceeded();
error PublicSaleClosed();
error TransfersLocked();
error NotAllowedByRegistry();
error RegistryNotSet();
error WrongWeiSent();
error MaxFeeExceeded();
error InputLengthsMismatch();
error InvalidMerkleProof();
error InvalidLaunchpadFee();
error InvalidLaunchpadFeeAddress();
error TransferFailed();
error PaymentTransferFailed();
error FeeTransferFailed();
error NotEnoughBalance();
error NotEnoughAllowance();

interface ICreatorToken {
    event TransferValidatorUpdated(address oldValidator, address newValidator);
    function getTransferValidator() external view returns (address validator);
    function getTransferValidationFunction() external view 
        returns (bytes4 functionSignature, bool isViewFunction);
    function setTransferValidator(address validator) external;
}

interface ITransferValidator {
    function validateTransfer(address caller, address from, address to, uint256 tokenId) external view;
}

interface IRegistry {
    function isAllowedOperator(address operator) external view returns (bool);
}

interface IERC20 {
    function transfer(address recipient, uint256 amount) external returns (bool);
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
    function isApprovedForAll(address owner, address spender) external view returns (bool);
    function approve(address spender, uint256 amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
}

contract reCAPTCHACHIBIS is Ownable, OperatorFilterer, ERC2981, ERC721A, ICreatorToken {

    // Transfer validator for royalty enforcement
    address private _transferValidator;
    bytes4 private constant VALIDATE_TRANSFER_SELECTOR = 0xcaee23ea;

    // Launchpad Fee
    uint256 public launchpadFee = 303739027427634;
    uint256 public launchpadCutBps = 400;
    address public launchpadFeeAddress = 0xbDb9e0b47a02C45E3b50973A18452DC23CE72697;
    event LaunchpadFeeSent(address indexed feeAddress, uint256 feeAmount);
    event TokenPaymentSent(address indexed recipient, uint256 amount);

    using BitMaps for BitMaps.BitMap;
    address public currency = 0x0000000000000000000000000000000000000000;
    uint256 public maxSupply = 1111;
    bool public operatorFilteringEnabled = true;
    bool public initialTransferLockOn = true;
    bool public isRegistryActive;
    address public registryAddress;
    string private _baseTokenURI = "";
    string private _placeHolderTokenURI = "https://mintify-launchpad.nyc3.cdn.digitaloceanspaces.com/36120786-aa6c-4180-ac07-44e7379c8abe.gif";

    
    // Phase 1 variables
    uint256 public startTimePhase1 = 1762549200;
    uint256 public endTimePhase1 = 1762567200;
    uint256 public maxSupplyPhase1 = 0;
    uint256 public totalSupplyPhase1;
    uint256 public pricePhase1 = 15000000000000000;
    uint256 public maxPerWalletPhase1 = 2;
    bytes32 public merkleRootPhase1 = 0x3c5c8c21401cfcc6e664e522e7fc22180dadf74ac482d265cc84c919b18e8dc7;
    mapping(address => uint256) public walletMintsPhase1;
    
    // Phase 2 variables
    uint256 public startTimePhase2 = 1762551840;
    uint256 public endTimePhase2 = 1762567200;
    uint256 public maxSupplyPhase2 = 0;
    uint256 public totalSupplyPhase2;
    uint256 public pricePhase2 = 20000000000000000;
    uint256 public maxPerWalletPhase2 = 10;
    bytes32 public merkleRootPhase2 = 0x0;
    mapping(address => uint256) public walletMintsPhase2;
    

    constructor() ERC721A("reCAPTCHACHIBIS", "CHIBI") Ownable(msg.sender) {

        // Register operator filtering
        _registerForOperatorFiltering();

        // Set initial royalty
        _setDefaultRoyalty(0x3BD9aD66b4508ba12385cbE78E76977b0Eb8CF35, 400);
        
        // Deployment Airdrop
        _mint(0x65Cb6fA48F9890a99dE39E11aB0889D3726833E5, 12);

    }

    // Phase 1 Mint
    function mintPhase1(bytes32[] calldata merkleProof, uint256 quantity) external payable {

        // Check if mint has started
        if (startTimePhase1 != 0 && block.timestamp < startTimePhase1) {
            revert PublicSaleClosed();
        }

        // Check if mint has ended
        if (endTimePhase1 != 0 && block.timestamp > endTimePhase1) {
            revert PublicSaleClosed();
        }

        // Check if the mint will exceed total max supply, if set.
        if (maxSupply != 0 && totalSupply() + quantity > maxSupply) {
            revert MaxSupplyExceeded();
        }

        // If phase max supply is set, check if it's exceeded
        if (maxSupplyPhase1 != 0 && totalSupplyPhase1 + quantity > maxSupplyPhase1) {
            revert MaxSupplyExceeded();
        }

        uint256 totalOrderPrice = (pricePhase1 + launchpadFee) * quantity;

        // Check if the price is correct if native currency
        if (currency == address(0)) {
            if (msg.value != totalOrderPrice) {
                revert WrongWeiSent();
            }
        }
        else {
            // Check if the user has enough balance and allowance if ERC20
            IERC20 token = IERC20(currency);
            if (token.balanceOf(msg.sender) < totalOrderPrice) {
                revert NotEnoughBalance();
            }
            if (token.allowance(msg.sender, address(this)) < totalOrderPrice) {
                revert NotEnoughAllowance();
            }
        }

         

        // Check if the proof is set, and if it is valid
        if (merkleRootPhase1 != bytes32(0)) {
            // Using Merkle Tree
            bytes32 node = keccak256(abi.encodePacked(msg.sender));
            if (!MerkleProof.verify(merkleProof, merkleRootPhase1, node)) {
                revert InvalidMerkleProof();
            }
        }
            
        // Check if we have exceeded phase max per wallet if set.
        if (maxPerWalletPhase1 != 0 && walletMintsPhase1[msg.sender] + quantity > maxPerWalletPhase1) {
            revert MaxSupplyExceeded();
        }

        uint256 flatFees = 0;
        // Get the Launchpad Flat Fee if set
        if (launchpadFee != 0 && launchpadFeeAddress != address(0)) {
            flatFees = launchpadFee * quantity;
        }

