// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (proxy/transparent/TransparentUpgradeableProxy.sol)
pragma solidity ^0.8.0;
import "ERC1967Proxy.sol";
/**
 * @dev This contract implements a proxy that is upgradeable by an admin.
 *
 * To avoid https://medium.com/nomic-labs-blog/malicious-backdoors-in-ethereum-proxies-62629adf3357[proxy selector
 * clashing], which can potentially be used in an attack, this contract uses the
 * https://blog.openzeppelin.com/the-transparent-proxy-pattern/[transparent proxy pattern]. This pattern implies two
 * things that go hand in hand:
 *
 * 1. If any account other than the admin calls the proxy, the call will be forwarded to the implementation, even if
 * that call matches one of the admin functions exposed by the proxy itself.
 * 2. If the admin calls the proxy, it can access the admin functions, but its calls will never be forwarded to the
 * implementation. If the admin tries to call a function on the implementation it will fail with an error that says
 * "admin cannot fallback to proxy target".
 *
 * These properties mean that the admin account can only be used for admin actions like upgrading the proxy or changing
 * the admin, so it's best if it's a dedicated account that is not used for anything else. This will avoid headaches due
 * to sudden errors when trying to call a function from the proxy implementation.
 *
 * Our recommendation is for the dedicated account to be an instance of the {ProxyAdmin} contract. If set up this way,
 * you should think of the `ProxyAdmin` instance as the real administrative interface of your proxy.
 */
contract TransparentUpgradeableProxy is ERC1967Proxy {
    /**
     * @dev Initializes an upgradeable proxy managed by `_admin`, backed by the implementation at `_logic`, and
     * optionally initialized with `_data` as explained in {ERC1967Proxy-constructor}.
     */
    constructor(
        address _logic,
        address admin_,
        bytes memory _data
    ) payable ERC1967Proxy(_logic, _data) {
        assert(_ADMIN_SLOT == bytes32(uint256(keccak256("eip1967.proxy.admin")) - 1));
        _changeAdmin(admin_);
    }
    /**
     * @dev Modifier used internally that will delegate the call to the implementation unless the sender is the admin.
     */
    modifier ifAdmin() {
        if (msg.sender == _getAdmin()) {
            _;
        } else {
            _fallback();
        }
    }
    /**
     * @dev Returns the current admin.
     *
     * NOTE: Only the admin can call this function. See {ProxyAdmin-getProxyAdmin}.
     *
     * TIP: To get this value clients can read directly from the storage slot shown below (specified by EIP1967) using the
     * https://eth.wiki/json-rpc/API#eth_getstorageat[`eth_getStorageAt`] RPC call.
     * `0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103`
     */
    function admin() external ifAdmin returns (address admin_) {
        admin_ = _getAdmin();
    }
    /**
     * @dev Returns the current implementation.
     *
     * NOTE: Only the admin can call this function. See {ProxyAdmin-getProxyImplementation}.
     *
     * TIP: To get this value clients can read directly from the storage slot shown below (specified by EIP1967) using the
     * https://eth.wiki/json-rpc/API#eth_getstorageat[`eth_getStorageAt`] RPC call.
     * `0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc`
     */
    function implementation() external ifAdmin returns (address implementation_) {
        implementation_ = _implementation();
    }
    /**
     * @dev Changes the admin of the proxy.
     *
     * Emits an {AdminChanged} event.
     *
     * NOTE: Only the admin can call this function. See {ProxyAdmin-changeProxyAdmin}.
     */
    function changeAdmin(address newAdmin) external virtual ifAdmin {
        _changeAdmin(newAdmin);
    }
    /**
     * @dev Upgrade the implementation of the proxy.
     *
     * NOTE: Only the admin can call this function. See {ProxyAdmin-upgrade}.
     */
    function upgradeTo(address newImplementation) external ifAdmin {
        _upgradeToAndCall(newImplementation, bytes(""), false);
    }
    /**
     * @dev Upgrade the implementation of the proxy, and then call a function from the new implementation as specified
     * by `data`, which should be an encoded function call. This is useful to initialize new storage variables in the
     * proxied contract.
     *
     * NOTE: Only the admin can call this function. See {ProxyAdmin-upgradeAndCall}.
     */
    function upgradeToAndCall(address newImplementation, bytes calldata data) external payable ifAdmin {
        _upgradeToAndCall(newImplementation, data, true);
    }
    /**
     * @dev Returns the current admin.
     */
    function _admin() internal view virtual returns (address) {
        return _getAdmin();
    }
    /**
     * @dev Makes sure the admin cannot access the fallback function. See {Proxy-_beforeFallback}.
     */
    function _beforeFallback() internal virtual override {
        require(msg.sender != _getAdmin(), "TransparentUpgradeableProxy: admin cannot fallback to proxy target");
        super._beforeFallback();
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (proxy/ERC1967/ERC1967Proxy.sol)
pragma solidity ^0.8.0;
import "Proxy.sol";
import "ERC1967Upgrade.sol";
/**
 * @dev This contract implements an upgradeable proxy. It is upgradeable because calls are delegated to an
 * implementation address that can be changed. This address is stored in storage in the location specified by
 * https://eips.ethereum.org/EIPS/eip-1967[EIP1967], so that it doesn't conflict with the storage layout of the
 * implementation behind the proxy.
 */
contract ERC1967Proxy is Proxy, ERC1967Upgrade {
    /**
     * @dev Initializes the upgradeable proxy with an initial implementation specified by `_logic`.
     *
     * If `_data` is nonempty, it's used as data in a delegate call to `_logic`. This will typically be an encoded
     * function call, and allows initializating the storage of the proxy like a Solidity constructor.
     */
    constructor(address _logic, bytes memory _data) payable {
        assert(_IMPLEMENTATION_SLOT == bytes32(uint256(keccak256("eip1967.proxy.implementation")) - 1));
        _upgradeToAndCall(_logic, _data, false);
    }
    /**
     * @dev Returns the current implementation address.
     */
    function _implementation() internal view virtual override returns (address impl) {
        return ERC1967Upgrade._getImplementation();
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (proxy/Proxy.sol)
pragma solidity ^0.8.0;
/**
 * @dev This abstract contract provides a fallback function that delegates all calls to another contract using the EVM
 * instruction `delegatecall`. We refer to the second contract as the _implementation_ behind the proxy, and it has to
 * be specified by overriding the virtual {_implementation} function.
 *
 * Additionally, delegation to the implementation can be triggered manually through the {_fallback} function, or to a
 * different contract through the {_delegate} function.
 *
 * The success and return data of the delegated call will be returned back to the caller of the proxy.
 */
abstract contract Proxy {
    /**
     * @dev Delegates the current call to `implementation`.
     *
     * This function does not return to its internall call site, it will return directly to the external caller.
     */
    function _delegate(address implementation) internal virtual {
        assembly {
            // Copy msg.data. We take full control of memory in this inline assembly
            // block because it will not return to Solidity code. We overwrite the
            // Solidity scratch pad at memory position 0.
            calldatacopy(0, 0, calldatasize())
            // Call the implementation.
            // out and outsize are 0 because we don't know the size yet.
            let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)
            // Copy the returned data.
            returndatacopy(0, 0, returndatasize())
            switch result
            // delegatecall returns 0 on error.
            case 0 {
                revert(0, returndatasize())
            }
            default {
                return(0, returndatasize())
            }
        }
    }
    /**
     * @dev This is a virtual function that should be overriden so it returns the address to which the fallback function
     * and {_fallback} should delegate.
     */
    function _implementation() internal view virtual returns (address);
    /**
     * @dev Delegates the current call to the address returned by `_implementation()`.
     *
     * This function does not return to its internall call site, it will return directly to the external caller.
     */
    function _fallback() internal virtual {
        _beforeFallback();
        _delegate(_implementation());
    }
    /**
     * @dev Fallback function that delegates calls to the address returned by `_implementation()`. Will run if no other
     * function in the contract matches the call data.
     */
    fallback() external payable virtual {
        _fallback();
    }
    /**
     * @dev Fallback function that delegates calls to the address returned by `_implementation()`. Will run if call data
     * is empty.
     */
    receive() external payable virtual {
        _fallback();
    }
    /**
     * @dev Hook that is called before falling back to the implementation. Can happen as part of a manual `_fallback`
     * call, or as part of the Solidity `fallback` or `receive` functions.
     *
     * If overriden should call `super._beforeFallback()`.
     */
    function _beforeFallback() internal virtual {}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (proxy/ERC1967/ERC1967Upgrade.sol)
pragma solidity ^0.8.2;
import "IBeacon.sol";
import "Address.sol";
import "StorageSlot.sol";
/**
 * @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 ERC1967Upgrade {
    // 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 StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
    }
    /**
     * @dev Stores a new address in the EIP1967 implementation slot.
     */
    function _setImplementation(address newImplementation) private {
        require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
        StorageSlot.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) {
            Address.functionDelegateCall(newImplementation, data);
        }
    }
    /**
     * @dev Perform implementation upgrade with security checks for UUPS proxies, and additional setup call.
     *
     * Emits an {Upgraded} event.
     */
    function _upgradeToAndCallSecure(
        address newImplementation,
        bytes memory data,
        bool forceCall
    ) internal {
        address oldImplementation = _getImplementation();
        // Initial upgrade and setup call
        _setImplementation(newImplementation);
        if (data.length > 0 || forceCall) {
            Address.functionDelegateCall(newImplementation, data);
        }
        // Perform rollback test if not already in progress
        StorageSlot.BooleanSlot storage rollbackTesting = StorageSlot.getBooleanSlot(_ROLLBACK_SLOT);
        if (!rollbackTesting.value) {
            // Trigger rollback using upgradeTo from the new implementation
            rollbackTesting.value = true;
            Address.functionDelegateCall(
                newImplementation,
                abi.encodeWithSignature("upgradeTo(address)", oldImplementation)
            );
            rollbackTesting.value = false;
            // Check rollback was effective
            require(oldImplementation == _getImplementation(), "ERC1967Upgrade: upgrade breaks further upgrades");
            // Finally reset to the new implementation and log the upgrade
            _upgradeTo(newImplementation);
        }
    }
    /**
     * @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 StorageSlot.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");
        StorageSlot.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 StorageSlot.getAddressSlot(_BEACON_SLOT).value;
    }
    /**
     * @dev Stores a new beacon in the EIP1967 beacon slot.
