// SPDX-License-Identifier: MIT
// File: @openzeppelin/contracts/utils/structs/EnumerableSet.sol


// OpenZeppelin Contracts (last updated v4.8.0) (utils/structs/EnumerableSet.sol)
// This file was procedurally generated from scripts/generate/templates/EnumerableSet.js.

pragma solidity ^0.8.0;

/**
 * @dev Library for managing
 * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
 * types.
 *
 * Sets have the following properties:
 *
 * - Elements are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Elements are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```
 * contract Example {
 *     // Add the library methods
 *     using EnumerableSet for EnumerableSet.AddressSet;
 *
 *     // Declare a set state variable
 *     EnumerableSet.AddressSet private mySet;
 * }
 * ```
 *
 * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
 * and `uint256` (`UintSet`) are supported.
 *
 * [WARNING]
 * ====
 * Trying to delete such a structure from storage will likely result in data corruption, rendering the structure
 * unusable.
 * See https://github.com/ethereum/solidity/pull/11843[ethereum/solidity#11843] for more info.
 *
 * In order to clean an EnumerableSet, you can either remove all elements one by one or create a fresh instance using an
 * array of EnumerableSet.
 * ====
 */
library EnumerableSet {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Set type with
    // bytes32 values.
    // The Set implementation uses private functions, and user-facing
    // implementations (such as AddressSet) are just wrappers around the
    // underlying Set.
    // This means that we can only create new EnumerableSets for types that fit
    // in bytes32.

    struct Set {
        // Storage of set values
        bytes32[] _values;
        // Position of the value in the `values` array, plus 1 because index 0
        // means a value is not in the set.
        mapping(bytes32 => uint256) _indexes;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            // The value is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function _remove(Set storage set, bytes32 value) private returns (bool) {
        // We read and store the value's index to prevent multiple reads from the same storage slot
        uint256 valueIndex = set._indexes[value];

        if (valueIndex != 0) {
            // Equivalent to contains(set, value)
            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
            // the array, and then remove the last element (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.

            uint256 toDeleteIndex = valueIndex - 1;
            uint256 lastIndex = set._values.length - 1;

            if (lastIndex != toDeleteIndex) {
                bytes32 lastValue = set._values[lastIndex];

                // Move the last value to the index where the value to delete is
                set._values[toDeleteIndex] = lastValue;
                // Update the index for the moved value
                set._indexes[lastValue] = valueIndex; // Replace lastValue's index to valueIndex
            }

            // Delete the slot where the moved value was stored
            set._values.pop();

            // Delete the index for the deleted slot
            delete set._indexes[value];

            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function _contains(Set storage set, bytes32 value) private view returns (bool) {
        return set._indexes[value] != 0;
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function _at(Set storage set, uint256 index) private view returns (bytes32) {
        return set._values[index];
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function _values(Set storage set) private view returns (bytes32[] memory) {
        return set._values;
    }

    // Bytes32Set

    struct Bytes32Set {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _add(set._inner, value);
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _remove(set._inner, value);
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
        return _contains(set._inner, value);
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(Bytes32Set storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
        return _at(set._inner, index);
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(Bytes32Set storage set) internal view returns (bytes32[] memory) {
        bytes32[] memory store = _values(set._inner);
        bytes32[] memory result;

        /// @solidity memory-safe-assembly
        assembly {
            result := store
        }

        return result;
    }

    // AddressSet

    struct AddressSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint160(uint256(_at(set._inner, index))));
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(AddressSet storage set) internal view returns (address[] memory) {
        bytes32[] memory store = _values(set._inner);
        address[] memory result;

        /// @solidity memory-safe-assembly
        assembly {
            result := store
        }

        return result;
    }

    // UintSet

    struct UintSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(UintSet storage set, uint256 value) internal returns (bool) {
        return _remove(set._inner, bytes32(value));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
        return _contains(set._inner, bytes32(value));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
        return uint256(_at(set._inner, index));
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(UintSet storage set) internal view returns (uint256[] memory) {
        bytes32[] memory store = _values(set._inner);
        uint256[] memory result;

        /// @solidity memory-safe-assembly
        assembly {
            result := store
        }

        return result;
    }
}

// File: contracts/IOperatorFilterRegistry.sol


pragma solidity ^0.8.13;

interface IOperatorFilterRegistry {
    function isOperatorAllowed(address registrant, address operator) external view returns (bool);
    function register(address registrant) external;
    function registerAndSubscribe(address registrant, address subscription) external;
    function registerAndCopyEntries(address registrant, address registrantToCopy) external;
    function unregister(address addr) external;
    function updateOperator(address registrant, address operator, bool filtered) external;
    function updateOperators(address registrant, address[] calldata operators, bool filtered) external;
    function updateCodeHash(address registrant, bytes32 codehash, bool filtered) external;
    function updateCodeHashes(address registrant, bytes32[] calldata codeHashes, bool filtered) external;
    function subscribe(address registrant, address registrantToSubscribe) external;
    function unsubscribe(address registrant, bool copyExistingEntries) external;
    function subscriptionOf(address addr) external returns (address registrant);
    function subscribers(address registrant) external returns (address[] memory);
    function subscriberAt(address registrant, uint256 index) external returns (address);
    function copyEntriesOf(address registrant, address registrantToCopy) external;
    function isOperatorFiltered(address registrant, address operator) external returns (bool);
    function isCodeHashOfFiltered(address registrant, address operatorWithCode) external returns (bool);
    function isCodeHashFiltered(address registrant, bytes32 codeHash) external returns (bool);
    function filteredOperators(address addr) external returns (address[] memory);
    function filteredCodeHashes(address addr) external returns (bytes32[] memory);
    function filteredOperatorAt(address registrant, uint256 index) external returns (address);
    function filteredCodeHashAt(address registrant, uint256 index) external returns (bytes32);
    function isRegistered(address addr) external returns (bool);
    function codeHashOf(address addr) external returns (bytes32);
}
// File: contracts/OperatorFilterer.sol


// OpenZeppelin Contracts (last updated v4.8.0) (access/Ownable2Step.sol)

pragma solidity ^0.8.0;

/**
 * @dev Contract module which provides access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership} and {acceptOwnership}.
 *
 * This module is used through inheritance. It will make available all functions
 * from parent (Ownable).
 */



pragma solidity ^0.8.13;

/**
 * @title  OwnedRegistrant
 * @notice Ownable contract that registers itself with the OperatorFilterRegistry and administers its own entries,
 *         to facilitate a subscription whose ownership can be transferred.
