organized_contracts/0c/0c0ac1ec0b9261cd14d39647678f6423de01bbf3524231e8851b84cd75e5e4cf/main.sol

// This contract is part of Zellic’s smart contract dataset, which is a collection of publicly available contract code gathered as of March 2023.

// File: @openzeppelin/contracts-upgradeable/utils/StorageSlotUpgradeable.sol


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

pragma solidity ^0.8.0;

/**

 * @dev Library for reading and writing primitive types to specific storage slots.

 *

 * Storage slots are often used to avoid storage conflict when dealing with upgradeable contracts.

 * This library helps with reading and writing to such slots without the need for inline assembly.

 *

 * The functions in this library return Slot structs that contain a `value` member that can be used to read or write.

 *

 * Example usage to set ERC1967 implementation slot:

 * ```

 * contract ERC1967 {

 *     bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;

 *

 *     function _getImplementation() internal view returns (address) {

 *         return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;

 *     }

 *

 *     function _setImplementation(address newImplementation) internal {

 *         require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");

 *         StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;

 *     }

 * }

 * ```

 *

 * _Available since v4.1 for `address`, `bool`, `bytes32`, and `uint256`._

 */
library StorageSlotUpgradeable {
    struct AddressSlot {
        address value;
    }

    struct BooleanSlot {
        bool value;
    }

    struct Bytes32Slot {
        bytes32 value;
    }

    struct Uint256Slot {
        uint256 value;
    }

    /**

     * @dev Returns an `AddressSlot` with member `value` located at `slot`.

     */
    function getAddressSlot(bytes32 slot) internal pure returns (AddressSlot storage r) {
        assembly {
            r.slot := slot
        }
    }

    /**

     * @dev Returns an `BooleanSlot` with member `value` located at `slot`.

     */
    function getBooleanSlot(bytes32 slot) internal pure returns (BooleanSlot storage r) {
        assembly {
            r.slot := slot
        }
    }

    /**

     * @dev Returns an `Bytes32Slot` with member `value` located at `slot`.

     */
    function getBytes32Slot(bytes32 slot) internal pure returns (Bytes32Slot storage r) {
        assembly {
            r.slot := slot
        }
    }

    /**

     * @dev Returns an `Uint256Slot` with member `value` located at `slot`.

     */
    function getUint256Slot(bytes32 slot) internal pure returns (Uint256Slot storage r) {
        assembly {
            r.slot := slot
        }
    }
}

// File: @openzeppelin/contracts-upgradeable/proxy/beacon/IBeaconUpgradeable.sol


// OpenZeppelin Contracts v4.4.1 (proxy/beacon/IBeacon.sol)

pragma solidity ^0.8.0;

/**

 * @dev This is the interface that {BeaconProxy} expects of its beacon.

 */
interface IBeaconUpgradeable {
    /**

     * @dev Must return an address that can be used as a delegate call target.

     *

     * {BeaconProxy} will check that this address is a contract.

     */
    function implementation() external view returns (address);
}

// File: @openzeppelin/contracts-upgradeable/interfaces/draft-IERC1822Upgradeable.sol


// OpenZeppelin Contracts (last updated v4.5.0) (interfaces/draft-IERC1822.sol)

pragma solidity ^0.8.0;

/**

 * @dev ERC1822: Universal Upgradeable Proxy Standard (UUPS) documents a method for upgradeability through a simplified

 * proxy whose upgrades are fully controlled by the current implementation.

 */
interface IERC1822ProxiableUpgradeable {
    /**

     * @dev Returns the storage slot that the proxiable contract assumes is being used to store the implementation

     * address.

     *

     * IMPORTANT: A proxy pointing at a proxiable contract should not be considered proxiable itself, because this risks

     * bricking a proxy that upgrades to it, by delegating to itself until out of gas. Thus it is critical that this

     * function revert if invoked through a proxy.

     */
    function proxiableUUID() external view returns (bytes32);
}

// File: @openzeppelin/contracts-upgradeable/utils/StringsUpgradeable.sol


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

pragma solidity ^0.8.0;

/**

 * @dev String operations.

 */
library StringsUpgradeable {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

    /**

     * @dev Converts a `uint256` to its ASCII `string` decimal representation.

     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**

     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.

     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**

     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.

     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _HEX_SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }
}

// File: @openzeppelin/contracts-upgradeable/utils/AddressUpgradeable.sol


// OpenZeppelin Contracts (last updated v4.5.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**

 * @dev Collection of functions related to the address type

 */
library AddressUpgradeable {
    /**

     * @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 functionCall(target, data, "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");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(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) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**

     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the

     * revert reason 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 {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol


// OpenZeppelin Contracts (last updated v4.6.0) (proxy/utils/Initializable.sol)

pragma solidity ^0.8.2;


/**

 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed

 * behind a proxy. Since proxied contracts do not make use of a constructor, it's common to move constructor logic to an

 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer

 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.

 *

 * The initialization functions use a version number. Once a version number is used, it is consumed and cannot be

 * reused. This mechanism prevents re-execution of each "step" but allows the creation of new initialization steps in

 * case an upgrade adds a module that needs to be initialized.

 *

 * For example:

 *

 * [.hljs-theme-light.nopadding]

 * ```

 * contract MyToken is ERC20Upgradeable {

 *     function initialize() initializer public {

 *         __ERC20_init("MyToken", "MTK");

 *     }

 * }

 * contract MyTokenV2 is MyToken, ERC20PermitUpgradeable {

 *     function initializeV2() reinitializer(2) public {

 *         __ERC20Permit_init("MyToken");

 *     }

 * }

 * ```

 *

 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as

 * possible by providing the encoded function call as the `_data` argument to {ERC1967Proxy-constructor}.

