//SPDX-License-Identifier: MIT
// File: @openzeppelin/contracts-upgradeable/utils/StorageSlotUpgradeable.sol


// OpenZeppelin Contracts (last updated v4.7.0) (utils/StorageSlot.sol)

pragma solidity ^0.8.0;

/**
 * @dev Library for reading and writing primitive types to specific storage slots.
 *
 * Storage slots are often used to avoid storage conflict when dealing with upgradeable contracts.
 * This library helps with reading and writing to such slots without the need for inline assembly.
 *
 * The functions in this library return Slot structs that contain a `value` member that can be used to read or write.
 *
 * Example usage to set ERC1967 implementation slot:
 * ```
 * contract ERC1967 {
 *     bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
 *
 *     function _getImplementation() internal view returns (address) {
 *         return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
 *     }
 *
 *     function _setImplementation(address newImplementation) internal {
 *         require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
 *         StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
 *     }
 * }
 * ```
 *
 * _Available since v4.1 for `address`, `bool`, `bytes32`, and `uint256`._
 */
library StorageSlotUpgradeable {
    struct AddressSlot {
        address value;
    }

    struct BooleanSlot {
        bool value;
    }

    struct Bytes32Slot {
        bytes32 value;
    }

    struct Uint256Slot {
        uint256 value;
    }

    /**
     * @dev Returns an `AddressSlot` with member `value` located at `slot`.
     */
    function getAddressSlot(bytes32 slot) internal pure returns (AddressSlot storage r) {
        /// @solidity memory-safe-assembly
        assembly {
            r.slot := slot
        }
    }

    /**
     * @dev Returns an `BooleanSlot` with member `value` located at `slot`.
     */
    function getBooleanSlot(bytes32 slot) internal pure returns (BooleanSlot storage r) {
        /// @solidity memory-safe-assembly
        assembly {
            r.slot := slot
        }
    }

    /**
     * @dev Returns an `Bytes32Slot` with member `value` located at `slot`.
     */
    function getBytes32Slot(bytes32 slot) internal pure returns (Bytes32Slot storage r) {
        /// @solidity memory-safe-assembly
        assembly {
            r.slot := slot
        }
    }

    /**
     * @dev Returns an `Uint256Slot` with member `value` located at `slot`.
     */
    function getUint256Slot(bytes32 slot) internal pure returns (Uint256Slot storage r) {
        /// @solidity memory-safe-assembly
        assembly {
            r.slot := slot
        }
    }
}

// File: @openzeppelin/contracts-upgradeable/proxy/beacon/IBeaconUpgradeable.sol


// OpenZeppelin Contracts v4.4.1 (proxy/beacon/IBeacon.sol)

pragma solidity ^0.8.0;

/**
 * @dev This is the interface that {BeaconProxy} expects of its beacon.
 */
interface IBeaconUpgradeable {
    /**
     * @dev Must return an address that can be used as a delegate call target.
     *
     * {BeaconProxy} will check that this address is a contract.
     */
    function implementation() external view returns (address);
}

// File: @openzeppelin/contracts-upgradeable/interfaces/draft-IERC1822Upgradeable.sol


// OpenZeppelin Contracts (last updated v4.5.0) (interfaces/draft-IERC1822.sol)

pragma solidity ^0.8.0;

/**
 * @dev ERC1822: Universal Upgradeable Proxy Standard (UUPS) documents a method for upgradeability through a simplified
 * proxy whose upgrades are fully controlled by the current implementation.
 */
interface IERC1822ProxiableUpgradeable {
    /**
     * @dev Returns the storage slot that the proxiable contract assumes is being used to store the implementation
     * address.
     *
     * IMPORTANT: A proxy pointing at a proxiable contract should not be considered proxiable itself, because this risks
     * bricking a proxy that upgrades to it, by delegating to itself until out of gas. Thus it is critical that this
     * function revert if invoked through a proxy.
     */
    function proxiableUUID() external view returns (bytes32);
}

// File: @openzeppelin/contracts-upgradeable/utils/AddressUpgradeable.sol


// OpenZeppelin Contracts (last updated v4.8.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library 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 functionCallWithValue(target, data, 0, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // Look for revert reason and bubble it up if present
        if (returndata.length > 0) {
            // The easiest way to bubble the revert reason is using memory via assembly
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert(errorMessage);
        }
    }
}

// File: @openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol


// OpenZeppelin Contracts (last updated v4.8.1) (proxy/utils/Initializable.sol)

pragma solidity ^0.8.2;


