// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

/// @title DN404
/// @notice DN404 is a hybrid ERC20 and ERC721 implementation that mints
/// and burns NFTs based on an account's ERC20 token balance.
///
/// @author vectorized.eth (@optimizoor)
/// @author Quit (@0xQuit)
/// @author Michael Amadi (@AmadiMichaels)
/// @author cygaar (@0xCygaar)
/// @author Thomas (@0xjustadev)
/// @author Harrison (@PopPunkOnChain)
///
/// @dev Note:
/// - The ERC721 data is stored in this base DN404 contract, however a
///   DN404Mirror contract ***MUST*** be deployed and linked during
///   initialization.
abstract contract DN404 {
    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                           EVENTS                           */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Emitted when `amount` tokens is transferred from `from` to `to`.
    event Transfer(address indexed from, address indexed to, uint256 amount);

    /// @dev Emitted when `amount` tokens is approved by `owner` to be used by `spender`.
    event Approval(address indexed owner, address indexed spender, uint256 amount);

    /// @dev Emitted when `target` sets their skipNFT flag to `status`.
    event SkipNFTSet(address indexed target, bool status);

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                        CUSTOM ERRORS                       */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Thrown when attempting to double-initialize the contract.
    error DNAlreadyInitialized();

    /// @dev Thrown when attempting to transfer or burn more tokens than sender's balance.
    error InsufficientBalance();

    /// @dev Thrown when a spender attempts to transfer tokens with an insufficient allowance.
    error InsufficientAllowance();

    /// @dev Thrown when minting an amount of tokens that would overflow the max tokens.
    error TotalSupplyOverflow();

    /// @dev Thrown when the caller for a fallback NFT function is not the mirror contract.
    error SenderNotMirror();

    /// @dev Thrown when attempting to transfer tokens to the zero address.
    error TransferToZeroAddress();

    /// @dev Thrown when the mirror address provided for initialization is the zero address.
    error MirrorAddressIsZero();

    /// @dev Thrown when the link call to the mirror contract reverts.
    error LinkMirrorContractFailed();

    /// @dev Thrown when setting an NFT token approval
    /// and the caller is not the owner or an approved operator.
    error ApprovalCallerNotOwnerNorApproved();

    /// @dev Thrown when transferring an NFT
    /// and the caller is not the owner or an approved operator.
    error TransferCallerNotOwnerNorApproved();

    /// @dev Thrown when transferring an NFT and the from address is not the current owner.
    error TransferFromIncorrectOwner();

    /// @dev Thrown when checking the owner or approved address for an non-existent NFT.
    error TokenDoesNotExist();

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                         CONSTANTS                          */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Amount of token balance that is equal to one NFT.
    uint256 internal constant _WAD = 10 ** 18;

    /// @dev The maximum token ID allowed for an NFT.
    uint256 internal constant _MAX_TOKEN_ID = 0xffffffff;

    /// @dev The maximum possible token supply.
    uint256 internal constant _MAX_SUPPLY = 10 ** 18 * 0xffffffff - 1;

    /// @dev The flag to denote that the address data is initialized.
    uint8 internal constant _ADDRESS_DATA_INITIALIZED_FLAG = 1 << 0;

    /// @dev The flag to denote that the address should skip NFTs.
    uint8 internal constant _ADDRESS_DATA_SKIP_NFT_FLAG = 1 << 1;

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                          STORAGE                           */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Struct containing an address's token data and settings.
    struct AddressData {
        // Auxiliary data.
        uint88 aux;
        // Flags for `initialized` and `skipNFT`.
        uint8 flags;
        // The alias for the address. Zero means absence of an alias.
        uint32 addressAlias;
        // The number of NFT tokens.
        uint32 ownedLength;
        // The token balance in wei.
        uint96 balance;
    }

    /// @dev A uint32 map in storage.
    struct Uint32Map {
        mapping(uint256 => uint256) map;
    }

    /// @dev Struct containing the base token contract storage.
    struct DN404Storage {
        // Current number of address aliases assigned.
        uint32 numAliases;
        // Next token ID to assign for an NFT mint.
        uint32 nextTokenId;
        // Total supply of minted NFTs.
        uint32 totalNFTSupply;
        // Total supply of tokens.
        uint96 totalSupply;
        // Address of the NFT mirror contract.
        address mirrorERC721;
        // Mapping of a user alias number to their address.
        mapping(uint32 => address) aliasToAddress;
        // Mapping of user operator approvals for NFTs.
        mapping(address => mapping(address => bool)) operatorApprovals;
        // Mapping of NFT token approvals to approved operators.
        mapping(uint256 => address) tokenApprovals;
        // Mapping of user allowances for token spenders.
        mapping(address => mapping(address => uint256)) allowance;
        // Mapping of NFT token IDs owned by an address.
        mapping(address => Uint32Map) owned;
        // Even indices: owner aliases. Odd indices: owned indices.
        Uint32Map oo;
        // Mapping of user account AddressData
        mapping(address => AddressData) addressData;
    }

    /// @dev Returns a storage pointer for DN404Storage.
    function _getDN404Storage() internal pure virtual returns (DN404Storage storage $) {
        /// @solidity memory-safe-assembly
        assembly {
            // `uint72(bytes9(keccak256("DN404_STORAGE")))`.
            $.slot := 0xa20d6e21d0e5255308 // Truncate to 9 bytes to reduce bytecode size.
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                         INITIALIZER                        */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Initializes the DN404 contract with an
    /// `initialTokenSupply`, `initialTokenOwner` and `mirror` NFT contract address.
    function _initializeDN404(
        uint256 initialTokenSupply,
        address initialSupplyOwner,
        address mirror
    ) internal virtual {
        DN404Storage storage $ = _getDN404Storage();

        if ($.nextTokenId != 0) revert DNAlreadyInitialized();

        if (mirror == address(0)) revert MirrorAddressIsZero();
        _linkMirrorContract(mirror);

        $.nextTokenId = 1;
        $.mirrorERC721 = mirror;

        if (initialTokenSupply > 0) {
            if (initialSupplyOwner == address(0)) revert TransferToZeroAddress();
            if (initialTokenSupply > _MAX_SUPPLY) revert TotalSupplyOverflow();

            $.totalSupply = uint96(initialTokenSupply);
            AddressData storage initialOwnerAddressData = _addressData(initialSupplyOwner);
            initialOwnerAddressData.balance = uint96(initialTokenSupply);

            emit Transfer(address(0), initialSupplyOwner, initialTokenSupply);

            _setSkipNFT(initialSupplyOwner, true);
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*               METADATA FUNCTIONS TO OVERRIDE               */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the name of the token.
    function name() public view virtual returns (string memory);