        // Get the Launchpad Percentage Fee if set
        uint256 percentageFees = 0;
        if (launchpadCutBps != 0 && launchpadFeeAddress != address(0)) {
            percentageFees = (launchpadCutBps * (totalOrderPrice - flatFees)) / 10000;
        }

        // Send the fees
        uint256 totalFees = flatFees + percentageFees;
        if (totalFees != 0) {
            _sendLaunchpadFee(totalFees);
        }

        // Transfer the payment if ERC20
        if (currency != address(0) && totalOrderPrice > totalFees) {
            _sendTokenPayment(address(this), totalOrderPrice - totalFees);    
        }

        // Mint the tokens
        walletMintsPhase1[msg.sender] += quantity;
        totalSupplyPhase1 += quantity;
        _mint(msg.sender, quantity);

    }

    // Phase 2 Mint
    function mintPhase2(uint256 quantity) external payable {

        // Check if mint has started
        if (startTimePhase2 != 0 && block.timestamp < startTimePhase2) {
            revert PublicSaleClosed();
        }

        // Check if mint has ended
        if (endTimePhase2 != 0 && block.timestamp > endTimePhase2) {
            revert PublicSaleClosed();
        }

        // Check if the mint will exceed total max supply, if set.
        if (maxSupply != 0 && totalSupply() + quantity > maxSupply) {
            revert MaxSupplyExceeded();
        }

        // If phase max supply is set, check if it's exceeded
        if (maxSupplyPhase2 != 0 && totalSupplyPhase2 + quantity > maxSupplyPhase2) {
            revert MaxSupplyExceeded();
        }

        uint256 totalOrderPrice = (pricePhase2 + launchpadFee) * quantity;

        // Check if the price is correct if native currency
        if (currency == address(0)) {
            if (msg.value != totalOrderPrice) {
                revert WrongWeiSent();
            }
        }
        else {
            // Check if the user has enough balance and allowance if ERC20
            IERC20 token = IERC20(currency);
            if (token.balanceOf(msg.sender) < totalOrderPrice) {
                revert NotEnoughBalance();
            }
            if (token.allowance(msg.sender, address(this)) < totalOrderPrice) {
                revert NotEnoughAllowance();
            }
        }

         
        // Check if we have exceeded phase max per wallet if set.
        if (maxPerWalletPhase2 != 0 && walletMintsPhase2[msg.sender] + quantity > maxPerWalletPhase2) {
            revert MaxSupplyExceeded();
        }

        uint256 flatFees = 0;
        // Get the Launchpad Flat Fee if set
        if (launchpadFee != 0 && launchpadFeeAddress != address(0)) {
            flatFees = launchpadFee * quantity;
        }

        // Get the Launchpad Percentage Fee if set
        uint256 percentageFees = 0;
        if (launchpadCutBps != 0 && launchpadFeeAddress != address(0)) {
            percentageFees = (launchpadCutBps * (totalOrderPrice - flatFees)) / 10000;
        }

        // Send the fees
        uint256 totalFees = flatFees + percentageFees;
        if (totalFees != 0) {
            _sendLaunchpadFee(totalFees);
        }

        // Transfer the payment if ERC20
        if (currency != address(0) && totalOrderPrice > totalFees) {
            _sendTokenPayment(address(this), totalOrderPrice - totalFees);    
        }

        // Mint the tokens
        walletMintsPhase2[msg.sender] += quantity;
        totalSupplyPhase2 += quantity;
        _mint(msg.sender, quantity);

    }

    

    // =========================================================================
    //                           Owner Only Functions
    // =========================================================================

    // Owner airdrop
    function airDrop(address[] memory users, uint256[] memory amounts) external onlyOwner {

        // iterate over users and amounts
        if (users.length != amounts.length) {
            revert InputLengthsMismatch();
        }
        for (uint256 i; i < users.length;) {
            if (maxSupply != 0 && totalSupply() + amounts[i] > maxSupply) {
                revert MaxSupplyExceeded();
            }
            _mint(users[i], amounts[i]);
            unchecked {
                ++i;
            }
        }

    }

    // Owner unrestricted mint
    function ownerMint(address to, uint256 quantity) external onlyOwner {
        if (maxSupply != 0 && totalSupply() + quantity > maxSupply) {
            revert MaxSupplyExceeded();
        }
        _mint(to, quantity);
    }

    // Set max supply
    function setMaxSupply(uint256 newMaxSupply) external onlyOwner {
        maxSupply = newMaxSupply;
    }

    // Withdraw Balance to owner
    function withdraw() public onlyOwner {
        (bool success, ) = payable(owner()).call{value: address(this).balance}("");
        if (!success) {
            revert TransferFailed();
        }
    }

    // Withdraw Balance to Address
    function withdrawTo(address payable _to) public onlyOwner {
        (bool success, ) = payable(_to).call{value: address(this).balance}("");
        if (!success) {
            revert TransferFailed();
        }
    }

    // Withdraw ERC20 to owner
    function withdrawERC20(address tokenAddress) public onlyOwner {
        IERC20 token = IERC20(tokenAddress);
        uint256 balance = token.balanceOf(address(this));
        if (balance == 0) {
            revert TransferFailed();
        }
        bool success = token.transfer(owner(), balance);
        if (!success) {
            revert TransferFailed();
        }
    }

    // Withdraw ERC20 to Address
    function withdrawERC20To(address tokenAddress, address to) public onlyOwner {
        IERC20 token = IERC20(tokenAddress);
        uint256 balance = token.balanceOf(address(this));
        if (balance == 0) {
            revert TransferFailed();
        }
        bool success = token.transfer(to, balance);
        if (!success) {
            revert TransferFailed();
        }
    }

    // Send Launchpad Flat Fee
    function _sendLaunchpadFee(uint256 feeAmount) private {
        if (feeAmount == 0) {
            revert InvalidLaunchpadFee();
        }
        if (launchpadFeeAddress == address(0)) {
            revert InvalidLaunchpadFeeAddress();
        }
        if (currency == address(0)) {
            (bool success, ) = payable(launchpadFeeAddress).call{value: feeAmount}("");
            if (!success) {
                revert FeeTransferFailed();
            }
        } 
        else {
            // Transfer the fee in the specified currency
            IERC20 token = IERC20(currency);
            try token.transferFrom(msg.sender, launchpadFeeAddress, feeAmount) {
                // Success
            } catch {
                revert FeeTransferFailed();
            }
        }
        emit LaunchpadFeeSent(launchpadFeeAddress, feeAmount);
    }