     */
    function _setBeacon(address newBeacon) private {
        require(Address.isContract(newBeacon), "ERC1967: new beacon is not a contract");
        require(
            Address.isContract(IBeacon(newBeacon).implementation()),
            "ERC1967: beacon implementation is not a contract"
        );
        StorageSlot.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) {
            Address.functionDelegateCall(IBeacon(newBeacon).implementation(), data);
        }
    }
}
// SPDX-License-Identifier: MIT
// 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 IBeacon {
    /**
     * @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);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Address.sol)
pragma solidity ^0.8.0;
/**
 * @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
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.
        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 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 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) {
        require(isContract(target), "Address: delegate call to non-contract");
        (bool success, bytes memory returndata) = target.delegatecall(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);
            }
        }
    }
}
// SPDX-License-Identifier: MIT
// 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 StorageSlot {
    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
        }
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;
import "iface.sol";
import "BytesLib.sol";
import "SafeERC20.sol";
import "Initializable.sol";
import "AccessControlUpgradeable.sol";
import "PausableUpgradeable.sol";
import "ReentrancyGuardUpgradeable.sol";
import "SafeCast.sol";
/**
 * @title Bedrock Ethereum 2.0 Staking Contract
 *
 * Description:
 * 
 * ───╔═╦═╗─╔╗╔═╗──────╔╗──╔╗╔╗─╔╦╗╔╗─╔═╗─╔╗───────╔╦╗
 * ╔═╗║═╣═╬═╣╚╣═╣╔══╗╔╗╠╬═╗║╚╬╬╗╠╣╚╬╬═╣═╣╔╝╚╗╔═╦═╦╦╬╣╚╦╦╗
 * ║╬╚╬═╠═║╩╣╔╬═║╠══╣║╚╣║╬╚╣╬║║╚╣║╔╣║╩╬═║╚╗╔╝║╩╣╬║║║║╔╣║║
 * ╚══╩═╩═╩═╩═╩═╝╚══╝╚═╩╩══╩═╩╩═╩╩═╩╩═╩═╝─╚╝─╚═╩╗╠═╩╩═╬╗║
 * ─────────────────────────────────────────────╚╝────╚═╝
 * 
 * Term:
 *  ExchangeRatio:              Exchange Ratio of xETH to ETH, normally >= 1.0
 *  TotalXETH:                  Total Supply of xETH
 *  TotalStaked:                Total Ethers Staked to Validators
 *  TotalDebts:                 Total unpaid debts(generated from redeemFromValidators), 
 *                              awaiting to be paid by turn off validators to clean debts.
 *  TotalPending:               Pending Ethers(<32 Ethers), awaiting to be staked
 *  RewardDebts:                The amount re-staked into TotalPending
 *
 *  AccountedUserRevenue:       Overall Net revenue which belongs to all xETH holders(excluded re-staked amount)
 *  ReportedValidators:         Latest Reported Validator Count
 *  ReportedValidatorBalance:   Latest Reported Validator Overall Balance
 *  RecentReceived:             The Amount this contract receives recently.
 *  CurrentReserve:             Assets Under Management
 *
 * Lemma 1: (AUM)
 *
 *          CurrentReserve = TotalPending + TotalStaked + AccountedUserRevenue - TotalDebts - RewardDebts
 *
 * Lemma 2: (Exchange Ratio)
 *
 *          ExchangeRatio = CurrentReserve / TotalXETH
 *
 * Rule 1: (function mint) For every mint operation, the ethers pays debt in priority the reset will be put in TotalPending(deprecated),
 *          ethersToMint:               The amount user deposits
 *
 *          TotalPending = TotalPending + ethersToMint
 *          TotalXETH = TotalXETH + ethersToMint / ExchangeRatio
 *
 * Rule 2: (function mint) At any time TotalPending has more than 32 Ethers, It will be staked, TotalPending
 *          moves to TotalStaked and keeps TotalPending less than 32 Ether.
 *
 *          TotalPending = TotalPending - ⌊TotalPending/32ETH⌋ * 32ETH
 *          TotalStaked = TotalStaked + ⌊TotalPending/32ETH⌋ * 32ETH
 *
 * Rule 3: (function validatorStopped) Whenever a validator stopped, all value pays debts in priority, then:
 *          valueStopped:               The value sent-back via receive() funtion
 *          amountUnstaked:             The amount of unstaked node (base 32ethers)
 *          validatorStopped:           The count of validator stopped
 *          
 *          incrRewardDebt := valueStopped - amountUnstaked
 *          RewardDebts = RewardDebt + incrRewardDebt
 *          RecentReceived = RecentReceived + valueStopped
 *          TotalPending = TotalPending + Max(0, amountUnstaked - TotalDebts) + incrRewardDebt
 *          TotalStaked = TotalStaked - validatorStopped * 32 ETH
 *
 * Rule 4.1: (function pushBeacon) Oracle push balance, rebase if new validator is alive:
 *          aliveValidator:             The count of validators alive
 *          
 *          RewardBase = ReportedValidatorBalance + Max(0, aliveValidator - ReportedValidators) * 32 ETH
 *
 * Rule 4.2: (function pushBeacon) Oracle push balance, revenue calculation:
 *          aliveBalance:               The balance of current alive validators
 *
 *          r := aliveBalance + RecentReceived - RewardBase
 *          AccountedUserRevenue = AccountedUserRevenue + r * (1000 - managerFeeShare) / 1000
 *          RecentReceived = 0
 *          ReportedValidators = aliveValidator
 *          ReportedValidatorBalance = aliveBalance
 */
contract Staking is Initializable, PausableUpgradeable, AccessControlUpgradeable, ReentrancyGuardUpgradeable {
    using SafeERC20 for IERC20;
    using Address for address payable;
    using Address for address;
    // stored credentials
    struct ValidatorCredential {
        bytes pubkey;
        bytes signature;
        bool stopped;
        bool restaking; // UPDATE(20240115) : flag the validator is using liquid staking address
        uint8 eigenpod; // UPDATE(20240402) : eigenpod id
    }
    // track ether debts to return to async caller
    struct Debt {
        address account;
        uint256 amount;
    }
    /**
        Incorrect storage preservation:
        |Implementation_v0   |Implementation_v1        |
        |--------------------|-------------------------|
        |address _owner      |address _lastContributor | <=== Storage collision!
        |mapping _balances   |address _owner           |
        |uint256 _supply     |mapping _balances        |
        |...                 |uint256 _supply          |
        |                    |...                      |
        Correct storage preservation:
        |Implementation_v0   |Implementation_v1        |
        |--------------------|-------------------------|
        |address _owner      |address _owner           |
        |mapping _balances   |mapping _balances        |
        |uint256 _supply     |uint256 _supply          |
        |...                 |address _lastContributor | <=== Storage extension.
        |                    |...                      |
    */
    // Always extend storage instead of modifying it
    // Variables in implementation v0 
    bytes32 public constant MANAGER_ROLE = keccak256("MANAGER_ROLE");
    bytes32 public constant ORACLE_ROLE = keccak256("ORACLE_ROLE");
    bytes32 public constant REGISTRY_ROLE = keccak256("REGISTRY_ROLE");
    bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
    uint256 public constant DEPOSIT_SIZE = 32 ether;
    uint256 public constant SAFE_PUSH_REWARDS = 30 ether;
    uint256 private constant MULTIPLIER = 1e18; 
    uint256 private constant DEPOSIT_AMOUNT_UNIT = 1000000000 wei;
    uint256 private constant SIGNATURE_LENGTH = 96;
    uint256 private constant PUBKEY_LENGTH = 48;
    address public ethDepositContract;      // ETH 2.0 Deposit contract
    address public xETHAddress;             // xETH token address
    address public redeemContract;          // redeeming contract for user to pull ethers
    uint256 public managerFeeShare;         // manager's fee in 1/1000
    bytes32 public withdrawalCredentials;   // WithdrawCredential for all validator
    // credentials, pushed by owner
    ValidatorCredential [] public validatorRegistry;
    mapping(bytes32 => uint256) private pubkeyIndices; // indices of validatorRegistry by pubkey hash, starts from 1
    // next validator id
    uint256 private nextValidatorId;
    // exchange ratio related variables
    // track user deposits & redeem (xETH mint & burn)
    uint256 private totalPending;           // track pending ethers awaiting to be staked to validators
    uint256 private totalStaked;            // track current staked ethers for validators, rounded to 32 ethers
    uint256 private totalDebts;             // track current unpaid debts
    // FIFO of debts from redeemFromValidators
    mapping(uint256=>Debt) private etherDebts;
    uint256 private firstDebt;
    uint256 private lastDebt;
    mapping(address=>uint256) private userDebts;    // debts from user's perspective
    // track revenue from validators to form exchange ratio
    uint256 private accountedUserRevenue;           // accounted shared user revenue
    uint256 private accountedManagerRevenue;        // accounted manager's revenue
    uint256 private rewardDebts;                    // check validatorStopped function
    // revenue related variables
    // track beacon validator & balance
    uint256 private reportedValidators;
    uint256 private reportedValidatorBalance;
    // balance tracking
    int256 private accountedBalance;                // tracked balance change in functions,
                                                    // NOTE(x): balance might be negative for not accounting validators's redeeming
    uint256 private __DEPRECATED_recentSlashed;     // track recently slashed value
    uint256 private recentReceived;                 // track recently received (un-accounted) value into this contract
    bytes32 private vectorClock;                    // a vector clock for detecting receive() & pushBeacon() causality violations
    uint256 private vectorClockTicks;               // record current vector clock step;
    // track stopped validators
    uint256 stoppedValidators;                      // track stopped validators count
    // phase switch from 0 to 1
    uint256 private __DEPRECATED_phase;
    // gas refunds
    uint256 [] private refunds;
    // PATCH VARIABLES(UPGRADES)
    uint256 private recentStopped;                  // track recent stopped validators(update: 20220927)
    /**
     * @dev empty reserved space for future adding of variables
     */
    uint256[31] private __gap;
    // KYC control
    mapping(address=>uint256) __DEPRECATED_quotaUsed;
    mapping(address=>bool) __DEPRECATED_whiteList;
    // auto-compounding
    bool private __DEPRECATED_autoCompoundEnabled;