 *

 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure

 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.

 *

 * [CAUTION]

 * ====

 * Avoid leaving a contract uninitialized.

 *

 * An uninitialized contract can be taken over by an attacker. This applies to both a proxy and its implementation

 * contract, which may impact the proxy. To prevent the implementation contract from being used, you should invoke

 * the {_disableInitializers} function in the constructor to automatically lock it when it is deployed:

 *

 * [.hljs-theme-light.nopadding]

 * ```

 * /// @custom:oz-upgrades-unsafe-allow constructor

 * constructor() {

 *     _disableInitializers();

 * }

 * ```

 * ====

 */
abstract contract Initializable {
    /**

     * @dev Indicates that the contract has been initialized.

     * @custom:oz-retyped-from bool

     */
    uint8 private _initialized;

    /**

     * @dev Indicates that the contract is in the process of being initialized.

     */
    bool private _initializing;

    /**

     * @dev Triggered when the contract has been initialized or reinitialized.

     */
    event Initialized(uint8 version);

    /**

     * @dev A modifier that defines a protected initializer function that can be invoked at most once. In its scope,

     * `onlyInitializing` functions can be used to initialize parent contracts. Equivalent to `reinitializer(1)`.

     */
    modifier initializer() {
        bool isTopLevelCall = _setInitializedVersion(1);
        if (isTopLevelCall) {
            _initializing = true;
        }
        _;
        if (isTopLevelCall) {
            _initializing = false;
            emit Initialized(1);
        }
    }

    /**

     * @dev A modifier that defines a protected reinitializer function that can be invoked at most once, and only if the

     * contract hasn't been initialized to a greater version before. In its scope, `onlyInitializing` functions can be

     * used to initialize parent contracts.

     *

     * `initializer` is equivalent to `reinitializer(1)`, so a reinitializer may be used after the original

     * initialization step. This is essential to configure modules that are added through upgrades and that require

     * initialization.

     *

     * Note that versions can jump in increments greater than 1; this implies that if multiple reinitializers coexist in

     * a contract, executing them in the right order is up to the developer or operator.

     */
    modifier reinitializer(uint8 version) {
        bool isTopLevelCall = _setInitializedVersion(version);
        if (isTopLevelCall) {
            _initializing = true;
        }
        _;
        if (isTopLevelCall) {
            _initializing = false;
            emit Initialized(version);
        }
    }

    /**

     * @dev Modifier to protect an initialization function so that it can only be invoked by functions with the

     * {initializer} and {reinitializer} modifiers, directly or indirectly.

     */
    modifier onlyInitializing() {
        require(_initializing, "Initializable: contract is not initializing");
        _;
    }

    /**

     * @dev Locks the contract, preventing any future reinitialization. This cannot be part of an initializer call.

     * Calling this in the constructor of a contract will prevent that contract from being initialized or reinitialized

     * to any version. It is recommended to use this to lock implementation contracts that are designed to be called

     * through proxies.

     */
    function _disableInitializers() internal virtual {
        _setInitializedVersion(type(uint8).max);
    }

    function _setInitializedVersion(uint8 version) private returns (bool) {
        // If the contract is initializing we ignore whether _initialized is set in order to support multiple
        // inheritance patterns, but we only do this in the context of a constructor, and for the lowest level
        // of initializers, because in other contexts the contract may have been reentered.
        if (_initializing) {
            require(
                version == 1 && !AddressUpgradeable.isContract(address(this)),
                "Initializable: contract is already initialized"
            );
            return false;
        } else {
            require(_initialized < version, "Initializable: contract is already initialized");
            _initialized = version;
            return true;
        }
    }
}

// File: @openzeppelin/contracts-upgradeable/proxy/ERC1967/ERC1967UpgradeUpgradeable.sol


// OpenZeppelin Contracts (last updated v4.5.0) (proxy/ERC1967/ERC1967Upgrade.sol)

pragma solidity ^0.8.2;






/**

 * @dev This abstract contract provides getters and event emitting update functions for

 * https://eips.ethereum.org/EIPS/eip-1967[EIP1967] slots.

 *

 * _Available since v4.1._

 *

 * @custom:oz-upgrades-unsafe-allow delegatecall

 */
abstract contract ERC1967UpgradeUpgradeable is Initializable {
    function __ERC1967Upgrade_init() internal onlyInitializing {
    }

    function __ERC1967Upgrade_init_unchained() internal onlyInitializing {
    }
    // This is the keccak-256 hash of "eip1967.proxy.rollback" subtracted by 1
    bytes32 private constant _ROLLBACK_SLOT = 0x4910fdfa16fed3260ed0e7147f7cc6da11a60208b5b9406d12a635614ffd9143;

    /**

     * @dev Storage slot with the address of the current implementation.

     * This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is

     * validated in the constructor.

     */
    bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;

    /**

     * @dev Emitted when the implementation is upgraded.

     */
    event Upgraded(address indexed implementation);

    /**

     * @dev Returns the current implementation address.

     */
    function _getImplementation() internal view returns (address) {
        return StorageSlotUpgradeable.getAddressSlot(_IMPLEMENTATION_SLOT).value;
    }

    /**

     * @dev Stores a new address in the EIP1967 implementation slot.