 */

pragma solidity ^0.8.13;

contract OperatorFilterRegistryErrorsAndEvents {
    error CannotFilterEOAs();
    error AddressAlreadyFiltered(address operator);
    error AddressNotFiltered(address operator);
    error CodeHashAlreadyFiltered(bytes32 codeHash);
    error CodeHashNotFiltered(bytes32 codeHash);
    error OnlyAddressOrOwner();
    error NotRegistered(address registrant);
    error AlreadyRegistered();
    error AlreadySubscribed(address subscription);
    error NotSubscribed();
    error CannotUpdateWhileSubscribed(address subscription);
    error CannotSubscribeToSelf();
    error CannotSubscribeToZeroAddress();
    error NotOwnable();
    error AddressFiltered(address filtered);
    error CodeHashFiltered(address account, bytes32 codeHash);
    error CannotSubscribeToRegistrantWithSubscription(address registrant);
    error CannotCopyFromSelf();

    event RegistrationUpdated(address indexed registrant, bool indexed registered);
    event OperatorUpdated(address indexed registrant, address indexed operator, bool indexed filtered);
    event OperatorsUpdated(address indexed registrant, address[] operators, bool indexed filtered);
    event CodeHashUpdated(address indexed registrant, bytes32 indexed codeHash, bool indexed filtered);
    event CodeHashesUpdated(address indexed registrant, bytes32[] codeHashes, bool indexed filtered);
    event SubscriptionUpdated(address indexed registrant, address indexed subscription, bool indexed subscribed);
}

pragma solidity ^0.8.13;

/**
 * @title  OperatorFilterRegistry
 * @notice Borrows heavily from the QQL BlacklistOperatorFilter contract:
 *         https://github.com/qql-art/contracts/blob/main/contracts/BlacklistOperatorFilter.sol
 * @notice This contracts allows tokens or token owners to register specific addresses or codeHashes that may be
 * *       restricted according to the isOperatorAllowed function.
 */
contract OperatorFilterRegistry is IOperatorFilterRegistry, OperatorFilterRegistryErrorsAndEvents {
    using EnumerableSet for EnumerableSet.AddressSet;
    using EnumerableSet for EnumerableSet.Bytes32Set;

    /// @dev initialized accounts have a nonzero codehash (see https://eips.ethereum.org/EIPS/eip-1052)
    /// Note that this will also be a smart contract's codehash when making calls from its constructor.
    bytes32 constant EOA_CODEHASH = keccak256("");

    mapping(address => EnumerableSet.AddressSet) private _filteredOperators;
    mapping(address => EnumerableSet.Bytes32Set) private _filteredCodeHashes;
    mapping(address => address) private _registrations;
    mapping(address => EnumerableSet.AddressSet) private _subscribers;

    /**
     * @notice restricts method caller to the address or EIP-173 "owner()"
     */
    modifier onlyAddressOrOwner(address addr) {
        if (msg.sender != addr) {
            try Ownable(addr).owner() returns (address owner) {
                if (msg.sender != owner) {
                    revert OnlyAddressOrOwner();
                }
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert NotOwnable();
                } else {
                    /// @solidity memory-safe-assembly
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        }
        _;
    }

    /**
     * @notice Returns true if operator is not filtered for a given token, either by address or codeHash. Also returns
     *         true if supplied registrant address is not registered.
     */
    function isOperatorAllowed(address registrant, address operator) external view returns (bool) {
        address registration = _registrations[registrant];
        if (registration != address(0)) {
            EnumerableSet.AddressSet storage filteredOperatorsRef;
            EnumerableSet.Bytes32Set storage filteredCodeHashesRef;

            filteredOperatorsRef = _filteredOperators[registration];
            filteredCodeHashesRef = _filteredCodeHashes[registration];

            if (filteredOperatorsRef.contains(operator)) {
                revert AddressFiltered(operator);
            }
            if (operator.code.length > 0) {
                bytes32 codeHash = operator.codehash;
                if (filteredCodeHashesRef.contains(codeHash)) {
                    revert CodeHashFiltered(operator, codeHash);
                }
            }
        }
        return true;
    }

    //////////////////
    // AUTH METHODS //
    //////////////////

    /**
     * @notice Registers an address with the registry. May be called by address itself or by EIP-173 owner.
     */
    function register(address registrant) external onlyAddressOrOwner(registrant) {
        if (_registrations[registrant] != address(0)) {
            revert AlreadyRegistered();
        }
        _registrations[registrant] = registrant;
        emit RegistrationUpdated(registrant, true);
    }

    /**
     * @notice Unregisters an address with the registry and removes its subscription. May be called by address itself or by EIP-173 owner.
     *         Note that this does not remove any filtered addresses or codeHashes.
     *         Also note that any subscriptions to this registrant will still be active and follow the existing filtered addresses and codehashes.
     */
    function unregister(address registrant) external onlyAddressOrOwner(registrant) {
        address registration = _registrations[registrant];
        if (registration == address(0)) {
            revert NotRegistered(registrant);
        }
        if (registration != registrant) {
            _subscribers[registration].remove(registrant);
            emit SubscriptionUpdated(registrant, registration, false);
        }
        _registrations[registrant] = address(0);
        emit RegistrationUpdated(registrant, false);
    }

    /**
     * @notice Registers an address with the registry and "subscribes" to another address's filtered operators and codeHashes.
     */
    function registerAndSubscribe(address registrant, address subscription) external onlyAddressOrOwner(registrant) {
        address registration = _registrations[registrant];
        if (registration != address(0)) {
            revert AlreadyRegistered();
        }
        if (registrant == subscription) {
            revert CannotSubscribeToSelf();
        }
        address subscriptionRegistration = _registrations[subscription];
        if (subscriptionRegistration == address(0)) {
            revert NotRegistered(subscription);
        }
        if (subscriptionRegistration != subscription) {
            revert CannotSubscribeToRegistrantWithSubscription(subscription);
        }

        _registrations[registrant] = subscription;
        _subscribers[subscription].add(registrant);
        emit RegistrationUpdated(registrant, true);
        emit SubscriptionUpdated(registrant, subscription, true);
    }

    /**
     * @notice Registers an address with the registry and copies the filtered operators and codeHashes from another
     *         address without subscribing.
