// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.1) (utils/Context.sol)

pragma solidity ^0.8.20;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }

    function _contextSuffixLength() internal view virtual returns (uint256) {
        return 0;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/structs/DoubleEndedQueue.sol)
// Modified by Pandora Labs to support native uint256 operations
pragma solidity ^0.8.20;

/**
 * @dev A sequence of items with the ability to efficiently push and pop items (i.e. insert and remove) on both ends of
 * the sequence (called front and back). Among other access patterns, it can be used to implement efficient LIFO and
 * FIFO queues. Storage use is optimized, and all operations are O(1) constant time. This includes {clear}, given that
 * the existing queue contents are left in storage.
 *
 * The struct is called `Uint256Deque`. This data structure can only be used in storage, and not in memory.
 *
 * ```solidity
 * DoubleEndedQueue.Uint256Deque queue;
 * ```
 */
library DoubleEndedQueue {
  /**
   * @dev An operation (e.g. {front}) couldn't be completed due to the queue being empty.
   */
  error QueueEmpty();

  /**
   * @dev A push operation couldn't be completed due to the queue being full.
   */
  error QueueFull();

  /**
   * @dev An operation (e.g. {at}) couldn't be completed due to an index being out of bounds.
   */
  error QueueOutOfBounds();

  /**
   * @dev Indices are 128 bits so begin and end are packed in a single storage slot for efficient access.
   *
   * Struct members have an underscore prefix indicating that they are "private" and should not be read or written to
   * directly. Use the functions provided below instead. Modifying the struct manually may violate assumptions and
   * lead to unexpected behavior.
   *
   * The first item is at data[begin] and the last item is at data[end - 1]. This range can wrap around.
   */
  struct Uint256Deque {
    uint128 _begin;
    uint128 _end;
    mapping(uint128 index => uint256) _data;
  }

  /**
   * @dev Inserts an item at the end of the queue.
   *
   * Reverts with {QueueFull} if the queue is full.
   */
  function pushBack(Uint256Deque storage deque, uint256 value) internal {
    unchecked {
      uint128 backIndex = deque._end;
      if (backIndex + 1 == deque._begin) revert QueueFull();
      deque._data[backIndex] = value;
      deque._end = backIndex + 1;
    }
  }

  /**
   * @dev Removes the item at the end of the queue and returns it.
   *
   * Reverts with {QueueEmpty} if the queue is empty.
   */
  function popBack(
    Uint256Deque storage deque
  ) internal returns (uint256 value) {
    unchecked {
      uint128 backIndex = deque._end;
      if (backIndex == deque._begin) revert QueueEmpty();
      --backIndex;
      value = deque._data[backIndex];
      delete deque._data[backIndex];
      deque._end = backIndex;
    }
  }

  /**
   * @dev Inserts an item at the beginning of the queue.
   *
   * Reverts with {QueueFull} if the queue is full.
   */
  function pushFront(Uint256Deque storage deque, uint256 value) internal {
    unchecked {
      uint128 frontIndex = deque._begin - 1;
      if (frontIndex == deque._end) revert QueueFull();
      deque._data[frontIndex] = value;
      deque._begin = frontIndex;
    }
  }

  /**
   * @dev Removes the item at the beginning of the queue and returns it.
   *
   * Reverts with `QueueEmpty` if the queue is empty.
   */
  function popFront(
    Uint256Deque storage deque
  ) internal returns (uint256 value) {
    unchecked {
      uint128 frontIndex = deque._begin;
      if (frontIndex == deque._end) revert QueueEmpty();
      value = deque._data[frontIndex];
      delete deque._data[frontIndex];
      deque._begin = frontIndex + 1;
    }
  }

  /**
   * @dev Returns the item at the beginning of the queue.
   *
   * Reverts with `QueueEmpty` if the queue is empty.
   */
  function front(
    Uint256Deque storage deque
  ) internal view returns (uint256 value) {
    if (empty(deque)) revert QueueEmpty();
    return deque._data[deque._begin];
  }

  /**
   * @dev Returns the item at the end of the queue.
   *
   * Reverts with `QueueEmpty` if the queue is empty.
   */
  function back(
    Uint256Deque storage deque
  ) internal view returns (uint256 value) {
    if (empty(deque)) revert QueueEmpty();
    unchecked {
      return deque._data[deque._end - 1];
    }
  }

  /**
   * @dev Return the item at a position in the queue given by `index`, with the first item at 0 and last item at
   * `length(deque) - 1`.
   *
   * Reverts with `QueueOutOfBounds` if the index is out of bounds.
   */
  function at(
    Uint256Deque storage deque,
    uint256 index
  ) internal view returns (uint256 value) {
    if (index >= length(deque)) revert QueueOutOfBounds();
    // By construction, length is a uint128, so the check above ensures that index can be safely downcast to uint128
    unchecked {
      return deque._data[deque._begin + uint128(index)];
    }
  }

  /**
   * @dev Resets the queue back to being empty.
   *
   * NOTE: The current items are left behind in storage. This does not affect the functioning of the queue, but misses
   * out on potential gas refunds.
   */
  function clear(Uint256Deque storage deque) internal {
    deque._begin = 0;
    deque._end = 0;
  }

  /**
   * @dev Returns the number of items in the queue.
   */
  function length(Uint256Deque storage deque) internal view returns (uint256) {
    unchecked {
      return uint256(deque._end - deque._begin);
    }
  }

  /**
   * @dev Returns true if the queue is empty.
   */
  function empty(Uint256Deque storage deque) internal view returns (bool) {
    return deque._end == deque._begin;
  }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

library ERC20Events {
  event Approval(address indexed owner, address indexed spender, uint256 value);
  event Transfer(address indexed from, address indexed to, uint256 amount);
}

//SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import {IERC721Receiver} from "@openzeppelin/contracts/interfaces/IERC721Receiver.sol";
import {IERC165} from "@openzeppelin/contracts/interfaces/IERC165.sol";
import {IERC404} from "./interfaces/IERC404.sol";
import {DoubleEndedQueue} from "./lib/DoubleEndedQueue.sol";
import {ERC721Events} from "./lib/ERC721Events.sol";
import {ERC20Events} from "./lib/ERC20Events.sol";

abstract contract ERC404 is IERC404 {
    using DoubleEndedQueue for DoubleEndedQueue.Uint256Deque;

    /// @dev The queue of ERC-721 tokens stored in the contract.
    DoubleEndedQueue.Uint256Deque private _storedERC721Ids;

    /// @dev Token name
    string public name;

    /// @dev Token symbol
    string public symbol;

    /// @dev Decimals for ERC-20 representation
    uint8 public immutable decimals;

    /// @dev Units for ERC-20 representation
    uint256 public immutable units;

    /// @dev Total supply in ERC-20 representation
    uint256 public totalSupply;

    /// @dev Current mint counter which also represents the highest
    ///      minted id, monotonically increasing to ensure accurate ownership
    uint256 public minted;

    /// @dev Initial chain id for EIP-2612 support
    uint256 internal immutable _INITIAL_CHAIN_ID;

    /// @dev Initial domain separator for EIP-2612 support
    bytes32 internal immutable _INITIAL_DOMAIN_SEPARATOR;

    /// @dev Balance of user in ERC-20 representation
    mapping(address => uint256) public balanceOf;

    /// @dev Allowance of user in ERC-20 representation
    mapping(address => mapping(address => uint256)) public allowance;

    /// @dev Approval in ERC-721 representaion
    mapping(uint256 => address) public getApproved;

    /// @dev Approval for all in ERC-721 representation
    mapping(address => mapping(address => bool)) public isApprovedForAll;

    /// @dev Packed representation of ownerOf and owned indices
    mapping(uint256 => uint256) internal _ownedData;

    /// @dev Array of owned ids in ERC-721 representation
    mapping(address => uint256[]) internal _owned;