    // Send ERC20 Payment
    function _sendTokenPayment(address recipient, uint256 amount) private {
        if (amount == 0) {
            revert PaymentTransferFailed();
        }
        if (recipient == address(0)) {
            revert PaymentTransferFailed();
        }
        // Transfer the fee in the specified currency
        IERC20 token = IERC20(currency);
        try token.transferFrom(msg.sender, address(this), amount) {
            // Success
        } catch {
            revert PaymentTransferFailed();
        }
        emit TokenPaymentSent(recipient, amount);
    }

    // Break Transfer Lock
    function breakLock() external onlyOwner {
        initialTransferLockOn = false;
    }

    // Set the start time for the phase
    function setStartTimePhase1(uint256 newStartTime) external onlyOwner {
        startTimePhase1 = newStartTime;
    }

    // Set the end time for the phase
    function setEndTimePhase1(uint256 newEndTime) external onlyOwner {
        endTimePhase1 = newEndTime;
    }

    // Set the max supply for the phase
    function setMaxSupplyPhase1(uint256 newMaxSupply) external onlyOwner {
        maxSupplyPhase1 = newMaxSupply;
    }

    // Set max per wallet for the phase
    function setMaxPerWalletPhase1(uint256 newMaxPerWallet) external onlyOwner {
        maxPerWalletPhase1 = newMaxPerWallet;
    }

    // Set the price for the phase
    function setPricePhase1(uint256 newPrice) external onlyOwner {
        pricePhase1 = newPrice;
    }

    // Set the merkle root for the phase
    function setMerkleRootPhase1(bytes32 newMerkleRoot) external onlyOwner {
        merkleRootPhase1 = newMerkleRoot;
    }// Set the start time for the phase
    function setStartTimePhase2(uint256 newStartTime) external onlyOwner {
        startTimePhase2 = newStartTime;
    }

    // Set the end time for the phase
    function setEndTimePhase2(uint256 newEndTime) external onlyOwner {
        endTimePhase2 = newEndTime;
    }

    // Set the max supply for the phase
    function setMaxSupplyPhase2(uint256 newMaxSupply) external onlyOwner {
        maxSupplyPhase2 = newMaxSupply;
    }

    // Set max per wallet for the phase
    function setMaxPerWalletPhase2(uint256 newMaxPerWallet) external onlyOwner {
        maxPerWalletPhase2 = newMaxPerWallet;
    }

    // Set the price for the phase
    function setPricePhase2(uint256 newPrice) external onlyOwner {
        pricePhase2 = newPrice;
    }

    // Set the merkle root for the phase
    function setMerkleRootPhase2(bytes32 newMerkleRoot) external onlyOwner {
        merkleRootPhase2 = newMerkleRoot;
    }

    // =========================================================================
    //                             ERC721A Misc
    // =========================================================================

    function _startTokenId() internal pure override returns (uint256) {
        return 1;
    }

    // =========================================================================
    //                        ICreatorToken Implementation
    // =========================================================================
    
    function getTransferValidator() external view override returns (address validator) {
        return _transferValidator;
    }
    
    function getTransferValidationFunction() external pure override 
        returns (bytes4 functionSignature, bool isViewFunction) {
        return (VALIDATE_TRANSFER_SELECTOR, true);
    }
    
    function setTransferValidator(address validator) external override onlyOwner {
        address oldValidator = _transferValidator;
        _transferValidator = validator;
        emit TransferValidatorUpdated(oldValidator, validator);
    }

    // =========================================================================
    //                           Operator filtering
    // =========================================================================

    function setApprovalForAll(address operator, bool approved)
        public
        override (ERC721A)
        onlyAllowedOperatorApproval(operator)
    {
        if (initialTransferLockOn) {
            revert TransfersLocked();
        }
        super.setApprovalForAll(operator, approved);
    }

    function approve(address operator, uint256 tokenId)
        public
        payable
        override (ERC721A)
        onlyAllowedOperatorApproval(operator)
    {
        if (initialTransferLockOn) {
            revert TransfersLocked();
        }
        super.approve(operator, tokenId);
    }

    function transferFrom(address from, address to, uint256 tokenId)
        public
        payable
        override (ERC721A)
        onlyAllowedOperator(from)
    {
        super.transferFrom(from, to, tokenId);
    }

    function safeTransferFrom(address from, address to, uint256 tokenId)
        public
        payable
        override (ERC721A)
        onlyAllowedOperator(from)
    {
        super.safeTransferFrom(from, to, tokenId);
    }

    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory data)
        public
        payable
        override (ERC721A)
        onlyAllowedOperator(from)
    {
        super.safeTransferFrom(from, to, tokenId, data);
    }

    function setOperatorFilteringEnabled(bool value) public onlyOwner {
        operatorFilteringEnabled = value;
    }

    function _operatorFilteringEnabled() internal view override returns (bool) {
        return operatorFilteringEnabled;
    }

    // =========================================================================
    //                             Registry Check
    // =========================================================================
    function _beforeTokenTransfers(
        address from,
        address to,
        uint256 startTokenId,
        uint256 quantity
    ) internal override {
        // Check transfer lock
        if (initialTransferLockOn && from != address(0) && to != address(0)) {
            revert TransfersLocked();
        }
        
        // Check your custom registry
        if (!_isValidAgainstRegistry(msg.sender)) {
            revert NotAllowedByRegistry();
        }
        
        // Add royalty enforcement validation (skip for minting)
        if (from != address(0) && _transferValidator != address(0)) {
            // For ERC721A batch transfers, validate each token
            for (uint256 i = 0; i < quantity; i++) {
                ITransferValidator(_transferValidator).validateTransfer(
                    msg.sender,
                    from,
                    to,
                    startTokenId + i
                );
            }
        }
        
        super._beforeTokenTransfers(from, to, startTokenId, quantity);
    }

    function _isValidAgainstRegistry(address operator)
        internal
        view
        returns (bool)
    {
        if (isRegistryActive) {
            IRegistry registry = IRegistry(registryAddress);
            return registry.isAllowedOperator(operator);
        }
        return true;
    }

    function setIsRegistryActive(bool _isRegistryActive) external onlyOwner {
        if (registryAddress == address(0)) revert RegistryNotSet();
        isRegistryActive = _isRegistryActive;
    }

    function setRegistryAddress(address _registryAddress) external onlyOwner {
        registryAddress = _registryAddress;
    }