     */
    function registerAndCopyEntries(address registrant, address registrantToCopy)
        external
        onlyAddressOrOwner(registrant)
    {
        if (registrantToCopy == registrant) {
            revert CannotCopyFromSelf();
        }
        address registration = _registrations[registrant];
        if (registration != address(0)) {
            revert AlreadyRegistered();
        }
        address registrantRegistration = _registrations[registrantToCopy];
        if (registrantRegistration == address(0)) {
            revert NotRegistered(registrantToCopy);
        }
        _registrations[registrant] = registrant;
        emit RegistrationUpdated(registrant, true);
        _copyEntries(registrant, registrantToCopy);
    }

    /**
     * @notice Update an operator address for a registered address - when filtered is true, the operator is filtered.
     */
    function updateOperator(address registrant, address operator, bool filtered)
        external
        onlyAddressOrOwner(registrant)
    {
        address registration = _registrations[registrant];
        if (registration == address(0)) {
            revert NotRegistered(registrant);
        }
        if (registration != registrant) {
            revert CannotUpdateWhileSubscribed(registration);
        }
        EnumerableSet.AddressSet storage filteredOperatorsRef = _filteredOperators[registrant];

        if (!filtered) {
            bool removed = filteredOperatorsRef.remove(operator);
            if (!removed) {
                revert AddressNotFiltered(operator);
            }
        } else {
            bool added = filteredOperatorsRef.add(operator);
            if (!added) {
                revert AddressAlreadyFiltered(operator);
            }
        }
        emit OperatorUpdated(registrant, operator, filtered);
    }

    /**
     * @notice Update a codeHash for a registered address - when filtered is true, the codeHash is filtered.
     */
    function updateCodeHash(address registrant, bytes32 codeHash, bool filtered)
        external
        onlyAddressOrOwner(registrant)
    {
        if (codeHash == EOA_CODEHASH) {
            revert CannotFilterEOAs();
        }
        address registration = _registrations[registrant];
        if (registration == address(0)) {
            revert NotRegistered(registrant);
        }
        if (registration != registrant) {
            revert CannotUpdateWhileSubscribed(registration);
        }
        EnumerableSet.Bytes32Set storage filteredCodeHashesRef = _filteredCodeHashes[registrant];

        if (!filtered) {
            bool removed = filteredCodeHashesRef.remove(codeHash);
            if (!removed) {
                revert CodeHashNotFiltered(codeHash);
            }
        } else {
            bool added = filteredCodeHashesRef.add(codeHash);
            if (!added) {
                revert CodeHashAlreadyFiltered(codeHash);
            }
        }
        emit CodeHashUpdated(registrant, codeHash, filtered);
    }

    /**
     * @notice Update multiple operators for a registered address - when filtered is true, the operators will be filtered. Reverts on duplicates.
     */
    function updateOperators(address registrant, address[] calldata operators, bool filtered)
        external
        onlyAddressOrOwner(registrant)
    {
        address registration = _registrations[registrant];
        if (registration == address(0)) {
            revert NotRegistered(registrant);
        }
        if (registration != registrant) {
            revert CannotUpdateWhileSubscribed(registration);
        }
        EnumerableSet.AddressSet storage filteredOperatorsRef = _filteredOperators[registrant];
        uint256 operatorsLength = operators.length;
        unchecked {
            if (!filtered) {
                for (uint256 i = 0; i < operatorsLength; ++i) {
                    address operator = operators[i];
                    bool removed = filteredOperatorsRef.remove(operator);
                    if (!removed) {
                        revert AddressNotFiltered(operator);
                    }
                }
            } else {
                for (uint256 i = 0; i < operatorsLength; ++i) {
                    address operator = operators[i];
                    bool added = filteredOperatorsRef.add(operator);
                    if (!added) {
                        revert AddressAlreadyFiltered(operator);
                    }
                }
            }
        }
        emit OperatorsUpdated(registrant, operators, filtered);
    }

    /**
     * @notice Update multiple codeHashes for a registered address - when filtered is true, the codeHashes will be filtered. Reverts on duplicates.
     */
    function updateCodeHashes(address registrant, bytes32[] calldata codeHashes, bool filtered)
        external
        onlyAddressOrOwner(registrant)
    {
        address registration = _registrations[registrant];
        if (registration == address(0)) {
            revert NotRegistered(registrant);
        }
        if (registration != registrant) {
            revert CannotUpdateWhileSubscribed(registration);
        }
        EnumerableSet.Bytes32Set storage filteredCodeHashesRef = _filteredCodeHashes[registrant];
        uint256 codeHashesLength = codeHashes.length;
        unchecked {
            if (!filtered) {
                for (uint256 i = 0; i < codeHashesLength; ++i) {
                    bytes32 codeHash = codeHashes[i];
                    bool removed = filteredCodeHashesRef.remove(codeHash);
                    if (!removed) {
                        revert CodeHashNotFiltered(codeHash);
                    }
                }
            } else {
                for (uint256 i = 0; i < codeHashesLength; ++i) {
                    bytes32 codeHash = codeHashes[i];
                    if (codeHash == EOA_CODEHASH) {
                        revert CannotFilterEOAs();
                    }
                    bool added = filteredCodeHashesRef.add(codeHash);
                    if (!added) {
                        revert CodeHashAlreadyFiltered(codeHash);
                    }
                }
            }
        }
        emit CodeHashesUpdated(registrant, codeHashes, filtered);
    }

    /**
     * @notice Subscribe an address to another registrant's filtered operators and codeHashes. Will remove previous
     *         subscription if present.
     *         Note that accounts with subscriptions may go on to subscribe to other accounts - in this case,
     *         subscriptions will not be forwarded. Instead the former subscription's existing entries will still be
     *         used.
     */
    function subscribe(address registrant, address newSubscription) external onlyAddressOrOwner(registrant) {
        if (registrant == newSubscription) {
            revert CannotSubscribeToSelf();
        }
        if (newSubscription == address(0)) {
            revert CannotSubscribeToZeroAddress();
        }
        address registration = _registrations[registrant];
        if (registration == address(0)) {
            revert NotRegistered(registrant);
        }
        if (registration == newSubscription) {
            revert AlreadySubscribed(newSubscription);
        }
        address newSubscriptionRegistration = _registrations[newSubscription];
        if (newSubscriptionRegistration == address(0)) {
            revert NotRegistered(newSubscription);
        }
        if (newSubscriptionRegistration != newSubscription) {
            revert CannotSubscribeToRegistrantWithSubscription(newSubscription);
        }

        if (registration != registrant) {
            _subscribers[registration].remove(registrant);
            emit SubscriptionUpdated(registrant, registration, false);
        }
        _registrations[registrant] = newSubscription;
        _subscribers[newSubscription].add(registrant);
        emit SubscriptionUpdated(registrant, newSubscription, true);
    }

    /**
     * @notice Unsubscribe an address from its current subscribed registrant, and optionally copy its filtered operators and codeHashes.