    /// @dev Addresses that are exempt from ERC-721 transfer, typically for gas savings (pairs, routers, etc)
    mapping(address => bool) internal _erc721TransferExempt;

    /// @dev EIP-2612 nonces
    mapping(address => uint256) public nonces;

    /// @dev Address bitmask for packed ownership data
    uint256 private constant _BITMASK_ADDRESS = (1 << 160) - 1;

    /// @dev Owned index bitmask for packed ownership data
    uint256 private constant _BITMASK_OWNED_INDEX = ((1 << 96) - 1) << 160;

    /// @dev Constant for token id encoding
    uint256 public constant ID_ENCODING_PREFIX = 1 << 255;

    constructor(string memory name_, string memory symbol_, uint8 decimals_) {
        name = name_;
        symbol = symbol_;

        if (decimals_ < 18) {
            revert DecimalsTooLow();
        }

        decimals = decimals_;
        units = 10 ** decimals;

        // EIP-2612 initialization
        _INITIAL_CHAIN_ID = block.chainid;
        _INITIAL_DOMAIN_SEPARATOR = _computeDomainSeparator();
    }

    /// @notice Function to find owner of a given ERC-721 token
    function ownerOf(
        uint256 id_
    ) public view virtual returns (address erc721Owner) {
        erc721Owner = _getOwnerOf(id_);

        if (!_isValidTokenId(id_)) {
            revert InvalidTokenId();
        }

        if (erc721Owner == address(0)) {
            revert NotFound();
        }
    }

    function owned(
        address owner_
    ) public view virtual returns (uint256[] memory) {
        return _owned[owner_];
    }

    function erc721BalanceOf(
        address owner_
    ) public view virtual returns (uint256) {
        return _owned[owner_].length;
    }

    function erc20BalanceOf(
        address owner_
    ) public view virtual returns (uint256) {
        return balanceOf[owner_];
    }

    function erc20TotalSupply() public view virtual returns (uint256) {
        return totalSupply;
    }

    function erc721TotalSupply() public view virtual returns (uint256) {
        return minted;
    }

    function getERC721QueueLength() public view virtual returns (uint256) {
        return _storedERC721Ids.length();
    }

    function getERC721TokensInQueue(
        uint256 start_,
        uint256 count_
    ) public view virtual returns (uint256[] memory) {
        uint256[] memory tokensInQueue = new uint256[](count_);

        for (uint256 i = start_; i < start_ + count_; ) {
            tokensInQueue[i - start_] = _storedERC721Ids.at(i);

            unchecked {
                ++i;
            }
        }

        return tokensInQueue;
    }

    /// @notice tokenURI must be implemented by child contract
    function tokenURI(uint256 id_) public view virtual returns (string memory);

    /// @notice Function for token approvals
    /// @dev This function assumes the operator is attempting to approve
    ///      an ERC-721 if valueOrId_ is a possibly valid ERC-721 token id.
    ///      Unlike setApprovalForAll, spender_ must be allowed to be 0x0 so
    ///      that approval can be revoked.
    function approve(
        address spender_,
        uint256 valueOrId_
    ) public virtual returns (bool) {
        if (_isValidTokenId(valueOrId_)) {
            erc721Approve(spender_, valueOrId_);
        } else {
            return erc20Approve(spender_, valueOrId_);
        }

        return true;
    }

    function erc721Approve(address spender_, uint256 id_) public virtual {
        // Intention is to approve as ERC-721 token (id).
        address erc721Owner = _getOwnerOf(id_);

        if (
            msg.sender != erc721Owner &&
            !isApprovedForAll[erc721Owner][msg.sender]
        ) {
            revert Unauthorized();
        }

        getApproved[id_] = spender_;

        emit ERC721Events.Approval(erc721Owner, spender_, id_);
    }

    /// @dev Providing type(uint256).max for approval value results in an
    ///      unlimited approval that is not deducted from on transfers.
    function erc20Approve(
        address spender_,
        uint256 value_
    ) public virtual returns (bool) {
        // Prevent granting 0x0 an ERC-20 allowance.
        if (spender_ == address(0)) {
            revert InvalidSpender();
        }

        allowance[msg.sender][spender_] = value_;

        emit ERC20Events.Approval(msg.sender, spender_, value_);

        return true;
    }

    /// @notice Function for ERC-721 approvals
    function setApprovalForAll(
        address operator_,
        bool approved_
    ) public virtual {
        // Prevent approvals to 0x0.
        if (operator_ == address(0)) {
            revert InvalidOperator();
        }
        isApprovedForAll[msg.sender][operator_] = approved_;
        emit ERC721Events.ApprovalForAll(msg.sender, operator_, approved_);
    }

    /// @notice Function for mixed transfers from an operator that may be different than 'from'.
    /// @dev This function assumes the operator is attempting to transfer an ERC-721
    ///      if valueOrId is a possible valid token id.
    function transferFrom(
        address from_,
        address to_,
        uint256 valueOrId_
    ) public virtual returns (bool) {
        if (_isValidTokenId(valueOrId_)) {
            erc721TransferFrom(from_, to_, valueOrId_);
        } else {
            // Intention is to transfer as ERC-20 token (value).
            return erc20TransferFrom(from_, to_, valueOrId_);
        }

        return true;
    }

    /// @notice Function for ERC-721 transfers from.
    /// @dev This function is recommended for ERC721 transfers.
    function erc721TransferFrom(
        address from_,
        address to_,
        uint256 id_
    ) public virtual {
        // Prevent minting tokens from 0x0.
        if (from_ == address(0)) {
            revert InvalidSender();
        }

        // Prevent burning tokens to 0x0.
        if (to_ == address(0)) {
            revert InvalidRecipient();
        }

        if (from_ != _getOwnerOf(id_)) {
            revert Unauthorized();
        }

        // Check that the operator is either the sender or approved for the transfer.
        if (
            msg.sender != from_ &&
            !isApprovedForAll[from_][msg.sender] &&
            msg.sender != getApproved[id_]
        ) {
            revert Unauthorized();
        }

        // We only need to check ERC-721 transfer exempt status for the recipient
        // since the sender being ERC-721 transfer exempt means they have already
        // had their ERC-721s stripped away during the rebalancing process.
        if (erc721TransferExempt(to_)) {
            revert RecipientIsERC721TransferExempt();
        }

        // Transfer 1 * units ERC-20 and 1 ERC-721 token.
        // ERC-721 transfer exemptions handled above. Can't make it to this point if either is transfer exempt.
        _transferERC20(from_, to_, units);
        _transferERC721(from_, to_, id_);
    }

    /// @notice Function for ERC-20 transfers from.
    /// @dev This function is recommended for ERC20 transfers
    function erc20TransferFrom(
        address from_,
        address to_,
        uint256 value_
    ) public virtual returns (bool) {
        // Prevent minting tokens from 0x0.
        if (from_ == address(0)) {
            revert InvalidSender();
        }

        // Prevent burning tokens to 0x0.
        if (to_ == address(0)) {
            revert InvalidRecipient();
        }

        uint256 allowed = allowance[from_][msg.sender];

        // Check that the operator has sufficient allowance.
        if (allowed != type(uint256).max) {
            allowance[from_][msg.sender] = allowed - value_;
        }

        // Transferring ERC-20s directly requires the _transferERC20WithERC721 function.
        // Handles ERC-721 exemptions internally.
        return _transferERC20WithERC721(from_, to_, value_);
    }

    /// @notice Function for ERC-20 transfers.
    /// @dev This function assumes the operator is attempting to transfer as ERC-20
    ///      given this function is only supported on the ERC-20 interface.
    ///      Treats even large amounts that are valid ERC-721 ids as ERC-20s.
    function transfer(
        address to_,
        uint256 value_
    ) public virtual returns (bool) {
        // Prevent burning tokens to 0x0.
        if (to_ == address(0)) {
            revert InvalidRecipient();
        }