    /// @dev Returns the symbol of the token.
    function symbol() public view virtual returns (string memory);

    /// @dev Returns the Uniform Resource Identifier (URI) for token `id`.
    function tokenURI(uint256 id) public view virtual returns (string memory);

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                      ERC20 OPERATIONS                      */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the decimals places of the token. Always 18.
    function decimals() public pure returns (uint8) {
        return 18;
    }

    /// @dev Returns the amount of tokens in existence.
    function totalSupply() public view virtual returns (uint256) {
        return uint256(_getDN404Storage().totalSupply);
    }

    /// @dev Returns the amount of tokens owned by `owner`.
    function balanceOf(address owner) public view virtual returns (uint256) {
        return _getDN404Storage().addressData[owner].balance;
    }

    /// @dev Returns the amount of tokens that `spender` can spend on behalf of `owner`.
    function allowance(address owner, address spender) public view returns (uint256) {
        return _getDN404Storage().allowance[owner][spender];
    }

    /// @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
    ///
    /// Emits a {Approval} event.
    function approve(address spender, uint256 amount) public virtual returns (bool) {
        DN404Storage storage $ = _getDN404Storage();

        $.allowance[msg.sender][spender] = amount;

        emit Approval(msg.sender, spender, amount);

        return true;
    }

    /// @dev Transfer `amount` tokens from the caller to `to`.
    ///
    /// Will burn sender NFTs if balance after transfer is less than
    /// the amount required to support the current NFT balance.
    ///
    /// Will mint NFTs to `to` if the recipient's new balance supports
    /// additional NFTs ***AND*** the `to` address's skipNFT flag is
    /// set to false.
    ///
    /// Requirements:
    /// - `from` must at least have `amount`.
    ///
    /// Emits a {Transfer} event.
    function transfer(address to, uint256 amount) public virtual returns (bool) {
        _transfer(msg.sender, to, amount);
        return true;
    }

    /// @dev Transfers `amount` tokens from `from` to `to`.
    ///
    /// Note: Does not update the allowance if it is the maximum uint256 value.
    ///
    /// Will burn sender NFTs if balance after transfer is less than
    /// the amount required to support the current NFT balance.
    ///
    /// Will mint NFTs to `to` if the recipient's new balance supports
    /// additional NFTs ***AND*** the `to` address's skipNFT flag is
    /// set to false.
    ///
    /// Requirements:
    /// - `from` must at least have `amount`.
    /// - The caller must have at least `amount` of allowance to transfer the tokens of `from`.
    ///
    /// Emits a {Transfer} event.
    function transferFrom(address from, address to, uint256 amount) public virtual returns (bool) {
        DN404Storage storage $ = _getDN404Storage();

        uint256 allowed = $.allowance[from][msg.sender];

        if (allowed != type(uint256).max) {
            if (amount > allowed) revert InsufficientAllowance();
            unchecked {
                $.allowance[from][msg.sender] = allowed - amount;
            }
        }

        _transfer(from, to, amount);

        return true;
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                  INTERNAL MINT FUNCTIONS                   */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Mints `amount` tokens to `to`, increasing the total supply.
    ///
    /// Will mint NFTs to `to` if the recipient's new balance supports
    /// additional NFTs ***AND*** the `to` address's skipNFT flag is
    /// set to false.
    ///
    /// Emits a {Transfer} event.
    function _mint(address to, uint256 amount) internal virtual {
        if (to == address(0)) revert TransferToZeroAddress();

        DN404Storage storage $ = _getDN404Storage();

        AddressData storage toAddressData = _addressData(to);

        unchecked {
            uint256 currentTokenSupply = uint256($.totalSupply) + amount;
            if (amount > _MAX_SUPPLY || currentTokenSupply > _MAX_SUPPLY) {
                revert TotalSupplyOverflow();
            }
            $.totalSupply = uint96(currentTokenSupply);

            uint256 toBalance = toAddressData.balance + amount;
            toAddressData.balance = uint96(toBalance);

            if (toAddressData.flags & _ADDRESS_DATA_SKIP_NFT_FLAG == 0) {
                Uint32Map storage toOwned = $.owned[to];
                uint256 toIndex = toAddressData.ownedLength;
                uint256 toEnd = toBalance / _WAD;
                _PackedLogs memory packedLogs = _packedLogsMalloc(_zeroFloorSub(toEnd, toIndex));

                if (packedLogs.logs.length != 0) {
                    uint256 maxNFTId = $.totalSupply / _WAD;
                    uint32 toAlias = _registerAndResolveAlias(toAddressData, to);
                    uint256 id = $.nextTokenId;
                    $.totalNFTSupply += uint32(packedLogs.logs.length);
                    toAddressData.ownedLength = uint32(toEnd);
                    // Mint loop.
                    do {
                        while (_get($.oo, _ownershipIndex(id)) != 0) {
                            if (++id > maxNFTId) id = 1;
                        }
                        _set(toOwned, toIndex, uint32(id));
                        _setOwnerAliasAndOwnedIndex($.oo, id, toAlias, uint32(toIndex++));
                        _packedLogsAppend(packedLogs, to, id, 0);
                        if (++id > maxNFTId) id = 1;
                    } while (toIndex != toEnd);
                    $.nextTokenId = uint32(id);
                    _packedLogsSend(packedLogs, $.mirrorERC721);
                }
            }
        }
        emit Transfer(address(0), to, amount);
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                  INTERNAL BURN FUNCTIONS                   */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Burns `amount` tokens from `from`, reducing the total supply.
    ///
    /// Will burn sender NFTs if balance after transfer is less than
    /// the amount required to support the current NFT balance.
    ///
    /// Emits a {Transfer} event.
    function _burn(address from, uint256 amount) internal virtual {
        DN404Storage storage $ = _getDN404Storage();

        AddressData storage fromAddressData = _addressData(from);

        uint256 fromBalance = fromAddressData.balance;
        if (amount > fromBalance) revert InsufficientBalance();

        uint256 currentTokenSupply = $.totalSupply;

        unchecked {
            fromBalance -= amount;
            fromAddressData.balance = uint96(fromBalance);
            currentTokenSupply -= amount;
            $.totalSupply = uint96(currentTokenSupply);

            Uint32Map storage fromOwned = $.owned[from];
            uint256 fromIndex = fromAddressData.ownedLength;
            uint256 nftAmountToBurn = _zeroFloorSub(fromIndex, fromBalance / _WAD);

            if (nftAmountToBurn != 0) {
                $.totalNFTSupply -= uint32(nftAmountToBurn);