    // =========================================================================
    //                                  ERC165
    // =========================================================================

    function supportsInterface(bytes4 interfaceId) public view override (ERC721A, ERC2981) returns (bool) {
        return 
            interfaceId == type(ICreatorToken).interfaceId ||
            ERC721A.supportsInterface(interfaceId) || 
            ERC2981.supportsInterface(interfaceId);
    }

    // =========================================================================
    //                                 ERC2891
    // =========================================================================

    function setDefaultRoyalty(address receiver, uint96 feeNumerator) public onlyOwner {
        if (feeNumerator > 1000) {
            revert MaxFeeExceeded();
        }
        _setDefaultRoyalty(receiver, feeNumerator);
    }

    function setTokenRoyalty(
        uint256 tokenId,
        address receiver,
        uint96 feeNumerator
    ) external onlyOwner {
        if (feeNumerator > 1000) {
            revert MaxFeeExceeded();
        }
        _setTokenRoyalty(tokenId, receiver, feeNumerator);
    }

    // =========================================================================
    //                                 Metadata
    // =========================================================================

    function setBaseURI(string calldata baseURI) external onlyOwner {
        _baseTokenURI = baseURI;
    }

    function setPlaceholderBaseURI(string calldata placeholderURI) external onlyOwner {
        _placeHolderTokenURI = placeholderURI;
    }

    function _baseURI() internal view override returns (string memory) {
        return _baseTokenURI;
    }

    function _placeHolderURI() internal view returns (string memory) {
        return _placeHolderTokenURI;
    }

    function tokenURI(uint256 tokenId) public view override returns (string memory) {
        
        if (!_exists(tokenId)) revert URIQueryForNonexistentToken();

        string memory baseURI = _baseURI();
        string memory placeHolderURI = _placeHolderURI();
        if (bytes(baseURI).length != 0) {
            return string(abi.encodePacked(baseURI, "/", _toString(tokenId), ".json"));
        }
        if (bytes(placeHolderURI).length != 0) {
            return placeHolderURI;
        }
        return "";

    }

}"
    },
    "lib/closedsea/lib/erc721a/contracts/ERC721A.sol": {
      "content": "// SPDX-License-Identifier: MIT
// ERC721A Contracts v4.2.3
// Creator: Chiru Labs

pragma solidity ^0.8.4;

import './IERC721A.sol';

/**
 * @dev Interface of ERC721 token receiver.
 */
interface ERC721A__IERC721Receiver {
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}

/**
 * @title ERC721A
 *
 * @dev Implementation of the [ERC721](https://eips.ethereum.org/EIPS/eip-721)
 * Non-Fungible Token Standard, including the Metadata extension.
 * Optimized for lower gas during batch mints.
 *
 * Token IDs are minted in sequential order (e.g. 0, 1, 2, 3, ...)
 * starting from `_startTokenId()`.
 *
 * Assumptions:
 *
 * - An owner cannot have more than 2**64 - 1 (max value of uint64) of supply.
 * - The maximum token ID cannot exceed 2**256 - 1 (max value of uint256).
 */
contract ERC721A is IERC721A {
    // Bypass for a `--via-ir` bug (https://github.com/chiru-labs/ERC721A/pull/364).
    struct TokenApprovalRef {
        address value;
    }

    // =============================================================
    //                           CONSTANTS
    // =============================================================

    // Mask of an entry in packed address data.
    uint256 private constant _BITMASK_ADDRESS_DATA_ENTRY = (1 << 64) - 1;

    // The bit position of `numberMinted` in packed address data.
    uint256 private constant _BITPOS_NUMBER_MINTED = 64;

    // The bit position of `numberBurned` in packed address data.
    uint256 private constant _BITPOS_NUMBER_BURNED = 128;

    // The bit position of `aux` in packed address data.
    uint256 private constant _BITPOS_AUX = 192;

    // Mask of all 256 bits in packed address data except the 64 bits for `aux`.
    uint256 private constant _BITMASK_AUX_COMPLEMENT = (1 << 192) - 1;

    // The bit position of `startTimestamp` in packed ownership.
    uint256 private constant _BITPOS_START_TIMESTAMP = 160;

    // The bit mask of the `burned` bit in packed ownership.
    uint256 private constant _BITMASK_BURNED = 1 << 224;

    // The bit position of the `nextInitialized` bit in packed ownership.
    uint256 private constant _BITPOS_NEXT_INITIALIZED = 225;

    // The bit mask of the `nextInitialized` bit in packed ownership.
    uint256 private constant _BITMASK_NEXT_INITIALIZED = 1 << 225;

    // The bit position of `extraData` in packed ownership.
    uint256 private constant _BITPOS_EXTRA_DATA = 232;

    // Mask of all 256 bits in a packed ownership except the 24 bits for `extraData`.
    uint256 private constant _BITMASK_EXTRA_DATA_COMPLEMENT = (1 << 232) - 1;

    // The mask of the lower 160 bits for addresses.
    uint256 private constant _BITMASK_ADDRESS = (1 << 160) - 1;

    // The maximum `quantity` that can be minted with {_mintERC2309}.
    // This limit is to prevent overflows on the address data entries.
    // For a limit of 5000, a total of 3.689e15 calls to {_mintERC2309}
    // is required to cause an overflow, which is unrealistic.
    uint256 private constant _MAX_MINT_ERC2309_QUANTITY_LIMIT = 5000;

    // The `Transfer` event signature is given by:
    // `keccak256(bytes("Transfer(address,address,uint256)"))`.
    bytes32 private constant _TRANSFER_EVENT_SIGNATURE =
        0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef;

    // =============================================================
    //                            STORAGE
    // =============================================================

    // The next token ID to be minted.
    uint256 private _currentIndex;

    // The number of tokens burned.
    uint256 private _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 {_packedOwnershipOf} implementation for details.
    //
    // Bits Layout:
    // - [0..159]   `addr`
    // - [160..223] `startTimestamp`
    // - [224]      `burned`
    // - [225]      `nextInitialized`
    // - [232..255] `extraData`
    mapping(uint256 => uint256) private _packedOwnerships;