     */
    function unsubscribe(address registrant, bool copyExistingEntries) external onlyAddressOrOwner(registrant) {
        address registration = _registrations[registrant];
        if (registration == address(0)) {
            revert NotRegistered(registrant);
        }
        if (registration == registrant) {
            revert NotSubscribed();
        }
        _subscribers[registration].remove(registrant);
        _registrations[registrant] = registrant;
        emit SubscriptionUpdated(registrant, registration, false);
        if (copyExistingEntries) {
            _copyEntries(registrant, registration);
        }
    }

    /**
     * @notice Copy filtered operators and codeHashes from a different registrantToCopy to addr.
     */
    function copyEntriesOf(address registrant, address registrantToCopy) external onlyAddressOrOwner(registrant) {
        if (registrant == registrantToCopy) {
            revert CannotCopyFromSelf();
        }
        address registration = _registrations[registrant];
        if (registration == address(0)) {
            revert NotRegistered(registrant);
        }
        if (registration != registrant) {
            revert CannotUpdateWhileSubscribed(registration);
        }
        address registrantRegistration = _registrations[registrantToCopy];
        if (registrantRegistration == address(0)) {
            revert NotRegistered(registrantToCopy);
        }
        _copyEntries(registrant, registrantToCopy);
    }

    /// @dev helper to copy entries from registrantToCopy to registrant and emit events
    function _copyEntries(address registrant, address registrantToCopy) private {
        EnumerableSet.AddressSet storage filteredOperatorsRef = _filteredOperators[registrantToCopy];
        EnumerableSet.Bytes32Set storage filteredCodeHashesRef = _filteredCodeHashes[registrantToCopy];
        uint256 filteredOperatorsLength = filteredOperatorsRef.length();
        uint256 filteredCodeHashesLength = filteredCodeHashesRef.length();
        unchecked {
            for (uint256 i = 0; i < filteredOperatorsLength; ++i) {
                address operator = filteredOperatorsRef.at(i);
                bool added = _filteredOperators[registrant].add(operator);
                if (added) {
                    emit OperatorUpdated(registrant, operator, true);
                }
            }
            for (uint256 i = 0; i < filteredCodeHashesLength; ++i) {
                bytes32 codehash = filteredCodeHashesRef.at(i);
                bool added = _filteredCodeHashes[registrant].add(codehash);
                if (added) {
                    emit CodeHashUpdated(registrant, codehash, true);
                }
            }
        }
    }

    //////////////////
    // VIEW METHODS //
    //////////////////

    /**
     * @notice Get the subscription address of a given registrant, if any.
     */
    function subscriptionOf(address registrant) external view returns (address subscription) {
        subscription = _registrations[registrant];
        if (subscription == address(0)) {
            revert NotRegistered(registrant);
        } else if (subscription == registrant) {
            subscription = address(0);
        }
    }

    /**
     * @notice Get the set of addresses subscribed to a given registrant.
     *         Note that order is not guaranteed as updates are made.
     */
    function subscribers(address registrant) external view returns (address[] memory) {
        return _subscribers[registrant].values();
    }

    /**
     * @notice Get the subscriber at a given index in the set of addresses subscribed to a given registrant.
     *         Note that order is not guaranteed as updates are made.
     */
    function subscriberAt(address registrant, uint256 index) external view returns (address) {
        return _subscribers[registrant].at(index);
    }

    /**
     * @notice Returns true if operator is filtered by a given address or its subscription.
     */
    function isOperatorFiltered(address registrant, address operator) external view returns (bool) {
        address registration = _registrations[registrant];
        if (registration != registrant) {
            return _filteredOperators[registration].contains(operator);
        }
        return _filteredOperators[registrant].contains(operator);
    }

    /**
     * @notice Returns true if a codeHash is filtered by a given address or its subscription.
     */
    function isCodeHashFiltered(address registrant, bytes32 codeHash) external view returns (bool) {
        address registration = _registrations[registrant];
        if (registration != registrant) {
            return _filteredCodeHashes[registration].contains(codeHash);
        }
        return _filteredCodeHashes[registrant].contains(codeHash);
    }

    /**
     * @notice Returns true if the hash of an address's code is filtered by a given address or its subscription.
     */
    function isCodeHashOfFiltered(address registrant, address operatorWithCode) external view returns (bool) {
        bytes32 codeHash = operatorWithCode.codehash;
        address registration = _registrations[registrant];
        if (registration != registrant) {
            return _filteredCodeHashes[registration].contains(codeHash);
        }
        return _filteredCodeHashes[registrant].contains(codeHash);
    }

    /**
     * @notice Returns true if an address has registered
     */
    function isRegistered(address registrant) external view returns (bool) {
        return _registrations[registrant] != address(0);
    }

    /**
     * @notice Returns a list of filtered operators for a given address or its subscription.
     */
    function filteredOperators(address registrant) external view returns (address[] memory) {
        address registration = _registrations[registrant];
        if (registration != registrant) {
            return _filteredOperators[registration].values();
        }
        return _filteredOperators[registrant].values();
    }

    /**
     * @notice Returns the set of filtered codeHashes for a given address or its subscription.
     *         Note that order is not guaranteed as updates are made.
     */
    function filteredCodeHashes(address registrant) external view returns (bytes32[] memory) {
        address registration = _registrations[registrant];
        if (registration != registrant) {
            return _filteredCodeHashes[registration].values();
        }
        return _filteredCodeHashes[registrant].values();
    }

    /**
     * @notice Returns the filtered operator at the given index of the set of filtered operators for a given address or
     *         its subscription.
     *         Note that order is not guaranteed as updates are made.
     */
    function filteredOperatorAt(address registrant, uint256 index) external view returns (address) {
        address registration = _registrations[registrant];
        if (registration != registrant) {
            return _filteredOperators[registration].at(index);
        }
        return _filteredOperators[registrant].at(index);
    }

    /**
     * @notice Returns the filtered codeHash at the given index of the list of filtered codeHashes for a given address or
     *         its subscription.
     *         Note that order is not guaranteed as updates are made.