                _PackedLogs memory packedLogs = _packedLogsMalloc(nftAmountToBurn);

                uint256 fromEnd = fromIndex - nftAmountToBurn;
                // Burn loop.
                do {
                    uint256 id = _get(fromOwned, --fromIndex);
                    _setOwnerAliasAndOwnedIndex($.oo, id, 0, 0);
                    delete $.tokenApprovals[id];
                    _packedLogsAppend(packedLogs, from, id, 1);
                } while (fromIndex != fromEnd);

                fromAddressData.ownedLength = uint32(fromIndex);
                _packedLogsSend(packedLogs, $.mirrorERC721);
            }
        }
        emit Transfer(from, address(0), amount);
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                INTERNAL TRANSFER FUNCTIONS                 */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Moves `amount` of tokens from `from` to `to`.
    ///
    /// Will burn sender NFTs if balance after transfer is less than
    /// the amount required to support the current NFT balance.
    ///
    /// Will mint NFTs to `to` if the recipient's new balance supports
    /// additional NFTs ***AND*** the `to` address's skipNFT flag is
    /// set to false.
    ///
    /// Emits a {Transfer} event.
    function _transfer(address from, address to, uint256 amount) internal virtual {
        if (to == address(0)) revert TransferToZeroAddress();

        DN404Storage storage $ = _getDN404Storage();

        AddressData storage fromAddressData = _addressData(from);
        AddressData storage toAddressData = _addressData(to);

        _TransferTemps memory t;
        t.fromOwnedLength = fromAddressData.ownedLength;
        t.toOwnedLength = toAddressData.ownedLength;
        t.fromBalance = fromAddressData.balance;

        if (amount > t.fromBalance) revert InsufficientBalance();

        unchecked {
            t.fromBalance -= amount;
            fromAddressData.balance = uint96(t.fromBalance);
            toAddressData.balance = uint96(t.toBalance = toAddressData.balance + amount);

            t.nftAmountToBurn = _zeroFloorSub(t.fromOwnedLength, t.fromBalance / _WAD);

            if (toAddressData.flags & _ADDRESS_DATA_SKIP_NFT_FLAG == 0) {
                if (from == to) t.toOwnedLength = t.fromOwnedLength - t.nftAmountToBurn;
                t.nftAmountToMint = _zeroFloorSub(t.toBalance / _WAD, t.toOwnedLength);
            }

            _PackedLogs memory packedLogs = _packedLogsMalloc(t.nftAmountToBurn + t.nftAmountToMint);

            if (t.nftAmountToBurn != 0) {
                Uint32Map storage fromOwned = $.owned[from];
                uint256 fromIndex = t.fromOwnedLength;
                uint256 fromEnd = fromIndex - t.nftAmountToBurn;
                $.totalNFTSupply -= uint32(t.nftAmountToBurn);
                fromAddressData.ownedLength = uint32(fromEnd);
                // Burn loop.
                do {
                    uint256 id = _get(fromOwned, --fromIndex);
                    _setOwnerAliasAndOwnedIndex($.oo, id, 0, 0);
                    delete $.tokenApprovals[id];
                    _packedLogsAppend(packedLogs, from, id, 1);
                } while (fromIndex != fromEnd);
            }

            if (t.nftAmountToMint != 0) {
                Uint32Map storage toOwned = $.owned[to];
                uint256 toIndex = t.toOwnedLength;
                uint256 toEnd = toIndex + t.nftAmountToMint;
                uint32 toAlias = _registerAndResolveAlias(toAddressData, to);
                uint256 maxNFTId = $.totalSupply / _WAD;
                uint256 id = $.nextTokenId;
                $.totalNFTSupply += uint32(t.nftAmountToMint);
                toAddressData.ownedLength = uint32(toEnd);
                // Mint loop.
                do {
                    while (_get($.oo, _ownershipIndex(id)) != 0) {
                        if (++id > maxNFTId) id = 1;
                    }
                    _set(toOwned, toIndex, uint32(id));
                    _setOwnerAliasAndOwnedIndex($.oo, id, toAlias, uint32(toIndex++));
                    _packedLogsAppend(packedLogs, to, id, 0);
                    if (++id > maxNFTId) id = 1;
                } while (toIndex != toEnd);
                $.nextTokenId = uint32(id);
            }

            if (packedLogs.logs.length != 0) {
                _packedLogsSend(packedLogs, $.mirrorERC721);
            }
        }
        emit Transfer(from, to, amount);
    }

    /// @dev Transfers token `id` from `from` to `to`.
    ///
    /// Requirements:
    ///
    /// - Call must originate from the mirror contract.
    /// - Token `id` must exist.
    /// - `from` must be the owner of the token.
    /// - `to` cannot be the zero address.
    ///   `msgSender` must be the owner of the token, or be approved to manage the token.
    ///
    /// Emits a {Transfer} event.
    function _transferFromNFT(address from, address to, uint256 id, address msgSender)
        internal
        virtual
    {
        DN404Storage storage $ = _getDN404Storage();

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

        address owner = $.aliasToAddress[_get($.oo, _ownershipIndex(id))];

        if (from != owner) revert TransferFromIncorrectOwner();

        if (msgSender != from) {
            if (!$.operatorApprovals[from][msgSender]) {
                if (msgSender != $.tokenApprovals[id]) {
                    revert TransferCallerNotOwnerNorApproved();
                }
            }
        }

        AddressData storage fromAddressData = _addressData(from);
        AddressData storage toAddressData = _addressData(to);

        fromAddressData.balance -= uint96(_WAD);

        unchecked {
            toAddressData.balance += uint96(_WAD);

            _set($.oo, _ownershipIndex(id), _registerAndResolveAlias(toAddressData, to));
            delete $.tokenApprovals[id];

            uint256 updatedId = _get($.owned[from], --fromAddressData.ownedLength);
            _set($.owned[from], _get($.oo, _ownedIndex(id)), uint32(updatedId));

            uint256 n = toAddressData.ownedLength++;
            _set($.oo, _ownedIndex(updatedId), _get($.oo, _ownedIndex(id)));
            _set($.owned[to], n, uint32(id));
            _set($.oo, _ownedIndex(id), uint32(n));
        }

        emit Transfer(from, to, _WAD);
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                 DATA HITCHHIKING FUNCTIONS                 */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the auxiliary data for `owner`.
    /// Minting, transferring, burning the tokens of `owner` will not change the auxiliary data.
    /// Auxiliary data can be set for any address, even if it does not have any tokens.
    function _getAux(address owner) internal view virtual returns (uint88) {
        return _getDN404Storage().addressData[owner].aux;
    }