    // Mapping owner address to address data.
    //
    // Bits Layout:
    // - [0..63]    `balance`
    // - [64..127]  `numberMinted`
    // - [128..191] `numberBurned`
    // - [192..255] `aux`
    mapping(address => uint256) private _packedAddressData;

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

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

    // =============================================================
    //                          CONSTRUCTOR
    // =============================================================

    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
        _currentIndex = _startTokenId();
    }

    // =============================================================
    //                   TOKEN COUNTING OPERATIONS
    // =============================================================

    /**
     * @dev Returns the starting token ID.
     * To change the starting token ID, please override this function.
     */
    function _startTokenId() internal view virtual returns (uint256) {
        return 0;
    }

    /**
     * @dev Returns the next token ID to be minted.
     */
    function _nextTokenId() internal view virtual returns (uint256) {
        return _currentIndex;
    }

    /**
     * @dev Returns the total number of tokens in existence.
     * Burned tokens will reduce the count.
     * To get the total number of tokens minted, please see {_totalMinted}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        // Counter underflow is impossible as _burnCounter cannot be incremented
        // more than `_currentIndex - _startTokenId()` times.
        unchecked {
            return _currentIndex - _burnCounter - _startTokenId();
        }
    }

    /**
     * @dev Returns the total amount of tokens minted in the contract.
     */
    function _totalMinted() internal view virtual returns (uint256) {
        // Counter underflow is impossible as `_currentIndex` does not decrement,
        // and it is initialized to `_startTokenId()`.
        unchecked {
            return _currentIndex - _startTokenId();
        }
    }

    /**
     * @dev Returns the total number of tokens burned.
     */
    function _totalBurned() internal view virtual returns (uint256) {
        return _burnCounter;
    }

    // =============================================================
    //                    ADDRESS DATA OPERATIONS
    // =============================================================

    /**
     * @dev Returns the number of tokens in `owner`'s account.
     */
    function balanceOf(address owner) public view virtual override returns (uint256) {
        if (owner == address(0)) revert BalanceQueryForZeroAddress();
        return _packedAddressData[owner] & _BITMASK_ADDRESS_DATA_ENTRY;
    }

    /**
     * Returns the number of tokens minted by `owner`.
     */
    function _numberMinted(address owner) internal view returns (uint256) {
        return (_packedAddressData[owner] >> _BITPOS_NUMBER_MINTED) & _BITMASK_ADDRESS_DATA_ENTRY;
    }

    /**
     * Returns the number of tokens burned by or on behalf of `owner`.
     */
    function _numberBurned(address owner) internal view returns (uint256) {
        return (_packedAddressData[owner] >> _BITPOS_NUMBER_BURNED) & _BITMASK_ADDRESS_DATA_ENTRY;
    }

    /**
     * Returns the auxiliary data for `owner`. (e.g. number of whitelist mint slots used).
     */
    function _getAux(address owner) internal view returns (uint64) {
        return uint64(_packedAddressData[owner] >> _BITPOS_AUX);
    }

    /**
     * Sets the auxiliary 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 virtual {
        uint256 packed = _packedAddressData[owner];
        uint256 auxCasted;
        // Cast `aux` with assembly to avoid redundant masking.
        assembly {
            auxCasted := aux
        }
        packed = (packed & _BITMASK_AUX_COMPLEMENT) | (auxCasted << _BITPOS_AUX);
        _packedAddressData[owner] = packed;
    }

    // =============================================================
    //                            IERC165
    // =============================================================

    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * [EIP section](https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified)
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30000 gas.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        // The interface IDs are constants representing the first 4 bytes
        // of the XOR of all function selectors in the interface.
        // See: [ERC165](https://eips.ethereum.org/EIPS/eip-165)
        // (e.g. `bytes4(i.functionA.selector ^ i.functionB.selector ^ ...)`)
        return
            interfaceId == 0x01ffc9a7 || // ERC165 interface ID for ERC165.
            interfaceId == 0x80ac58cd || // ERC165 interface ID for ERC721.
            interfaceId == 0x5b5e139f; // ERC165 interface ID for ERC721Metadata.
    }

    // =============================================================
    //                        IERC721Metadata
    // =============================================================

    /**
     * @dev Returns the token collection name.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the token collection symbol.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
     */
    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, _toString(tokenId))) : '';
    }

    /**
     * @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, it can be overridden in child contracts.
     */
    function _baseURI() internal view virtual returns (string memory) {
        return '';
    }

    // =============================================================
    //                     OWNERSHIPS OPERATIONS
    // =============================================================

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) public view virtual override returns (address) {
        return address(uint160(_packedOwnershipOf(tokenId)));
    }

    /**
     * @dev Gas spent here starts off proportional to the maximum mint batch size.
     * It gradually moves to O(1) as tokens get transferred around over time.
     */
    function _ownershipOf(uint256 tokenId) internal view virtual returns (TokenOwnership memory) {
        return _unpackedOwnership(_packedOwnershipOf(tokenId));
    }

    /**
     * @dev Returns the unpacked `TokenOwnership` struct at `index`.
     */
    function _ownershipAt(uint256 index) internal view virtual returns (TokenOwnership memory) {
        return _unpackedOwnership(_packedOwnerships[index]);
    }

    /**
     * @dev Initializes the ownership slot minted at `index` for efficiency purposes.
     */
    function _initializeOwnershipAt(uint256 index) internal virtual {
        if (_packedOwnerships[index] == 0) {
            _packedOwnerships[index] = _packedOwnershipOf(index);
        }
    }

    /**
     * Returns the packed ownership data of `tokenId`.
     */
    function _packedOwnershipOf(uint256 tokenId) private view returns (uint256 packed) {
        if (_startTokenId() <= tokenId) {
            packed = _packedOwnerships[tokenId];
            // If not burned.
            if (packed & _BITMASK_BURNED == 0) {
                // If the data at the starting slot does not exist, start the scan.
                if (packed == 0) {
                    if (tokenId >= _currentIndex) revert OwnerQueryForNonexistentToken();
                    // Invariant:
                    // There will always be an initialized ownership slot
                    // (i.e. `ownership.addr != address(0) && ownership.burned == false`)
                    // before an unintialized ownership slot
                    // (i.e. `ownership.addr == address(0) && ownership.burned == false`)
                    // Hence, `tokenId` will not underflow.
                    //
                    // We can directly compare the packed value.
                    // If the address is zero, packed will be zero.
                    for (;;) {
                        unchecked {
                            packed = _packedOwnerships[--tokenId];
                        }
                        if (packed == 0) continue;
                        return packed;
                    }
                }
                // Otherwise, the data exists and is not burned. We can skip the scan.
                // This is possible because we have already achieved the target condition.
                // This saves 2143 gas on transfers of initialized tokens.
                return packed;
            }
        }
        revert OwnerQueryForNonexistentToken();
    }