    // DEPRECATED(20240130): eigenlayer's restaking withdrawal credential
    bytes32 private __DEPRECATED_restakingWithdrawalCredentials;
    address private __DEPRECATED_restakingAddress;
    // UPDATE(20240130): use variable instead of constant, require upgradeAndCall to set it's value
    address public restakingContract;
    // UPDATE(20240405): record latest unrealized profits
    uint256 private reportedUnrealizedProfits;
    /** 
     * ======================================================================================
     * 
     * SYSTEM SETTINGS, OPERATED VIA OWNER(DAO/TIMELOCK)
     * 
     * ======================================================================================
     */
    receive() external payable { }
    constructor() { _disableInitializers(); }
    /**
     * @dev pause the contract
     */
    function pause() public onlyRole(PAUSER_ROLE) {
        _pause();
    }
    /**
     * @dev unpause the contract
     */
    function unpause() public onlyRole(PAUSER_ROLE) {
        _unpause();
    }
    /**
     * @dev initialization address
     */
    /*
    function initialize() initializer public {
        __Pausable_init();
        __AccessControl_init();
        __ReentrancyGuard_init();
        _grantRole(DEFAULT_ADMIN_ROLE, msg.sender);
        _grantRole(ORACLE_ROLE, msg.sender);
        _grantRole(REGISTRY_ROLE, msg.sender);
        _grantRole(PAUSER_ROLE, msg.sender);
        _grantRole(MANAGER_ROLE, msg.sender);
        // init default values
        managerFeeShare = 5;
        firstDebt = 1;
        lastDebt = 0;
        phase = 0;
        _vectorClockTick();
        // initiate default withdrawal credential to the contract itself
        // uint8('0x1') + 11 bytes(0) + this.address
        bytes memory cred = abi.encodePacked(bytes1(0x01), new bytes(11), address(this));
        withdrawalCredentials = BytesLib.toBytes32(cred, 0);
    }
   */
   
    /**
     * UPDATE(20240130): to set a variable after upgrades
     * use upgradeAndCall to initializeV2
     */ 
    /*
    function initializeV2(address restakingContract_) reinitializer(2) public {
        restakingContract = restakingContract_;
    }
    */
    /**
     * @dev replace validators in batch
     */
    function replaceValidators(
        bytes [] calldata oldpubkeys, 
        bytes [] calldata pubkeys, 
        bytes [] calldata signatures, 
        bool restaking, 
        uint8 [] calldata podIds) external onlyRole(REGISTRY_ROLE) {
        _require(pubkeys.length == signatures.length, "SYS007");
        _require(oldpubkeys.length == pubkeys.length, "SYS007");
        _require(pubkeys.length == podIds.length, "SYS007");
        uint256 n = pubkeys.length;
        for(uint256 i=0;i<n;i++) {
            _require(oldpubkeys[i].length == PUBKEY_LENGTH, "SYS004");
            _require(pubkeys[i].length == PUBKEY_LENGTH, "SYS004");
            _require(signatures[i].length == SIGNATURE_LENGTH, "SYS003");
            // mark old pub key to false
            bytes32 oldPubKeyHash = keccak256(oldpubkeys[i]);
            _require(pubkeyIndices[oldPubKeyHash] > 0, "SYS006");
            uint256 index = pubkeyIndices[oldPubKeyHash] - 1;
            delete pubkeyIndices[oldPubKeyHash];
            // set new pubkey
            bytes32 pubkeyHash = keccak256(pubkeys[i]);
            ValidatorCredential storage validator = validatorRegistry[index];
            validator.pubkey = pubkeys[i];
            validator.signature = signatures[i];
            validator.restaking = restaking;
            validator.eigenpod = podIds[i];
            pubkeyIndices[pubkeyHash] = index+1;
        }
    }
    /**
     * @dev register a batch of validators
     */
    function registerValidators(bytes [] calldata pubkeys, bytes [] calldata signatures) external onlyRole(REGISTRY_ROLE) {
        _require(pubkeys.length == signatures.length, "SYS007");
        uint256 n = pubkeys.length;
        for(uint256 i=0;i<n;i++) {
            _require(pubkeys[i].length == PUBKEY_LENGTH, "SYS004");
            _require(signatures[i].length == SIGNATURE_LENGTH, "SYS003");
            bytes32 pubkeyHash = keccak256(pubkeys[i]);
            _require(pubkeyIndices[pubkeyHash] == 0, "SYS005");
            validatorRegistry.push(ValidatorCredential({pubkey:pubkeys[i], signature:signatures[i], stopped:false, restaking: false, eigenpod: 0}));
            pubkeyIndices[pubkeyHash] = validatorRegistry.length;
        }
    }
    /**
     * @dev register a batch of LRT validators
     * UPDATE(20240115): register a batch of validators for Liquid Restaking (EigenLayer)
     */
    function registerRestakingValidators(bytes [] calldata pubkeys, bytes [] calldata signatures) external onlyRole(REGISTRY_ROLE) {
        _require(pubkeys.length == signatures.length, "SYS007");
        uint256 n = pubkeys.length;
        for(uint256 i=0;i<n;i++) {
            _require(pubkeys[i].length == PUBKEY_LENGTH, "SYS004");
            _require(signatures[i].length == SIGNATURE_LENGTH, "SYS003");
            bytes32 pubkeyHash = keccak256(pubkeys[i]);
            _require(pubkeyIndices[pubkeyHash] == 0, "SYS005");
            validatorRegistry.push(ValidatorCredential({pubkey:pubkeys[i], signature:signatures[i], stopped:false, restaking: true, eigenpod: 0}));
            pubkeyIndices[pubkeyHash] = validatorRegistry.length;
        }
    }
    /**
     * @dev register a batch of LRT validators
     * UPDATE(20240402): register a batch of validators for Liquid Restaking (EigenLayer) with given eigenpod id
     */
    function registerRestakingValidators(
        bytes [] calldata pubkeys, 
        bytes [] calldata signatures, 
        uint8 [] calldata podIds) external onlyRole(REGISTRY_ROLE) {
        _require(pubkeys.length == signatures.length, "SYS007");
        _require(pubkeys.length == podIds.length, "SYS007");
        uint256 n = pubkeys.length;
        uint256 maxPods = IRestaking(restakingContract).getTotalPods();
        for(uint256 i=0;i<n;i++) {
            _require(pubkeys[i].length == PUBKEY_LENGTH, "SYS004");
            _require(signatures[i].length == SIGNATURE_LENGTH, "SYS003");
            _require(podIds[i] < maxPods, "SYS031");
            bytes32 pubkeyHash = keccak256(pubkeys[i]);
            _require(pubkeyIndices[pubkeyHash] == 0, "SYS005");
            validatorRegistry.push(ValidatorCredential({pubkey:pubkeys[i], signature:signatures[i], stopped:false, restaking: true, eigenpod: podIds[i]}));
            pubkeyIndices[pubkeyHash] = validatorRegistry.length;
        }
    }
    /**
     * @dev set manager's fee in 1/1000
     */
    function setManagerFeeShare(uint256 milli) external onlyRole(DEFAULT_ADMIN_ROLE)  {
        _require(milli >=0 && milli <=1000, "SYS008");
        managerFeeShare = milli;
        emit ManagerFeeSet(milli);
    }
    /**
     * @dev set eth deposit contract address
     */
    function setETHDepositContract(address _ethDepositContract) external onlyRole(DEFAULT_ADMIN_ROLE) {
        ethDepositContract = _ethDepositContract;
        emit DepositContractSet(_ethDepositContract);
    }
    /**
     * @dev set withdraw credential to receive revenue, usually this should be the contract itself.
     */
    function setWithdrawCredential(bytes32 withdrawalCredentials_) external onlyRole(DEFAULT_ADMIN_ROLE) {
        withdrawalCredentials = withdrawalCredentials_;
        emit WithdrawCredentialSet(withdrawalCredentials);
    } 
    
    /**
     * @dev stake into eth2 staking contract by calling this function
     */
    function stake() external { _stakeInternal(); }
    /**
     * @dev internal entry of stake() external 
     */
    function _stakeInternal() internal {
        // spin max nodes
        uint256 numValidators = totalPending / DEPOSIT_SIZE;
        uint256 maxValidators = (nextValidatorId + numValidators <= validatorRegistry.length)?
                                    numValidators:
                                    validatorRegistry.length - nextValidatorId;
        for (uint256 i = 0;i<maxValidators;i++) {
            _spinup();
        }
        if (maxValidators > 0) {
            emit ValidatorActivated(nextValidatorId);
        }
    }
    /**
     * @dev manager withdraw fees as uniETH
     */
    function withdrawManagerFee(address to) external onlyRole(MANAGER_ROLE) {
        IERC20(xETHAddress).safeTransfer(to, IERC20(xETHAddress).balanceOf(address(this)));
    }
    /**
     * @dev compound manager's revenue
     *  NOTE(20240406): this MUST be called in pushBeacon, to make sure debts are paied in priority, otherwise
     *      debts may be used to pay as the manager's revenue(that may take serveral months to come back).
     */
    function _compoundManagerRevenue() internal {
        uint256 freeEthers = address(this).balance - totalPending;
        uint256 amountEthers = freeEthers < accountedManagerRevenue ? freeEthers:accountedManagerRevenue;
        if (amountEthers > 0) {
            uint256 totalSupply = IERC20(xETHAddress).totalSupply();
            uint256 totalEthers = currentReserve();
            uint256 tokensToMint = totalSupply * amountEthers / totalEthers;
            // swapping
            // uint256 ratio = _exchangeRatioInternal();           // RATIO GUARD BEGIN
            IMintableContract(xETHAddress).mint(address(this), tokensToMint);
            totalPending += amountEthers;
            accountedManagerRevenue -= amountEthers;
            // assert(ratio == _exchangeRatioInternal());          // RATIO GUARD END
            emit ManagerRevenueCompounded(amountEthers);
        }
    }
    /**
     * @dev balance sync, also moves the vector clock if it has different value
     */
    function syncBalance() external { _syncBalance(); }
    
    /**
     * @dev balance sync, also moves the vector clock if it has different value
     */
    function _syncBalance() internal {
        // account restaking values
        IRestaking(restakingContract).update();
        assert(SafeCast.toInt256(address(this).balance) >= accountedBalance);
        uint256 diff = SafeCast.toUint256(SafeCast.toInt256(address(this).balance) - accountedBalance);
        if (diff > 0) {
            accountedBalance = SafeCast.toInt256(address(this).balance);
            recentReceived += diff;
            _vectorClockTick();
            emit BalanceSynced(diff);
        }
    }
    
    /**
     * @dev public invokable settlement to update exchangeRatio with default revenue limit.
     */
    function pushBeacon() external { _pushBeacon(vectorClock, SAFE_PUSH_REWARDS); }
    /**
     * @dev operators to settle revenue with custom revenue limit under abnormal conditions.