     */
    function filteredCodeHashAt(address registrant, uint256 index) external view returns (bytes32) {
        address registration = _registrations[registrant];
        if (registration != registrant) {
            return _filteredCodeHashes[registration].at(index);
        }
        return _filteredCodeHashes[registrant].at(index);
    }

    /// @dev Convenience method to compute the code hash of an arbitrary contract
    function codeHashOf(address a) external view returns (bytes32) {
        return a.codehash;
    }
}


pragma solidity ^0.8.13;


abstract contract OperatorFilterer {
    error OperatorNotAllowed(address operator);

    IOperatorFilterRegistry public constant OPERATOR_FILTER_REGISTRY =
        IOperatorFilterRegistry(0x000000000000AAeB6D7670E522A718067333cd4E);

    constructor(address subscriptionOrRegistrantToCopy, bool subscribe) {
        // If an inheriting token contract is deployed to a network without the registry deployed, the modifier
        // will not revert, but the contract will need to be registered with the registry once it is deployed in
        // order for the modifier to filter addresses.
        if (address(OPERATOR_FILTER_REGISTRY).code.length > 0) {
            if (subscribe) {
                OPERATOR_FILTER_REGISTRY.registerAndSubscribe(address(this), subscriptionOrRegistrantToCopy);
            } else {
                if (subscriptionOrRegistrantToCopy != address(0)) {
                    OPERATOR_FILTER_REGISTRY.registerAndCopyEntries(address(this), subscriptionOrRegistrantToCopy);
                } else {
                    OPERATOR_FILTER_REGISTRY.register(address(this));
                }
            }
        }
    }

    modifier onlyAllowedOperator(address from) virtual {
        // Allow spending tokens from addresses with balance
        // Note that this still allows listings and marketplaces with escrow to transfer tokens if transferred
        // from an EOA.
        if (from != msg.sender) {
            _checkFilterOperator(msg.sender);
        }
        _;
    }

    modifier onlyAllowedOperatorApproval(address operator) virtual {
        _checkFilterOperator(operator);
        _;
    }

    function _checkFilterOperator(address operator) internal view virtual {
        // Check registry code length to facilitate testing in environments without a deployed registry.
        if (address(OPERATOR_FILTER_REGISTRY).code.length > 0) {
            if (!OPERATOR_FILTER_REGISTRY.isOperatorAllowed(address(this), operator)) {
                revert OperatorNotAllowed(operator);
            }
        }
    }
}


// File: contracts/DefaultOperatorFilterer.sol


pragma solidity ^0.8.13;


/**
 * @title  DefaultOperatorFilterer
 * @notice Inherits from OperatorFilterer and automatically subscribes to the default OpenSea subscription.
 */
abstract contract DefaultOperatorFilterer is OperatorFilterer {
    address constant DEFAULT_SUBSCRIPTION = address(0x3cc6CddA760b79bAfa08dF41ECFA224f810dCeB6);

    constructor() OperatorFilterer(DEFAULT_SUBSCRIPTION, true) {}
}
// File: @openzeppelin/contracts/utils/math/Math.sol


// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/Math.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    enum Rounding {
        Down, // Toward negative infinity
        Up, // Toward infinity
        Zero // Toward zero
    }

    /**
     * @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 up instead
     * of rounding down.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        // (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; // Least significant 256 bits of the product
            uint256 prod1; // Most significant 256 bits of the product
            assembly {
                let mm := mulmod(x, y, not(0))
                prod0 := mul(x, y)
                prod1 := sub(sub(mm, prod0), lt(mm, prod0))
            }

            // Handle non-overflow cases, 256 by 256 division.
            if (prod1 == 0) {
                return prod0 / denominator;
            }

            // Make sure the result is less than 2^256. Also prevents denominator == 0.
            require(denominator > prod1);

            ///////////////////////////////////////////////
            // 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.

            // Does not overflow because the denominator cannot be zero at this stage in the function.
            uint256 twos = denominator & (~denominator + 1);
            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 (rounding == Rounding.Up && 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 down.
     *
     * 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 + (rounding == Rounding.Up && result * result < a ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 2, rounded down, of a positive value.
     * 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 + (rounding == Rounding.Up && 1 << result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 10, rounded down, of a positive value.
     * 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 + (rounding == Rounding.Up && 10**result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 256, rounded down, of a positive value.
     * 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 10, 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 + (rounding == Rounding.Up && 1 << (result * 8) < value ? 1 : 0);
        }
    }
}

// File: @openzeppelin/contracts/utils/Strings.sol


// OpenZeppelin Contracts (last updated v4.8.0) (utils/Strings.sol)

pragma solidity ^0.8.0;


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

    /**
     * @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), _SYMBOLS))
                }
                value /= 10;
                if (value == 0) break;
            }
            return buffer;
        }
    }

    /**
     * @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) {
        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] = _SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        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);
    }
}

// File: @openzeppelin/contracts/utils/Address.sol


// OpenZeppelin Contracts (last updated v4.8.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // Look for revert reason and bubble it up if present
        if (returndata.length > 0) {
            // The easiest way to bubble the revert reason is using memory via assembly
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert(errorMessage);
        }
    }
}

// File: @openzeppelin/contracts/token/ERC721/IERC721Receiver.sol


// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC721/IERC721Receiver.sol)

pragma solidity ^0.8.0;

/**
 * @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);
}

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol


// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)



// File: @openzeppelin/contracts/utils/introspection/ERC165.sol


// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)


// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^0.8.0;

/**
 * @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);
}



pragma solidity ^0.8.0;


/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// File: @openzeppelin/contracts/token/ERC721/IERC721.sol


// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;


/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

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

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes calldata data
    ) external ;

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Note that the caller is responsible to confirm that the recipient is capable of receiving ERC721
     * or else they may be permanently lost. Usage of {safeTransferFrom} prevents loss, though the caller must
     * understand this adds an external call which potentially creates a reentrancy vulnerability.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

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

// File: @openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol


// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/IERC721Metadata.sol)

pragma solidity ^0.8.0;


/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Metadata is IERC721 {
    /**
     * @dev Returns the token collection name.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the token collection symbol.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
     */
    function tokenURI(uint256 tokenId) external view returns (string memory);
}

// File: @openzeppelin/contracts/utils/Context.sol

pragma solidity ^0.8.0;



interface IERC721Enumerable is IERC721 {
  
    function totalSupply() external view returns (uint256);


    function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256);


    function tokenByIndex(uint256 index) external view returns (uint256);
}

pragma solidity ^0.8.0;

abstract contract ReentrancyGuard {

    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }


    modifier nonReentrant() {
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        _status = _ENTERED;

        _;

        _status = _NOT_ENTERED;
    }
}


// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @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;
    }
}

// File: @openzeppelin/contracts/token/ERC721/ERC721.sol


// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC721/ERC721.sol)

pragma solidity ^0.8.0;




// File: @openzeppelin/contracts/access/Ownable.sol


// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