        // Transferring ERC-20s directly requires the _transferERC20WithERC721 function.
        // Handles ERC-721 exemptions internally.
        return _transferERC20WithERC721(msg.sender, to_, value_);
    }

    /// @notice Function for ERC-721 transfers with contract support.
    /// This function only supports moving valid ERC-721 ids, as it does not exist on the ERC-20
    /// spec and will revert otherwise.
    function safeTransferFrom(
        address from_,
        address to_,
        uint256 id_
    ) public virtual {
        safeTransferFrom(from_, to_, id_, "");
    }

    /// @notice Function for ERC-721 transfers with contract support and callback data.
    /// This function only supports moving valid ERC-721 ids, as it does not exist on the
    /// ERC-20 spec and will revert otherwise.
    function safeTransferFrom(
        address from_,
        address to_,
        uint256 id_,
        bytes memory data_
    ) public virtual {
        if (!_isValidTokenId(id_)) {
            revert InvalidTokenId();
        }

        transferFrom(from_, to_, id_);

        if (
            to_.code.length != 0 &&
            IERC721Receiver(to_).onERC721Received(
                msg.sender,
                from_,
                id_,
                data_
            ) !=
            IERC721Receiver.onERC721Received.selector
        ) {
            revert UnsafeRecipient();
        }
    }

    /// @notice Function for EIP-2612 permits (ERC-20 only).
    /// @dev Providing type(uint256).max for permit value results in an
    ///      unlimited approval that is not deducted from on transfers.
    function permit(
        address owner_,
        address spender_,
        uint256 value_,
        uint256 deadline_,
        uint8 v_,
        bytes32 r_,
        bytes32 s_
    ) public virtual {
        if (deadline_ < block.timestamp) {
            revert PermitDeadlineExpired();
        }

        // permit cannot be used for ERC-721 token approvals, so ensure
        // the value does not fall within the valid range of ERC-721 token ids.
        if (_isValidTokenId(value_)) {
            revert InvalidApproval();
        }

        if (spender_ == address(0)) {
            revert InvalidSpender();
        }

        unchecked {
            address recoveredAddress = ecrecover(
                keccak256(
                    abi.encodePacked(
                        "\x19\x01",
                        DOMAIN_SEPARATOR(),
                        keccak256(
                            abi.encode(
                                keccak256(
                                    "Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"
                                ),
                                owner_,
                                spender_,
                                value_,
                                nonces[owner_]++,
                                deadline_
                            )
                        )
                    )
                ),
                v_,
                r_,
                s_
            );

            if (recoveredAddress == address(0) || recoveredAddress != owner_) {
                revert InvalidSigner();
            }

            allowance[recoveredAddress][spender_] = value_;
        }

        emit ERC20Events.Approval(owner_, spender_, value_);
    }

    /// @notice Returns domain initial domain separator, or recomputes if chain id is not equal to initial chain id
    function DOMAIN_SEPARATOR() public view virtual returns (bytes32) {
        return
            block.chainid == _INITIAL_CHAIN_ID
                ? _INITIAL_DOMAIN_SEPARATOR
                : _computeDomainSeparator();
    }

    function supportsInterface(
        bytes4 interfaceId
    ) public view virtual returns (bool) {
        return
            interfaceId == type(IERC404).interfaceId ||
            interfaceId == type(IERC165).interfaceId;
    }

    /// @notice Function for self-exemption
    function setSelfERC721TransferExempt(bool state_) public virtual {
        _setERC721TransferExempt(msg.sender, state_);
    }

    /// @notice Function to check if address is transfer exempt
    function erc721TransferExempt(
        address target_
    ) public view virtual returns (bool) {
        return target_ == address(0) || _erc721TransferExempt[target_];
    }

    /// @notice For a token token id to be considered valid, it just needs
    ///         to fall within the range of possible token ids, it does not
    ///         necessarily have to be minted yet.
    function _isValidTokenId(uint256 id_) internal pure returns (bool) {
        return id_ > ID_ENCODING_PREFIX && id_ != type(uint256).max;
    }

    /// @notice Internal function to compute domain separator for EIP-2612 permits
    function _computeDomainSeparator() internal view virtual returns (bytes32) {
        return
            keccak256(
                abi.encode(
                    keccak256(
                        "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
                    ),
                    keccak256(bytes(name)),
                    keccak256("1"),
                    block.chainid,
                    address(this)
                )
            );
    }

    /// @notice This is the lowest level ERC-20 transfer function, which
    ///         should be used for both normal ERC-20 transfers as well as minting.
    /// Note that this function allows transfers to and from 0x0.
    function _transferERC20(
        address from_,
        address to_,
        uint256 value_
    ) internal virtual {
        // Minting is a special case for which we should not check the balance of
        // the sender, and we should increase the total supply.
        if (from_ == address(0)) {
            totalSupply += value_;
        } else {
            // Deduct value from sender's balance.
            balanceOf[from_] -= value_;
        }

        // Update the recipient's balance.
        // Can be unchecked because on mint, adding to totalSupply is checked, and on transfer balance deduction is checked.
        unchecked {
            balanceOf[to_] += value_;
        }

        emit ERC20Events.Transfer(from_, to_, value_);
    }

    /// @notice Consolidated record keeping function for transferring ERC-721s.
    /// @dev Assign the token to the new owner, and remove from the old owner.
    /// Note that this function allows transfers to and from 0x0.
    /// Does not handle ERC-721 exemptions.
    function _transferERC721(
        address from_,
        address to_,
        uint256 id_
    ) internal virtual {
        // If this is not a mint, handle record keeping for transfer from previous owner.
        if (from_ != address(0)) {
            // On transfer of an NFT, any previous approval is reset.
            delete getApproved[id_];

            uint256 updatedId = _owned[from_][_owned[from_].length - 1];
            if (updatedId != id_) {
                uint256 updatedIndex = _getOwnedIndex(id_);
                // update _owned for sender
                _owned[from_][updatedIndex] = updatedId;
                // update index for the moved id
                _setOwnedIndex(updatedId, updatedIndex);
            }

            // pop
            _owned[from_].pop();
        }

        // Check if this is a burn.
        if (to_ != address(0)) {
            // If not a burn, update the owner of the token to the new owner.
            // Update owner of the token to the new owner.
            _setOwnerOf(id_, to_);
            // Push token onto the new owner's stack.
            _owned[to_].push(id_);
            // Update index for new owner's stack.
            _setOwnedIndex(id_, _owned[to_].length - 1);
        } else {
            // If this is a burn, reset the owner of the token to 0x0 by deleting the token from _ownedData.
            delete _ownedData[id_];
        }

        emit ERC721Events.Transfer(from_, to_, id_);
    }

    /// @notice Internal function for ERC-20 transfers. Also handles any ERC-721 transfers that may be required.
    // Handles ERC-721 exemptions.
    function _transferERC20WithERC721(
        address from_,
        address to_,
        uint256 value_
    ) internal virtual returns (bool) {
        uint256 erc20BalanceOfSenderBefore = erc20BalanceOf(from_);
        uint256 erc20BalanceOfReceiverBefore = erc20BalanceOf(to_);

        _transferERC20(from_, to_, value_);

        // Preload for gas savings on branches
        bool isFromERC721TransferExempt = erc721TransferExempt(from_);
        bool isToERC721TransferExempt = erc721TransferExempt(to_);