     */
    function _setImplementation(address newImplementation) private {
        require(AddressUpgradeable.isContract(newImplementation), "ERC1967: new implementation is not a contract");
        StorageSlotUpgradeable.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
    }

    /**

     * @dev Perform implementation upgrade

     *

     * Emits an {Upgraded} event.

     */
    function _upgradeTo(address newImplementation) internal {
        _setImplementation(newImplementation);
        emit Upgraded(newImplementation);
    }

    /**

     * @dev Perform implementation upgrade with additional setup call.

     *

     * Emits an {Upgraded} event.

     */
    function _upgradeToAndCall(
        address newImplementation,
        bytes memory data,
        bool forceCall
    ) internal {
        _upgradeTo(newImplementation);
        if (data.length > 0 || forceCall) {
            _functionDelegateCall(newImplementation, data);
        }
    }

    /**

     * @dev Perform implementation upgrade with security checks for UUPS proxies, and additional setup call.

     *

     * Emits an {Upgraded} event.

     */
    function _upgradeToAndCallUUPS(
        address newImplementation,
        bytes memory data,
        bool forceCall
    ) internal {
        // Upgrades from old implementations will perform a rollback test. This test requires the new
        // implementation to upgrade back to the old, non-ERC1822 compliant, implementation. Removing
        // this special case will break upgrade paths from old UUPS implementation to new ones.
        if (StorageSlotUpgradeable.getBooleanSlot(_ROLLBACK_SLOT).value) {
            _setImplementation(newImplementation);
        } else {
            try IERC1822ProxiableUpgradeable(newImplementation).proxiableUUID() returns (bytes32 slot) {
                require(slot == _IMPLEMENTATION_SLOT, "ERC1967Upgrade: unsupported proxiableUUID");
            } catch {
                revert("ERC1967Upgrade: new implementation is not UUPS");
            }
            _upgradeToAndCall(newImplementation, data, forceCall);
        }
    }

    /**

     * @dev Storage slot with the admin of the contract.

     * This is the keccak-256 hash of "eip1967.proxy.admin" subtracted by 1, and is

     * validated in the constructor.

     */
    bytes32 internal constant _ADMIN_SLOT = 0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103;

    /**

     * @dev Emitted when the admin account has changed.

     */
    event AdminChanged(address previousAdmin, address newAdmin);

    /**

     * @dev Returns the current admin.

     */
    function _getAdmin() internal view returns (address) {
        return StorageSlotUpgradeable.getAddressSlot(_ADMIN_SLOT).value;
    }

    /**

     * @dev Stores a new address in the EIP1967 admin slot.

     */
    function _setAdmin(address newAdmin) private {
        require(newAdmin != address(0), "ERC1967: new admin is the zero address");
        StorageSlotUpgradeable.getAddressSlot(_ADMIN_SLOT).value = newAdmin;
    }

    /**

     * @dev Changes the admin of the proxy.

     *

     * Emits an {AdminChanged} event.

     */
    function _changeAdmin(address newAdmin) internal {
        emit AdminChanged(_getAdmin(), newAdmin);
        _setAdmin(newAdmin);
    }

    /**

     * @dev The storage slot of the UpgradeableBeacon contract which defines the implementation for this proxy.

     * This is bytes32(uint256(keccak256('eip1967.proxy.beacon')) - 1)) and is validated in the constructor.

     */
    bytes32 internal constant _BEACON_SLOT = 0xa3f0ad74e5423aebfd80d3ef4346578335a9a72aeaee59ff6cb3582b35133d50;

    /**

     * @dev Emitted when the beacon is upgraded.

     */
    event BeaconUpgraded(address indexed beacon);

    /**

     * @dev Returns the current beacon.

     */
    function _getBeacon() internal view returns (address) {
        return StorageSlotUpgradeable.getAddressSlot(_BEACON_SLOT).value;
    }

    /**

     * @dev Stores a new beacon in the EIP1967 beacon slot.

     */
    function _setBeacon(address newBeacon) private {
        require(AddressUpgradeable.isContract(newBeacon), "ERC1967: new beacon is not a contract");
        require(
            AddressUpgradeable.isContract(IBeaconUpgradeable(newBeacon).implementation()),
            "ERC1967: beacon implementation is not a contract"
        );
        StorageSlotUpgradeable.getAddressSlot(_BEACON_SLOT).value = newBeacon;
    }

    /**

     * @dev Perform beacon upgrade with additional setup call. Note: This upgrades the address of the beacon, it does

     * not upgrade the implementation contained in the beacon (see {UpgradeableBeacon-_setImplementation} for that).

     *

     * Emits a {BeaconUpgraded} event.

     */
    function _upgradeBeaconToAndCall(
        address newBeacon,
        bytes memory data,
        bool forceCall
    ) internal {
        _setBeacon(newBeacon);
        emit BeaconUpgraded(newBeacon);
        if (data.length > 0 || forceCall) {
            _functionDelegateCall(IBeaconUpgradeable(newBeacon).implementation(), data);
        }
    }

    /**

     * @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) private returns (bytes memory) {
        require(AddressUpgradeable.isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return AddressUpgradeable.verifyCallResult(success, returndata, "Address: low-level delegate call failed");
    }

    /**

     * @dev This empty reserved space is put in place to allow future versions to add new

     * variables without shifting down storage in the inheritance chain.