    /// @dev Set the auxiliary data for `owner` to `value`.
    /// Minting, transferring, burning the tokens of `owner` will not change the auxiliary data.
    /// Auxiliary data can be set for any address, even if it does not have any tokens.
    function _setAux(address owner, uint88 value) internal virtual {
        _getDN404Storage().addressData[owner].aux = value;
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                     SKIP NFT FUNCTIONS                     */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns true if account `a` will skip NFT minting on token mints and transfers.
    /// Returns false if account `a` will mint NFTs on token mints and transfers.
    function getSkipNFT(address a) public view virtual returns (bool) {
        AddressData storage d = _getDN404Storage().addressData[a];
        if (d.flags & _ADDRESS_DATA_INITIALIZED_FLAG == 0) return _hasCode(a);
        return d.flags & _ADDRESS_DATA_SKIP_NFT_FLAG != 0;
    }

    /// @dev Internal function to set account `a` skipNFT flag to `state`
    ///
    /// Initializes account `a` AddressData if it is not currently initialized.
    ///
    /// Emits a {SkipNFTSet} event.
    function _setSkipNFT(address a, bool state) internal virtual {
        AddressData storage d = _addressData(a);
        if ((d.flags & _ADDRESS_DATA_SKIP_NFT_FLAG != 0) != state) {
            d.flags ^= _ADDRESS_DATA_SKIP_NFT_FLAG;
        }
        emit SkipNFTSet(a, state);
    }

    /// @dev Returns a storage data pointer for account `a` AddressData
    ///
    /// Initializes account `a` AddressData if it is not currently initialized.
    function _addressData(address a) internal virtual returns (AddressData storage d) {
        DN404Storage storage $ = _getDN404Storage();
        d = $.addressData[a];

        if (d.flags & _ADDRESS_DATA_INITIALIZED_FLAG == 0) {
            uint8 flags = _ADDRESS_DATA_INITIALIZED_FLAG;
            if (_hasCode(a)) flags |= _ADDRESS_DATA_SKIP_NFT_FLAG;
            d.flags = flags;
        }
    }

    /// @dev Returns the `addressAlias` of account `to`.
    ///
    /// Assigns and registers the next alias if `to` alias was not previously registered.
    function _registerAndResolveAlias(AddressData storage toAddressData, address to)
        internal
        virtual
        returns (uint32 addressAlias)
    {
        DN404Storage storage $ = _getDN404Storage();
        addressAlias = toAddressData.addressAlias;
        if (addressAlias == 0) {
            addressAlias = ++$.numAliases;
            toAddressData.addressAlias = addressAlias;
            $.aliasToAddress[addressAlias] = to;
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                     MIRROR OPERATIONS                      */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the address of the mirror NFT contract.
    function mirrorERC721() public view virtual returns (address) {
        return _getDN404Storage().mirrorERC721;
    }

    /// @dev Returns the total NFT supply.
    function _totalNFTSupply() internal view virtual returns (uint256) {
        return _getDN404Storage().totalNFTSupply;
    }

    /// @dev Returns `owner` NFT balance.
    function _balanceOfNFT(address owner) internal view virtual returns (uint256) {
        return _getDN404Storage().addressData[owner].ownedLength;
    }

    /// @dev Returns the owner of token `id`.
    /// Returns the zero address instead of reverting if the token does not exist.
    function _ownerAt(uint256 id) internal view virtual returns (address) {
        DN404Storage storage $ = _getDN404Storage();
        return $.aliasToAddress[_get($.oo, _ownershipIndex(id))];
    }

    /// @dev Returns the owner of token `id`.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    function _ownerOf(uint256 id) internal view virtual returns (address) {
        if (!_exists(id)) revert TokenDoesNotExist();
        return _ownerAt(id);
    }

    /// @dev Returns if token `id` exists.
    function _exists(uint256 id) internal view virtual returns (bool) {
        return _ownerAt(id) != address(0);
    }

    /// @dev Returns the account approved to manage token `id`.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    function _getApproved(uint256 id) internal view virtual returns (address) {
        if (!_exists(id)) revert TokenDoesNotExist();
        return _getDN404Storage().tokenApprovals[id];
    }

    /// @dev Sets `spender` as the approved account to manage token `id`, using `msgSender`.
    ///
    /// Requirements:
    /// - `msgSender` must be the owner or an approved operator for the token owner.
    function _approveNFT(address spender, uint256 id, address msgSender)
        internal
        virtual
        returns (address)
    {
        DN404Storage storage $ = _getDN404Storage();

        address owner = $.aliasToAddress[_get($.oo, _ownershipIndex(id))];

        if (msgSender != owner) {
            if (!$.operatorApprovals[owner][msgSender]) {
                revert ApprovalCallerNotOwnerNorApproved();
            }
        }

        $.tokenApprovals[id] = spender;

        return owner;
    }

    /// @dev Approve or remove the `operator` as an operator for `msgSender`,
    /// without authorization checks.
    function _setApprovalForAll(address operator, bool approved, address msgSender)
        internal
        virtual
    {
        _getDN404Storage().operatorApprovals[msgSender][operator] = approved;
    }

    /// @dev Calls the mirror contract to link it to this contract.
    ///
    /// Reverts if the call to the mirror contract reverts.
    function _linkMirrorContract(address mirror) internal virtual {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, 0x0f4599e5) // `linkMirrorContract(address)`.
            mstore(0x20, caller())
            if iszero(and(eq(mload(0x00), 1), call(gas(), mirror, 0, 0x1c, 0x24, 0x00, 0x20))) {
                mstore(0x00, 0xd125259c) // `LinkMirrorContractFailed()`.
                revert(0x1c, 0x04)
            }
        }
    }

    /// @dev Fallback modifier to dispatch calls from the mirror NFT contract
    /// to internal functions in this contract.
    modifier dn404Fallback() virtual {
        DN404Storage storage $ = _getDN404Storage();

        uint256 fnSelector = _calldataload(0x00) >> 224;

        // `isApprovedForAll(address,address)`.
        if (fnSelector == 0xe985e9c5) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x44) revert();

            address owner = address(uint160(_calldataload(0x04)));
            address operator = address(uint160(_calldataload(0x24)));

            _return($.operatorApprovals[owner][operator] ? 1 : 0);
        }
        // `ownerOf(uint256)`.
        if (fnSelector == 0x6352211e) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x24) revert();

            uint256 id = _calldataload(0x04);