     */
    function pushBeacon(bytes32 clock, uint256 maxRewards) external onlyRole(ORACLE_ROLE) { _pushBeacon(clock, maxRewards); }
    function _pushBeacon(bytes32 clock, uint256 maxRewards) internal {
        _require(vectorClock == clock, "SYS012");
        // Collect new revenue if there is any.
        _syncBalance();
        
        // Check recentStopped and recentReceived to see they match,
        // recentStopped MUST be aligned to recentReceived, clear
        // debts first if there are debts to pay.
        if (totalDebts > 0) {
            _require(recentReceived/DEPOSIT_SIZE == recentStopped, "SYS030");
        }
        // Check if new validators increased
        // and adjust rewardBase to include the new validators' value
        uint256 rewardBase = reportedValidatorBalance + reportedUnrealizedProfits;
        uint256 _aliveValidators = nextValidatorId - stoppedValidators;
        if (_aliveValidators + recentStopped > reportedValidators) {
            // newly launched validators
            uint256 newValidators = _aliveValidators + recentStopped - reportedValidators;
            rewardBase += newValidators * DEPOSIT_SIZE;
        }
        // Rewards calculation, this also considers recentReceived ethers from 
        // either stopped validators or withdrawed ethers as rewards.
        //
        // During two consecutive pushBeacon operation, the ethers will ONLY: 
        //  1. staked to new validators
        //  2. move from active validators to this contract
        // 
        // so, at any time, revenue generated if:
        //
        //  current active validator balance 
        //      + recent received from validators(since last pushBeacon) 
        //  >（GREATER THAN) reward base(last active validator balance + new nodes balance)
        uint256 _aliveBalance = _aliveValidators * DEPOSIT_SIZE;  // computed balance
        uint256 _unrealizedProfits = IRestaking(restakingContract).getPendingWithdrawalAmount();   // get unrealized profits
        _require(_aliveBalance + _unrealizedProfits + recentReceived >= rewardBase, "SYS015");
        uint256 rewards = _aliveBalance + _unrealizedProfits + recentReceived - rewardBase;
        _require(rewards <= maxRewards, "SYS016");
        _distributeRewards(rewards);
        _compoundManagerRevenue();
        _autocompound();
        // Update reportedValidators & reportedValidatorBalance
        // reset the recentReceived to 0
        reportedValidatorBalance = _aliveBalance; 
        reportedValidators = _aliveValidators;
        reportedUnrealizedProfits = _unrealizedProfits;
        recentReceived = 0;
        recentStopped = 0;
    }
    /**
     * @dev notify some validators stopped, and pay the debts
     */
    function validatorStopped(bytes [] calldata _stoppedPubKeys, bytes32 clock) external nonReentrant onlyRole(ORACLE_ROLE) {
        _require(vectorClock == clock, "SYS012");
        uint256 amountUnstaked = _stoppedPubKeys.length * DEPOSIT_SIZE;
        _require(_stoppedPubKeys.length > 0, "SYS017");
        _require(_stoppedPubKeys.length + stoppedValidators <= nextValidatorId, "SYS018");
        _require(address(this).balance >= amountUnstaked + totalPending, "SYS019");
        // track stopped validators
        for (uint i=0;i<_stoppedPubKeys.length;i++) {
            bytes32 pubkeyHash = keccak256(_stoppedPubKeys[i]);
            _require(pubkeyIndices[pubkeyHash] > 0, "SYS006");
            uint256 index = pubkeyIndices[pubkeyHash] - 1;
            _require(!validatorRegistry[index].stopped, "SYS020");
            validatorRegistry[index].stopped = true;
        }
        stoppedValidators += _stoppedPubKeys.length;
        recentStopped += _stoppedPubKeys.length;
        // NOTE(x) The following procedure MUST keep currentReserve unchanged:
        uint256 ratio = _exchangeRatioInternal();           // RATIO GUARD BEGIN
        // pay debts
        uint256 paid = _payDebts(amountUnstaked);
        assert(paid % DEPOSIT_SIZE == 0);   // debts are in N * 32ETH
        // track total staked ethers
        totalStaked -= amountUnstaked;
        // CAUTION: for unexpected exiting of validators, 
        // we put back the extra ethers back to pending queue.
        uint256 remain = amountUnstaked - paid;
        totalPending += remain;
        assert(ratio == _exchangeRatioInternal());          // RATIO GUARD END
        // log
        emit ValidatorStopped(_stoppedPubKeys.length);
        // vector clock moves
        _vectorClockTick();
    }
    /**
     * ======================================================================================
     * 
     * VIEW FUNCTIONS
     * 
     * ======================================================================================
     */
    /**
     * @dev returns current reserve of ethers
     */
    function currentReserve() public view returns(uint256) {
        return totalPending + totalStaked + accountedUserRevenue - totalDebts - rewardDebts;
    }
    /*
     * @dev returns current vector clock
     */
    function getVectorClock() external view returns(bytes32) { return vectorClock; }
    /*
     * @dev returns current accounted balance
     */
    function getAccountedBalance() external view returns(int256) { return accountedBalance; }
    /**
     * @dev return total staked ethers
     */
    function getTotalStaked() external view returns (uint256) { return totalStaked; }
    /**
     * @dev return pending ethers
     */
    function getPendingEthers() external view returns (uint256) { return totalPending; }
    /**
     * @dev return reward debts(total compounded ethers)
     */
    function getRewardDebts() external view returns (uint256) { return rewardDebts; }
    /**
     * @dev return current debts
     */
    function getCurrentDebts() external view returns (uint256) { return totalDebts; }
    /**
     * @dev returns the accounted user revenue
     */
    function getAccountedUserRevenue() external view returns (uint256) { return accountedUserRevenue; }
    /**
     * @dev returns the accounted manager's revenue
     */
    function getAccountedManagerRevenue() external view returns (uint256) { return accountedManagerRevenue; }
    /*
     * @dev returns accumulated beacon validators
     */
    function getReportedValidators() external view returns (uint256) { return reportedValidators; }
    /*
     * @dev returns reported validator balance snapshot
     */
    function getReportedValidatorBalance() external view returns (uint256) { return reportedValidatorBalance; }
    /*
     * @dev returns recent received value
     */
    function getRecentReceived() external view returns (uint256) { return recentReceived; }
    /*
     * @dev returns recent received value
     */
    function getRecentStopped() external view returns (uint256) { return recentStopped; }
    /**
     * @dev return debt for an account
     */
    function debtOf(address account) external view returns (uint256) {
        return userDebts[account];
    }
    /**
     * @dev return number of registered validator
     */
    function getRegisteredValidatorsCount() external view returns (uint256) {
        return validatorRegistry.length;
    }
    
    /**
     * @dev return a batch of validators credential
     */
    function getRegisteredValidators(uint256 idx_from, uint256 idx_to) external view returns (bytes [] memory pubkeys, bytes [] memory signatures, bool[] memory stopped) {
        pubkeys = new bytes[](idx_to - idx_from);
        signatures = new bytes[](idx_to - idx_from);
        stopped = new bool[](idx_to - idx_from);
        uint counter = 0;
        for (uint i = idx_from; i < idx_to;i++) {
            pubkeys[counter] = validatorRegistry[i].pubkey;
            signatures[counter] = validatorRegistry[i].signature;
            stopped[counter] = validatorRegistry[i].stopped;
            counter++;
        }
    }
    /**
     * @dev return a batch of validators information
     * UPDATE(20240119): V2 returns restaking info
     */
    function getRegisteredValidatorsV2(uint256 idx_from, uint256 idx_to) external view returns (
         bytes [] memory pubkeys,
         bytes [] memory signatures,
         bool [] memory stopped,
         bool [] memory restaking)
    {
        pubkeys = new bytes[](idx_to - idx_from);
        signatures = new bytes[](idx_to - idx_from);
        stopped = new bool[](idx_to - idx_from);
        restaking = new bool[](idx_to - idx_from);
        uint counter = 0;
        for (uint i = idx_from; i < idx_to;i++) {
            pubkeys[counter] = validatorRegistry[i].pubkey;
            signatures[counter] = validatorRegistry[i].signature;
            stopped[counter] = validatorRegistry[i].stopped;
            restaking[counter] = validatorRegistry[i].restaking;
            counter++;
        }
    }
    /**
     * @dev return next validator id
     */
    function getNextValidatorId() external view returns (uint256) { return nextValidatorId; }
    /**
     * @dev return exchange ratio for 1 uniETH to ETH, multiplied by 1e18
     */
    function exchangeRatio() external view returns (uint256) { return _exchangeRatioInternal(); }
    function _exchangeRatioInternal() internal view returns (uint256) {
        uint256 xETHAmount = IERC20(xETHAddress).totalSupply();
        if (xETHAmount == 0) {
            return 1 * MULTIPLIER;
        }
        uint256 ratio = currentReserve() * MULTIPLIER / xETHAmount;
        return ratio;
    }
    /**
     * @dev return debt of index
     */
    function checkDebt(uint256 index) external view returns (address account, uint256 amount) {
        Debt memory debt = etherDebts[index];
        return (debt.account, debt.amount);
    }
    /**
     * @dev return debt queue index
     */
    function getDebtQueue() external view returns (uint256 first, uint256 last) {
        return (firstDebt, lastDebt);
    }
    /**
     * @dev get stopped validators count
     */
    function getStoppedValidatorsCount() external view returns (uint256) { return stoppedValidators; }
    /**
     * ======================================================================================
     * 
     * EXTERNAL FUNCTIONS
     * 
     * ======================================================================================
     */
    /**
     * @dev mint xETH with ETH
     */
    function mint(uint256 minToMint, uint256 deadline) external payable nonReentrant whenNotPaused returns(uint256 minted) {
        _require(block.timestamp < deadline, "USR001");
        _require(msg.value > 0, "USR002");
        // track balance
        _balanceIncrease(msg.value);
        // mint xETH while keeping the exchange ratio invariant
        uint256 totalXETH = IERC20(xETHAddress).totalSupply();
        uint256 totalEthers = currentReserve();
        uint256 toMint = 1 * msg.value;  // default exchange ratio 1:1
        if (totalEthers > 0) { // avert division overflow
            toMint = totalXETH * msg.value / totalEthers;
        }
        _require(toMint >= minToMint, "USR004");
        // mint token while keeping exchange ratio invariant
        // uint256 ratio = _exchangeRatioInternal();           // RATIO GUARD BEGIN
        IMintableContract(xETHAddress).mint(msg.sender, toMint);
        totalPending += msg.value;
        // assert(ratio == _exchangeRatioInternal());          // RATIO GUARD END
        // try to initiate stake()
        _stakeInternal();
        return toMint;
    }
    /** 
     * @dev preview instant payment at CURRENT exchangeRatio
     */
    function previewInstantSwap(uint256 tokenAmount) external view returns(
        uint256 maxEthersToSwap,
        uint256 maxTokensToBurn
    ) {
        return _instantSwapRate(tokenAmount);
    }
    /** 
     * @dev instant payment as much as possbile from pending ethers at CURRENT exchangeRatio
     */
    function instantSwap(uint256 tokenAmount) external nonReentrant whenNotPaused {
        (uint256 maxEthersToSwap, uint256 maxTokensToBurn) = _instantSwapRate(tokenAmount);
        // _require(maxTokensToBurn > 0 && maxEthersToSwap > 0, "USR007");
        // uint256 ratio = _exchangeRatioInternal();               // RATIO GUARD BEGIN
        // transfer token from user and burn, substract ethers from pending ethers
        IMintableContract(xETHAddress).burnFrom(msg.sender, maxTokensToBurn);
        totalPending -= maxEthersToSwap;
        // assert(ratio == _exchangeRatioInternal());              // RATIO GUARD END
        // track balance change
        _balanceDecrease(maxEthersToSwap);
        // transfer ethers to users
        payable(msg.sender).sendValue(maxEthersToSwap);
    }
    /**
     * @dev internal function for the calculation of max allowed instant swap rate
     */
    function _instantSwapRate(uint256 tokenAmount) internal view returns (
        uint256 maxEthersToSwap,
        uint256 maxTokensToBurn
    ) {
        // find max instant swappable ethers
        uint256 totalSupply = IERC20(xETHAddress).totalSupply();
        uint256 r = currentReserve();
        uint256 expectedEthersToSwap =  tokenAmount * r / totalSupply;
        maxEthersToSwap = expectedEthersToSwap > totalPending ? totalPending:expectedEthersToSwap;
        // reverse calculation for how much token to burn.
