Contract Source Code:

// SPDX-License-Identifier: MIT
 
pragma solidity ^0.8.0;
 
abstract contract ReentrancyGuard {
 
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;
 
    uint256 private _status;
 
    constructor() {
        _status = _NOT_ENTERED;
    }
    modifier nonReentrant() {
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
        _status = _ENTERED;
        _;
        _status = _NOT_ENTERED;
    }
}
 
 
library MerkleProof {
 
    function verify(
        bytes32[] memory proof,
        bytes32 root,
        bytes32 leaf
    ) internal pure returns (bool) {
        return processProof(proof, leaf) == root;
    }
 
    function processProof(bytes32[] memory proof, bytes32 leaf) internal pure returns (bytes32) {
        bytes32 computedHash = leaf;
        for (uint256 i = 0; i < proof.length; i++) {
            bytes32 proofElement = proof[i];
            if (computedHash <= proofElement) {
                // Hash(current computed hash + current element of the proof)
                computedHash = _efficientHash(computedHash, proofElement);
            } else {
                // Hash(current element of the proof + current computed hash)
                computedHash = _efficientHash(proofElement, computedHash);
            }
        }
        return computedHash;
    }
 
    function _efficientHash(bytes32 a, bytes32 b) private pure returns (bytes32 value) {
        assembly {
            mstore(0x00, a)
            mstore(0x20, b)
            value := keccak256(0x00, 0x40)
        }
    }
}
 
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";
 
    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);
    }
}
 
 
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }
 
    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}
 
 
abstract contract Ownable is Context {
    address private _owner;
 
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
    constructor() {
        _transferOwnership(_msgSender());
    }
 
    function owner() public view virtual returns (address) {
        return _owner;
    }
 
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }
 
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }
 
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }
 
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}
 
 
library Address {
 
    function isContract(address account) internal view returns (bool) {
        return account.code.length > 0;
    }
 
    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");
    }
 
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }
 
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }
 
    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");
    }
 
    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);
    }
 
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }
 
    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);
    }
 
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }
 
    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);
    }
 
    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);
            }
        }
    }
}
 
 
interface IERC721Receiver {
 
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}
 
interface IERC165 {
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}
 
 
abstract contract ERC165 is IERC165 {
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}
 
 
interface IERC721 is IERC165 {
 
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
 
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
 
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);
 
    function balanceOf(address owner) external view returns (uint256 balance);
 
    function ownerOf(uint256 tokenId) external view returns (address owner);
 
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;
 
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;
 
    function approve(address to, uint256 tokenId) external;
 
    function getApproved(uint256 tokenId) external view returns (address operator);
 
    function setApprovalForAll(address operator, bool _approved) external;
 
    function isApprovedForAll(address owner, address operator) external view returns (bool);
 
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes calldata data
    ) external;
}
 
 
interface IERC721Enumerable is IERC721 {
 
    function totalSupply() external view returns (uint256);
 
    function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256);
 
    function tokenByIndex(uint256 index) external view returns (uint256);
}
 
 
interface IERC721Metadata is IERC721 {
 
    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function tokenURI(uint256 tokenId) external view returns (string memory);
}
 
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();
 
 
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 {}
}
 
 
error ReserveEmpty();
error AllReadyClaimed();
error AllBagFull();
error LowReserveLeft();
 
contract FloatiesNft is ERC721A, Ownable, ReentrancyGuard {
 
    using Strings for uint256;
 
    bytes32 public merkleRoot;
 
    string public uriPrefix = "";
    string public uriSuffix = ".json";
 
    uint256 public cost = 0.005 ether;
 
    uint256 public maxSupply = 3333;  
 
    uint public maxMintAmountPerTx;
    uint public walletLimit;
 
    bool public whitelistMintEnabled = false;
    bool public publicMintEnabled = false;
 
    mapping (address => bool) public WhitelistClaimed;
    mapping (address => uint256) public NftBag;
 
    constructor(uint _MaxTx, uint _MaxWallet) ERC721A("Floaties", "FLOAT") {
        setMaxTxLimit(_MaxTx);
        setMaxWalletLimit(_MaxWallet);
    }
 
    modifier mintCompliance(uint256 _mintAmount) {
        require(totalSupply() + _mintAmount <= maxSupply, "Max supply exceeded!");
        _;
    }
 