    /**
     * @dev Returns the unpacked `TokenOwnership` struct from `packed`.
     */
    function _unpackedOwnership(uint256 packed) private pure returns (TokenOwnership memory ownership) {
        ownership.addr = address(uint160(packed));
        ownership.startTimestamp = uint64(packed >> _BITPOS_START_TIMESTAMP);
        ownership.burned = packed & _BITMASK_BURNED != 0;
        ownership.extraData = uint24(packed >> _BITPOS_EXTRA_DATA);
    }

    /**
     * @dev Packs ownership data into a single uint256.
     */
    function _packOwnershipData(address owner, uint256 flags) private view returns (uint256 result) {
        assembly {
            // Mask `owner` to the lower 160 bits, in case the upper bits somehow aren't clean.
            owner := and(owner, _BITMASK_ADDRESS)
            // `owner | (block.timestamp << _BITPOS_START_TIMESTAMP) | flags`.
            result := or(owner, or(shl(_BITPOS_START_TIMESTAMP, timestamp()), flags))
        }
    }

    /**
     * @dev Returns the `nextInitialized` flag set if `quantity` equals 1.
     */
    function _nextInitializedFlag(uint256 quantity) private pure returns (uint256 result) {
        // For branchless setting of the `nextInitialized` flag.
        assembly {
            // `(quantity == 1) << _BITPOS_NEXT_INITIALIZED`.
            result := shl(_BITPOS_NEXT_INITIALIZED, eq(quantity, 1))
        }
    }

    // =============================================================
    //                      APPROVAL OPERATIONS
    // =============================================================

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account. See {ERC721A-_approve}.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     */
    function approve(address to, uint256 tokenId) public payable virtual override {
        _approve(to, tokenId, true);
    }

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) public view virtual override returns (address) {
        if (!_exists(tokenId)) revert ApprovalQueryForNonexistentToken();

        return _tokenApprovals[tokenId].value;
    }

    /**
     * @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) public virtual override {
        _operatorApprovals[_msgSenderERC721A()][operator] = approved;
        emit ApprovalForAll(_msgSenderERC721A(), operator, approved);
    }

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}.
     */
    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
        return _operatorApprovals[owner][operator];
    }

    /**
     * @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. See {_mint}.
     */
    function _exists(uint256 tokenId) internal view virtual returns (bool) {
        return
            _startTokenId() <= tokenId &&
            tokenId < _currentIndex && // If within bounds,
            _packedOwnerships[tokenId] & _BITMASK_BURNED == 0; // and not burned.
    }

    /**
     * @dev Returns whether `msgSender` is equal to `approvedAddress` or `owner`.
     */
    function _isSenderApprovedOrOwner(
        address approvedAddress,
        address owner,
        address msgSender
    ) private pure returns (bool result) {
        assembly {
            // Mask `owner` to the lower 160 bits, in case the upper bits somehow aren't clean.
            owner := and(owner, _BITMASK_ADDRESS)
            // Mask `msgSender` to the lower 160 bits, in case the upper bits somehow aren't clean.
            msgSender := and(msgSender, _BITMASK_ADDRESS)
            // `msgSender == owner || msgSender == approvedAddress`.
            result := or(eq(msgSender, owner), eq(msgSender, approvedAddress))
        }
    }

    /**
     * @dev Returns the storage slot and value for the approved address of `tokenId`.
     */
    function _getApprovedSlotAndAddress(uint256 tokenId)
        private
        view
        returns (uint256 approvedAddressSlot, address approvedAddress)
    {
        TokenApprovalRef storage tokenApproval = _tokenApprovals[tokenId];
        // The following is equivalent to `approvedAddress = _tokenApprovals[tokenId].value`.
        assembly {
            approvedAddressSlot := tokenApproval.slot
            approvedAddress := sload(approvedAddressSlot)
        }
    }

    // =============================================================
    //                      TRANSFER OPERATIONS
    // =============================================================

    /**
     * @dev Transfers `tokenId` from `from` to `to`.
     *
     * 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
    ) public payable virtual override {
        uint256 prevOwnershipPacked = _packedOwnershipOf(tokenId);

        if (address(uint160(prevOwnershipPacked)) != from) revert TransferFromIncorrectOwner();

        (uint256 approvedAddressSlot, address approvedAddress) = _getApprovedSlotAndAddress(tokenId);

        // The nested ifs save around 20+ gas over a compound boolean condition.
        if (!_isSenderApprovedOrOwner(approvedAddress, from, _msgSenderERC721A()))
            if (!isApprovedForAll(from, _msgSenderERC721A())) revert TransferCallerNotOwnerNorApproved();

        if (to == address(0)) revert TransferToZeroAddress();

        _beforeTokenTransfers(from, to, tokenId, 1);

        // Clear approvals from the previous owner.
        assembly {
            if approvedAddress {
                // This is equivalent to `delete _tokenApprovals[tokenId]`.
                sstore(approvedAddressSlot, 0)
            }
        }

        // 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 {
            // We can directly increment and decrement the balances.
            --_packedAddressData[from]; // Updates: `balance -= 1`.
            ++_packedAddressData[to]; // Updates: `balance += 1`.