     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps

     */
    uint256[50] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol


// OpenZeppelin Contracts (last updated v4.5.0) (proxy/utils/UUPSUpgradeable.sol)

pragma solidity ^0.8.0;




/**

 * @dev An upgradeability mechanism designed for UUPS proxies. The functions included here can perform an upgrade of an

 * {ERC1967Proxy}, when this contract is set as the implementation behind such a proxy.

 *

 * A security mechanism ensures that an upgrade does not turn off upgradeability accidentally, although this risk is

 * reinstated if the upgrade retains upgradeability but removes the security mechanism, e.g. by replacing

 * `UUPSUpgradeable` with a custom implementation of upgrades.

 *

 * The {_authorizeUpgrade} function must be overridden to include access restriction to the upgrade mechanism.

 *

 * _Available since v4.1._

 */
abstract contract UUPSUpgradeable is Initializable, IERC1822ProxiableUpgradeable, ERC1967UpgradeUpgradeable {
    function __UUPSUpgradeable_init() internal onlyInitializing {
    }

    function __UUPSUpgradeable_init_unchained() internal onlyInitializing {
    }
    /// @custom:oz-upgrades-unsafe-allow state-variable-immutable state-variable-assignment
    address private immutable __self = address(this);

    /**

     * @dev Check that the execution is being performed through a delegatecall call and that the execution context is

     * a proxy contract with an implementation (as defined in ERC1967) pointing to self. This should only be the case

     * for UUPS and transparent proxies that are using the current contract as their implementation. Execution of a

     * function through ERC1167 minimal proxies (clones) would not normally pass this test, but is not guaranteed to

     * fail.

     */
    modifier onlyProxy() {
        require(address(this) != __self, "Function must be called through delegatecall");
        require(_getImplementation() == __self, "Function must be called through active proxy");
        _;
    }

    /**

     * @dev Check that the execution is not being performed through a delegate call. This allows a function to be

     * callable on the implementing contract but not through proxies.

     */
    modifier notDelegated() {
        require(address(this) == __self, "UUPSUpgradeable: must not be called through delegatecall");
        _;
    }

    /**

     * @dev Implementation of the ERC1822 {proxiableUUID} function. This returns the storage slot used by the

     * implementation. It is used to validate that the this implementation remains valid after an upgrade.

     *

     * IMPORTANT: A proxy pointing at a proxiable contract should not be considered proxiable itself, because this risks

     * bricking a proxy that upgrades to it, by delegating to itself until out of gas. Thus it is critical that this

     * function revert if invoked through a proxy. This is guaranteed by the `notDelegated` modifier.

     */
    function proxiableUUID() external view virtual override notDelegated returns (bytes32) {
        return _IMPLEMENTATION_SLOT;
    }

    /**

     * @dev Upgrade the implementation of the proxy to `newImplementation`.

     *

     * Calls {_authorizeUpgrade}.

     *

     * Emits an {Upgraded} event.

     */
    function upgradeTo(address newImplementation) external virtual onlyProxy {
        _authorizeUpgrade(newImplementation);
        _upgradeToAndCallUUPS(newImplementation, new bytes(0), false);
    }

    /**

     * @dev Upgrade the implementation of the proxy to `newImplementation`, and subsequently execute the function call

     * encoded in `data`.

     *

     * Calls {_authorizeUpgrade}.

     *

     * Emits an {Upgraded} event.

     */
    function upgradeToAndCall(address newImplementation, bytes memory data) external payable virtual onlyProxy {
        _authorizeUpgrade(newImplementation);
        _upgradeToAndCallUUPS(newImplementation, data, true);
    }

    /**

     * @dev Function that should revert when `msg.sender` is not authorized to upgrade the contract. Called by

     * {upgradeTo} and {upgradeToAndCall}.

     *

     * Normally, this function will use an xref:access.adoc[access control] modifier such as {Ownable-onlyOwner}.

     *

     * ```solidity

     * function _authorizeUpgrade(address) internal override onlyOwner {}

     * ```

     */
    function _authorizeUpgrade(address newImplementation) internal virtual;

    /**

     * @dev This empty reserved space is put in place to allow future versions to add new

     * variables without shifting down storage in the inheritance chain.

     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps

     */
    uint256[50] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/utils/ContextUpgradeable.sol


// 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 ContextUpgradeable is Initializable {
    function __Context_init() internal onlyInitializing {
    }

    function __Context_init_unchained() internal onlyInitializing {
    }
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

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

    /**

     * @dev This empty reserved space is put in place to allow future versions to add new

     * variables without shifting down storage in the inheritance chain.

     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps

     */
    uint256[50] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol


// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)

pragma solidity ^0.8.0;



/**

 * @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 OwnableUpgradeable is Initializable, ContextUpgradeable {
    address private _owner;

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

    /**

     * @dev Initializes the contract setting the deployer as the initial owner.

     */
    function __Ownable_init() internal onlyInitializing {
        __Ownable_init_unchained();
    }

    function __Ownable_init_unchained() internal onlyInitializing {
        _transferOwnership(_msgSender());
    }

    /**

     * @dev Returns the address of the current owner.

     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**

     * @dev Throws if called by any account other than the owner.

     */
    modifier onlyOwner() {
        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);
    }

    /**

     * @dev This empty reserved space is put in place to allow future versions to add new

     * variables without shifting down storage in the inheritance chain.

     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps

     */
    uint256[49] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/security/PausableUpgradeable.sol


// OpenZeppelin Contracts v4.4.1 (security/Pausable.sol)

pragma solidity ^0.8.0;



/**

 * @dev Contract module which allows children to implement an emergency stop

 * mechanism that can be triggered by an authorized account.