            _return(uint160(_ownerOf(id)));
        }
        // `transferFromNFT(address,address,uint256,address)`.
        if (fnSelector == 0xe5eb36c8) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x84) revert();

            address from = address(uint160(_calldataload(0x04)));
            address to = address(uint160(_calldataload(0x24)));
            uint256 id = _calldataload(0x44);
            address msgSender = address(uint160(_calldataload(0x64)));

            _transferFromNFT(from, to, id, msgSender);
            _return(1);
        }
        // `setApprovalForAll(address,bool,address)`.
        if (fnSelector == 0x813500fc) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x64) revert();

            address spender = address(uint160(_calldataload(0x04)));
            bool status = _calldataload(0x24) != 0;
            address msgSender = address(uint160(_calldataload(0x44)));

            _setApprovalForAll(spender, status, msgSender);
            _return(1);
        }
        // `approveNFT(address,uint256,address)`.
        if (fnSelector == 0xd10b6e0c) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x64) revert();

            address spender = address(uint160(_calldataload(0x04)));
            uint256 id = _calldataload(0x24);
            address msgSender = address(uint160(_calldataload(0x44)));

            _return(uint160(_approveNFT(spender, id, msgSender)));
        }
        // `getApproved(uint256)`.
        if (fnSelector == 0x081812fc) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x24) revert();

            uint256 id = _calldataload(0x04);

            _return(uint160(_getApproved(id)));
        }
        // `balanceOfNFT(address)`.
        if (fnSelector == 0xf5b100ea) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x24) revert();

            address owner = address(uint160(_calldataload(0x04)));

            _return(_balanceOfNFT(owner));
        }
        // `totalNFTSupply()`.
        if (fnSelector == 0xe2c79281) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x04) revert();

            _return(_totalNFTSupply());
        }
        // `implementsDN404()`.
        if (fnSelector == 0xb7a94eb8) {
            _return(1);
        }
        _;
    }

    /// @dev Fallback function for calls from mirror NFT contract.
    fallback() external payable virtual dn404Fallback {}

    receive() external payable virtual {}

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                      PRIVATE HELPERS                       */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Struct containing packed log data for `Transfer` events to be
    /// emitted by the mirror NFT contract.
    struct _PackedLogs {
        uint256[] logs;
        uint256 offset;
    }

    /// @dev Initiates memory allocation for packed logs with `n` log items.
    function _packedLogsMalloc(uint256 n) private pure returns (_PackedLogs memory p) {
        /// @solidity memory-safe-assembly
        assembly {
            let logs := add(mload(0x40), 0x40) // Offset by 2 words for `_packedLogsSend`.
            mstore(logs, n)
            let offset := add(0x20, logs)
            mstore(0x40, add(offset, shl(5, n)))
            mstore(p, logs)
            mstore(add(0x20, p), offset)
        }
    }

    /// @dev Adds a packed log item to `p` with address `a`, token `id` and burn flag `burnBit`.
    function _packedLogsAppend(_PackedLogs memory p, address a, uint256 id, uint256 burnBit)
        private
        pure
    {
        /// @solidity memory-safe-assembly
        assembly {
            let offset := mload(add(0x20, p))
            mstore(offset, or(or(shl(96, a), shl(8, id)), burnBit))
            mstore(add(0x20, p), add(offset, 0x20))
        }
    }

    /// @dev Calls the `mirror` NFT contract to emit Transfer events for packed logs `p`.
    function _packedLogsSend(_PackedLogs memory p, address mirror) private {
        /// @solidity memory-safe-assembly
        assembly {
            let logs := mload(p)
            let o := sub(logs, 0x40) // Start of calldata to send.
            mstore(o, 0x263c69d6) // `logTransfer(uint256[])`.
            mstore(add(o, 0x20), 0x20) // Offset of `logs` in the calldata to send.
            let n := add(0x44, shl(5, mload(logs))) // Length of calldata to send.
            if iszero(and(eq(mload(o), 1), call(gas(), mirror, 0, add(o, 0x1c), n, o, 0x20))) {
                revert(o, 0x00)
            }
        }
    }

    /// @dev Struct of temporary variables for transfers.
    struct _TransferTemps {
        uint256 nftAmountToBurn;
        uint256 nftAmountToMint;
        uint256 fromBalance;
        uint256 toBalance;
        uint256 fromOwnedLength;
        uint256 toOwnedLength;
    }

    /// @dev Returns if `a` has bytecode of non-zero length.
    function _hasCode(address a) private view returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := extcodesize(a) // Can handle dirty upper bits.
        }
    }

    /// @dev Returns the calldata value at `offset`.
    function _calldataload(uint256 offset) private pure returns (uint256 value) {
        /// @solidity memory-safe-assembly
        assembly {
            value := calldataload(offset)
        }
    }

    /// @dev Executes a return opcode to return `x` and end the current call frame.
    function _return(uint256 x) private pure {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, x)
            return(0x00, 0x20)
        }
    }

    /// @dev Returns `max(0, x - y)`.
    function _zeroFloorSub(uint256 x, uint256 y) private pure returns (uint256 z) {
        /// @solidity memory-safe-assembly
        assembly {
            z := mul(gt(x, y), sub(x, y))
        }
    }

    /// @dev Returns `i << 1`.
    function _ownershipIndex(uint256 i) private pure returns (uint256) {
        return i << 1;
    }

    /// @dev Returns `(i << 1) + 1`.
    function _ownedIndex(uint256 i) private pure returns (uint256) {
        unchecked {
            return (i << 1) + 1;
        }
    }

    /// @dev Returns the uint32 value at `index` in `map`.
    function _get(Uint32Map storage map, uint256 index) private view returns (uint32 result) {
        result = uint32(map.map[index >> 3] >> ((index & 7) << 5));
    }

    /// @dev Updates the uint32 value at `index` in `map`.
    function _set(Uint32Map storage map, uint256 index, uint32 value) private {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, map.slot)
            mstore(0x00, shr(3, index))
            let s := keccak256(0x00, 0x40) // Storage slot.
            let o := shl(5, and(index, 7)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffffffff // Value mask.
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), value)))))
        }
    }

    /// @dev Sets the owner alias and the owned index together.
    function _setOwnerAliasAndOwnedIndex(
        Uint32Map storage map,
        uint256 id,
        uint32 ownership,
        uint32 ownedIndex
    ) private {
        /// @solidity memory-safe-assembly
        assembly {
            let value := or(shl(32, ownedIndex), and(0xffffffff, ownership))
            mstore(0x20, map.slot)
            mstore(0x00, shr(2, id))
            let s := keccak256(0x00, 0x40) // Storage slot.
            let o := shl(6, and(id, 3)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffffffffffffffff // Value mask.
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), value)))))
        }
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