        // Skip _withdrawAndStoreERC721 and/or _retrieveOrMintERC721 for ERC-721 transfer exempt addresses
        // 1) to save gas
        // 2) because ERC-721 transfer exempt addresses won't always have/need ERC-721s corresponding to their ERC20s.
        if (isFromERC721TransferExempt && isToERC721TransferExempt) {
            // Case 1) Both sender and recipient are ERC-721 transfer exempt. No ERC-721s need to be transferred.
            // NOOP.
        } else if (isFromERC721TransferExempt) {
            // Case 2) The sender is ERC-721 transfer exempt, but the recipient is not. Contract should not attempt
            //         to transfer ERC-721s from the sender, but the recipient should receive ERC-721s
            //         from the bank/minted for any whole number increase in their balance.
            // Only cares about whole number increments.
            uint256 tokensToRetrieveOrMint = (balanceOf[to_] / units) -
                (erc20BalanceOfReceiverBefore / units);
            for (uint256 i = 0; i < tokensToRetrieveOrMint; ) {
                _retrieveOrMintERC721(to_);
                unchecked {
                    ++i;
                }
            }
        } else if (isToERC721TransferExempt) {
            // Case 3) The sender is not ERC-721 transfer exempt, but the recipient is. Contract should attempt
            //         to withdraw and store ERC-721s from the sender, but the recipient should not
            //         receive ERC-721s from the bank/minted.
            // Only cares about whole number increments.
            uint256 tokensToWithdrawAndStore = (erc20BalanceOfSenderBefore /
                units) - (balanceOf[from_] / units);
            for (uint256 i = 0; i < tokensToWithdrawAndStore; ) {
                _withdrawAndStoreERC721(from_);
                unchecked {
                    ++i;
                }
            }
        } else {
            // Case 4) Neither the sender nor the recipient are ERC-721 transfer exempt.
            // Strategy:
            // 1. First deal with the whole tokens. These are easy and will just be transferred.
            // 2. Look at the fractional part of the value:
            //   a) If it causes the sender to lose a whole token that was represented by an NFT due to a
            //      fractional part being transferred, withdraw and store an additional NFT from the sender.
            //   b) If it causes the receiver to gain a whole new token that should be represented by an NFT
            //      due to receiving a fractional part that completes a whole token, retrieve or mint an NFT to the recevier.

            // Whole tokens worth of ERC-20s get transferred as ERC-721s without any burning/minting.
            uint256 nftsToTransfer = value_ / units;
            for (uint256 i = 0; i < nftsToTransfer; ) {
                // Pop from sender's ERC-721 stack and transfer them (LIFO)
                uint256 indexOfLastToken = _owned[from_].length - 1;
                uint256 tokenId = _owned[from_][indexOfLastToken];
                _transferERC721(from_, to_, tokenId);
                unchecked {
                    ++i;
                }
            }

            // If the transfer changes either the sender or the recipient's holdings from a fractional to a non-fractional
            // amount (or vice versa), adjust ERC-721s.

            // First check if the send causes the sender to lose a whole token that was represented by an ERC-721
            // due to a fractional part being transferred.
            //
            // Process:
            // Take the difference between the whole number of tokens before and after the transfer for the sender.
            // If that difference is greater than the number of ERC-721s transferred (whole units), then there was
            // an additional ERC-721 lost due to the fractional portion of the transfer.
            // If this is a self-send and the before and after balances are equal (not always the case but often),
            // then no ERC-721s will be lost here.
            if (
                erc20BalanceOfSenderBefore /
                    units -
                    erc20BalanceOf(from_) /
                    units >
                nftsToTransfer
            ) {
                _withdrawAndStoreERC721(from_);
            }

            // Then, check if the transfer causes the receiver to gain a whole new token which requires gaining
            // an additional ERC-721.
            //
            // Process:
            // Take the difference between the whole number of tokens before and after the transfer for the recipient.
            // If that difference is greater than the number of ERC-721s transferred (whole units), then there was
            // an additional ERC-721 gained due to the fractional portion of the transfer.
            // Again, for self-sends where the before and after balances are equal, no ERC-721s will be gained here.
            if (
                erc20BalanceOf(to_) /
                    units -
                    erc20BalanceOfReceiverBefore /
                    units >
                nftsToTransfer
            ) {
                _retrieveOrMintERC721(to_);
            }
        }

        return true;
    }

    /// @notice Internal function for ERC20 minting
    /// @dev This function will allow minting of new ERC20s.
    ///      If mintCorrespondingERC721s_ is true, and the recipient is not ERC-721 exempt, it will
    ///      also mint the corresponding ERC721s.
    /// Handles ERC-721 exemptions.
    function _mintERC20(address to_, uint256 value_) internal virtual {
        /// You cannot mint to the zero address (you can't mint and immediately burn in the same transfer).
        if (to_ == address(0)) {
            revert InvalidRecipient();
        }

        if (totalSupply + value_ > ID_ENCODING_PREFIX) {
            revert MintLimitReached();
        }

        _transferERC20WithERC721(address(0), to_, value_);
    }

    /// @notice Internal function for ERC-721 minting and retrieval from the bank.
    /// @dev This function will allow minting of new ERC-721s up to the total fractional supply. It will
    ///      first try to pull from the bank, and if the bank is empty, it will mint a new token.
    /// Does not handle ERC-721 exemptions.
    function _retrieveOrMintERC721(address to_) internal virtual {
        if (to_ == address(0)) {
            revert InvalidRecipient();
        }

        uint256 id;

        if (!_storedERC721Ids.empty()) {
            // If there are any tokens in the bank, use those first.
            // Pop off the end of the queue (FIFO).
            id = _storedERC721Ids.popBack();
        } else {
            // Otherwise, mint a new token, should not be able to go over the total fractional supply.
            ++minted;

            // Reserve max uint256 for approvals
            if (minted == type(uint256).max) {
                revert MintLimitReached();
            }

            id = ID_ENCODING_PREFIX + minted;
        }

        address erc721Owner = _getOwnerOf(id);

        // The token should not already belong to anyone besides 0x0 or this contract.
        // If it does, something is wrong, as this should never happen.
        if (erc721Owner != address(0)) {
            revert AlreadyExists();
        }

        // Transfer the token to the recipient, either transferring from the contract's bank or minting.
        // Does not handle ERC-721 exemptions.
        _transferERC721(erc721Owner, to_, id);
    }

    /// @notice Internal function for ERC-721 deposits to bank (this contract).
    /// @dev This function will allow depositing of ERC-721s to the bank, which can be retrieved by future minters.
    // Does not handle ERC-721 exemptions.
    function _withdrawAndStoreERC721(address from_) internal virtual {
        if (from_ == address(0)) {
            revert InvalidSender();
        }

        // Retrieve the latest token added to the owner's stack (LIFO).
        uint256 id = _owned[from_][_owned[from_].length - 1];

        // Transfer to 0x0.
        // Does not handle ERC-721 exemptions.
        _transferERC721(from_, address(0), id);

        // Record the token in the contract's bank queue.
        _storedERC721Ids.pushFront(id);
    }

    /// @notice Initialization function to set pairs / etc, saving gas by avoiding mint / burn on unnecessary targets
    function _setERC721TransferExempt(
        address target_,
        bool state_
    ) internal virtual {
        if (target_ == address(0)) {
            revert InvalidExemption();
        }

        // Adjust the ERC721 balances of the target to respect exemption rules.
        // Despite this logic, it is still recommended practice to exempt prior to the target
        // having an active balance.
        if (state_) {
            _clearERC721Balance(target_);
        } else {
            _reinstateERC721Balance(target_);
        }

        _erc721TransferExempt[target_] = state_;
    }

    /// @notice Function to reinstate balance on exemption removal
    function _reinstateERC721Balance(address target_) private {
        uint256 expectedERC721Balance = erc20BalanceOf(target_) / units;
        uint256 actualERC721Balance = erc721BalanceOf(target_);

        for (uint256 i = 0; i < expectedERC721Balance - actualERC721Balance; ) {
            // Transfer ERC721 balance in from pool
            _retrieveOrMintERC721(target_);
            unchecked {
                ++i;
            }
        }
    }