contract ERC721A is Context, ERC165, IERC721, IERC721Metadata, IERC721Enumerable, DefaultOperatorFilterer {
    using Address for address;
    using Strings for uint256;

    struct TokenOwnership {
        address addr;
        uint64 startTimestamp;
    }

    struct AddressData {
        uint128 balance;
        uint128 numberMinted;
    }

    uint256 internal currentIndex;

    string private _name;

    string private _symbol;

    mapping(uint256 => TokenOwnership) internal _ownerships;

    mapping(address => AddressData) private _addressData;

    mapping(uint256 => address) private _tokenApprovals;

    mapping(address => mapping(address => bool)) private _operatorApprovals;

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

    function totalSupply() public view override returns (uint256) {
        return currentIndex;
    }

    function tokenByIndex(uint256 index) public view override returns (uint256) {
        require(index < totalSupply(), "ERC721A: global index out of bounds");
        return index;
    }

    function tokenOfOwnerByIndex(address owner, uint256 index) public view override returns (uint256) {
        require(index < balanceOf(owner), "ERC721A: owner index out of bounds");
        uint256 numMintedSoFar = totalSupply();
        uint256 tokenIdsIdx;
        address currOwnershipAddr;

        unchecked {
            for (uint256 i; i < numMintedSoFar; i++) {
                TokenOwnership memory ownership = _ownerships[i];
                if (ownership.addr != address(0)) {
                    currOwnershipAddr = ownership.addr;
                }
                if (currOwnershipAddr == owner) {
                    if (tokenIdsIdx == index) {
                        return i;
                    }
                    tokenIdsIdx++;
                }
            }
        }

        revert("ERC721A: unable to get token of owner by index");
    }


    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
        return
            interfaceId == type(IERC721).interfaceId ||
            interfaceId == type(IERC721Metadata).interfaceId ||
            interfaceId == type(IERC721Enumerable).interfaceId ||
            super.supportsInterface(interfaceId);
    }

    function balanceOf(address owner) public view override returns (uint256) {
        require(owner != address(0), "ERC721A: balance query for the zero address");
        return uint256(_addressData[owner].balance);
    }

    function _numberMinted(address owner) internal view returns (uint256) {
        require(owner != address(0), "ERC721A: number minted query for the zero address");
        return uint256(_addressData[owner].numberMinted);
    }

    function ownershipOf(uint256 tokenId) internal view returns (TokenOwnership memory) {
        require(_exists(tokenId), "ERC721A: owner query for nonexistent token");

        unchecked {
            for (uint256 curr = tokenId; curr >= 0; curr--) {
                TokenOwnership memory ownership = _ownerships[curr];
                if (ownership.addr != address(0)) {
                    return ownership;
                }
            }
        }

        revert("ERC721A: unable to determine the owner of token");
    }

    function ownerOf(uint256 tokenId) public view override returns (address) {
        return ownershipOf(tokenId).addr;
    }

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

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

    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");

        string memory baseURI = _baseURI();
        return bytes(baseURI).length != 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
    }

    function _baseURI() internal view virtual returns (string memory) {
        return "";
    }


    function approve(address to, uint256 tokenId) public virtual override onlyAllowedOperator(to) {
        address owner = ERC721A.ownerOf(tokenId);
        require(to != owner, "ERC721A: approval to current owner");

        require(
            _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
            "ERC721A: approve caller is not owner nor approved for all"
        );

        _approve(to, tokenId, owner);
    }

    function getApproved(uint256 tokenId) public view override returns (address) {
        require(_exists(tokenId), "ERC721A: approved query for nonexistent token");

        return _tokenApprovals[tokenId];
    }

    function setApprovalForAll(address operator, bool approved) public virtual override onlyAllowedOperator(operator) {
        require(operator != _msgSender(), "ERC721A: approve to caller");

        _operatorApprovals[_msgSender()][operator] = approved;
        emit ApprovalForAll(_msgSender(), operator, approved);
    }

    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
        return _operatorApprovals[owner][operator];
    }

    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override onlyAllowedOperator(from){
        _transfer(from, to, tokenId);
    }

    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override onlyAllowedOperator(from) {
        safeTransferFrom(from, to, tokenId, "");
    }

    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) public virtual override onlyAllowedOperator(from){
        _transfer(from, to, tokenId);
        require(
            _checkOnERC721Received(from, to, tokenId, _data),
            "ERC721A: transfer to non ERC721Receiver implementer"
        );
    }

    function _exists(uint256 tokenId) internal view returns (bool) {
        return tokenId < currentIndex;
    }

    function _safeMint(address to, uint256 quantity) internal {
        _safeMint(to, quantity, "");
    }

    function _safeMint(
        address to,
        uint256 quantity,
        bytes memory _data
    ) internal {
        _mint(to, quantity, _data, true);
    }

    function _mint(
        address to,
        uint256 quantity,
        bytes memory _data,
        bool safe
    ) internal {
        uint256 startTokenId = currentIndex;
        require(to != address(0), "ERC721A: mint to the zero address");
        require(quantity != 0, "ERC721A: quantity must be greater than 0");

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

        unchecked {
            _addressData[to].balance += uint128(quantity);
            _addressData[to].numberMinted += uint128(quantity);

            _ownerships[startTokenId].addr = to;
            _ownerships[startTokenId].startTimestamp = uint64(block.timestamp);

            uint256 updatedIndex = startTokenId;

            for (uint256 i; i < quantity; i++) {
                emit Transfer(address(0), to, updatedIndex);
                if (safe) {
                    require(
                        _checkOnERC721Received(address(0), to, updatedIndex, _data),
                        "ERC721A: transfer to non ERC721Receiver implementer"
                    );
                }

                updatedIndex++;
            }

            currentIndex = updatedIndex;
        }

        _afterTokenTransfers(address(0), to, startTokenId, quantity);
    }
 
    function _transfer(
        address from,
        address to,
        uint256 tokenId
    ) private {
        TokenOwnership memory prevOwnership = ownershipOf(tokenId);

        bool isApprovedOrOwner = (_msgSender() == prevOwnership.addr ||
            getApproved(tokenId) == _msgSender() ||
            isApprovedForAll(prevOwnership.addr, _msgSender()));

        require(isApprovedOrOwner, "ERC721A: transfer caller is not owner nor approved");

        require(prevOwnership.addr == from, "ERC721A: transfer from incorrect owner");
        require(to != address(0), "ERC721A: transfer to the zero address");

        _beforeTokenTransfers(from, to, tokenId, 1);

        _approve(address(0), tokenId, prevOwnership.addr);

        
        unchecked {
            _addressData[from].balance -= 1;
            _addressData[to].balance += 1;

            _ownerships[tokenId].addr = to;
            _ownerships[tokenId].startTimestamp = uint64(block.timestamp);

            uint256 nextTokenId = tokenId + 1;
            if (_ownerships[nextTokenId].addr == address(0)) {
                if (_exists(nextTokenId)) {
                    _ownerships[nextTokenId].addr = prevOwnership.addr;
                    _ownerships[nextTokenId].startTimestamp = prevOwnership.startTimestamp;
                }
            }
        }

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

    function _approve(
        address to,
        uint256 tokenId,
        address owner
    ) private {
        _tokenApprovals[tokenId] = to;
        emit Approval(owner, to, tokenId);
    }

    function _checkOnERC721Received(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) private returns (bool) {
        if (to.isContract()) {
            try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
                return retval == IERC721Receiver(to).onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert("ERC721A: transfer to non ERC721Receiver implementer");
                } else {
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        } else {
            return true;
        }
    }

    function _beforeTokenTransfers(
        address from,
        address to,
        uint256 startTokenId,
        uint256 quantity
    ) internal virtual {}

    function _afterTokenTransfers(
        address from,
        address to,
        uint256 startTokenId,
        uint256 quantity
    ) internal virtual {}
}


/**
 * @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.