/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since proxied contracts do not make use of a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * The initialization functions use a version number. Once a version number is used, it is consumed and cannot be
 * reused. This mechanism prevents re-execution of each "step" but allows the creation of new initialization steps in
 * case an upgrade adds a module that needs to be initialized.
 *
 * For example:
 *
 * [.hljs-theme-light.nopadding]
 * ```
 * contract MyToken is ERC20Upgradeable {
 *     function initialize() initializer public {
 *         __ERC20_init("MyToken", "MTK");
 *     }
 * }
 * contract MyTokenV2 is MyToken, ERC20PermitUpgradeable {
 *     function initializeV2() reinitializer(2) public {
 *         __ERC20Permit_init("MyToken");
 *     }
 * }
 * ```
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {ERC1967Proxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 *
 * [CAUTION]
 * ====
 * Avoid leaving a contract uninitialized.
 *
 * An uninitialized contract can be taken over by an attacker. This applies to both a proxy and its implementation
 * contract, which may impact the proxy. To prevent the implementation contract from being used, you should invoke
 * the {_disableInitializers} function in the constructor to automatically lock it when it is deployed:
 *
 * [.hljs-theme-light.nopadding]
 * ```
 * /// @custom:oz-upgrades-unsafe-allow constructor
 * constructor() {
 *     _disableInitializers();
 * }
 * ```
 * ====
 */
abstract contract Initializable {
    /**
     * @dev Indicates that the contract has been initialized.
     * @custom:oz-retyped-from bool
     */
    uint8 private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Triggered when the contract has been initialized or reinitialized.
     */
    event Initialized(uint8 version);

    /**
     * @dev A modifier that defines a protected initializer function that can be invoked at most once. In its scope,
     * `onlyInitializing` functions can be used to initialize parent contracts.
     *
     * Similar to `reinitializer(1)`, except that functions marked with `initializer` can be nested in the context of a
     * constructor.
     *
     * Emits an {Initialized} event.
     */
    modifier initializer() {
        bool isTopLevelCall = !_initializing;
        require(
            (isTopLevelCall && _initialized < 1) || (!AddressUpgradeable.isContract(address(this)) && _initialized == 1),
            "Initializable: contract is already initialized"
        );
        _initialized = 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.
     *
     * 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.
     *
     * When `version` is 1, this modifier is similar to `initializer`, except that functions marked with `reinitializer`
     * cannot be nested. If one is invoked in the context of another, execution will revert.
     *
     * 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.
     *
     * WARNING: setting the version to 255 will prevent any future reinitialization.
     *
     * Emits an {Initialized} event.
     */
    modifier reinitializer(uint8 version) {
        require(!_initializing && _initialized < version, "Initializable: contract is already initialized");
        _initialized = version;
        _initializing = true;
        _;
        _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.
     *
     * Emits an {Initialized} event the first time it is successfully executed.
     */
    function _disableInitializers() internal virtual {
        require(!_initializing, "Initializable: contract is initializing");
        if (_initialized < type(uint8).max) {
            _initialized = type(uint8).max;
            emit Initialized(type(uint8).max);
        }
    }

    /**
     * @dev Returns the highest version that has been initialized. See {reinitializer}.
     */
    function _getInitializedVersion() internal view returns (uint8) {
        return _initialized;
    }

    /**
     * @dev Returns `true` if the contract is currently initializing. See {onlyInitializing}.
     */
    function _isInitializing() internal view returns (bool) {
        return _initializing;
    }
}

// File: @openzeppelin/contracts-upgradeable/utils/ContextUpgradeable.sol


// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;


/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract ContextUpgradeable is Initializable {
    function __Context_init() internal onlyInitializing {
    }

    function __Context_init_unchained() internal onlyInitializing {
    }
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }

    /**
     * @dev This empty reserved space is put in place to allow future versions to add new
     * variables without shifting down storage in the inheritance chain.
     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
     */
    uint256[50] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol


// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;



/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract OwnableUpgradeable is Initializable, ContextUpgradeable {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    function __Ownable_init() internal onlyInitializing {
        __Ownable_init_unchained();
    }

    function __Ownable_init_unchained() internal onlyInitializing {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }

    /**
     * @dev This empty reserved space is put in place to allow future versions to add new
     * variables without shifting down storage in the inheritance chain.
     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
     */
    uint256[49] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/proxy/ERC1967/ERC1967UpgradeUpgradeable.sol


