// Contract: starfighter
// Target function: function _transfer(address from, address to, uint256 tokenId) private
    //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
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;

    //Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients are aware of the ERC721 protocol to prevent tokens from being forever locked.
    //Requirements: `from` cannot be the zero address.
    //              `to` cannot be the zero address.
    //              `tokenId` token must exist and be owned by `from`
    //              If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}
    //              If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer
    function safeTransferFrom(address from, address to, uint256 tokenId) external;

    //Transfers `tokenId` token 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}
    function transferFrom(address from, address to, uint256 tokenId) external;

    //Gives permission to `to` to transfer `tokenId` token to another account
    function approve(address to, uint256 tokenId) external;

    //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.
    function setApprovalForAll(address operator, bool _approved) external;

    //Returns the account approved for `tokenId` token.
    //Requirements: `tokenId` must exist
    function getApproved(uint256 tokenId) external view returns (address operator);

    //Returns if the `operator` is allowed to manage all of the assets of `owner`
    function isApprovedForAll(address owner, address operator) external view returns (bool);

    //Returns the token collection name
    function name() external view returns (string memory);

    //Returns the token collection symbol
    function symbol() external view returns (string memory);

    //Returns the Uniform Resource Identifier (URI) for `tokenId` token
    function tokenURI(uint256 tokenId) external view returns (string memory);}

interface ERC721A__IERC721Receiver {
    function onERC721Received(address operator, address from, uint256 tokenId, bytes calldata data) external returns (bytes4);}

contract ERC721A is IERC721A {
    // 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 tokenId of the next token 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`
    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 => 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();}

    //Returns the starting token ID
    function _startTokenId() internal view virtual returns (uint256) {
        return 0;}

    //Returns the next token ID to be minted
    function _nextTokenId() internal view returns (uint256) {
        return _currentIndex;}

    //Returns the total number of tokens in existence
    function totalSupply() public view override 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();}}

    //Returns the total number of tokens burned
    function _totalBurned() internal view returns (uint256) {
        return _burnCounter;}

    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: https://eips.ethereum.org/EIPS/eip-165
        // e.g. `bytes4(i.functionA.selector ^ i.functionB.selector ^ ...)`
        return
            interfaceId == 0x01ffc9a7 || interfaceId == 0x80ac58cd || interfaceId == 0x5b5e139f;}

    function balanceOf(address owner) public view override returns (uint256) {
        if (owner == address(0)) revert BalanceQueryForZeroAddress();
        return _packedAddressData[owner] & BITMASK_ADDRESS_DATA_ENTRY;}

    function _numberMinted(address owner) internal view returns (uint256) {
        return (_packedAddressData[owner] >> BITPOS_NUMBER_MINTED) & BITMASK_ADDRESS_DATA_ENTRY;}

    function _numberBurned(address owner) internal view returns (uint256) {
        return (_packedAddressData[owner] >> BITPOS_NUMBER_BURNED) & BITMASK_ADDRESS_DATA_ENTRY;}

    function _getAux(address owner) internal view returns (uint64) {
        return uint64(_packedAddressData[owner] >> BITPOS_AUX);}

    function _setAux(address owner, uint64 aux) internal {
        uint256 packed = _packedAddressData[owner];
        uint256 auxCasted;
        assembly { // Cast aux without masking.
            auxCasted := aux}
        packed = (packed & BITMASK_AUX_COMPLEMENT) | (auxCasted << BITPOS_AUX);
        _packedAddressData[owner] = packed;}

    function _packedOwnershipOf(uint256 tokenId) private view returns (uint256) {
        uint256 curr = tokenId;
        unchecked {
            if (_startTokenId() <= curr)
                if (curr < _currentIndex) {
                    uint256 packed = _packedOwnerships[curr];
                    // If not burned.
                    if (packed & BITMASK_BURNED == 0) {
                        // 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.
                        //
                        // We can directly compare the packed value.
                        // If the address is zero, packed is zero.
                        while (packed == 0) {
                            packed = _packedOwnerships[--curr];}
                        return packed;}}}
        revert OwnerQueryForNonexistentToken();}