    modifier mintPriceCompliance(uint256 _mintAmount) {
        require(msg.value >= cost * _mintAmount, "Insufficient funds!");
        _;
    }
 
    function whitelistMint(bytes32[] calldata _merkleProof) public mintCompliance(1) {
        require(whitelistMintEnabled,"Whitelist Mint Paused!!");
        require(tx.origin == msg.sender,"Error: Invalid Caller!");
        address account = msg.sender;
        if(WhitelistClaimed[account]) {
            revert AllReadyClaimed();
        }
        bytes32 leaf = keccak256(abi.encodePacked(account));
        require(MerkleProof.verify(_merkleProof, merkleRoot, leaf), "Invalid proof!");
        _safeMint(account, 1);
        WhitelistClaimed[account] = true;
    }
 
    function publicMint(uint256 _mintAmount) public payable mintCompliance(_mintAmount) mintPriceCompliance(_mintAmount) {
        require(publicMintEnabled,"Public Mint Paused!!");
        require(tx.origin == msg.sender,"Error: Invalid Caller!");
        require(_mintAmount <= maxMintAmountPerTx, "Invalid mint amount!");
        address account = msg.sender;
        if(NftBag[account] + _mintAmount > walletLimit) {
            revert AllBagFull();
        }
        _safeMint(account, _mintAmount);
        NftBag[account] += _mintAmount;
    }
 
 
    /* ========================  Owner Minter ========================= */
 
    function mintTeam(address _adr, uint256 _mintAmount) public mintCompliance(_mintAmount) onlyOwner {
        _safeMint(_adr, _mintAmount);
    }
 
    function walletOfOwner(address _owner) public view returns (uint256[] memory) {
        uint256 ownerTokenCount = balanceOf(_owner);
        uint256[] memory ownedTokenIds = new uint256[](ownerTokenCount);
        uint256 currentTokenId = _startTokenId();
        uint256 ownedTokenIndex = 0;
        address latestOwnerAddress;
 
        while (ownedTokenIndex < ownerTokenCount && currentTokenId <= maxSupply) {
            TokenOwnership memory ownership = _ownerships[currentTokenId];
 
            if (!ownership.burned && ownership.addr != address(0)) {
                latestOwnerAddress = ownership.addr;
            }
 
            if (latestOwnerAddress == _owner) {
                ownedTokenIds[ownedTokenIndex] = currentTokenId;
 
                ownedTokenIndex++;
            }
 
            currentTokenId++;
        }
 
        return ownedTokenIds;
    }
 
    function _startTokenId() internal view virtual override returns (uint256) {
        return 1;
    }
 
    function tokenURI(uint256 _tokenId) public view virtual override returns (string memory) {
        require(_exists(_tokenId), "ERC721Metadata: URI query for nonexistent token");
 
        string memory currentBaseURI = _baseURI();
        return bytes(currentBaseURI).length > 0
            ? string(abi.encodePacked(currentBaseURI, _tokenId.toString(), uriSuffix))
            : '';
    }
 
    function enableDisableWhitelistMint(bool _status) public onlyOwner {
        whitelistMintEnabled = _status;
    }
 
    function enableDisablePublicMint(bool _status) public onlyOwner {
        publicMintEnabled = _status;
    }
 
    function setCost(uint256 _cost) public onlyOwner {
        cost = _cost;
    }
 
    function setMaxTxLimit(uint _value) public onlyOwner {
        maxMintAmountPerTx = _value;
    }
 
    function setMaxWalletLimit(uint _value) public onlyOwner {
        walletLimit = _value;
    }
 
    function setUriPrefix(string memory _uriPrefix) public onlyOwner {
        uriPrefix = _uriPrefix;
    }
 
    function setUriSuffix(string memory _uriSuffix) public onlyOwner {
        uriSuffix = _uriSuffix;
    }
 
    function setMerkleRoot(bytes32 _merkleRoot) public onlyOwner {
        merkleRoot = _merkleRoot;
    }
 
    function withdraw() public onlyOwner nonReentrant {
        (bool os, ) = payable(owner()).call{value: address(this).balance}('');
        require(os);
    }
 
    function _baseURI() internal view virtual override returns (string memory) {
        return uriPrefix;
    }
 
}