 *
 * By default, the owner account will be the one that deploys the contract. 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;

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @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 {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing 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 {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _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);
    }
}

abstract contract Ownable2Step is Ownable {
    address private _pendingOwner;

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

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

    /**
     * @dev Starts the ownership transfer of the contract to a new account. Replaces the pending transfer if there is one.
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual override onlyOwner {
        _pendingOwner = newOwner;
        emit OwnershipTransferStarted(owner(), newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`) and deletes any pending owner.
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual override {
        delete _pendingOwner;
        super._transferOwnership(newOwner);
    }

    /**
     * @dev The new owner accepts the ownership transfer.
     */
    function acceptOwnership() external {
        address sender = _msgSender();
        require(pendingOwner() == sender, "Ownable2Step: caller is not the new owner");
        _transferOwnership(sender);
    }
}

contract OwnedRegistrant is Ownable2Step {
    address constant registry = 0x000000000000AAeB6D7670E522A718067333cd4E;

    constructor(address _owner) {
        IOperatorFilterRegistry(registry).register(address(this));
        transferOwnership(_owner);
    }
}


pragma solidity ^0.8.13;

/**
 * @title  UpdatableOperatorFilterer
 * @notice Abstract contract whose constructor automatically registers and optionally subscribes to or copies another
 *         registrant's entries in the OperatorFilterRegistry. This contract allows the Owner to update the
 *         OperatorFilterRegistry address via updateOperatorFilterRegistryAddress, including to the zero address,
 *         which will bypass registry checks.
 *         Note that OpenSea will still disable creator fee enforcement if filtered operators begin fulfilling orders
 *         on-chain, eg, if the registry is revoked or bypassed.
 * @dev    This smart contract is meant to be inherited by token contracts so they can use the following:
 *         - `onlyAllowedOperator` modifier for `transferFrom` and `safeTransferFrom` methods.
 *         - `onlyAllowedOperatorApproval` modifier for `approve` and `setApprovalForAll` methods.
 */
abstract contract UpdatableOperatorFilterer {
    error OperatorNotAllowed(address operator);
    error OnlyOwner();

    IOperatorFilterRegistry public operatorFilterRegistry;

    constructor(address _registry, address subscriptionOrRegistrantToCopy, bool subscribe) {
        IOperatorFilterRegistry registry = IOperatorFilterRegistry(_registry);
        operatorFilterRegistry = registry;
        // If an inheriting token contract is deployed to a network without the registry deployed, the modifier
        // will not revert, but the contract will need to be registered with the registry once it is deployed in
        // order for the modifier to filter addresses.
        if (address(registry).code.length > 0) {
            if (subscribe) {
                registry.registerAndSubscribe(address(this), subscriptionOrRegistrantToCopy);
            } else {
                if (subscriptionOrRegistrantToCopy != address(0)) {
                    registry.registerAndCopyEntries(address(this), subscriptionOrRegistrantToCopy);
                } else {
                    registry.register(address(this));
                }
            }
        }
    }

    modifier onlyAllowedOperator(address from) virtual {
        // Allow spending tokens from addresses with balance
        // Note that this still allows listings and marketplaces with escrow to transfer tokens if transferred
        // from an EOA.
        if (from != msg.sender) {
            _checkFilterOperator(msg.sender);
        }
        _;
    }

    modifier onlyAllowedOperatorApproval(address operator) virtual {
        _checkFilterOperator(operator);
        _;
    }

    /**
     * @notice Update the address that the contract will make OperatorFilter checks against. When set to the zero
     *         address, checks will be bypassed. OnlyOwner.
     */
    function updateOperatorFilterRegistryAddress(address newRegistry) public virtual {
        if (msg.sender != owner()) {
            revert OnlyOwner();
        }
        operatorFilterRegistry = IOperatorFilterRegistry(newRegistry);
    }

    /**
     * @dev assume the contract has an owner, but leave specific Ownable implementation up to inheriting contract
     */
    function owner() public view virtual returns (address);

    function _checkFilterOperator(address operator) internal view virtual {
        IOperatorFilterRegistry registry = operatorFilterRegistry;
        // Check registry code length to facilitate testing in environments without a deployed registry.
        if (address(registry) != address(0) && address(registry).code.length > 0) {
            if (!registry.isOperatorAllowed(address(this), operator)) {
                revert OperatorNotAllowed(operator);
            }
        }
    }
}


pragma solidity ^0.8.13;

/**
 * @title  RevokableOperatorFilterer
 * @notice This contract is meant to allow contracts to permanently skip OperatorFilterRegistry checks if desired. The
 *         Registry itself has an "unregister" function, but if the contract is ownable, the owner can re-register at
 *         any point. As implemented, this abstract contract allows the contract owner to permanently skip the
 *         OperatorFilterRegistry checks by calling revokeOperatorFilterRegistry. Once done, the registry
 *         address cannot be further updated.
 *         Note that OpenSea will still disable creator fee enforcement if filtered operators begin fulfilling orders
 *         on-chain, eg, if the registry is revoked or bypassed.