    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;}

    function _ownershipAt(uint256 index) internal view returns (TokenOwnership memory) {
        return _unpackedOwnership(_packedOwnerships[index]);}

    function _initializeOwnershipAt(uint256 index) internal {
        if (_packedOwnerships[index] == 0) {
            _packedOwnerships[index] = _packedOwnershipOf(index);}}

    function _ownershipOf(uint256 tokenId) internal view returns (TokenOwnership memory) {
        return _unpackedOwnership(_packedOwnershipOf(tokenId));}

    function ownerOf(uint256 tokenId) public view override returns (address) {
        return address(uint160(_packedOwnershipOf(tokenId)));}

    function name() public view virtual override returns (string memory) {
        return _name;}

    function symbol() public view virtual override returns (string memory) {
        return _symbol;}

    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))) : '';}

    //Base URI for computing {tokenURI}. 
    function _baseURI() internal view virtual returns (string memory) {
        return '';}

    function _addressToUint256(address value) private pure returns (uint256 result) {
        assembly {
            result := value}}

    function _boolToUint256(bool value) private pure returns (uint256 result) {
        assembly {
            result := value}}

    function approve(address to, uint256 tokenId) public override {
        address owner = address(uint160(_packedOwnershipOf(tokenId)));
        if (to == owner) revert ApprovalToCurrentOwner();
        if (_msgSenderERC721A() != owner)
            if (!isApprovedForAll(owner, _msgSenderERC721A())) {
                revert ApprovalCallerNotOwnerNorApproved();}
        _tokenApprovals[tokenId] = to;
        emit Approval(owner, to, tokenId);}

    function getApproved(uint256 tokenId) public view override returns (address) {
        if (!_exists(tokenId)) revert ApprovalQueryForNonexistentToken();
        return _tokenApprovals[tokenId];}

    function setApprovalForAll(address operator, bool approved) public virtual override {
        if (operator == _msgSenderERC721A()) revert ApproveToCaller();
        _operatorApprovals[_msgSenderERC721A()][operator] = approved;
        emit ApprovalForAll(_msgSenderERC721A(), operator, approved);}

    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
        return _operatorApprovals[owner][operator];}

    function transferFrom(address from, address to, uint256 tokenId) public virtual override {
        _transfer(from, to, tokenId);}

    function safeTransferFrom(address from, address to, uint256 tokenId) public virtual override {
        safeTransferFrom(from, to, tokenId, '');}

    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory _data) public virtual override {
        _transfer(from, to, tokenId);
        if (to.code.length != 0)
            if (!_checkContractOnERC721Received(from, to, tokenId, _data)) {
                revert TransferToNonERC721ReceiverImplementer();}}

    //Returns whether `tokenId` exists
    function _exists(uint256 tokenId) internal view returns (bool) {
        return _startTokenId() <= tokenId && tokenId < _currentIndex && _packedOwnerships[tokenId] & BITMASK_BURNED == 0;}

    //Equivalent to `_safeMint(to, quantity, '')`
    function _safeMint(address to, uint256 quantity) internal {
        _safeMint(to, quantity, '');}

    //Safely mints `quantity` tokens and transfers them to `to`
    function _safeMint(address to, uint256 quantity, bytes memory _data) 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 {
            // Updates:
            // - `balance += quantity`.
            // - `numberMinted += quantity`.
            //
            // We can directly add to the balance and number minted.
            _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] =
                _addressToUint256(to) |
                (block.timestamp << BITPOS_START_TIMESTAMP) |
                (_boolToUint256(quantity == 1) << BITPOS_NEXT_INITIALIZED);
            uint256 updatedIndex = startTokenId;
            uint256 end = updatedIndex + quantity;
            if (to.code.length != 0) {
                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);}

    //Mints `quantity` tokens and transfers them to `to`
    function _mint(address to, uint256 quantity) 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 {
            // Updates:
            // - `balance += quantity`.
            // - `numberMinted += quantity`.
            //
            // We can directly add to the balance and number minted.
            _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] =
                _addressToUint256(to) |
                (block.timestamp << BITPOS_START_TIMESTAMP) |
                (_boolToUint256(quantity == 1) << BITPOS_NEXT_INITIALIZED);
            uint256 updatedIndex = startTokenId;
            uint256 end = updatedIndex + quantity;
            do {emit Transfer(address(0), to, updatedIndex++);} while (updatedIndex < end);
            _currentIndex = updatedIndex;}
        _afterTokenTransfers(address(0), to, startTokenId, quantity);}