            // Updates:
            // - `address` to the next owner.
            // - `startTimestamp` to the timestamp of transfering.
            // - `burned` to `false`.
            // - `nextInitialized` to `true`.
            _packedOwnerships[tokenId] = _packOwnershipData(
                to,
                _BITMASK_NEXT_INITIALIZED | _nextExtraData(from, to, prevOwnershipPacked)
            );

            // If the next slot may not have been initialized (i.e. `nextInitialized == false`) .
            if (prevOwnershipPacked & _BITMASK_NEXT_INITIALIZED == 0) {
                uint256 nextTokenId = tokenId + 1;
                // If the next slot's address is zero and not burned (i.e. packed value is zero).
                if (_packedOwnerships[nextTokenId] == 0) {
                    // If the next slot is within bounds.
                    if (nextTokenId != _currentIndex) {
                        // Initialize the next slot to maintain correctness for `ownerOf(tokenId + 1)`.
                        _packedOwnerships[nextTokenId] = prevOwnershipPacked;
                    }
                }
            }
        }

        emit Transfer(from, to, tokenId);
        _afterTokenTransfers(from, to, tokenId, 1);
    }

    /**
     * @dev Equivalent to `safeTransferFrom(from, to, tokenId, '')`.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public payable virtual override {
        safeTransferFrom(from, to, tokenId, '');
    }

    /**
     * @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 memory _data
    ) public payable virtual override {
        transferFrom(from, to, tokenId);
        if (to.code.length != 0)
            if (!_checkContractOnERC721Received(from, to, tokenId, _data)) {
                revert TransferToNonERC721ReceiverImplementer();
            }
    }

    /**
     * @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 {}

    /**
     * @dev Private function to invoke {IERC721Receiver-onERC721Received} on a target contract.
     *
     * `from` - Previous owner of the given token ID.
     * `to` - Target address that will receive the token.
     * `tokenId` - Token ID to be transferred.
     * `_data` - Optional data to send along with the call.
     *
     * Returns whether the call correctly returned the expected magic value.
     */
    function _checkContractOnERC721Received(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) private returns (bool) {
        try ERC721A__IERC721Receiver(to).onERC721Received(_msgSenderERC721A(), from, tokenId, _data) returns (
            bytes4 retval
        ) {
            return retval == ERC721A__IERC721Receiver(to).onERC721Received.selector;
        } catch (bytes memory reason) {
            if (reason.length == 0) {
                revert TransferToNonERC721ReceiverImplementer();
            } else {
                assembly {
                    revert(add(32, reason), mload(reason))
                }
            }
        }
    }

    // =============================================================
    //                        MINT OPERATIONS
    // =============================================================

    /**
     * @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 for each mint.
     */
    function _mint(address to, uint256 quantity) internal virtual {
        uint256 startTokenId = _currentIndex;
        if (quantity == 0) revert MintZeroQuantity();

        _beforeTokenTransfers(address(0), to, startTokenId, quantity);

        // Overflows are incredibly unrealistic.
        // `balance` and `numberMinted` have a maximum limit of 2**64.
        // `tokenId` has a maximum limit of 2**256.
        unchecked {
            // Updates:
            // - `balance += quantity`.
            // - `numberMinted += quantity`.
            //
            // We can directly add to the `balance` and `numberMinted`.
            _packedAddressData[to] += quantity * ((1 << _BITPOS_NUMBER_MINTED) | 1);

            // Updates:
            // - `address` to the owner.
            // - `startTimestamp` to the timestamp of minting.
            // - `burned` to `false`.
            // - `nextInitialized` to `quantity == 1`.
            _packedOwnerships[startTokenId] = _packOwnershipData(
                to,
                _nextInitializedFlag(quantity) | _nextExtraData(address(0), to, 0)
            );

            uint256 toMasked;
            uint256 end = startTokenId + quantity;

            // Use assembly to loop and emit the `Transfer` event for gas savings.
            // The duplicated `log4` removes an extra check and reduces stack juggling.
            // The assembly, together with the surrounding Solidity code, have been
            // delicately arranged to nudge the compiler into producing optimized opcodes.
            assembly {
                // Mask `to` to the lower 160 bits, in case the upper bits somehow aren't clean.
                toMasked := and(to, _BITMASK_ADDRESS)
                // Emit the `Transfer` event.
                log4(
                    0, // Start of data (0, since no data).
                    0, // End of data (0, since no data).
                    _TRANSFER_EVENT_SIGNATURE, // Signature.
                    0, // `address(0)`.
                    toMasked, // `to`.
                    startTokenId // `tokenId`.
                )

                // The `iszero(eq(,))` check ensures that large values of `quantity`
                // that overflows uint256 will make the loop run out of gas.
                // The compiler will optimize the `iszero` away for performance.
                for {
                    let tokenId := add(startTokenId, 1)
                } iszero(eq(tokenId, end)) {
                    tokenId := add(tokenId, 1)
                } {
                    // Emit the `Transfer` event. Similar to above.
                    log4(0, 0, _TRANSFER_EVENT_SIGNATURE, 0, toMasked, tokenId)
                }
            }
            if (toMasked == 0) revert MintToZeroAddress();

            _currentIndex = end;
        }
        _afterTokenTransfers(address(0), to, startTokenId, quantity);
    }

    /**
     * @dev Mints `quantity` tokens and transfers them to `to`.
     *
     * This function is intended for efficient minting only during contract creation.
     *
     * It emits only one {ConsecutiveTransfer} as defined in
     * [ERC2309](https://eips.ethereum.org/EIPS/eip-2309),
     * instead of a sequence of {Transfer} event(s).
     *
     * Calling this function outside of contract creation WILL make your contract
     * non-compliant with the ERC721 standard.
     * For full ERC721 compliance, substituting ERC721 {Transfer} event(s) with the ERC2309
     * {ConsecutiveTransfer} event is only permissible during contract creation.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - `quantity` must be greater than 0.
     *
     * Emits a {ConsecutiveTransfer} event.
     */
    function _mintERC2309(address to, uint256 quantity) internal virtual {
        uint256 startTokenId = _currentIndex;
        if (to == address(0)) revert MintToZeroAddress();
        if (quantity == 0) revert MintZeroQuantity();
        if (quantity > _MAX_MINT_ERC2309_QUANTITY_LIMIT) revert MintERC2309QuantityExceedsLimit();

        _beforeTokenTransfers(address(0), to, startTokenId, quantity);

        // Overflows are unrealistic due to the above check for `quantity` to be below the limit.
        unchecked {
            // Updates:
            // - `balance += quantity`.
            // - `numberMinted += quantity`.
            //
            // We can directly add to the `balance` and `numberMinted`.
            _packedAddressData[to] += quantity * ((1 << _BITPOS_NUMBER_MINTED) | 1);

            // Updates:
            // - `address` to the owner.
            // - `startTimestamp` to the timestamp of minting.
            // - `burned` to `false`.
            // - `nextInitialized` to `quantity == 1`.
            _packedOwnerships[startTokenId] = _packOwnershipData(
                to,
                _nextInitializedFlag(quantity) | _nextExtraData(address(0), to, 0)
            );

            emit ConsecutiveTransfer(startTokenId, startTokenId + quantity - 1, address(0), to);