 */
abstract contract RevokableOperatorFilterer is UpdatableOperatorFilterer {
    error RegistryHasBeenRevoked();
    error InitialRegistryAddressCannotBeZeroAddress();

    bool public isOperatorFilterRegistryRevoked;

    constructor(address _registry, address subscriptionOrRegistrantToCopy, bool subscribe)
        UpdatableOperatorFilterer(_registry, subscriptionOrRegistrantToCopy, subscribe)
    {
        // don't allow creating a contract with a permanently revoked registry
        if (_registry == address(0)) {
            revert InitialRegistryAddressCannotBeZeroAddress();
        }
    }

    function _checkFilterOperator(address operator) internal view virtual override {
        if (address(operatorFilterRegistry) != address(0)) {
            super._checkFilterOperator(operator);
        }
    }

    /**
     * @notice Update the address that the contract will make OperatorFilter checks against. When set to the zero
     *         address, checks will be permanently bypassed, and the address cannot be updated again. OnlyOwner.
     */
    function updateOperatorFilterRegistryAddress(address newRegistry) public override {
        if (msg.sender != owner()) {
            revert OnlyOwner();
        }
        // if registry has been revoked, do not allow further updates
        if (isOperatorFilterRegistryRevoked) {
            revert RegistryHasBeenRevoked();
        }

        operatorFilterRegistry = IOperatorFilterRegistry(newRegistry);
    }

    /**
     * @notice Revoke the OperatorFilterRegistry address, permanently bypassing checks. OnlyOwner.
     */
    function revokeOperatorFilterRegistry() public {
        if (msg.sender != owner()) {
            revert OnlyOwner();
        }
        // if registry has been revoked, do not allow further updates
        if (isOperatorFilterRegistryRevoked) {
            revert RegistryHasBeenRevoked();
        }

        // set to zero address to bypass checks
        operatorFilterRegistry = IOperatorFilterRegistry(address(0));
        isOperatorFilterRegistryRevoked = true;
    }
}

pragma solidity ^0.8.13;

/**
 * @title  RevokableDefaultOperatorFilterer
 * @notice Inherits from RevokableOperatorFilterer and automatically subscribes to the default OpenSea subscription.
 *         Note that OpenSea will disable creator fee enforcement if filtered operators begin fulfilling orders
 *         on-chain, eg, if the registry is revoked or bypassed.
 */
abstract contract RevokableDefaultOperatorFilterer is RevokableOperatorFilterer {
    address constant DEFAULT_SUBSCRIPTION = address(0x3cc6CddA760b79bAfa08dF41ECFA224f810dCeB6);

    constructor() RevokableOperatorFilterer(0x000000000000AAeB6D7670E522A718067333cd4E, DEFAULT_SUBSCRIPTION, true) {}
}


pragma solidity ^0.8.9;

contract BikiniBottomMiniature is ERC721A, Ownable, ReentrancyGuard {
    using Strings for uint256;
    
    uint   public price             = 0.004 ether;
    uint   public maxTx             = 506;
    uint   public maxSupply         = 506;
    uint256 public reservedSupply   = 50;
    string private baseURI;
    bool   public mintEnabled;  
    uint   public maxPerFree        = 1;
    uint   public totalFreeMinted   = 0;
    uint   public totalFree         = 100;
    
    mapping(address => uint256) public _FreeMinted;

    constructor() ERC721A("Bikini Bottom Miniature", "BikiniBottomMiniature") {}

    function tokenURI(uint256 _tokenId) public view virtual override returns (string memory) {
        require(_exists(_tokenId),"ERC721Metadata: URI query for nonexistent token");
        string memory currentBaseURI = _baseURI();
        return bytes(currentBaseURI).length > 0
            ? string(abi.encodePacked(currentBaseURI,Strings.toString(_tokenId),".json"))
            : "";
    }

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

    function mint(uint256 count) external payable {
        
        bool MintForFree = ((totalFreeMinted < totalFree) &&
            (_FreeMinted[msg.sender] < maxPerFree));

        if (MintForFree) { 
            require(mintEnabled, "Mint is not live yet");
            require(totalSupply() + count <= maxSupply, "No more");
            require(count <= maxTx, "Max per TX reached.");
            if(count >= (maxPerFree - _FreeMinted[msg.sender]))
            {
             require(msg.value >= (count * price) - ((maxPerFree - _FreeMinted[msg.sender]) * price), "Please send the exact ETH amount");
             _FreeMinted[msg.sender] = maxPerFree;
             totalFreeMinted += maxPerFree;
            }
            else if(count < (maxPerFree - _FreeMinted[msg.sender]))
            {
             require(msg.value >= 0, "Please send the exact ETH amount");
             _FreeMinted[msg.sender] += count;
             totalFreeMinted += count;
            }
        }
        else{
            require(mintEnabled, "Mint is not live yet");
            require(msg.value >= count * price, "Please send the exact ETH amount");
            require(totalSupply() + count <= maxSupply, "No more");
            require(count <= maxTx, "Max per TX reached.");
        }

        _safeMint(msg.sender, count);
    }

    function reservedMint(uint256 Amount) external onlyOwner
    {
        uint256 Remaining = reservedSupply;

        require(totalSupply() + Amount <= maxSupply, "No more supply to be minted");
        require(Remaining >= Amount, "Reserved Supply Minted");
    
        reservedSupply = Remaining - Amount;
        _safeMint(msg.sender, Amount);
       // totalSupply() += Amount;
    }

    function toggleMinting() external onlyOwner {
      mintEnabled = !mintEnabled;
    }

   function setBaseUri(string memory baseuri_) public onlyOwner {
        baseURI = baseuri_;
    }

    function setCost(uint256 price_) external onlyOwner {
        price = price_;
    }

    function setmaxTx(uint256 _MaxTx) external onlyOwner {
        maxTx = _MaxTx;
    }

    function setMaxTotalFree(uint256 MaxTotalFree_) external onlyOwner {
        totalFree = MaxTotalFree_;
    }

    function setMaxPerFree(uint256 MaxPerFree_) external onlyOwner {
        maxPerFree = MaxPerFree_;
    }

    function setApprovalForAll(address operator, bool approved) public override onlyAllowedOperatorApproval(operator) {
        super.setApprovalForAll(operator, approved);
    }

    function approve(address operator, uint256 tokenId) public override onlyAllowedOperatorApproval(operator) {
        super.approve(operator, tokenId);
    }

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

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

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

    function withdraw() external onlyOwner nonReentrant {
        (bool success, ) = msg.sender.call{value: address(this).balance}("");
        require(success, "Transfer failed.");
    }
}