/// @title DN404Mirror
/// @notice DN404Mirror provides an interface for interacting with the
/// NFT tokens in a DN404 implementation.
///
/// @author vectorized.eth (@optimizoor)
/// @author Quit (@0xQuit)
/// @author Michael Amadi (@AmadiMichaels)
/// @author cygaar (@0xCygaar)
/// @author Thomas (@0xjustadev)
/// @author Harrison (@PopPunkOnChain)
///
/// @dev Note:
/// - The ERC721 data is stored in the base DN404 contract.
contract DN404Mirror {
    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                           EVENTS                           */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Emitted when token `id` is transferred from `from` to `to`.
    event Transfer(address indexed from, address indexed to, uint256 indexed id);

    /// @dev Emitted when `owner` enables `account` to manage the `id` token.
    event Approval(address indexed owner, address indexed account, uint256 indexed id);

    /// @dev Emitted when `owner` enables or disables `operator` to manage all of their tokens.
    event ApprovalForAll(address indexed owner, address indexed operator, bool isApproved);

    /// @dev `keccak256(bytes("Transfer(address,address,uint256)"))`.
    uint256 private constant _TRANSFER_EVENT_SIGNATURE =
        0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef;

    /// @dev `keccak256(bytes("Approval(address,address,uint256)"))`.
    uint256 private constant _APPROVAL_EVENT_SIGNATURE =
        0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925;

    /// @dev `keccak256(bytes("ApprovalForAll(address,address,bool)"))`.
    uint256 private constant _APPROVAL_FOR_ALL_EVENT_SIGNATURE =
        0x17307eab39ab6107e8899845ad3d59bd9653f200f220920489ca2b5937696c31;

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                        CUSTOM ERRORS                       */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Thrown when a call for an NFT function did not originate
    /// from the base DN404 contract.
    error SenderNotBase();

    /// @dev Thrown when a call for an NFT function did not originate from the deployer.
    error SenderNotDeployer();

    /// @dev Thrown when transferring an NFT to a contract address that
    /// does not implement ERC721Receiver.
    error TransferToNonERC721ReceiverImplementer();

    /// @dev Thrown when linking to the DN404 base contract and the
    /// DN404 supportsInterface check fails or the call reverts.
    error CannotLink();

    /// @dev Thrown when a linkMirrorContract call is received and the
    /// NFT mirror contract has already been linked to a DN404 base contract.
    error AlreadyLinked();

    /// @dev Thrown when retrieving the base DN404 address when a link has not
    /// been established.
    error NotLinked();

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                          STORAGE                           */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Struct contain the NFT mirror contract storage.
    struct DN404NFTStorage {
        address baseERC20;
        address deployer;
    }

    /// @dev Returns a storage pointer for DN404NFTStorage.
    function _getDN404NFTStorage() internal pure virtual returns (DN404NFTStorage storage $) {
        /// @solidity memory-safe-assembly
        assembly {
            // `uint72(bytes9(keccak256("DN404_MIRROR_STORAGE")))`.
            $.slot := 0x3602298b8c10b01230 // Truncate to 9 bytes to reduce bytecode size.
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                        CONSTRUCTOR                         */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    constructor(address deployer) {
        // For non-proxies, we will store the deployer so that only the deployer can
        // link the base contract.
        _getDN404NFTStorage().deployer = deployer;
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                     ERC721 OPERATIONS                      */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the token collection name from the base DN404 contract.
    function name() public view virtual returns (string memory result) {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(0x40)
            mstore(0x00, 0x06fdde03) // `name()`.
            if iszero(staticcall(gas(), base, 0x1c, 0x04, 0x00, 0x00)) {
                returndatacopy(result, 0x00, returndatasize())
                revert(result, returndatasize())
            }
            returndatacopy(0x00, 0x00, 0x20)
            returndatacopy(result, mload(0x00), 0x20)
            returndatacopy(add(result, 0x20), add(mload(0x00), 0x20), mload(result))
            mstore(0x40, add(add(result, 0x20), mload(result)))
        }
    }

    /// @dev Returns the token collection symbol from the base DN404 contract.
    function symbol() public view virtual returns (string memory result) {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(0x40)
            mstore(0x00, 0x95d89b41) // `symbol()`.
            if iszero(staticcall(gas(), base, 0x1c, 0x04, 0x00, 0x00)) {
                returndatacopy(result, 0x00, returndatasize())
                revert(result, returndatasize())
            }
            returndatacopy(0x00, 0x00, 0x20)
            returndatacopy(result, mload(0x00), 0x20)
            returndatacopy(add(result, 0x20), add(mload(0x00), 0x20), mload(result))
            mstore(0x40, add(add(result, 0x20), mload(result)))
        }
    }

    /// @dev Returns the Uniform Resource Identifier (URI) for token `id` from
    /// the base DN404 contract.
    function tokenURI(uint256 id) public view virtual returns (string memory result) {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(0x40)
            mstore(0x20, id)
            mstore(0x00, 0xc87b56dd) // `tokenURI()`.
            if iszero(staticcall(gas(), base, 0x1c, 0x24, 0x00, 0x00)) {
                returndatacopy(result, 0x00, returndatasize())
                revert(result, returndatasize())
            }
            returndatacopy(0x00, 0x00, 0x20)
            returndatacopy(result, mload(0x00), 0x20)
            returndatacopy(add(result, 0x20), add(mload(0x00), 0x20), mload(result))
            mstore(0x40, add(add(result, 0x20), mload(result)))
        }
    }

    /// @dev Returns the total NFT supply from the base DN404 contract.
    function totalSupply() public view virtual returns (uint256 result) {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, 0xe2c79281) // `totalNFTSupply()`.
            if iszero(
                and(gt(returndatasize(), 0x1f), staticcall(gas(), base, 0x1c, 0x04, 0x00, 0x20))
            ) {
                returndatacopy(mload(0x40), 0x00, returndatasize())
                revert(mload(0x40), returndatasize())
            }
            result := mload(0x00)
        }
    }

    /// @dev Returns the number of NFT tokens owned by `owner` from the base DN404 contract.
    ///
    /// Requirements:
    /// - `owner` must not be the zero address.
    function balanceOf(address owner) public view virtual returns (uint256 result) {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, shr(96, shl(96, owner)))
            mstore(0x00, 0xf5b100ea) // `balanceOfNFT(address)`.
            if iszero(
                and(gt(returndatasize(), 0x1f), staticcall(gas(), base, 0x1c, 0x24, 0x00, 0x20))
            ) {
                returndatacopy(mload(0x40), 0x00, returndatasize())
                revert(mload(0x40), returndatasize())
            }
            result := mload(0x00)
        }
    }