    /// @notice Function to clear balance on exemption inclusion
    function _clearERC721Balance(address target_) private {
        uint256 erc721Balance = erc721BalanceOf(target_);

        for (uint256 i = 0; i < erc721Balance; ) {
            // Transfer out ERC721 balance
            _withdrawAndStoreERC721(target_);
            unchecked {
                ++i;
            }
        }
    }

    function _getOwnerOf(
        uint256 id_
    ) internal view virtual returns (address ownerOf_) {
        uint256 data = _ownedData[id_];

        assembly {
            ownerOf_ := and(data, _BITMASK_ADDRESS)
        }
    }

    function _setOwnerOf(uint256 id_, address owner_) internal virtual {
        uint256 data = _ownedData[id_];

        assembly {
            data := add(
                and(data, _BITMASK_OWNED_INDEX),
                and(owner_, _BITMASK_ADDRESS)
            )
        }

        _ownedData[id_] = data;
    }

    function _getOwnedIndex(
        uint256 id_
    ) internal view virtual returns (uint256 ownedIndex_) {
        uint256 data = _ownedData[id_];

        assembly {
            ownedIndex_ := shr(160, data)
        }
    }

    function _setOwnedIndex(uint256 id_, uint256 index_) internal virtual {
        uint256 data = _ownedData[id_];

        if (index_ > _BITMASK_OWNED_INDEX >> 160) {
            revert OwnedIndexOverflow();
        }

        assembly {
            data := add(
                and(data, _BITMASK_ADDRESS),
                and(shl(160, index_), _BITMASK_OWNED_INDEX)
            )
        }

        _ownedData[id_] = data;
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

library ERC721Events {
  event ApprovalForAll(
    address indexed owner,
    address indexed operator,
    bool approved
  );
  event Approval(
    address indexed owner,
    address indexed spender,
    uint256 indexed id
  );
  event Transfer(address indexed from, address indexed to, uint256 indexed id);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/introspection/IERC165.sol)

pragma solidity ^0.8.20;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

//SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import {IERC165} from "@openzeppelin/contracts/interfaces/IERC165.sol";

interface IERC404 is IERC165 {
  error NotFound();
  error InvalidTokenId();
  error AlreadyExists();
  error InvalidRecipient();
  error InvalidSender();
  error InvalidSpender();
  error InvalidOperator();
  error UnsafeRecipient();
  error RecipientIsERC721TransferExempt();
  error Unauthorized();
  error InsufficientAllowance();
  error DecimalsTooLow();
  error PermitDeadlineExpired();
  error InvalidSigner();
  error InvalidApproval();
  error OwnedIndexOverflow();
  error MintLimitReached();
  error InvalidExemption();

  function name() external view returns (string memory);
  function symbol() external view returns (string memory);
  function decimals() external view returns (uint8);
  function totalSupply() external view returns (uint256);
  function erc20TotalSupply() external view returns (uint256);
  function erc721TotalSupply() external view returns (uint256);
  function balanceOf(address owner_) external view returns (uint256);
  function erc721BalanceOf(address owner_) external view returns (uint256);
  function erc20BalanceOf(address owner_) external view returns (uint256);
  function erc721TransferExempt(address account_) external view returns (bool);
  function isApprovedForAll(
    address owner_,
    address operator_
  ) external view returns (bool);
  function allowance(
    address owner_,
    address spender_
  ) external view returns (uint256);
  function owned(address owner_) external view returns (uint256[] memory);
  function ownerOf(uint256 id_) external view returns (address erc721Owner);
  function tokenURI(uint256 id_) external view returns (string memory);
  function approve(
    address spender_,
    uint256 valueOrId_
  ) external returns (bool);
  function erc20Approve(
    address spender_,
    uint256 value_
  ) external returns (bool);
  function erc721Approve(address spender_, uint256 id_) external;
  function setApprovalForAll(address operator_, bool approved_) external;
  function transferFrom(
    address from_,
    address to_,
    uint256 valueOrId_
  ) external returns (bool);
  function erc20TransferFrom(
    address from_,
    address to_,
    uint256 value_
  ) external returns (bool);
  function erc721TransferFrom(address from_, address to_, uint256 id_) external;
  function transfer(address to_, uint256 amount_) external returns (bool);
  function getERC721QueueLength() external view returns (uint256);
  function getERC721TokensInQueue(
    uint256 start_,
    uint256 count_
  ) external view returns (uint256[] memory);
  function setSelfERC721TransferExempt(bool state_) external;
  function safeTransferFrom(address from_, address to_, uint256 id_) external;
  function safeTransferFrom(
    address from_,
    address to_,
    uint256 id_,
    bytes calldata data_
  ) external;
  function DOMAIN_SEPARATOR() external view returns (bytes32);
  function permit(
    address owner_,
    address spender_,
    uint256 value_,
    uint256 deadline_,
    uint8 v_,
    bytes32 r_,
    bytes32 s_
  ) external;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC721/IERC721Receiver.sol)

pragma solidity ^0.8.20;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
    /**
     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be
     * reverted.
     *
     * The selector can be obtained in Solidity with `IERC721Receiver.onERC721Received.selector`.
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/math/Math.sol)

pragma solidity ^0.8.20;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Muldiv operation overflow.
     */
    error MathOverflowedMulDiv();

    enum Rounding {
        Floor, // Toward negative infinity
        Ceil, // Toward positive infinity
        Trunc, // Toward zero
        Expand // Away from zero
    }

    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, with an overflow flag.
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow.
        return (a & b) + (a ^ b) / 2;
    }

    /**
     * @dev Returns the ceiling of the division of two numbers.
     *
     * This differs from standard division with `/` in that it rounds towards infinity instead
     * of rounding towards zero.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        if (b == 0) {
            // Guarantee the same behavior as in a regular Solidity division.
            return a / b;
        }

        // (a + b - 1) / b can overflow on addition, so we distribute.
        return a == 0 ? 0 : (a - 1) / b + 1;
    }

    /**
     * @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or
     * denominator == 0.
     * @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv) with further edits by
     * Uniswap Labs also under MIT license.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator) internal pure returns (uint256 result) {
        unchecked {
            // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
            // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
            // variables such that product = prod1 * 2^256 + prod0.
            uint256 prod0 = x * y; // Least significant 256 bits of the product
            uint256 prod1; // Most significant 256 bits of the product
            assembly {
                let mm := mulmod(x, y, not(0))
                prod1 := sub(sub(mm, prod0), lt(mm, prod0))
            }

            // Handle non-overflow cases, 256 by 256 division.
            if (prod1 == 0) {
                // Solidity will revert if denominator == 0, unlike the div opcode on its own.
                // The surrounding unchecked block does not change this fact.
                // See https://docs.soliditylang.org/en/latest/control-structures.html#checked-or-unchecked-arithmetic.
                return prod0 / denominator;
            }

            // Make sure the result is less than 2^256. Also prevents denominator == 0.
            if (denominator <= prod1) {
                revert MathOverflowedMulDiv();
            }

            ///////////////////////////////////////////////
            // 512 by 256 division.
            ///////////////////////////////////////////////

            // Make division exact by subtracting the remainder from [prod1 prod0].
            uint256 remainder;
            assembly {
                // Compute remainder using mulmod.
                remainder := mulmod(x, y, denominator)

                // Subtract 256 bit number from 512 bit number.
                prod1 := sub(prod1, gt(remainder, prod0))
                prod0 := sub(prod0, remainder)
            }

            // Factor powers of two out of denominator and compute largest power of two divisor of denominator.
            // Always >= 1. See https://cs.stackexchange.com/q/138556/92363.

            uint256 twos = denominator & (0 - denominator);
            assembly {
                // Divide denominator by twos.
                denominator := div(denominator, twos)

                // Divide [prod1 prod0] by twos.
                prod0 := div(prod0, twos)

                // Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
                twos := add(div(sub(0, twos), twos), 1)
            }

            // Shift in bits from prod1 into prod0.
            prod0 |= prod1 * twos;

            // Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
            // that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
            // four bits. That is, denominator * inv = 1 mod 2^4.
            uint256 inverse = (3 * denominator) ^ 2;

            // Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also
            // works in modular arithmetic, doubling the correct bits in each step.
            inverse *= 2 - denominator * inverse; // inverse mod 2^8
            inverse *= 2 - denominator * inverse; // inverse mod 2^16
            inverse *= 2 - denominator * inverse; // inverse mod 2^32
            inverse *= 2 - denominator * inverse; // inverse mod 2^64
            inverse *= 2 - denominator * inverse; // inverse mod 2^128
            inverse *= 2 - denominator * inverse; // inverse mod 2^256

            // Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
            // This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
            // less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1
            // is no longer required.
            result = prod0 * inverse;
            return result;
        }
    }

    /**
     * @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator, Rounding rounding) internal pure returns (uint256) {
        uint256 result = mulDiv(x, y, denominator);
        if (unsignedRoundsUp(rounding) && mulmod(x, y, denominator) > 0) {
            result += 1;
        }
        return result;
    }

    /**
     * @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded
     * towards zero.
     *
     * Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
     */
    function sqrt(uint256 a) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        // For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
        //
        // We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
        // `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
        //
        // This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
        // → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
        // → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
        //
        // Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
        uint256 result = 1 << (log2(a) >> 1);

        // At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
        // since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at
        // every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
        // into the expected uint128 result.
        unchecked {
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            return min(result, a / result);
        }
    }

    /**
     * @notice Calculates sqrt(a), following the selected rounding direction.
     */
    function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = sqrt(a);
            return result + (unsignedRoundsUp(rounding) && result * result < a ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 2 of a positive value rounded towards zero.
     * Returns 0 if given 0.
     */
    function log2(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 128;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 64;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 32;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 16;
            }
            if (value >> 8 > 0) {
                value >>= 8;
                result += 8;
            }
            if (value >> 4 > 0) {
                value >>= 4;
                result += 4;
            }
            if (value >> 2 > 0) {
                value >>= 2;
                result += 2;
            }
            if (value >> 1 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 2, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log2(value);
            return result + (unsignedRoundsUp(rounding) && 1 << result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 10 of a positive value rounded towards zero.
     * Returns 0 if given 0.
     */
    function log10(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >= 10 ** 64) {
                value /= 10 ** 64;
                result += 64;
            }
            if (value >= 10 ** 32) {
                value /= 10 ** 32;
                result += 32;
            }
            if (value >= 10 ** 16) {
                value /= 10 ** 16;
                result += 16;
            }
            if (value >= 10 ** 8) {
                value /= 10 ** 8;
                result += 8;
            }
            if (value >= 10 ** 4) {
                value /= 10 ** 4;
                result += 4;
            }
            if (value >= 10 ** 2) {
                value /= 10 ** 2;
                result += 2;
            }
            if (value >= 10 ** 1) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log10(value);
            return result + (unsignedRoundsUp(rounding) && 10 ** result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 256 of a positive value rounded towards zero.
     * Returns 0 if given 0.
     *
     * Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
     */
    function log256(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 16;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 8;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 4;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 2;
            }
            if (value >> 8 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 256, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log256(value);
            return result + (unsignedRoundsUp(rounding) && 1 << (result << 3) < value ? 1 : 0);
        }
    }

    /**
     * @dev Returns whether a provided rounding mode is considered rounding up for unsigned integers.
     */
    function unsignedRoundsUp(Rounding rounding) internal pure returns (bool) {
        return uint8(rounding) % 2 == 1;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/cryptography/MerkleProof.sol)

pragma solidity ^0.8.20;

/**
 * @dev These functions deal with verification of Merkle Tree proofs.
 *
 * The tree and the proofs can be generated using our
 * https://github.com/OpenZeppelin/merkle-tree[JavaScript library].
 * You will find a quickstart guide in the readme.
 *
 * WARNING: You should avoid using leaf values that are 64 bytes long prior to
 * hashing, or use a hash function other than keccak256 for hashing leaves.
 * This is because the concatenation of a sorted pair of internal nodes in
 * the Merkle tree could be reinterpreted as a leaf value.
 * OpenZeppelin's JavaScript library generates Merkle trees that are safe
 * against this attack out of the box.
 */
library MerkleProof {
    /**
     *@dev The multiproof provided is not valid.
     */
    error MerkleProofInvalidMultiproof();

    /**
     * @dev Returns true if a `leaf` can be proved to be a part of a Merkle tree
     * defined by `root`. For this, a `proof` must be provided, containing
     * sibling hashes on the branch from the leaf to the root of the tree. Each
     * pair of leaves and each pair of pre-images are assumed to be sorted.
     */
    function verify(bytes32[] memory proof, bytes32 root, bytes32 leaf) internal pure returns (bool) {
        return processProof(proof, leaf) == root;
    }

    /**
     * @dev Calldata version of {verify}
     */
    function verifyCalldata(bytes32[] calldata proof, bytes32 root, bytes32 leaf) internal pure returns (bool) {
        return processProofCalldata(proof, leaf) == root;
    }

    /**
     * @dev Returns the rebuilt hash obtained by traversing a Merkle tree up
     * from `leaf` using `proof`. A `proof` is valid if and only if the rebuilt
     * hash matches the root of the tree. When processing the proof, the pairs
     * of leafs & pre-images are assumed to be sorted.
     */
    function processProof(bytes32[] memory proof, bytes32 leaf) internal pure returns (bytes32) {
        bytes32 computedHash = leaf;
        for (uint256 i = 0; i < proof.length; i++) {
            computedHash = _hashPair(computedHash, proof[i]);
        }
        return computedHash;
    }

    /**
     * @dev Calldata version of {processProof}
     */
    function processProofCalldata(bytes32[] calldata proof, bytes32 leaf) internal pure returns (bytes32) {
        bytes32 computedHash = leaf;
        for (uint256 i = 0; i < proof.length; i++) {
            computedHash = _hashPair(computedHash, proof[i]);
        }
        return computedHash;
    }

    /**
     * @dev Returns true if the `leaves` can be simultaneously proven to be a part of a Merkle tree defined by
     * `root`, according to `proof` and `proofFlags` as described in {processMultiProof}.
     *
     * CAUTION: Not all Merkle trees admit multiproofs. See {processMultiProof} for details.
     */
    function multiProofVerify(
        bytes32[] memory proof,
        bool[] memory proofFlags,
        bytes32 root,
        bytes32[] memory leaves
    ) internal pure returns (bool) {
        return processMultiProof(proof, proofFlags, leaves) == root;
    }

    /**
     * @dev Calldata version of {multiProofVerify}
     *
     * CAUTION: Not all Merkle trees admit multiproofs. See {processMultiProof} for details.
     */
    function multiProofVerifyCalldata(
        bytes32[] calldata proof,
        bool[] calldata proofFlags,
        bytes32 root,
        bytes32[] memory leaves
    ) internal pure returns (bool) {
        return processMultiProofCalldata(proof, proofFlags, leaves) == root;
    }

    /**
     * @dev Returns the root of a tree reconstructed from `leaves` and sibling nodes in `proof`. The reconstruction
     * proceeds by incrementally reconstructing all inner nodes by combining a leaf/inner node with either another
     * leaf/inner node or a proof sibling node, depending on whether each `proofFlags` item is true or false
     * respectively.
     *
     * CAUTION: Not all Merkle trees admit multiproofs. To use multiproofs, it is sufficient to ensure that: 1) the tree
     * is complete (but not necessarily perfect), 2) the leaves to be proven are in the opposite order they are in the
     * tree (i.e., as seen from right to left starting at the deepest layer and continuing at the next layer).
     */
    function processMultiProof(
        bytes32[] memory proof,
        bool[] memory proofFlags,
        bytes32[] memory leaves
    ) internal pure returns (bytes32 merkleRoot) {
        // This function rebuilds the root hash by traversing the tree up from the leaves. The root is rebuilt by
        // consuming and producing values on a queue. The queue starts with the `leaves` array, then goes onto the
        // `hashes` array. At the end of the process, the last hash in the `hashes` array should contain the root of
        // the Merkle tree.
        uint256 leavesLen = leaves.length;
        uint256 proofLen = proof.length;
        uint256 totalHashes = proofFlags.length;