        maxTokensToBurn = totalSupply * maxEthersToSwap / r;
    }
    /**
     * @dev redeem N * 32Ethers, which will turn off validadators,
     * note this function is asynchronous, the caller will only receive his ethers
     * after the validator has turned off.
     *
     * this function is dedicated for institutional operations.
     * 
     * redeem keeps the ratio invariant
     */
    function redeemFromValidators(uint256 ethersToRedeem, uint256 maxToBurn, uint256 deadline) external nonReentrant returns(uint256 burned) {
        _require(block.timestamp < deadline, "USR001");
        _require(ethersToRedeem % DEPOSIT_SIZE == 0, "USR005");
        _require(ethersToRedeem > 0, "USR005");
        uint256 totalXETH = IERC20(xETHAddress).totalSupply();
        uint256 xETHToBurn = totalXETH * ethersToRedeem / currentReserve();
        _require(xETHToBurn <= maxToBurn, "USR004");
        // NOTE: the following procdure must keep exchangeRatio invariant:
        // transfer xETH from sender & burn
        // uint256 ratio = _exchangeRatioInternal();           // RATIO GUARD BEGIN
        IMintableContract(xETHAddress).burnFrom(msg.sender, xETHToBurn);
        _enqueueDebt(msg.sender, ethersToRedeem);           // queue ether debts
        // assert(ratio == _exchangeRatioInternal());          // RATIO GUARD END
        // return burned 
        return xETHToBurn;
    }
    /** 
     * ======================================================================================
     * 
     * INTERNAL FUNCTIONS
     * 
     * ======================================================================================
     */
    function _balanceIncrease(uint256 amount) internal { accountedBalance += SafeCast.toInt256(amount); }
    function _balanceDecrease(uint256 amount) internal { accountedBalance -= SafeCast.toInt256(amount); }
    function _vectorClockTick() internal {
        vectorClockTicks++;
        vectorClock = keccak256(abi.encodePacked(vectorClock, block.timestamp, vectorClockTicks));
    }
    function _enqueueDebt(address account, uint256 amount) internal {
        // debt is paid in FIFO queue
        lastDebt += 1;
        etherDebts[lastDebt] = Debt({account:account, amount:amount});
        // track user debts
        userDebts[account] += amount;
        // track total debts
        totalDebts += amount;
        // log
        emit DebtQueued(account, amount);
    }
    function _dequeueDebt() internal returns (Debt memory debt) {
        _require(lastDebt >= firstDebt, "SYS022");  // non-empty queue
        debt = etherDebts[firstDebt];
        delete etherDebts[firstDebt];
        firstDebt += 1;
    }
    /**
     * @dev pay debts for a given amount
     */
    function _payDebts(uint256 total) internal returns(uint256 amountPaid) {
        // ethers to pay
        for (uint i=firstDebt;i<=lastDebt;i++) {
            if (total == 0) {
                break;
            }
            Debt storage debt = etherDebts[i];
            // clean debts
            uint256 toPay = debt.amount <= total? debt.amount:total;
            debt.amount -= toPay;
            total -= toPay;
            userDebts[debt.account] -= toPay;
            amountPaid += toPay;
            // transfer money to debt contract
            IRockXRedeem(redeemContract).pay{value:toPay}(debt.account);
            // dequeue if cleared 
            if (debt.amount == 0) {
                _dequeueDebt();
            }
        }
        
        totalDebts -= amountPaid;
        
        // track balance
        _balanceDecrease(amountPaid);
    }
    /**
     * @dev distribute revenue
     */
    function _distributeRewards(uint256 rewards) internal {
        // rewards distribution
        uint256 fee = rewards * managerFeeShare / 1000;
        accountedManagerRevenue += fee;
        accountedUserRevenue += rewards - fee;
        emit RevenueAccounted(rewards);
    }
    /**
     * @dev auto compounding, after shanghai merge, called in pushBeacon
     *  NOTE(20240406): this MUST be called in pushBeacon, to make sure debts are paied in priority, otherwise
     *      debts may be used to pay as the users' revenue(that may take serveral months to come back).
     */
    function _autocompound() internal {
        uint256 maxCompound = accountedUserRevenue - rewardDebts;
        uint256 maxUsable = address(this).balance - totalPending;
        uint256 effectiveEthers = maxCompound < maxUsable? maxCompound:maxUsable;
        if (effectiveEthers > 0) {
            totalPending += effectiveEthers;
            rewardDebts += effectiveEthers;
            emit UserRevenueCompounded(effectiveEthers);
        }
    }
    /**
     * @dev spin up the node
     */
    function _spinup() internal {
         // load credential
        ValidatorCredential memory cred = validatorRegistry[nextValidatorId];
        
        // UPDATE(20240115):
        //  switch withdrawal credential based on it's registration
        if (!cred.restaking) {
            _stake(cred.pubkey, cred.signature, withdrawalCredentials);
        } else {
            address eigenPod = IRestaking(restakingContract).getPod(cred.eigenpod);
            bytes memory eigenPodCred = abi.encodePacked(bytes1(0x01), new bytes(11), eigenPod);
            bytes32 restakingWithdrawalCredentials = BytesLib.toBytes32(eigenPodCred, 0);
            _stake(cred.pubkey, cred.signature, restakingWithdrawalCredentials);
        }
        nextValidatorId++;        
        // track total staked & total pending ethers
        totalStaked += DEPOSIT_SIZE;
        totalPending -= DEPOSIT_SIZE;
    }
    /**
     * @dev Invokes a deposit call to the official Deposit contract
     *      UPDATE(20240115): add param withCred, instead of using contract variable
     */
    function _stake(bytes memory pubkey, bytes memory signature, bytes32 withCred) internal {
        _require(withCred != bytes32(0x0), "SYS024");
        uint256 value = DEPOSIT_SIZE;
        uint256 depositAmount = DEPOSIT_SIZE / DEPOSIT_AMOUNT_UNIT;
        assert(depositAmount * DEPOSIT_AMOUNT_UNIT == value);    // properly rounded
        // Compute deposit data root (`DepositData` hash tree root)
        // https://etherscan.io/address/0x00000000219ab540356cbb839cbe05303d7705fa#code
        bytes32 pubkey_root = sha256(abi.encodePacked(pubkey, bytes16(0)));
        bytes32 signature_root = sha256(abi.encodePacked(
            sha256(BytesLib.slice(signature, 0, 64)),
            sha256(abi.encodePacked(BytesLib.slice(signature, 64, SIGNATURE_LENGTH - 64), bytes32(0)))
        ));
        
        bytes memory amount = to_little_endian_64(uint64(depositAmount));
        bytes32 depositDataRoot = sha256(abi.encodePacked(
            sha256(abi.encodePacked(pubkey_root, withCred)),
            sha256(abi.encodePacked(amount, bytes24(0), signature_root))
        ));
        IDepositContract(ethDepositContract).deposit{value:DEPOSIT_SIZE} (
            pubkey, abi.encodePacked(withCred), signature, depositDataRoot);
        // track balance
        _balanceDecrease(DEPOSIT_SIZE);
    }
    /**
     * @dev to little endian
     * https://etherscan.io/address/0x00000000219ab540356cbb839cbe05303d7705fa#code
     */
    function to_little_endian_64(uint64 value) internal pure returns (bytes memory ret) {
        ret = new bytes(8);
        bytes8 bytesValue = bytes8(value);
        // Byteswapping during copying to bytes.
        ret[0] = bytesValue[7];
        ret[1] = bytesValue[6];
        ret[2] = bytesValue[5];
        ret[3] = bytesValue[4];
        ret[4] = bytesValue[3];
        ret[5] = bytesValue[2];
        ret[6] = bytesValue[1];
        ret[7] = bytesValue[0];
    }
    /**
     * @dev function version of _require, which could make the code size smaller
     */
    function _require(bool condition, string memory text) private pure {
        require(condition, text);
    }
    /**
     * ======================================================================================
     * 
     * CONTRCT EVENTS
     *
     * ======================================================================================
     */
    event ValidatorActivated(uint256 nextValidatorId);
    event ValidatorStopped(uint256 stoppedCount);
    event RevenueAccounted(uint256 amount);
    event ValidatorSlashedStopped(uint256 stoppedCount);
    event ManagerAccountSet(address account);
    event ManagerFeeSet(uint256 milli);
    event ManagerFeeWithdrawed(uint256 amount, address);
    event WithdrawCredentialSet(bytes32 withdrawCredential);
    event RestakingAddressSet(address addr);
    event DebtQueued(address creditor, uint256 amountEther);
    event DepositContractSet(address addr);
    event BalanceSynced(uint256 diff);
    event WhiteListToggle(address account, bool enabled);
    event ManagerRevenueCompounded(uint256 amount);
    event UserRevenueCompounded(uint256 amount);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;
import "IERC20.sol";
interface IMintableContract is IERC20 {
    function mint(address account, uint256 amount) external;
    function burn(uint256 amount) external;
    function burnFrom(address account, uint256 amount) external;
}
// This interface is designed to be compatible with the Vyper version.