    /// @dev Returns the owner of token `id` from the base DN404 contract.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    function ownerOf(uint256 id) public view virtual returns (address result) {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, 0x6352211e) // `ownerOf(uint256)`.
            mstore(0x20, id)
            if iszero(
                and(gt(returndatasize(), 0x1f), staticcall(gas(), base, 0x1c, 0x24, 0x00, 0x20))
            ) {
                returndatacopy(mload(0x40), 0x00, returndatasize())
                revert(mload(0x40), returndatasize())
            }
            result := shr(96, mload(0x0c))
        }
    }

    /// @dev Sets `spender` as the approved account to manage token `id` in
    /// the base DN404 contract.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    /// - The caller must be the owner of the token,
    ///   or an approved operator for the token owner.
    ///
    /// Emits an {Approval} event.
    function approve(address spender, uint256 id) public virtual {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            spender := shr(96, shl(96, spender))
            let m := mload(0x40)
            mstore(0x00, 0xd10b6e0c) // `approveNFT(address,uint256,address)`.
            mstore(0x20, spender)
            mstore(0x40, id)
            mstore(0x60, caller())
            if iszero(
                and(
                    gt(returndatasize(), 0x1f),
                    call(gas(), base, callvalue(), 0x1c, 0x64, 0x00, 0x20)
                )
            ) {
                returndatacopy(m, 0x00, returndatasize())
                revert(m, returndatasize())
            }
            mstore(0x40, m) // Restore the free memory pointer.
            mstore(0x60, 0) // Restore the zero pointer.
            // Emit the {Approval} event.
            log4(codesize(), 0x00, _APPROVAL_EVENT_SIGNATURE, shr(96, mload(0x0c)), spender, id)
        }
    }

    /// @dev Returns the account approved to manage token `id` from
    /// the base DN404 contract.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    function getApproved(uint256 id) public view virtual returns (address result) {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, 0x081812fc) // `getApproved(uint256)`.
            mstore(0x20, id)
            if iszero(
                and(gt(returndatasize(), 0x1f), staticcall(gas(), base, 0x1c, 0x24, 0x00, 0x20))
            ) {
                returndatacopy(mload(0x40), 0x00, returndatasize())
                revert(mload(0x40), returndatasize())
            }
            result := shr(96, mload(0x0c))
        }
    }

    /// @dev Sets whether `operator` is approved to manage the tokens of the caller in
    /// the base DN404 contract.
    ///
    /// Emits an {ApprovalForAll} event.
    function setApprovalForAll(address operator, bool approved) public virtual {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            operator := shr(96, shl(96, operator))
            let m := mload(0x40)
            mstore(0x00, 0x813500fc) // `setApprovalForAll(address,bool,address)`.
            mstore(0x20, operator)
            mstore(0x40, iszero(iszero(approved)))
            mstore(0x60, caller())
            if iszero(
                and(eq(mload(0x00), 1), call(gas(), base, callvalue(), 0x1c, 0x64, 0x00, 0x20))
            ) {
                returndatacopy(m, 0x00, returndatasize())
                revert(m, returndatasize())
            }
            // Emit the {ApprovalForAll} event.
            log3(0x40, 0x20, _APPROVAL_FOR_ALL_EVENT_SIGNATURE, caller(), operator)
            mstore(0x40, m) // Restore the free memory pointer.
            mstore(0x60, 0) // Restore the zero pointer.
        }
    }

    /// @dev Returns whether `operator` is approved to manage the tokens of `owner` from
    /// the base DN404 contract.
    function isApprovedForAll(address owner, address operator)
        public
        view
        virtual
        returns (bool result)
    {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            let m := mload(0x40)
            mstore(0x40, operator)
            mstore(0x2c, shl(96, owner))
            mstore(0x0c, 0xe985e9c5000000000000000000000000) // `isApprovedForAll(address,address)`.
            if iszero(
                and(gt(returndatasize(), 0x1f), staticcall(gas(), base, 0x1c, 0x44, 0x00, 0x20))
            ) {
                returndatacopy(m, 0x00, returndatasize())
                revert(m, returndatasize())
            }
            mstore(0x40, m) // Restore the free memory pointer.
            result := iszero(iszero(mload(0x00)))
        }
    }

    /// @dev Transfers token `id` from `from` to `to`.
    ///
    /// Requirements:
    ///
    /// - Token `id` must exist.
    /// - `from` must be the owner of the token.
    /// - `to` cannot be the zero address.
    /// - The caller must be the owner of the token, or be approved to manage the token.
    ///
    /// Emits a {Transfer} event.
    function transferFrom(address from, address to, uint256 id) public virtual {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            from := shr(96, shl(96, from))
            to := shr(96, shl(96, to))
            let m := mload(0x40)
            mstore(m, 0xe5eb36c8) // `transferFromNFT(address,address,uint256,address)`.
            mstore(add(m, 0x20), from)
            mstore(add(m, 0x40), to)
            mstore(add(m, 0x60), id)
            mstore(add(m, 0x80), caller())
            if iszero(
                and(eq(mload(m), 1), call(gas(), base, callvalue(), add(m, 0x1c), 0x84, m, 0x20))
            ) {
                returndatacopy(m, 0x00, returndatasize())
                revert(m, returndatasize())
            }
            // Emit the {Transfer} event.
            log4(codesize(), 0x00, _TRANSFER_EVENT_SIGNATURE, from, to, id)
        }
    }

    /// @dev Equivalent to `safeTransferFrom(from, to, id, "")`.
    function safeTransferFrom(address from, address to, uint256 id) public payable virtual {
        transferFrom(from, to, id);

        if (_hasCode(to)) _checkOnERC721Received(from, to, id, "");
    }

    /// @dev Transfers token `id` from `from` to `to`.
    ///
    /// Requirements:
    ///
    /// - Token `id` must exist.
    /// - `from` must be the owner of the token.
    /// - `to` cannot be the zero address.
    /// - The caller must be the owner of the token, or be approved to manage the token.
    /// - 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 id, bytes calldata data)
        public
        virtual
    {
        transferFrom(from, to, id);

        if (_hasCode(to)) _checkOnERC721Received(from, to, id, data);
    }

    /// @dev Returns true if this contract implements the interface defined by `interfaceId`.
    /// See: https://eips.ethereum.org/EIPS/eip-165
    /// This function call must use less than 30000 gas.
    function supportsInterface(bytes4 interfaceId) public view virtual returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            let s := shr(224, interfaceId)
            // ERC165: 0x01ffc9a7, ERC721: 0x80ac58cd, ERC721Metadata: 0x5b5e139f.
            result := or(or(eq(s, 0x01ffc9a7), eq(s, 0x80ac58cd)), eq(s, 0x5b5e139f))
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                     MIRROR OPERATIONS                      */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the address of the base DN404 contract.
    function baseERC20() public view virtual returns (address base) {
        base = _getDN404NFTStorage().baseERC20;
        if (base == address(0)) revert NotLinked();
    }