 *

 * This module is used through inheritance. It will make available the

 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to

 * the functions of your contract. Note that they will not be pausable by

 * simply including this module, only once the modifiers are put in place.

 */
abstract contract PausableUpgradeable is Initializable, ContextUpgradeable {
    /**

     * @dev Emitted when the pause is triggered by `account`.

     */
    event Paused(address account);

    /**

     * @dev Emitted when the pause is lifted by `account`.

     */
    event Unpaused(address account);

    bool private _paused;

    /**

     * @dev Initializes the contract in unpaused state.

     */
    function __Pausable_init() internal onlyInitializing {
        __Pausable_init_unchained();
    }

    function __Pausable_init_unchained() internal onlyInitializing {
        _paused = false;
    }

    /**

     * @dev Returns true if the contract is paused, and false otherwise.

     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**

     * @dev Modifier to make a function callable only when the contract is not paused.

     *

     * Requirements:

     *

     * - The contract must not be paused.

     */
    modifier whenNotPaused() {
        require(!paused(), "Pausable: paused");
        _;
    }

    /**

     * @dev Modifier to make a function callable only when the contract is paused.

     *

     * Requirements:

     *

     * - The contract must be paused.

     */
    modifier whenPaused() {
        require(paused(), "Pausable: not paused");
        _;
    }

    /**

     * @dev Triggers stopped state.

     *

     * Requirements:

     *

     * - The contract must not be paused.

     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**

     * @dev Returns to normal state.

     *

     * Requirements:

     *

     * - The contract must be paused.

     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }

    /**

     * @dev This empty reserved space is put in place to allow future versions to add new

     * variables without shifting down storage in the inheritance chain.

     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps

     */
    uint256[49] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/token/ERC721/IERC721ReceiverUpgradeable.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 IERC721ReceiverUpgradeable {
    /**

     * @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-upgradeable/utils/introspection/IERC165Upgradeable.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 IERC165Upgradeable {
    /**

     * @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);
}

// File: @openzeppelin/contracts-upgradeable/utils/introspection/ERC165Upgradeable.sol


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

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 ERC165Upgradeable is Initializable, IERC165Upgradeable {
    function __ERC165_init() internal onlyInitializing {
    }

    function __ERC165_init_unchained() internal onlyInitializing {
    }
    /**

     * @dev See {IERC165-supportsInterface}.

     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165Upgradeable).interfaceId;
    }

    /**

     * @dev This empty reserved space is put in place to allow future versions to add new

     * variables without shifting down storage in the inheritance chain.

     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps

     */
    uint256[50] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/token/ERC721/IERC721Upgradeable.sol


// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;


/**

 * @dev Required interface of an ERC721 compliant contract.

 */
interface IERC721Upgradeable is IERC165Upgradeable {
    /**

     * @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 be have been allowed to move this token by either {approve} or {setApprovalForAll}.

     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.

     *

     * Emits a {Transfer} event.

     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**

     * @dev Transfers `tokenId` token from `from` to `to`.

     *

     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.

     *

     * 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-upgradeable/token/ERC721/extensions/IERC721MetadataUpgradeable.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 IERC721MetadataUpgradeable is IERC721Upgradeable {
    /**

     * @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-upgradeable/token/ERC721/ERC721Upgradeable.sol


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

pragma solidity ^0.8.0;









/**

 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including

 * the Metadata extension, but not including the Enumerable extension, which is available separately as

 * {ERC721Enumerable}.

 */
contract ERC721Upgradeable is Initializable, ContextUpgradeable, ERC165Upgradeable, IERC721Upgradeable, IERC721MetadataUpgradeable {
    using AddressUpgradeable for address;
    using StringsUpgradeable for uint256;

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    // Mapping from token ID to owner address
    mapping(uint256 => address) private _owners;

    // Mapping owner address to token count
    mapping(address => uint256) private _balances;

    // Mapping from token ID to approved address
    mapping(uint256 => address) private _tokenApprovals;

    // Mapping from owner to operator approvals
    mapping(address => mapping(address => bool)) private _operatorApprovals;

    /**

     * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.

     */
    function __ERC721_init(string memory name_, string memory symbol_) internal onlyInitializing {
        __ERC721_init_unchained(name_, symbol_);
    }

    function __ERC721_init_unchained(string memory name_, string memory symbol_) internal onlyInitializing {
        _name = name_;
        _symbol = symbol_;
    }

    /**

     * @dev See {IERC165-supportsInterface}.

     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165Upgradeable, IERC165Upgradeable) returns (bool) {
        return
            interfaceId == type(IERC721Upgradeable).interfaceId ||
            interfaceId == type(IERC721MetadataUpgradeable).interfaceId ||
            super.supportsInterface(interfaceId);
    }

    /**

     * @dev See {IERC721-balanceOf}.

     */
    function balanceOf(address owner) public view virtual override returns (uint256) {
        require(owner != address(0), "ERC721: balance query for the zero address");
        return _balances[owner];
    }

    /**

     * @dev See {IERC721-ownerOf}.

     */
    function ownerOf(uint256 tokenId) public view virtual override returns (address) {
        address owner = _owners[tokenId];
        require(owner != address(0), "ERC721: owner query for nonexistent token");
        return owner;
    }

    /**

     * @dev See {IERC721Metadata-name}.

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

    /**

     * @dev See {IERC721Metadata-symbol}.

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

    /**

     * @dev See {IERC721Metadata-tokenURI}.