/// @notice This is the Ethereum 2.0 deposit contract interface.
/// For more information see the Phase 0 specification under https://github.com/ethereum/eth2.0-specs
interface IDepositContract {
    /// @notice A processed deposit event.
    event DepositEvent(
        bytes pubkey,
        bytes withdrawal_credentials,
        bytes amount,
        bytes signature,
        bytes index
    );
    /// @notice Submit a Phase 0 DepositData object.
    /// @param pubkey A BLS12-381 public key.
    /// @param withdrawal_credentials Commitment to a public key for withdrawals.
    /// @param signature A BLS12-381 signature.
    /// @param deposit_data_root The SHA-256 hash of the SSZ-encoded DepositData object.
    /// Used as a protection against malformed input.
    function deposit(
        bytes calldata pubkey,
        bytes calldata withdrawal_credentials,
        bytes calldata signature,
        bytes32 deposit_data_root
    ) external payable;
    /// @notice Query the current deposit root hash.
    /// @return The deposit root hash.
    function get_deposit_root() external view returns (bytes32);
    /// @notice Query the current deposit count.
    /// @return The deposit count encoded as a little endian 64-bit number.
    function get_deposit_count() external view returns (bytes memory);
}
interface IRockXRedeem {
    function pay(address account) external payable;
}
interface IRestaking {
    function update() external;
    function getPendingWithdrawalAmount() external view returns (uint256);
    function eigenPod() external view returns (address);
    function getPod(uint256 i) external view returns (address);
    function getTotalPods() external view returns (uint256);
}
interface IPodOwner {
    function transfer(address target, uint256 amount) external;
    function execute(address target, bytes memory data) external returns(bytes memory);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/IERC20.sol)
pragma solidity ^0.8.0;
/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);
    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);
    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);
    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);
    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);
    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);
    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}
// SPDX-License-Identifier: Unlicense
/*
 * @title Solidity Bytes Arrays Utils
 * @author Gonçalo Sá <goncalo.sa@consensys.net>
 *
 * @dev Bytes tightly packed arrays utility library for ethereum contracts written in Solidity.
 *      The library lets you concatenate, slice and type cast bytes arrays both in memory and storage.
 */
pragma solidity >=0.8.0 <0.9.0;
library BytesLib {
    function concat(
        bytes memory _preBytes,
        bytes memory _postBytes
    )
        internal
        pure
        returns (bytes memory)
    {
        bytes memory tempBytes;
        assembly {
            // Get a location of some free memory and store it in tempBytes as
            // Solidity does for memory variables.
            tempBytes := mload(0x40)
            // Store the length of the first bytes array at the beginning of
            // the memory for tempBytes.
            let length := mload(_preBytes)
            mstore(tempBytes, length)
            // Maintain a memory counter for the current write location in the
            // temp bytes array by adding the 32 bytes for the array length to
            // the starting location.
            let mc := add(tempBytes, 0x20)
            // Stop copying when the memory counter reaches the length of the
            // first bytes array.
            let end := add(mc, length)
            for {
                // Initialize a copy counter to the start of the _preBytes data,
                // 32 bytes into its memory.
                let cc := add(_preBytes, 0x20)
            } lt(mc, end) {
                // Increase both counters by 32 bytes each iteration.
                mc := add(mc, 0x20)
                cc := add(cc, 0x20)
            } {
                // Write the _preBytes data into the tempBytes memory 32 bytes
                // at a time.
                mstore(mc, mload(cc))
            }
            // Add the length of _postBytes to the current length of tempBytes
            // and store it as the new length in the first 32 bytes of the
            // tempBytes memory.
            length := mload(_postBytes)
            mstore(tempBytes, add(length, mload(tempBytes)))
            // Move the memory counter back from a multiple of 0x20 to the
            // actual end of the _preBytes data.
            mc := end
            // Stop copying when the memory counter reaches the new combined
            // length of the arrays.
            end := add(mc, length)
            for {
                let cc := add(_postBytes, 0x20)
            } lt(mc, end) {
                mc := add(mc, 0x20)
                cc := add(cc, 0x20)
            } {
                mstore(mc, mload(cc))
            }
            // Update the free-memory pointer by padding our last write location
            // to 32 bytes: add 31 bytes to the end of tempBytes to move to the
            // next 32 byte block, then round down to the nearest multiple of
            // 32. If the sum of the length of the two arrays is zero then add
            // one before rounding down to leave a blank 32 bytes (the length block with 0).
            mstore(0x40, and(
              add(add(end, iszero(add(length, mload(_preBytes)))), 31),
              not(31) // Round down to the nearest 32 bytes.
            ))
        }
        return tempBytes;
    }
    function concatStorage(bytes storage _preBytes, bytes memory _postBytes) internal {
        assembly {
            // Read the first 32 bytes of _preBytes storage, which is the length
            // of the array. (We don't need to use the offset into the slot
            // because arrays use the entire slot.)
            let fslot := sload(_preBytes.slot)
            // Arrays of 31 bytes or less have an even value in their slot,
            // while longer arrays have an odd value. The actual length is
            // the slot divided by two for odd values, and the lowest order
            // byte divided by two for even values.
            // If the slot is even, bitwise and the slot with 255 and divide by
            // two to get the length. If the slot is odd, bitwise and the slot
            // with -1 and divide by two.
            let slength := div(and(fslot, sub(mul(0x100, iszero(and(fslot, 1))), 1)), 2)
            let mlength := mload(_postBytes)
            let newlength := add(slength, mlength)
            // slength can contain both the length and contents of the array
            // if length < 32 bytes so let's prepare for that
            // v. http://solidity.readthedocs.io/en/latest/miscellaneous.html#layout-of-state-variables-in-storage
            switch add(lt(slength, 32), lt(newlength, 32))
            case 2 {
                // Since the new array still fits in the slot, we just need to
                // update the contents of the slot.
                // uint256(bytes_storage) = uint256(bytes_storage) + uint256(bytes_memory) + new_length
                sstore(
                    _preBytes.slot,
                    // all the modifications to the slot are inside this
                    // next block
                    add(
                        // we can just add to the slot contents because the
                        // bytes we want to change are the LSBs
                        fslot,
                        add(
                            mul(
                                div(
                                    // load the bytes from memory
                                    mload(add(_postBytes, 0x20)),
                                    // zero all bytes to the right
                                    exp(0x100, sub(32, mlength))
                                ),
                                // and now shift left the number of bytes to
                                // leave space for the length in the slot
                                exp(0x100, sub(32, newlength))
                            ),
                            // increase length by the double of the memory
                            // bytes length
                            mul(mlength, 2)
                        )
                    )
                )
            }
            case 1 {
                // The stored value fits in the slot, but the combined value
                // will exceed it.
                // get the keccak hash to get the contents of the array
                mstore(0x0, _preBytes.slot)
                let sc := add(keccak256(0x0, 0x20), div(slength, 32))
                // save new length
                sstore(_preBytes.slot, add(mul(newlength, 2), 1))
                // The contents of the _postBytes array start 32 bytes into
                // the structure. Our first read should obtain the `submod`
                // bytes that can fit into the unused space in the last word
                // of the stored array. To get this, we read 32 bytes starting
                // from `submod`, so the data we read overlaps with the array
                // contents by `submod` bytes. Masking the lowest-order
                // `submod` bytes allows us to add that value directly to the
                // stored value.
                let submod := sub(32, slength)
                let mc := add(_postBytes, submod)
                let end := add(_postBytes, mlength)
                let mask := sub(exp(0x100, submod), 1)
                sstore(
                    sc,
                    add(
                        and(
                            fslot,
                            0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff00
                        ),
                        and(mload(mc), mask)
                    )
                )
                for {
                    mc := add(mc, 0x20)
                    sc := add(sc, 1)
                } lt(mc, end) {
                    sc := add(sc, 1)
                    mc := add(mc, 0x20)
                } {
                    sstore(sc, mload(mc))
                }
                mask := exp(0x100, sub(mc, end))
                sstore(sc, mul(div(mload(mc), mask), mask))
            }
            default {
                // get the keccak hash to get the contents of the array
                mstore(0x0, _preBytes.slot)
                // Start copying to the last used word of the stored array.
                let sc := add(keccak256(0x0, 0x20), div(slength, 32))
                // save new length
                sstore(_preBytes.slot, add(mul(newlength, 2), 1))
                // Copy over the first `submod` bytes of the new data as in
                // case 1 above.
                let slengthmod := mod(slength, 32)
                let mlengthmod := mod(mlength, 32)
                let submod := sub(32, slengthmod)
                let mc := add(_postBytes, submod)
                let end := add(_postBytes, mlength)
                let mask := sub(exp(0x100, submod), 1)
                sstore(sc, add(sload(sc), and(mload(mc), mask)))
                for {
                    sc := add(sc, 1)
                    mc := add(mc, 0x20)
                } lt(mc, end) {
                    sc := add(sc, 1)
                    mc := add(mc, 0x20)
                } {
                    sstore(sc, mload(mc))
                }
                mask := exp(0x100, sub(mc, end))
                sstore(sc, mul(div(mload(mc), mask), mask))
            }
        }
    }
    function slice(
        bytes memory _bytes,
        uint256 _start,
        uint256 _length
    )
        internal
        pure
        returns (bytes memory)
    {
        require(_length + 31 >= _length, "slice_overflow");
        require(_bytes.length >= _start + _length, "slice_outOfBounds");
        bytes memory tempBytes;
        assembly {
            switch iszero(_length)
            case 0 {
                // Get a location of some free memory and store it in tempBytes as
                // Solidity does for memory variables.
                tempBytes := mload(0x40)
                // The first word of the slice result is potentially a partial
                // word read from the original array. To read it, we calculate
                // the length of that partial word and start copying that many
                // bytes into the array. The first word we copy will start with
                // data we don't care about, but the last `lengthmod` bytes will
                // land at the beginning of the contents of the new array. When
                // we're done copying, we overwrite the full first word with
                // the actual length of the slice.