// OpenZeppelin Contracts (last updated v4.5.0) (proxy/ERC1967/ERC1967Upgrade.sol)

pragma solidity ^0.8.2;






/**
 * @dev This abstract contract provides getters and event emitting update functions for
 * https://eips.ethereum.org/EIPS/eip-1967[EIP1967] slots.
 *
 * _Available since v4.1._
 *
 * @custom:oz-upgrades-unsafe-allow delegatecall
 */
abstract contract ERC1967UpgradeUpgradeable is Initializable {
    function __ERC1967Upgrade_init() internal onlyInitializing {
    }

    function __ERC1967Upgrade_init_unchained() internal onlyInitializing {
    }
    // This is the keccak-256 hash of "eip1967.proxy.rollback" subtracted by 1
    bytes32 private constant _ROLLBACK_SLOT = 0x4910fdfa16fed3260ed0e7147f7cc6da11a60208b5b9406d12a635614ffd9143;

    /**
     * @dev Storage slot with the address of the current implementation.
     * This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
     * validated in the constructor.
     */
    bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;

    /**
     * @dev Emitted when the implementation is upgraded.
     */
    event Upgraded(address indexed implementation);

    /**
     * @dev Returns the current implementation address.
     */
    function _getImplementation() internal view returns (address) {
        return StorageSlotUpgradeable.getAddressSlot(_IMPLEMENTATION_SLOT).value;
    }

    /**
     * @dev Stores a new address in the EIP1967 implementation slot.
     */
    function _setImplementation(address newImplementation) private {
        require(AddressUpgradeable.isContract(newImplementation), "ERC1967: new implementation is not a contract");
        StorageSlotUpgradeable.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
    }

    /**
     * @dev Perform implementation upgrade
     *
     * Emits an {Upgraded} event.
     */
    function _upgradeTo(address newImplementation) internal {
        _setImplementation(newImplementation);
        emit Upgraded(newImplementation);
    }

    /**
     * @dev Perform implementation upgrade with additional setup call.
     *
     * Emits an {Upgraded} event.
     */
    function _upgradeToAndCall(
        address newImplementation,
        bytes memory data,
        bool forceCall
    ) internal {
        _upgradeTo(newImplementation);
        if (data.length > 0 || forceCall) {
            _functionDelegateCall(newImplementation, data);
        }
    }

    /**
     * @dev Perform implementation upgrade with security checks for UUPS proxies, and additional setup call.
     *
     * Emits an {Upgraded} event.
     */
    function _upgradeToAndCallUUPS(
        address newImplementation,
        bytes memory data,
        bool forceCall
    ) internal {
        // Upgrades from old implementations will perform a rollback test. This test requires the new
        // implementation to upgrade back to the old, non-ERC1822 compliant, implementation. Removing
        // this special case will break upgrade paths from old UUPS implementation to new ones.
        if (StorageSlotUpgradeable.getBooleanSlot(_ROLLBACK_SLOT).value) {
            _setImplementation(newImplementation);
        } else {
            try IERC1822ProxiableUpgradeable(newImplementation).proxiableUUID() returns (bytes32 slot) {
                require(slot == _IMPLEMENTATION_SLOT, "ERC1967Upgrade: unsupported proxiableUUID");
            } catch {
                revert("ERC1967Upgrade: new implementation is not UUPS");
            }
            _upgradeToAndCall(newImplementation, data, forceCall);
        }
    }

    /**
     * @dev Storage slot with the admin of the contract.
     * This is the keccak-256 hash of "eip1967.proxy.admin" subtracted by 1, and is
     * validated in the constructor.
     */
    bytes32 internal constant _ADMIN_SLOT = 0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103;

    /**
     * @dev Emitted when the admin account has changed.
     */
    event AdminChanged(address previousAdmin, address newAdmin);

    /**
     * @dev Returns the current admin.
     */
    function _getAdmin() internal view returns (address) {
        return StorageSlotUpgradeable.getAddressSlot(_ADMIN_SLOT).value;
    }

    /**
     * @dev Stores a new address in the EIP1967 admin slot.
     */
    function _setAdmin(address newAdmin) private {
        require(newAdmin != address(0), "ERC1967: new admin is the zero address");
        StorageSlotUpgradeable.getAddressSlot(_ADMIN_SLOT).value = newAdmin;
    }

    /**
     * @dev Changes the admin of the proxy.
     *
     * Emits an {AdminChanged} event.
     */
    function _changeAdmin(address newAdmin) internal {
        emit AdminChanged(_getAdmin(), newAdmin);
        _setAdmin(newAdmin);
    }