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

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

    /**

     * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each

     * token will be the concatenation of the `baseURI` and the `tokenId`. Empty

     * by default, can be overridden in child contracts.

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

    /**

     * @dev See {IERC721-approve}.

     */
    function approve(address to, uint256 tokenId) public virtual override {
        address owner = ERC721Upgradeable.ownerOf(tokenId);
        require(to != owner, "ERC721: approval to current owner");

        require(
            _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
            "ERC721: approve caller is not owner nor approved for all"
        );

        _approve(to, tokenId);
    }

    /**

     * @dev See {IERC721-getApproved}.

     */
    function getApproved(uint256 tokenId) public view virtual override returns (address) {
        require(_exists(tokenId), "ERC721: approved query for nonexistent token");

        return _tokenApprovals[tokenId];
    }

    /**

     * @dev See {IERC721-setApprovalForAll}.

     */
    function setApprovalForAll(address operator, bool approved) public virtual override {
        _setApprovalForAll(_msgSender(), operator, approved);
    }

    /**

     * @dev See {IERC721-isApprovedForAll}.

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

    /**

     * @dev See {IERC721-transferFrom}.

     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");

        _transfer(from, to, tokenId);
    }

    /**

     * @dev See {IERC721-safeTransferFrom}.

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

    /**

     * @dev See {IERC721-safeTransferFrom}.

     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
        _safeTransfer(from, to, tokenId, _data);
    }

    /**

     * @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.

     *

     * `_data` is additional data, it has no specified format and it is sent in call to `to`.

     *

     * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.

     * implement alternative mechanisms to perform token transfer, such as signature-based.

     *

     * Requirements:

     *

     * - `from` cannot be the zero address.

     * - `to` cannot be the zero address.

     * - `tokenId` token must exist and be owned by `from`.

     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.

     *

     * Emits a {Transfer} event.

     */
    function _safeTransfer(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) internal virtual {
        _transfer(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**

     * @dev Returns whether `tokenId` exists.

     *

     * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.

     *

     * Tokens start existing when they are minted (`_mint`),

     * and stop existing when they are burned (`_burn`).

     */
    function _exists(uint256 tokenId) internal view virtual returns (bool) {
        return _owners[tokenId] != address(0);
    }

    /**

     * @dev Returns whether `spender` is allowed to manage `tokenId`.

     *

     * Requirements:

     *

     * - `tokenId` must exist.

     */
    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
        require(_exists(tokenId), "ERC721: operator query for nonexistent token");
        address owner = ERC721Upgradeable.ownerOf(tokenId);
        return (spender == owner || isApprovedForAll(owner, spender) || getApproved(tokenId) == spender);
    }

    /**

     * @dev Safely mints `tokenId` and transfers it to `to`.

     *

     * Requirements:

     *

     * - `tokenId` must not exist.

     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.

     *

     * Emits a {Transfer} event.

     */
    function _safeMint(address to, uint256 tokenId) internal virtual {
        _safeMint(to, tokenId, "");
    }

    /**

     * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is

     * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.

     */
    function _safeMint(
        address to,
        uint256 tokenId,
        bytes memory _data
    ) internal virtual {
        _mint(to, tokenId);
        require(
            _checkOnERC721Received(address(0), to, tokenId, _data),
            "ERC721: transfer to non ERC721Receiver implementer"
        );
    }

    /**

     * @dev Mints `tokenId` and transfers it to `to`.

     *

     * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible

     *

     * Requirements:

     *

     * - `tokenId` must not exist.

     * - `to` cannot be the zero address.

     *

     * Emits a {Transfer} event.

     */
    function _mint(address to, uint256 tokenId) internal virtual {
        require(to != address(0), "ERC721: mint to the zero address");
        require(!_exists(tokenId), "ERC721: token already minted");

        _beforeTokenTransfer(address(0), to, tokenId);

        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(address(0), to, tokenId);

        _afterTokenTransfer(address(0), to, tokenId);
    }

    /**

     * @dev Destroys `tokenId`.

     * The approval is cleared when the token is burned.

     *

     * Requirements:

     *

     * - `tokenId` must exist.

     *

     * Emits a {Transfer} event.

     */
    function _burn(uint256 tokenId) internal virtual {
        address owner = ERC721Upgradeable.ownerOf(tokenId);

        _beforeTokenTransfer(owner, address(0), tokenId);

        // Clear approvals
        _approve(address(0), tokenId);

        _balances[owner] -= 1;
        delete _owners[tokenId];

        emit Transfer(owner, address(0), tokenId);

        _afterTokenTransfer(owner, address(0), tokenId);
    }

    /**

     * @dev Transfers `tokenId` from `from` to `to`.

     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.

     *

     * Requirements:

     *

     * - `to` cannot be the zero address.

     * - `tokenId` token must be owned by `from`.

     *

     * Emits a {Transfer} event.

     */
    function _transfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {
        require(ERC721Upgradeable.ownerOf(tokenId) == from, "ERC721: transfer from incorrect owner");
        require(to != address(0), "ERC721: transfer to the zero address");

        _beforeTokenTransfer(from, to, tokenId);

        // Clear approvals from the previous owner
        _approve(address(0), tokenId);

        _balances[from] -= 1;
        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(from, to, tokenId);

        _afterTokenTransfer(from, to, tokenId);
    }

    /**

     * @dev Approve `to` to operate on `tokenId`

     *

     * Emits a {Approval} event.