                let lengthmod := and(_length, 31)
                // The multiplication in the next line is necessary
                // because when slicing multiples of 32 bytes (lengthmod == 0)
                // the following copy loop was copying the origin's length
                // and then ending prematurely not copying everything it should.
                let mc := add(add(tempBytes, lengthmod), mul(0x20, iszero(lengthmod)))
                let end := add(mc, _length)
                for {
                    // The multiplication in the next line has the same exact purpose
                    // as the one above.
                    let cc := add(add(add(_bytes, lengthmod), mul(0x20, iszero(lengthmod))), _start)
                } lt(mc, end) {
                    mc := add(mc, 0x20)
                    cc := add(cc, 0x20)
                } {
                    mstore(mc, mload(cc))
                }
                mstore(tempBytes, _length)
                //update free-memory pointer
                //allocating the array padded to 32 bytes like the compiler does now
                mstore(0x40, and(add(mc, 31), not(31)))
            }
            //if we want a zero-length slice let's just return a zero-length array
            default {
                tempBytes := mload(0x40)
                //zero out the 32 bytes slice we are about to return
                //we need to do it because Solidity does not garbage collect
                mstore(tempBytes, 0)
                mstore(0x40, add(tempBytes, 0x20))
            }
        }
        return tempBytes;
    }
    function toAddress(bytes memory _bytes, uint256 _start) internal pure returns (address) {
        require(_bytes.length >= _start + 20, "toAddress_outOfBounds");
        address tempAddress;
        assembly {
            tempAddress := div(mload(add(add(_bytes, 0x20), _start)), 0x1000000000000000000000000)
        }
        return tempAddress;
    }
    function toUint8(bytes memory _bytes, uint256 _start) internal pure returns (uint8) {
        require(_bytes.length >= _start + 1 , "toUint8_outOfBounds");
        uint8 tempUint;
        assembly {
            tempUint := mload(add(add(_bytes, 0x1), _start))
        }
        return tempUint;
    }
    function toUint16(bytes memory _bytes, uint256 _start) internal pure returns (uint16) {
        require(_bytes.length >= _start + 2, "toUint16_outOfBounds");
        uint16 tempUint;
        assembly {
            tempUint := mload(add(add(_bytes, 0x2), _start))
        }
        return tempUint;
    }
    function toUint32(bytes memory _bytes, uint256 _start) internal pure returns (uint32) {
        require(_bytes.length >= _start + 4, "toUint32_outOfBounds");
        uint32 tempUint;
        assembly {
            tempUint := mload(add(add(_bytes, 0x4), _start))
        }
        return tempUint;
    }
    function toUint64(bytes memory _bytes, uint256 _start) internal pure returns (uint64) {
        require(_bytes.length >= _start + 8, "toUint64_outOfBounds");
        uint64 tempUint;
        assembly {
            tempUint := mload(add(add(_bytes, 0x8), _start))
        }
        return tempUint;
    }
    function toUint96(bytes memory _bytes, uint256 _start) internal pure returns (uint96) {
        require(_bytes.length >= _start + 12, "toUint96_outOfBounds");
        uint96 tempUint;
        assembly {
            tempUint := mload(add(add(_bytes, 0xc), _start))
        }
        return tempUint;
    }
    function toUint128(bytes memory _bytes, uint256 _start) internal pure returns (uint128) {
        require(_bytes.length >= _start + 16, "toUint128_outOfBounds");
        uint128 tempUint;
        assembly {
            tempUint := mload(add(add(_bytes, 0x10), _start))
        }
        return tempUint;
    }
    function toUint256(bytes memory _bytes, uint256 _start) internal pure returns (uint256) {
        require(_bytes.length >= _start + 32, "toUint256_outOfBounds");
        uint256 tempUint;
        assembly {
            tempUint := mload(add(add(_bytes, 0x20), _start))
        }
        return tempUint;
    }
    function toBytes32(bytes memory _bytes, uint256 _start) internal pure returns (bytes32) {
        require(_bytes.length >= _start + 32, "toBytes32_outOfBounds");
        bytes32 tempBytes32;
        assembly {
            tempBytes32 := mload(add(add(_bytes, 0x20), _start))
        }
        return tempBytes32;
    }
    function equal(bytes memory _preBytes, bytes memory _postBytes) internal pure returns (bool) {
        bool success = true;
        assembly {
            let length := mload(_preBytes)
            // if lengths don't match the arrays are not equal
            switch eq(length, mload(_postBytes))
            case 1 {
                // cb is a circuit breaker in the for loop since there's
                //  no said feature for inline assembly loops
                // cb = 1 - don't breaker
                // cb = 0 - break
                let cb := 1
                let mc := add(_preBytes, 0x20)
                let end := add(mc, length)
                for {
                    let cc := add(_postBytes, 0x20)
                // the next line is the loop condition:
                // while(uint256(mc < end) + cb == 2)
                } eq(add(lt(mc, end), cb), 2) {
                    mc := add(mc, 0x20)
                    cc := add(cc, 0x20)
                } {
                    // if any of these checks fails then arrays are not equal
                    if iszero(eq(mload(mc), mload(cc))) {
                        // unsuccess:
                        success := 0
                        cb := 0
                    }
                }
            }
            default {
                // unsuccess:
                success := 0
            }
        }
        return success;
    }
    function equalStorage(
        bytes storage _preBytes,
        bytes memory _postBytes
    )
        internal
        view
        returns (bool)
    {
        bool success = true;
        assembly {
            // we know _preBytes_offset is 0
            let fslot := sload(_preBytes.slot)
            // Decode the length of the stored array like in concatStorage().
            let slength := div(and(fslot, sub(mul(0x100, iszero(and(fslot, 1))), 1)), 2)
            let mlength := mload(_postBytes)
            // if lengths don't match the arrays are not equal
            switch eq(slength, mlength)
            case 1 {
                // slength can contain both the length and contents of the array
                // if length < 32 bytes so let's prepare for that
                // v. http://solidity.readthedocs.io/en/latest/miscellaneous.html#layout-of-state-variables-in-storage
                if iszero(iszero(slength)) {
                    switch lt(slength, 32)
                    case 1 {
                        // blank the last byte which is the length
                        fslot := mul(div(fslot, 0x100), 0x100)
                        if iszero(eq(fslot, mload(add(_postBytes, 0x20)))) {
                            // unsuccess:
                            success := 0
                        }
                    }
                    default {
                        // cb is a circuit breaker in the for loop since there's
                        //  no said feature for inline assembly loops
                        // cb = 1 - don't breaker
                        // cb = 0 - break
                        let cb := 1
                        // get the keccak hash to get the contents of the array
                        mstore(0x0, _preBytes.slot)
                        let sc := keccak256(0x0, 0x20)
                        let mc := add(_postBytes, 0x20)
                        let end := add(mc, mlength)
                        // the next line is the loop condition:
                        // while(uint256(mc < end) + cb == 2)
                        for {} eq(add(lt(mc, end), cb), 2) {
                            sc := add(sc, 1)
                            mc := add(mc, 0x20)
                        } {
                            if iszero(eq(sload(sc), mload(mc))) {
                                // unsuccess:
                                success := 0
                                cb := 0
                            }
                        }
                    }
                }
            }
            default {
                // unsuccess:
                success := 0
            }
        }
        return success;
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)
pragma solidity ^0.8.0;
import "IERC20.sol";
import "Address.sol";
/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;
    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }
    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }
    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }
    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }
    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }
    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.
        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Address.sol)
pragma solidity ^0.8.0;
/**
 * @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
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.
        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 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 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) {
        require(isContract(target), "Address: delegate call to non-contract");
        (bool success, bytes memory returndata) = target.delegatecall(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);
            }
        }
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (proxy/utils/Initializable.sol)
pragma solidity ^0.8.2;
import "AddressUpgradeable.sol";
/**
 * @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;
        }
    }
}
// SPDX-License-Identifier: MIT
// 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);
            }
        }
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (access/AccessControl.sol)
pragma solidity ^0.8.0;
import "IAccessControlUpgradeable.sol";
import "ContextUpgradeable.sol";
import "StringsUpgradeable.sol";
import "ERC165Upgradeable.sol";
import "Initializable.sol";
/**
 * @dev Contract module that allows children to implement role-based access
 * control mechanisms. This is a lightweight version that doesn't allow enumerating role
 * members except through off-chain means by accessing the contract event logs. Some
 * applications may benefit from on-chain enumerability, for those cases see
 * {AccessControlEnumerable}.
 *
 * Roles are referred to by their `bytes32` identifier. These should be exposed
 * in the external API and be unique. The best way to achieve this is by
 * using `public constant` hash digests:
 *
 * ```
 * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
 * ```
 *
 * Roles can be used to represent a set of permissions. To restrict access to a
 * function call, use {hasRole}:
 *
 * ```
 * function foo() public {
 *     require(hasRole(MY_ROLE, msg.sender));
 *     ...
 * }
 * ```
 *
 * Roles can be granted and revoked dynamically via the {grantRole} and
 * {revokeRole} functions. Each role has an associated admin role, and only
 * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
 *
 * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
 * that only accounts with this role will be able to grant or revoke other
 * roles. More complex role relationships can be created by using
 * {_setRoleAdmin}.
 *
 * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
 * grant and revoke this role. Extra precautions should be taken to secure
 * accounts that have been granted it.
 */
abstract contract AccessControlUpgradeable is Initializable, ContextUpgradeable, IAccessControlUpgradeable, ERC165Upgradeable {
    function __AccessControl_init() internal onlyInitializing {
    }
    function __AccessControl_init_unchained() internal onlyInitializing {
    }
    struct RoleData {
        mapping(address => bool) members;
        bytes32 adminRole;
    }
    mapping(bytes32 => RoleData) private _roles;
    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;
    /**
     * @dev Modifier that checks that an account has a specific role. Reverts
     * with a standardized message including the required role.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
     *
     * _Available since v4.1._
     */
    modifier onlyRole(bytes32 role) {
        _checkRole(role);
        _;
    }
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IAccessControlUpgradeable).interfaceId || super.supportsInterface(interfaceId);
    }
    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) public view virtual override returns (bool) {
        return _roles[role].members[account];
    }
    /**
     * @dev Revert with a standard message if `_msgSender()` is missing `role`.
     * Overriding this function changes the behavior of the {onlyRole} modifier.
     *
     * Format of the revert message is described in {_checkRole}.