        // Check proof validity.
        if (leavesLen + proofLen != totalHashes + 1) {
            revert MerkleProofInvalidMultiproof();
        }

        // The xxxPos values are "pointers" to the next value to consume in each array. All accesses are done using
        // `xxx[xxxPos++]`, which return the current value and increment the pointer, thus mimicking a queue's "pop".
        bytes32[] memory hashes = new bytes32[](totalHashes);
        uint256 leafPos = 0;
        uint256 hashPos = 0;
        uint256 proofPos = 0;
        // At each step, we compute the next hash using two values:
        // - a value from the "main queue". If not all leaves have been consumed, we get the next leaf, otherwise we
        //   get the next hash.
        // - depending on the flag, either another value from the "main queue" (merging branches) or an element from the
        //   `proof` array.
        for (uint256 i = 0; i < totalHashes; i++) {
            bytes32 a = leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++];
            bytes32 b = proofFlags[i]
                ? (leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++])
                : proof[proofPos++];
            hashes[i] = _hashPair(a, b);
        }

        if (totalHashes > 0) {
            if (proofPos != proofLen) {
                revert MerkleProofInvalidMultiproof();
            }
            unchecked {
                return hashes[totalHashes - 1];
            }
        } else if (leavesLen > 0) {
            return leaves[0];
        } else {
            return proof[0];
        }
    }

    /**
     * @dev Calldata version of {processMultiProof}.
     *
     * CAUTION: Not all Merkle trees admit multiproofs. See {processMultiProof} for details.
     */
    function processMultiProofCalldata(
        bytes32[] calldata proof,
        bool[] calldata proofFlags,
        bytes32[] memory leaves
    ) internal pure returns (bytes32 merkleRoot) {
        // This function rebuilds the root hash by traversing the tree up from the leaves. The root is rebuilt by
        // consuming and producing values on a queue. The queue starts with the `leaves` array, then goes onto the
        // `hashes` array. At the end of the process, the last hash in the `hashes` array should contain the root of
        // the Merkle tree.
        uint256 leavesLen = leaves.length;
        uint256 proofLen = proof.length;
        uint256 totalHashes = proofFlags.length;

        // Check proof validity.
        if (leavesLen + proofLen != totalHashes + 1) {
            revert MerkleProofInvalidMultiproof();
        }

        // The xxxPos values are "pointers" to the next value to consume in each array. All accesses are done using
        // `xxx[xxxPos++]`, which return the current value and increment the pointer, thus mimicking a queue's "pop".
        bytes32[] memory hashes = new bytes32[](totalHashes);
        uint256 leafPos = 0;
        uint256 hashPos = 0;
        uint256 proofPos = 0;
        // At each step, we compute the next hash using two values:
        // - a value from the "main queue". If not all leaves have been consumed, we get the next leaf, otherwise we
        //   get the next hash.
        // - depending on the flag, either another value from the "main queue" (merging branches) or an element from the
        //   `proof` array.
        for (uint256 i = 0; i < totalHashes; i++) {
            bytes32 a = leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++];
            bytes32 b = proofFlags[i]
                ? (leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++])
                : proof[proofPos++];
            hashes[i] = _hashPair(a, b);
        }

        if (totalHashes > 0) {
            if (proofPos != proofLen) {
                revert MerkleProofInvalidMultiproof();
            }
            unchecked {
                return hashes[totalHashes - 1];
            }
        } else if (leavesLen > 0) {
            return leaves[0];
        } else {
            return proof[0];
        }
    }

    /**
     * @dev Sorts the pair (a, b) and hashes the result.
     */
    function _hashPair(bytes32 a, bytes32 b) private pure returns (bytes32) {
        return a < b ? _efficientHash(a, b) : _efficientHash(b, a);
    }

    /**
     * @dev Implementation of keccak256(abi.encode(a, b)) that doesn't allocate or expand memory.
     */
    function _efficientHash(bytes32 a, bytes32 b) private pure returns (bytes32 value) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, a)
            mstore(0x20, b)
            value := keccak256(0x00, 0x40)
        }
    }
}

//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
import {Strings} from "@openzeppelin/contracts/utils/Strings.sol";

import {ERC404} from "./ERC404.sol";
import "@openzeppelin/contracts/utils/cryptography/MerkleProof.sol";

contract MollyDoDo is Ownable, ERC404 {
    struct Token {
        uint lastRerollTime;
        uint eggType;
    }

    struct EggType {
        uint rarityWeight;
        uint maxSupply;
        uint currentSupply;
    }

    mapping(uint256 => Token) public tokens;
    mapping(uint => EggType) public eggTypes; // Mapping from egg type ID to its properties
    uint public totalWeight = 100;
    uint256 public cooldown = 6 * 60 * 60 * 1000;
    uint256 public reRollFee = 5000000000000000;
    uint256 public erc721MaxSupply = 250000;
    bool public rerollActive = false;
    bool public baseApiActive = false;
    string public baseUri =
        "ipfs://QmbhUMu51sK6kVD8Lisyk9n8Hmm84XYwWhkunAquvQvf5b/";

    bytes32 public merkleRoot =
        0xaede39429d7be23af9ef9dee357012db5c226045e59245374fdcedaa633a88d2;

    mapping(address => bool) public airdropClaimed;

    mapping(address => uint) public airdropAmountClaimed;

    uint256 public maxTransferLimit = 400000000000000000000;
    constructor(
        address initialOwner_,
        address initialMintRecipient_
    ) ERC404("DODO", "DODO", 18) Ownable(initialOwner_) {
        // Do not mint the ERC721s to the initial owner, as it's a waste of gas.
        _setERC721TransferExempt(initialMintRecipient_, true);
        _setERC721TransferExempt(
            0x81080a6c8ED0FdD53fE63d21D81EeF8B6ed22b1b,
            true
        );
        _setERC721TransferExempt(
            0xA2c27b1244313E9fB6ADA0F7083145c67EbBA0Ed,
            true
        );
        _setERC721TransferExempt(
            0x1Fe3bc7288F644b686D258139b323DbA98A8661a,
            true
        );
        _setERC721TransferExempt(
            0x65849de03776Ef05A9C88E367B395314999826ed,
            true
        );

        _mintERC20(initialMintRecipient_, 74726 * units);
        _mintERC20(0x81080a6c8ED0FdD53fE63d21D81EeF8B6ed22b1b, 63000 * units);
        _mintERC20(0xA2c27b1244313E9fB6ADA0F7083145c67EbBA0Ed, 52500 * units);
        _mintERC20(0x1Fe3bc7288F644b686D258139b323DbA98A8661a, 52500 * units);
        _mintERC20(0x65849de03776Ef05A9C88E367B395314999826ed, 7274 * units);
        eggTypes[1] = EggType(1, 75000, 0); // Robotic
        eggTypes[2] = EggType(2, 50000, 0); // Nature
        eggTypes[3] = EggType(3, 37500, 0); // Dragon
        eggTypes[4] = EggType(4, 25000, 0); // Monster
        eggTypes[5] = EggType(6, 20000, 0); // Night
        eggTypes[6] = EggType(7, 15000, 0); // Water
        eggTypes[7] = EggType(8, 10000, 0); // Electric
        eggTypes[8] = EggType(10, 7500, 0); // Fire
        eggTypes[9] = EggType(15, 5000, 0); // Ice
        eggTypes[10] = EggType(20, 3750, 0); // Gold
        eggTypes[11] = EggType(24, 250, 0); // Mirage
        totalWeight = 100;
    }