     */
    function _approve(address to, uint256 tokenId) internal virtual {
        _tokenApprovals[tokenId] = to;
        emit Approval(ERC721Upgradeable.ownerOf(tokenId), to, tokenId);
    }

    /**

     * @dev Approve `operator` to operate on all of `owner` tokens

     *

     * Emits a {ApprovalForAll} event.

     */
    function _setApprovalForAll(
        address owner,
        address operator,
        bool approved
    ) internal virtual {
        require(owner != operator, "ERC721: approve to caller");
        _operatorApprovals[owner][operator] = approved;
        emit ApprovalForAll(owner, operator, approved);
    }

    /**

     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.

     * The call is not executed if the target address is not a contract.

     *

     * @param from address representing the previous owner of the given token ID

     * @param to target address that will receive the tokens

     * @param tokenId uint256 ID of the token to be transferred

     * @param _data bytes optional data to send along with the call

     * @return bool whether the call correctly returned the expected magic value

     */
    function _checkOnERC721Received(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) private returns (bool) {
        if (to.isContract()) {
            try IERC721ReceiverUpgradeable(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
                return retval == IERC721ReceiverUpgradeable.onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert("ERC721: transfer to non ERC721Receiver implementer");
                } else {
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        } else {
            return true;
        }
    }

    /**

     * @dev Hook that is called before any token transfer. This includes minting

     * and burning.

     *

     * Calling conditions:

     *

     * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be

     * transferred to `to`.

     * - When `from` is zero, `tokenId` will be minted for `to`.

     * - When `to` is zero, ``from``'s `tokenId` will be burned.

     * - `from` and `to` are never both zero.

     *

     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].

     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {}

    /**

     * @dev Hook that is called after any transfer of tokens. This includes

     * minting and burning.

     *

     * Calling conditions:

     *

     * - when `from` and `to` are both non-zero.

     * - `from` and `to` are never both zero.

     *

     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].

     */
    function _afterTokenTransfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {}

    /**

     * @dev This empty reserved space is put in place to allow future versions to add new

     * variables without shifting down storage in the inheritance chain.

     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps

     */
    uint256[44] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/token/ERC721/extensions/ERC721BurnableUpgradeable.sol


// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/ERC721Burnable.sol)

pragma solidity ^0.8.0;




/**

 * @title ERC721 Burnable Token

 * @dev ERC721 Token that can be irreversibly burned (destroyed).

 */
abstract contract ERC721BurnableUpgradeable is Initializable, ContextUpgradeable, ERC721Upgradeable {
    function __ERC721Burnable_init() internal onlyInitializing {
    }

    function __ERC721Burnable_init_unchained() internal onlyInitializing {
    }
    /**

     * @dev Burns `tokenId`. See {ERC721-_burn}.

     *

     * Requirements:

     *

     * - The caller must own `tokenId` or be an approved operator.

     */
    function burn(uint256 tokenId) public virtual {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721Burnable: caller is not owner nor approved");
        _burn(tokenId);
    }

    /**

     * @dev This empty reserved space is put in place to allow future versions to add new

     * variables without shifting down storage in the inheritance chain.

     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps

     */
    uint256[50] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/token/ERC721/extensions/ERC721URIStorageUpgradeable.sol


// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/ERC721URIStorage.sol)

pragma solidity ^0.8.0;



/**

 * @dev ERC721 token with storage based token URI management.

 */
abstract contract ERC721URIStorageUpgradeable is Initializable, ERC721Upgradeable {
    function __ERC721URIStorage_init() internal onlyInitializing {
    }

    function __ERC721URIStorage_init_unchained() internal onlyInitializing {
    }
    using StringsUpgradeable for uint256;

    // Optional mapping for token URIs
    mapping(uint256 => string) private _tokenURIs;

    /**

     * @dev See {IERC721Metadata-tokenURI}.

     */
    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        require(_exists(tokenId), "ERC721URIStorage: URI query for nonexistent token");

        string memory _tokenURI = _tokenURIs[tokenId];
        string memory base = _baseURI();

        // If there is no base URI, return the token URI.
        if (bytes(base).length == 0) {
            return _tokenURI;
        }
        // If both are set, concatenate the baseURI and tokenURI (via abi.encodePacked).
        if (bytes(_tokenURI).length > 0) {
            return string(abi.encodePacked(base, _tokenURI));
        }

        return super.tokenURI(tokenId);
    }

    /**

     * @dev Sets `_tokenURI` as the tokenURI of `tokenId`.

     *

     * Requirements:

     *

     * - `tokenId` must exist.

     */
    function _setTokenURI(uint256 tokenId, string memory _tokenURI) internal virtual {
        require(_exists(tokenId), "ERC721URIStorage: URI set of nonexistent token");
        _tokenURIs[tokenId] = _tokenURI;
    }

    /**

     * @dev Destroys `tokenId`.

     * The approval is cleared when the token is burned.

     *

     * Requirements:

     *

     * - `tokenId` must exist.

     *

     * Emits a {Transfer} event.

     */
    function _burn(uint256 tokenId) internal virtual override {
        super._burn(tokenId);

        if (bytes(_tokenURIs[tokenId]).length != 0) {
            delete _tokenURIs[tokenId];
        }
    }

    /**

     * @dev This empty reserved space is put in place to allow future versions to add new

     * variables without shifting down storage in the inheritance chain.