    /**
     * @dev The storage slot of the UpgradeableBeacon contract which defines the implementation for this proxy.
     * This is bytes32(uint256(keccak256('eip1967.proxy.beacon')) - 1)) and is validated in the constructor.
     */
    bytes32 internal constant _BEACON_SLOT = 0xa3f0ad74e5423aebfd80d3ef4346578335a9a72aeaee59ff6cb3582b35133d50;

    /**
     * @dev Emitted when the beacon is upgraded.
     */
    event BeaconUpgraded(address indexed beacon);

    /**
     * @dev Returns the current beacon.
     */
    function _getBeacon() internal view returns (address) {
        return StorageSlotUpgradeable.getAddressSlot(_BEACON_SLOT).value;
    }

    /**
     * @dev Stores a new beacon in the EIP1967 beacon slot.
     */
    function _setBeacon(address newBeacon) private {
        require(AddressUpgradeable.isContract(newBeacon), "ERC1967: new beacon is not a contract");
        require(
            AddressUpgradeable.isContract(IBeaconUpgradeable(newBeacon).implementation()),
            "ERC1967: beacon implementation is not a contract"
        );
        StorageSlotUpgradeable.getAddressSlot(_BEACON_SLOT).value = newBeacon;
    }

    /**
     * @dev Perform beacon upgrade with additional setup call. Note: This upgrades the address of the beacon, it does
     * not upgrade the implementation contained in the beacon (see {UpgradeableBeacon-_setImplementation} for that).
     *
     * Emits a {BeaconUpgraded} event.
     */
    function _upgradeBeaconToAndCall(
        address newBeacon,
        bytes memory data,
        bool forceCall
    ) internal {
        _setBeacon(newBeacon);
        emit BeaconUpgraded(newBeacon);
        if (data.length > 0 || forceCall) {
            _functionDelegateCall(IBeaconUpgradeable(newBeacon).implementation(), data);
        }
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function _functionDelegateCall(address target, bytes memory data) private returns (bytes memory) {
        require(AddressUpgradeable.isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return AddressUpgradeable.verifyCallResult(success, returndata, "Address: low-level delegate call failed");
    }

    /**
     * @dev This empty reserved space is put in place to allow future versions to add new
     * variables without shifting down storage in the inheritance chain.
     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
     */
    uint256[50] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol


// OpenZeppelin Contracts (last updated v4.8.0) (proxy/utils/UUPSUpgradeable.sol)

pragma solidity ^0.8.0;




/**
 * @dev An upgradeability mechanism designed for UUPS proxies. The functions included here can perform an upgrade of an
 * {ERC1967Proxy}, when this contract is set as the implementation behind such a proxy.
 *
 * A security mechanism ensures that an upgrade does not turn off upgradeability accidentally, although this risk is
 * reinstated if the upgrade retains upgradeability but removes the security mechanism, e.g. by replacing
 * `UUPSUpgradeable` with a custom implementation of upgrades.
 *
 * The {_authorizeUpgrade} function must be overridden to include access restriction to the upgrade mechanism.
 *
 * _Available since v4.1._
 */
abstract contract UUPSUpgradeable is Initializable, IERC1822ProxiableUpgradeable, ERC1967UpgradeUpgradeable {
    function __UUPSUpgradeable_init() internal onlyInitializing {
    }

    function __UUPSUpgradeable_init_unchained() internal onlyInitializing {
    }
    /// @custom:oz-upgrades-unsafe-allow state-variable-immutable state-variable-assignment
    address private immutable __self = address(this);

    /**
     * @dev Check that the execution is being performed through a delegatecall call and that the execution context is
     * a proxy contract with an implementation (as defined in ERC1967) pointing to self. This should only be the case
     * for UUPS and transparent proxies that are using the current contract as their implementation. Execution of a
     * function through ERC1167 minimal proxies (clones) would not normally pass this test, but is not guaranteed to
     * fail.
     */
    modifier onlyProxy() {
        require(address(this) != __self, "Function must be called through delegatecall");
        require(_getImplementation() == __self, "Function must be called through active proxy");
        _;
    }

    /**
     * @dev Check that the execution is not being performed through a delegate call. This allows a function to be
     * callable on the implementing contract but not through proxies.
     */
    modifier notDelegated() {
        require(address(this) == __self, "UUPSUpgradeable: must not be called through delegatecall");
        _;
    }