     *
     * _Available since v4.6._
     */
    function _checkRole(bytes32 role) internal view virtual {
        _checkRole(role, _msgSender());
    }
    /**
     * @dev Revert with a standard message if `account` is missing `role`.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
     */
    function _checkRole(bytes32 role, address account) internal view virtual {
        if (!hasRole(role, account)) {
            revert(
                string(
                    abi.encodePacked(
                        "AccessControl: account ",
                        StringsUpgradeable.toHexString(uint160(account), 20),
                        " is missing role ",
                        StringsUpgradeable.toHexString(uint256(role), 32)
                    )
                )
            );
        }
    }
    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) public view virtual override returns (bytes32) {
        return _roles[role].adminRole;
    }
    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _grantRole(role, account);
    }
    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _revokeRole(role, account);
    }
    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been revoked `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) public virtual override {
        require(account == _msgSender(), "AccessControl: can only renounce roles for self");
        _revokeRole(role, account);
    }
    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event. Note that unlike {grantRole}, this function doesn't perform any
     * checks on the calling account.
     *
     * [WARNING]
     * ====
     * This function should only be called from the constructor when setting
     * up the initial roles for the system.
     *
     * Using this function in any other way is effectively circumventing the admin
     * system imposed by {AccessControl}.
     * ====
     *
     * NOTE: This function is deprecated in favor of {_grantRole}.
     */
    function _setupRole(bytes32 role, address account) internal virtual {
        _grantRole(role, account);
    }
    /**
     * @dev Sets `adminRole` as ``role``'s admin role.
     *
     * Emits a {RoleAdminChanged} event.
     */
    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
        bytes32 previousAdminRole = getRoleAdmin(role);
        _roles[role].adminRole = adminRole;
        emit RoleAdminChanged(role, previousAdminRole, adminRole);
    }
    /**
     * @dev Grants `role` to `account`.
     *
     * Internal function without access restriction.
     */
    function _grantRole(bytes32 role, address account) internal virtual {
        if (!hasRole(role, account)) {
            _roles[role].members[account] = true;
            emit RoleGranted(role, account, _msgSender());
        }
    }
    /**
     * @dev Revokes `role` from `account`.
     *
     * Internal function without access restriction.
     */
    function _revokeRole(bytes32 role, address account) internal virtual {
        if (hasRole(role, account)) {
            _roles[role].members[account] = false;
            emit RoleRevoked(role, account, _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;
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (access/IAccessControl.sol)
pragma solidity ^0.8.0;
/**
 * @dev External interface of AccessControl declared to support ERC165 detection.
 */
interface IAccessControlUpgradeable {
    /**
     * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
     *
     * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
     * {RoleAdminChanged} not being emitted signaling this.
     *
     * _Available since v3.1._
     */
    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);
    /**
     * @dev Emitted when `account` is granted `role`.
     *
     * `sender` is the account that originated the contract call, an admin role
     * bearer except when using {AccessControl-_setupRole}.
     */
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);
    /**
     * @dev Emitted when `account` is revoked `role`.
     *
     * `sender` is the account that originated the contract call:
     *   - if using `revokeRole`, it is the admin role bearer
     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
     */
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);
    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) external view returns (bool);
    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {AccessControl-_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) external view returns (bytes32);
    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) external;
    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) external;
    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) external;
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)
pragma solidity ^0.8.0;
import "Initializable.sol";
/**
 * @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;
}
// SPDX-License-Identifier: MIT
// 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);
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)
pragma solidity ^0.8.0;
import "IERC165Upgradeable.sol";
import "Initializable.sol";
/**
 * @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;
}
// SPDX-License-Identifier: MIT
// 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);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (security/Pausable.sol)
pragma solidity ^0.8.0;
import "ContextUpgradeable.sol";
import "Initializable.sol";
/**
 * @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;
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (security/ReentrancyGuard.sol)
pragma solidity ^0.8.0;
import "Initializable.sol";
/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuardUpgradeable is Initializable {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.
    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;
    uint256 private _status;
    function __ReentrancyGuard_init() internal onlyInitializing {
        __ReentrancyGuard_init_unchained();
    }
    function __ReentrancyGuard_init_unchained() internal onlyInitializing {
        _status = _NOT_ENTERED;
    }
    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;
        _;
        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
    /**
     * @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;
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/math/SafeCast.sol)
pragma solidity ^0.8.0;
/**
 * @dev Wrappers over Solidity's uintXX/intXX casting operators with added overflow
 * checks.
 *
 * Downcasting from uint256/int256 in Solidity does not revert on overflow. This can
 * easily result in undesired exploitation or bugs, since developers usually
 * assume that overflows raise errors. `SafeCast` restores this intuition by
 * reverting the transaction when such an operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 *
 * Can be combined with {SafeMath} and {SignedSafeMath} to extend it to smaller types, by performing
 * all math on `uint256` and `int256` and then downcasting.
 */
library SafeCast {
    /**
     * @dev Returns the downcasted uint224 from uint256, reverting on
     * overflow (when the input is greater than largest uint224).
     *
     * Counterpart to Solidity's `uint224` operator.
     *
     * Requirements:
     *
     * - input must fit into 224 bits
     */
    function toUint224(uint256 value) internal pure returns (uint224) {
        require(value <= type(uint224).max, "SafeCast: value doesn't fit in 224 bits");
        return uint224(value);
    }
    /**
     * @dev Returns the downcasted uint128 from uint256, reverting on
     * overflow (when the input is greater than largest uint128).
     *
     * Counterpart to Solidity's `uint128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     */
    function toUint128(uint256 value) internal pure returns (uint128) {
        require(value <= type(uint128).max, "SafeCast: value doesn't fit in 128 bits");
        return uint128(value);
    }
    /**
     * @dev Returns the downcasted uint96 from uint256, reverting on
     * overflow (when the input is greater than largest uint96).
     *
     * Counterpart to Solidity's `uint96` operator.
     *
     * Requirements:
     *
     * - input must fit into 96 bits
     */
    function toUint96(uint256 value) internal pure returns (uint96) {
        require(value <= type(uint96).max, "SafeCast: value doesn't fit in 96 bits");
        return uint96(value);
    }
    /**
     * @dev Returns the downcasted uint64 from uint256, reverting on
     * overflow (when the input is greater than largest uint64).
     *
     * Counterpart to Solidity's `uint64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     */
    function toUint64(uint256 value) internal pure returns (uint64) {
        require(value <= type(uint64).max, "SafeCast: value doesn't fit in 64 bits");
        return uint64(value);
    }
    /**
     * @dev Returns the downcasted uint32 from uint256, reverting on
     * overflow (when the input is greater than largest uint32).
     *
     * Counterpart to Solidity's `uint32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     */
    function toUint32(uint256 value) internal pure returns (uint32) {
        require(value <= type(uint32).max, "SafeCast: value doesn't fit in 32 bits");
        return uint32(value);
    }
    /**
     * @dev Returns the downcasted uint16 from uint256, reverting on
     * overflow (when the input is greater than largest uint16).
     *
     * Counterpart to Solidity's `uint16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     */
    function toUint16(uint256 value) internal pure returns (uint16) {
        require(value <= type(uint16).max, "SafeCast: value doesn't fit in 16 bits");
        return uint16(value);
    }
    /**
     * @dev Returns the downcasted uint8 from uint256, reverting on
     * overflow (when the input is greater than largest uint8).
     *
     * Counterpart to Solidity's `uint8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits.
     */
    function toUint8(uint256 value) internal pure returns (uint8) {
        require(value <= type(uint8).max, "SafeCast: value doesn't fit in 8 bits");
        return uint8(value);
    }
    /**
     * @dev Converts a signed int256 into an unsigned uint256.
     *
     * Requirements:
     *
     * - input must be greater than or equal to 0.
     */
    function toUint256(int256 value) internal pure returns (uint256) {
        require(value >= 0, "SafeCast: value must be positive");
        return uint256(value);
    }
    /**
     * @dev Returns the downcasted int128 from int256, reverting on
     * overflow (when the input is less than smallest int128 or
     * greater than largest int128).
     *
     * Counterpart to Solidity's `int128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     *
     * _Available since v3.1._
     */
    function toInt128(int256 value) internal pure returns (int128) {
        require(value >= type(int128).min && value <= type(int128).max, "SafeCast: value doesn't fit in 128 bits");
        return int128(value);
    }
    /**
     * @dev Returns the downcasted int64 from int256, reverting on
     * overflow (when the input is less than smallest int64 or
     * greater than largest int64).
     *
     * Counterpart to Solidity's `int64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     *
     * _Available since v3.1._
     */
    function toInt64(int256 value) internal pure returns (int64) {
        require(value >= type(int64).min && value <= type(int64).max, "SafeCast: value doesn't fit in 64 bits");
        return int64(value);
    }
    /**
     * @dev Returns the downcasted int32 from int256, reverting on
     * overflow (when the input is less than smallest int32 or
     * greater than largest int32).
     *
     * Counterpart to Solidity's `int32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     *
     * _Available since v3.1._
     */
    function toInt32(int256 value) internal pure returns (int32) {
        require(value >= type(int32).min && value <= type(int32).max, "SafeCast: value doesn't fit in 32 bits");
        return int32(value);
    }
    /**
     * @dev Returns the downcasted int16 from int256, reverting on
     * overflow (when the input is less than smallest int16 or
     * greater than largest int16).
     *
     * Counterpart to Solidity's `int16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     *
     * _Available since v3.1._
     */
    function toInt16(int256 value) internal pure returns (int16) {
        require(value >= type(int16).min && value <= type(int16).max, "SafeCast: value doesn't fit in 16 bits");
        return int16(value);
    }
    /**
     * @dev Returns the downcasted int8 from int256, reverting on
     * overflow (when the input is less than smallest int8 or
     * greater than largest int8).
     *
     * Counterpart to Solidity's `int8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits.
     *
     * _Available since v3.1._
     */
    function toInt8(int256 value) internal pure returns (int8) {
        require(value >= type(int8).min && value <= type(int8).max, "SafeCast: value doesn't fit in 8 bits");
        return int8(value);
    }
    /**
     * @dev Converts an unsigned uint256 into a signed int256.
     *
     * Requirements:
     *
     * - input must be less than or equal to maxInt256.
     */
    function toInt256(uint256 value) internal pure returns (int256) {
        // Note: Unsafe cast below is okay because `type(int256).max` is guaranteed to be positive
        require(value <= uint256(type(int256).max), "SafeCast: value doesn't fit in an int256");
        return int256(value);
    }
}