            _currentIndex = startTokenId + quantity;
        }
        _afterTokenTransfers(address(0), to, startTokenId, 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.
     *
     * See {_mint}.
     *
     * Emits a {Transfer} event for each mint.
     */
    function _safeMint(
        address to,
        uint256 quantity,
        bytes memory _data
    ) internal virtual {
        _mint(to, quantity);

        unchecked {
            if (to.code.length != 0) {
                uint256 end = _currentIndex;
                uint256 index = end - quantity;
                do {
                    if (!_checkContractOnERC721Received(address(0), to, index++, _data)) {
                        revert TransferToNonERC721ReceiverImplementer();
                    }
                } while (index < end);
                // Reentrancy protection.
                if (_currentIndex != end) revert();
            }
        }
    }

    /**
     * @dev Equivalent to `_safeMint(to, quantity, '')`.
     */
    function _safeMint(address to, uint256 quantity) internal virtual {
        _safeMint(to, quantity, '');
    }

    // =============================================================
    //                       APPROVAL OPERATIONS
    // =============================================================

    /**
     * @dev Equivalent to `_approve(to, tokenId, false)`.
     */
    function _approve(address to, uint256 tokenId) internal virtual {
        _approve(to, tokenId, false);
    }

    /**
     * @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:
     *
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function _approve(
        address to,
        uint256 tokenId,
        bool approvalCheck
    ) internal virtual {
        address owner = ownerOf(tokenId);

        if (approvalCheck)
            if (_msgSenderERC721A() != owner)
                if (!isApprovedForAll(owner, _msgSenderERC721A())) {
                    revert ApprovalCallerNotOwnerNorApproved();
                }

        _tokenApprovals[tokenId].value = to;
        emit Approval(owner, to, tokenId);
    }

    // =============================================================
    //                        BURN OPERATIONS
    // =============================================================

    /**
     * @dev Equivalent to `_burn(tokenId, false)`.
     */
    function _burn(uint256 tokenId) internal virtual {
        _burn(tokenId, false);
    }

    /**
     * @dev Destroys `tokenId`.
     * The approval is cleared when the token is burned.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     *
     * Emits a {Transfer} event.
     */
    function _burn(uint256 tokenId, bool approvalCheck) internal virtual {
        uint256 prevOwnershipPacked = _packedOwnershipOf(tokenId);

        address from = address(uint160(prevOwnershipPacked));

        (uint256 approvedAddressSlot, address approvedAddress) = _getApprovedSlotAndAddress(tokenId);

        if (approvalCheck) {
            // The nested ifs save around 20+ gas over a compound boolean condition.
            if (!_isSenderApprovedOrOwner(approvedAddress, from, _msgSenderERC721A()))
                if (!isApprovedForAll(from, _msgSenderERC721A())) revert TransferCallerNotOwnerNorApproved();
        }

        _beforeTokenTransfers(from, address(0), tokenId, 1);

        // Clear approvals from the previous owner.
        assembly {
            if approvedAddress {
                // This is equivalent to `delete _tokenApprovals[tokenId]`.
                sstore(approvedAddressSlot, 0)
            }
        }

        // 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 {
            // Updates:
            // - `balance -= 1`.
            // - `numberBurned += 1`.
            //
            // We can directly decrement the balance, and increment the number burned.
            // This is equivalent to `packed -= 1; packed += 1 << _BITPOS_NUMBER_BURNED;`.
            _packedAddressData[from] += (1 << _BITPOS_NUMBER_BURNED) - 1;

            // Updates:
            // - `address` to the last owner.
            // - `startTimestamp` to the timestamp of burning.
            // - `burned` to `true`.
            // - `nextInitialized` to `true`.
            _packedOwnerships[tokenId] = _packOwnershipData(
                from,
                (_BITMASK_BURNED | _BITMASK_NEXT_INITIALIZED) | _nextExtraData(from, address(0), prevOwnershipPacked)
            );

            // If the next slot may not have been initialized (i.e. `nextInitialized == false`) .
            if (prevOwnershipPacked & _BITMASK_NEXT_INITIALIZED == 0) {
                uint256 nextTokenId = tokenId + 1;
                // If the next slot's address is zero and not burned (i.e. packed value is zero).
                if (_packedOwnerships[nextTokenId] == 0) {
                    // If the next slot is within bounds.
                    if (nextTokenId != _currentIndex) {
                        // Initialize the next slot to maintain correctness for `ownerOf(tokenId + 1)`.
                        _packedOwnerships[nextTokenId] = prevOwnershipPacked;
                    }
                }
            }
        }

        emit Transfer(from, address(0), tokenId);
        _afterTokenTransfers(from, address(0), tokenId, 1);

        // Overflow not possible, as _burnCounter cannot be exceed _currentIndex times.
        unchecked {
            _burnCounter++;
        }
    }

    // =============================================================
    //                     EXTRA DATA OPERATIONS
    // =============================================================

    /**
     * @dev Directly sets the extra data for the ownership data `index`.
     */
    function _setExtraDataAt(uint256 index, uint24 extraData) internal virtual {
        uint256 packed = _packedOwnerships[index];
        if (packed == 0) revert OwnershipNotInitializedForExtraData();
        uint256 extraDataCasted;
        // Cast `extraData` with assembly to avoid redundant masking.
        assembly {
            extraDataCasted := extraData
        }
        packed = (packed & _BITMASK_EXTRA_DATA_COMPLEMENT) | (extraDataCasted << _BITPOS_EXTRA_DATA);
        _packedOwnerships[index] = packed;
    }

    /**
     * @dev Called during each token transfer to set the 24bit `extraData` field.
     * Intended to be overridden by the cosumer contract.
     *
     * `previousExtraData` - the value of `extraData` before transfer.
     *
     * 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 _extraData(
        address from,
        address to,
        uint24 previousExtraData
    ) internal view virtual returns (uint24) {}

    /**
     * @dev Returns the next extra data for the packed ownership data.
     * The returned result is shifted into position.
     */
    function _nextExtraData(
        address from,
        address to,
        uint256 prevOwnershipPacked
    ) private view returns (uint256) {
        uint24 extraData = uint24(prevO