    /**
     * @dev Implementation of the ERC1822 {proxiableUUID} function. This returns the storage slot used by the
     * implementation. It is used to validate the implementation's compatibility when performing an upgrade.
     *
     * IMPORTANT: A proxy pointing at a proxiable contract should not be considered proxiable itself, because this risks
     * bricking a proxy that upgrades to it, by delegating to itself until out of gas. Thus it is critical that this
     * function revert if invoked through a proxy. This is guaranteed by the `notDelegated` modifier.
     */
    function proxiableUUID() external view virtual override notDelegated returns (bytes32) {
        return _IMPLEMENTATION_SLOT;
    }

    /**
     * @dev Upgrade the implementation of the proxy to `newImplementation`.
     *
     * Calls {_authorizeUpgrade}.
     *
     * Emits an {Upgraded} event.
     */
    function upgradeTo(address newImplementation) external virtual onlyProxy {
        _authorizeUpgrade(newImplementation);
        _upgradeToAndCallUUPS(newImplementation, new bytes(0), false);
    }

    /**
     * @dev Upgrade the implementation of the proxy to `newImplementation`, and subsequently execute the function call
     * encoded in `data`.
     *
     * Calls {_authorizeUpgrade}.
     *
     * Emits an {Upgraded} event.
     */
    function upgradeToAndCall(address newImplementation, bytes memory data) external payable virtual onlyProxy {
        _authorizeUpgrade(newImplementation);
        _upgradeToAndCallUUPS(newImplementation, data, true);
    }

    /**
     * @dev Function that should revert when `msg.sender` is not authorized to upgrade the contract. Called by
     * {upgradeTo} and {upgradeToAndCall}.
     *
     * Normally, this function will use an xref:access.adoc[access control] modifier such as {Ownable-onlyOwner}.
     *
     * ```solidity
     * function _authorizeUpgrade(address) internal override onlyOwner {}
     * ```
     */
    function _authorizeUpgrade(address newImplementation) internal virtual;

    /**
     * @dev This empty reserved space is put in place to allow future versions to add new
     * variables without shifting down storage in the inheritance chain.
     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
     */
    uint256[50] private __gap;
}

// File: contracts/BTCVaultImplementationV1.sol



pragma solidity >=0.8.0;




interface IERC20 {
    function mint(address creator, uint256 amount) external;
    function burn(address creator, uint256 amount) external;
    function transfer(
        address to, uint256 amount
    ) external returns (bool);
    function transferFrom(
        address from, address to, uint256 amount
    ) external returns (bool);
}

interface AggregatorV3Interface {
  function latestRoundData()
    external
    view
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    );
}

contract VaultBase {
    /// @notice Amount incorrect
    error INVALID_AMOUNT();

    /// @notice Collateral percentage does not comply to specified range
    error INVALID_COLLATERAL();

    /// @notice Caller does not have access to perform the action
    error INVALID_CALLER();

    /// @notice Creation of a new vault
    event VaultCreated(uint256 id, uint256 amountAmerG, uint256 creationTimestamp);

    /// @notice Deposit to an existing vault
    event VaultDeposit(uint256 id, uint256 amountAmerG, uint256 amountCollateral, uint256 depositTimestamp);

    /// @notice Payment of interest for a specific vault
    event InterestPaid(uint256 indexed id, uint256 amountPaid, uint256 paymentTimestamp);

    /// @notice Manual interest collection performed for a specific vault
    event InterestCollected(uint256 amountCollateralCollected, uint256 collectionTimestamp);

    struct Vault {
        uint256 amountAmerG;

        uint256 amountCollateral;

        uint256 collateralPercentage;

        uint256 lastPaymentTimestamp;

        uint256 accumulatedInterest;

        address creator;
    }
}

contract BTCVaultImplementationV1 is Initializable, UUPSUpgradeable, OwnableUpgradeable, VaultBase {

    // =============================================================
    //                            STORAGE
    // =============================================================

    uint256 private _counter; 

    uint256 public minimumCollateralPercentage;
    uint256 public maximumCollateralPercentage;
    uint256 public refinanceFeePercentage;

    uint256[6] public interestRates; 
    
    address private _cold;
    
    IERC20 public constant BTC   = IERC20(0x2260FAC5E5542a773Aa44fBCfeDf7C193bc2C599); 
    IERC20 public constant AMERG = IERC20(0x3963A62009C56634f9b5F115f8dB17C39D88B633); 