     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps

     */
    uint256[49] private __gap;
}

// File: contracts/trumint_v0.1.sol



/// @author: Isaiah Olson

pragma solidity ^0.8.4;








contract TruMintNFT is Initializable, ERC721Upgradeable, ERC721URIStorageUpgradeable, PausableUpgradeable, OwnableUpgradeable, ERC721BurnableUpgradeable, UUPSUpgradeable {
    
    // Mapping from token ID to approved for transfer
    mapping(uint256 => bool) private _tokenTransferApprovals;
    
    // approved Transfer recipient
    mapping(uint256 => address) private _tokenTransferRecipientApprovals;
    
    /// Events
    
    // approve token transfer
    event ApproveTokenTransfer(uint256 indexed tokenId, address indexed recipient, bool approved);
    
    // NFT Revoked
    event NFTRevoked( uint256 indexed tokenId, address indexed owner, address indexed revokedTo);
    
    
    /// @custom:oz-upgrades-unsafe-allow constructor
    constructor() {
        _disableInitializers();
    }

    function initialize() initializer public {
        __ERC721_init("TruMintNFT", "TRU");
        __ERC721URIStorage_init();
        __Pausable_init();
        __Ownable_init();
        __ERC721Burnable_init();
        __UUPSUpgradeable_init();
    }

    function pause() public onlyOwner {
        _pause();
    }

    function unpause() public onlyOwner {
        _unpause();
    }

    function safeMint(address to, uint256 tokenId, string memory uri)
        public
        onlyOwner
    {
        _safeMint(to, tokenId);
        _setTokenURI(tokenId, uri);
    }

    function _beforeTokenTransfer(address from, address to, uint256 tokenId)
        internal
        whenNotPaused
        override
    {
        super._beforeTokenTransfer(from, to, tokenId);
    }

    function _authorizeUpgrade(address newImplementation)
        internal
        onlyOwner
        override
    {}

    // The following functions are overrides required by Solidity.

    function _burn(uint256 tokenId)
        internal
        override(ERC721Upgradeable, ERC721URIStorageUpgradeable)
    {
        super._burn(tokenId);
    }

    function tokenURI(uint256 tokenId)
        public
        view
        override(ERC721Upgradeable, ERC721URIStorageUpgradeable)
        returns (string memory)
    {
        return super.tokenURI(tokenId);
    }
    
    // custom
    
    function _approveTokenTransfer(uint256 tokenId, address recipient, bool approved)
        internal
    {
        _tokenTransferApprovals[tokenId] = approved;
        
        if(approved) {
            _tokenTransferRecipientApprovals[tokenId] = recipient;  
        } else {
            delete _tokenTransferRecipientApprovals[tokenId]; 
        }
        // emit event
        emit ApproveTokenTransfer(tokenId, recipient, approved);
    }
    
     /**

     * @dev Returns whether `transferer` is contract owner and transfering to themselves

     */
    function approveTokenTransfer(uint256 tokenId, address recipient, bool approved)
        public
        onlyOwner
    {
        _approveTokenTransfer(tokenId, recipient, approved);
    }
    
    /**

     * @dev Returns whether `transferer` is contract owner and transfering to themselves

     */
   
    function _isApprovedRevoking(address transferer, address transferee) internal view virtual returns (bool) {
        // owner is transfering to themselves
        return (transferer == owner() && transferee == owner());
    }
    
    /**

     * @dev Returns whether `transferer` is allowed to move `tokenId` to the `transferee` 

     *

     * Requirements:

     *

     * - `tokenId` must exist.

     */
    function _isApprovedForTransfer(address transferer, address transferee,  uint256 tokenId) internal view virtual returns (bool) {
        require(_exists(tokenId), "operator query for nonexistent token");
        // check if _isApprovedOrOwner(spender, tokenId) or if being revoked
        bool isApprovedTransferer = (_isApprovedOrOwner(transferer, tokenId) || _isApprovedRevoking(transferer, transferee));

        // check if NFT is approved for transfer and that it is being sent to approved recipient
        bool isApprovedTransferTo = (_tokenTransferRecipientApprovals[tokenId] == transferee);
        
        return (isApprovedTransferer && isApprovedTransferTo );
    }
    
    // overrides
    
    /**

     * @dev override of transferFrom

     * adds ability for contract owner to transfer token

     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
        // if owner than it should only be to the owners address

        _transfer(from, to, tokenId);
    }

    /**

     * @dev override of safeTransferFrom

     * adds ability for contract owner to transfer token

     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
        // if owner than it should only be to the owners address
        
        _safeTransfer(from, to, tokenId, _data);
    }
    
     /**

     * @dev Transfers `tokenId` from `from` to `to`.

     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.

     *

     * added requirements:

     * token must be approved

     * recipieint must be approved

     */
    function _transfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual override {
        require(_isApprovedForTransfer(from, to, tokenId), "token not approved for transfer");
        
        // remove token transfer approval
        _approveTokenTransfer(tokenId, to, false);
        
        super._transfer(from, to, tokenId);
    }
    
    /// custom functions
    
    /**

    * @dev allows the owner to update the tokenURI of a token

     */
    function setURI(uint256 tokenId, string memory uri)
        public
        onlyOwner
    {
        _setTokenURI(tokenId, uri);
    }
    
    
    /**

    * @dev allows the owner to revoke NFT ownership

     */
    function revokeNFT(uint256 tokenId, address from)
        public
        onlyOwner
    {
        approveTokenTransfer(tokenId, owner(), true);
        _transfer(from, owner(), tokenId);
        
        // emit event
        emit NFTRevoked(tokenId, from, owner());
    }
}