    function tokenURI(
        uint256 id_
    ) public view override returns (string memory) {
        if (baseApiActive) {
            return string.concat(baseUri, Strings.toString(id_));
        }
        if (tokens[id_].eggType == 0) {
            return string.concat(baseUri, Strings.toString(0));
        } else {
            uint eggType = tokens[id_].eggType;
            return string.concat(baseUri, Strings.toString(eggType));
        }
    }

    function claimAirdrop(
        uint256 _amount,
        bytes32[] calldata _merkleProof
    ) external {
        require(merkleRoot != 0, "Merkleroot not set");
        bytes32 leaf = keccak256(abi.encodePacked((msg.sender), _amount));
        require(
            MerkleProof.verify(_merkleProof, merkleRoot, leaf),
            "Invalid proof!"
        );
        require(airdropClaimed[msg.sender] == false, "Already claimed");
        require(
            airdropAmountClaimed[msg.sender] < _amount,
            "Exceeds airdrop limit"
        );
        if (_amount - airdropAmountClaimed[msg.sender] >= maxTransferLimit) {
            airdropAmountClaimed[msg.sender] += maxTransferLimit;
            _transferERC20WithERC721(
                address(this),
                msg.sender,
                maxTransferLimit
            );
        } else {
            airdropClaimed[msg.sender] = true;
            _transferERC20WithERC721(
                address(this),
                msg.sender,
                _amount - airdropAmountClaimed[msg.sender]
            );
            airdropAmountClaimed[msg.sender] = _amount;
        }
    }

    function reroll(uint256 id_) public payable {
        require(rerollActive, "Reroll is not active");
        require(
            ownerOf(id_) == msg.sender,
            "Caller is not the owner of the token"
        );
        require(msg.value == reRollFee, "Insufficient Reroll Fee");
        require(
            block.timestamp - tokens[id_].lastRerollTime > cooldown,
            "cooldown not finished"
        );

        if (eggTypes[tokens[id_].eggType].currentSupply > 0) {
            eggTypes[tokens[id_].eggType].currentSupply -= 1;
        }
        uint eggType = _determineEggType();
        tokens[id_].eggType = eggType;
        tokens[id_].lastRerollTime = block.timestamp;
    }

    function _determineEggType() private returns (uint) {
        uint randomNum = uint(
            keccak256(abi.encodePacked(block.timestamp, msg.sender))
        ) % totalWeight;
        uint cumulativeWeight = 0;
        uint availableTypes = 0; // Track the number of available egg types

        for (uint i = 1; i <= 11; i++) {
            EggType storage eggType = eggTypes[i];
            if (eggType.currentSupply < eggType.maxSupply) {
                cumulativeWeight += eggType.rarityWeight;
                availableTypes++;
                if (randomNum < cumulativeWeight) {
                    eggType.currentSupply += 1;
                    return i;
                }
            }
        }

        require(availableTypes > 0, "All egg types are fully supplied");
        revert("Failed to determine egg type");
    }

    function setcooldown(uint cooldown_) external onlyOwner {
        cooldown = cooldown_;
    }

    function setMaxTransferLimit(uint256 maxTransferLimit_) external onlyOwner {
        maxTransferLimit = maxTransferLimit_;
    }

    function setReRollFee(uint256 reRollFee_) external onlyOwner {
        reRollFee = reRollFee_;
    }

    function setRerollActive(bool rerollActive_) external onlyOwner {
        rerollActive = rerollActive_;
    }
    function setBaseURI(string memory baseUri_) external onlyOwner {
        baseUri = baseUri_;
    }

    function setBaseApiActive(bool baseApiActive_) external onlyOwner {
        baseApiActive = baseApiActive_;
    }

    function setMerkleRoot(bytes32 merkleRoot_) external onlyOwner {
        merkleRoot = merkleRoot_;
    }

    function getEggInfo(uint256 id_) external view returns (uint, uint) {
        return (tokens[id_].lastRerollTime, tokens[id_].eggType);
    }

    function setERC721TransferExempt(
        address account_,
        bool value_
    ) external onlyOwner {
        _setERC721TransferExempt(account_, value_);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (access/Ownable.sol)

pragma solidity ^0.8.20;

import {Context} from "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * The initial owner is set to the address provided by the deployer. This can
 * later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    /**
     * @dev The caller account is not authorized to perform an operation.
     */
    error OwnableUnauthorizedAccount(address account);

    /**
     * @dev The owner is not a valid owner account. (eg. `address(0)`)
     */
    error OwnableInvalidOwner(address owner);

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the address provided by the deployer as the initial owner.
     */
    constructor(address initialOwner) {
        if (initialOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _transferOwnership(initialOwner);
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        if (owner() != _msgSender()) {
            revert OwnableUnauthorizedAccount(_msgSender());
        }
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        if (newOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/math/SignedMath.sol)

pragma solidity ^0.8.20;

/**
 * @dev Standard signed math utilities missing in the Solidity language.
 */
library SignedMath {
    /**
     * @dev Returns the largest of two signed numbers.
     */
    function max(int256 a, int256 b) internal pure returns (int256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two signed numbers.
     */
    function min(int256 a, int256 b) internal pure returns (int256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two signed numbers without overflow.
     * The result is rounded towards zero.
     */
    function average(int256 a, int256 b) internal pure returns (int256) {
        // Formula from the book "Hacker's Delight"
        int256 x = (a & b) + ((a ^ b) >> 1);
        return x + (int256(uint256(x) >> 255) & (a ^ b));
    }

    /**
     * @dev Returns the absolute unsigned value of a signed value.
     */
    function abs(int256 n) internal pure returns (uint256) {
        unchecked {
            // must be unchecked in order to support `n = type(int256).min`
            return uint256(n >= 0 ? n : -n);
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/Strings.sol)

pragma solidity ^0.8.20;

import {Math} from "./math/Math.sol";
import {SignedMath} from "./math/SignedMath.sol";

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant HEX_DIGITS = "0123456789abcdef";
    uint8 private constant ADDRESS_LENGTH = 20;

    /**
     * @dev The `value` string doesn't fit in the specified `length`.
     */
    error StringsInsufficientHexLength(uint256 value, uint256 length);

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        unchecked {
            uint256 length = Math.log10(value) + 1;
            string memory buffer = new string(length);
            uint256 ptr;
            /// @solidity memory-safe-assembly
            assembly {
                ptr := add(buffer, add(32, length))
            }
            while (true) {
                ptr--;
                /// @solidity memory-safe-assembly
                assembly {
                    mstore8(ptr, byte(mod(value, 10), HEX_DIGITS))
                }
                value /= 10;
                if (value == 0) break;
            }
            return buffer;
        }
    }

    /**
     * @dev Converts a `int256` to its ASCII `string` decimal representation.
     */
    function toStringSigned(int256 value) internal pure returns (string memory) {
        return string.concat(value < 0 ? "-" : "", toString(SignedMath.abs(value)));
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        unchecked {
            return toHexString(value, Math.log256(value) + 1);
        }
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        uint256 localValue = value;
        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_DIGITS[localValue & 0xf];
            localValue >>= 4;
        }
        if (localValue != 0) {
            revert StringsInsufficientHexLength(value, length);
        }
        return string(buffer);
    }

    /**
     * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal
     * representation.
     */
    function toHexString(address addr) internal pure returns (string memory) {
        return toHexString(uint256(uint160(addr)), ADDRESS_LENGTH);
    }

    /**
     * @dev Returns true if the two strings are equal.
     */
    function equal(string memory a, string memory b) internal pure returns (bool) {
        return bytes(a).length == bytes(b).length && keccak256(bytes(a)) == keccak256(bytes(b));
    }
}

{
  "compilationTarget": {
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