    /// @dev Fallback modifier to execute calls from the base DN404 contract.
    modifier dn404NFTFallback() virtual {
        DN404NFTStorage storage $ = _getDN404NFTStorage();

        uint256 fnSelector = _calldataload(0x00) >> 224;

        // `logTransfer(uint256[])`.
        if (fnSelector == 0x263c69d6) {
            if (msg.sender != $.baseERC20) revert SenderNotBase();
            /// @solidity memory-safe-assembly
            assembly {
                // When returndatacopy copies 1 or more out-of-bounds bytes, it reverts.
                returndatacopy(0x00, returndatasize(), lt(calldatasize(), 0x20))
                let o := add(0x24, calldataload(0x04)) // Packed logs offset.
                returndatacopy(0x00, returndatasize(), lt(calldatasize(), o))
                let end := add(o, shl(5, calldataload(sub(o, 0x20))))
                returndatacopy(0x00, returndatasize(), lt(calldatasize(), end))

                for {} iszero(eq(o, end)) { o := add(0x20, o) } {
                    let d := calldataload(o) // Entry in the packed logs.
                    let a := shr(96, d) // The address.
                    let b := and(1, d) // Whether it is a burn.
                    log4(
                        codesize(),
                        0x00,
                        _TRANSFER_EVENT_SIGNATURE,
                        mul(a, b),
                        mul(a, iszero(b)),
                        shr(168, shl(160, d))
                    )
                }
                mstore(0x00, 0x01)
                return(0x00, 0x20)
            }
        }
        // `linkMirrorContract(address)`.
        if (fnSelector == 0x0f4599e5) {
            if ($.deployer != address(0)) {
                if (address(uint160(_calldataload(0x04))) != $.deployer) {
                    revert SenderNotDeployer();
                }
            }
            if ($.baseERC20 != address(0)) revert AlreadyLinked();
            $.baseERC20 = msg.sender;
            /// @solidity memory-safe-assembly
            assembly {
                mstore(0x00, 0x01)
                return(0x00, 0x20)
            }
        }
        _;
    }

    /// @dev Fallback function for calls from base DN404 contract.
    fallback() external payable virtual dn404NFTFallback {}

    receive() external payable virtual {}

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                      PRIVATE HELPERS                       */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the calldata value at `offset`.
    function _calldataload(uint256 offset) private pure returns (uint256 value) {
        /// @solidity memory-safe-assembly
        assembly {
            value := calldataload(offset)
        }
    }

    /// @dev Returns if `a` has bytecode of non-zero length.
    function _hasCode(address a) private view returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := extcodesize(a) // Can handle dirty upper bits.
        }
    }

    /// @dev Perform a call to invoke {IERC721Receiver-onERC721Received} on `to`.
    /// Reverts if the target does not support the function correctly.
    function _checkOnERC721Received(address from, address to, uint256 id, bytes memory data)
        private
    {
        /// @solidity memory-safe-assembly
        assembly {
            // Prepare the calldata.
            let m := mload(0x40)
            let onERC721ReceivedSelector := 0x150b7a02
            mstore(m, onERC721ReceivedSelector)
            mstore(add(m, 0x20), caller()) // The `operator`, which is always `msg.sender`.
            mstore(add(m, 0x40), shr(96, shl(96, from)))
            mstore(add(m, 0x60), id)
            mstore(add(m, 0x80), 0x80)
            let n := mload(data)
            mstore(add(m, 0xa0), n)
            if n { pop(staticcall(gas(), 4, add(data, 0x20), n, add(m, 0xc0), n)) }
            // Revert if the call reverts.
            if iszero(call(gas(), to, 0, add(m, 0x1c), add(n, 0xa4), m, 0x20)) {
                if returndatasize() {
                    // Bubble up the revert if the call reverts.
                    returndatacopy(m, 0x00, returndatasize())
                    revert(m, returndatasize())
                }
            }
            // Load the returndata and compare it.
            if iszero(eq(mload(m), shl(224, onERC721ReceivedSelector))) {
                mstore(0x00, 0xd1a57ed6) // `TransferToNonERC721ReceiverImplementer()`.
                revert(0x1c, 0x04)
            }
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.4;

import "./DN404/DN404.sol";
import "./DN404/DN404Mirror.sol";
import {Ownable} from "https://github.com/Vectorized/solady/blob/main/src/auth/Ownable.sol";
import {LibString} from "https://github.com/Vectorized/solady/blob/main/src/utils/LibString.sol";
import {SafeTransferLib} from "https://github.com/Vectorized/solady/blob/main/src/utils/SafeTransferLib.sol";

contract DeezNutsToken is DN404, Ownable {
    string private _name;
    string private _symbol;
    string private _baseURI;

    constructor(
        string memory name_,
        string memory symbol_,
        uint96 initialTokenSupply,
        address initialSupplyOwner
    ) {
        _initializeOwner(msg.sender);

        _name = name_;
        _symbol = symbol_;

        address mirror = address(new DN404Mirror(msg.sender));
        _initializeDN404(initialTokenSupply, initialSupplyOwner, mirror);
    }

    function name() public view override returns (string memory) {
        return _name;
    }

    function symbol() public view override returns (string memory) {
        return _symbol;
    }

    function tokenURI(uint256 tokenId) public view override returns (string memory result) {
        if (bytes(_baseURI).length != 0) {
            result = string(abi.encodePacked(_baseURI, LibString.toString(tokenId)));
        }
    }

    // This allows the owner of the contract to mint more tokens.
    function mint(address to, uint256 amount) public onlyOwner {
        _mint(to, amount);
    }

    function setBaseURI(string calldata baseURI_) public onlyOwner {
        _baseURI = baseURI_;
    }

    /// @dev Sets the caller's skipNFT flag to `skipNFT`
    ///
    /// Emits a {SkipNFTSet} event.
    function setSkipNFT(address account, bool skipNFT) public onlyOwner {
        _setSkipNFT(account, skipNFT);
    }

    function withdraw() public onlyOwner {
        SafeTransferLib.safeTransferAllETH(msg.sender);
    }
}

{
  "compilationTarget": {
    "contracts/DN/DeezNutsToken.sol": "DeezNutsToken"
  },
  "evmVersion": "shanghai",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}