    AggregatorV3Interface 
    private 
    constant 
    _BTC_PRICE_FEED = AggregatorV3Interface(0xF4030086522a5bEEa4988F8cA5B36dbC97BeE88c);  // Mainnet BTC / USD Chainlink oracle

    mapping(uint256 => Vault)     public vaults;
    mapping(address => uint256[]) private _vaultIds;

    // =============================================================
    //                     INITIALIZE IMPLEMENTATION
    // =============================================================
    
    function initialize() initializer public {
        minimumCollateralPercentage = 120;
        maximumCollateralPercentage = 500;
        refinanceFeePercentage = 12;
        interestRates = [
            25, 99, 199, 299, 399, 449
        ];

        _cold = 0x8eC873F2FCFA6E1167Fcb5E180aE3918Dc9F01cb;

        __Ownable_init();
        __UUPSUpgradeable_init();
    }

    function _authorizeUpgrade(address) internal override onlyOwner {}

    // =============================================================
    //                       VAULT FUNCTIONS
    // =============================================================

    /**
     * @notice Creates a new vault and mints `amountAmerG` tokens to the caller
     * @param amountCollateral amount of wrapped BTC to deposit
     * @param amountAmerG amount of tokens to be minted
     *
     * Requirements:
     *
     * - `amountCollateral` sent should produce a collateral percentage within the specified range
     * - `amountAmerG` should be greater than zero
     * - Caller must approve `amountCollateral` beforehand
     *
     */
    function createVault(uint256 amountCollateral, uint256 amountAmerG) external {
        if(amountCollateral == 0 || amountAmerG == 0) revert INVALID_AMOUNT();

        uint256 collateralPercentage = (amountCollateral * _getRate() * 10000) / amountAmerG; 

        if(collateralPercentage < minimumCollateralPercentage || collateralPercentage > maximumCollateralPercentage) {
            revert INVALID_COLLATERAL();
        }

        uint256 vaultId;

        unchecked {
            vaultId = _counter++;
        }

        vaults[vaultId] = Vault(
            amountAmerG, 
            amountCollateral, 
            collateralPercentage, 
            block.timestamp, 
            0,
            msg.sender
        );

        _vaultIds[msg.sender].push(vaultId);

        BTC.transferFrom(msg.sender, address(this), amountCollateral);
        
        AMERG.mint(msg.sender, amountAmerG);

        emit VaultCreated(vaultId, amountAmerG, block.timestamp);
    }
    
    /**
     * @notice Deposit BTC to `vaultId`
     * `amountAmerG` tokens minted to caller
     *
     * @param vaultId id of vault to deposit to
     * @param amountCollateral amount of wrapped BTC to deposit
     * @param amountAmerG amount of tokens to be minted
     * 
     * Requirements:
     * 
     * - `amountCollateral` should be greater than zero
     * - `amountAmerG` should be greater than zero
     * - Caller must be vault owner
     * - New collateral % must be within valid range
     *
     */
    function depositToVault(uint256 vaultId, uint256 amountCollateral, uint256 amountAmerG) external {
        if(amountCollateral == 0 || amountAmerG == 0) revert INVALID_AMOUNT();
        Vault storage vault = vaults[vaultId];

        if(msg.sender != vault.creator) 
            revert INVALID_CALLER();

        uint256 totalAmerG = vault.amountAmerG + amountAmerG;
        uint256 totalBTC = vault.amountCollateral + amountCollateral;
        uint256 newCollateralPercentage;

        unchecked { 
            newCollateralPercentage = (totalBTC * _getRate() * 10000) / totalAmerG;
        }

        if(newCollateralPercentage < minimumCollateralPercentage || newCollateralPercentage > maximumCollateralPercentage) {
            revert INVALID_COLLATERAL();
        }

        vault.accumulatedInterest = totalInterest(vaultId);
        vault.lastPaymentTimestamp = block.timestamp;

        vault.amountAmerG = totalAmerG;
        vault.amountCollateral = totalBTC;
        vault.collateralPercentage = newCollateralPercentage;
        
        BTC.transferFrom(msg.sender, address(this), amountCollateral);

        AMERG.mint(msg.sender, amountAmerG);

        emit VaultDeposit(vaultId, amountAmerG, amountCollateral, block.timestamp);
    }

    /**
     * @notice Pay accumulated interest for `vaultId`
     * @param vaultId id of vault to pay interest for
     * 
     * Requirements:
     *
     * - `vaultId` must have unpaid interest
     * - Caller must have approved sufficient amerG tokens beforehand
     *
     * NOTE: Caller is not required to be the owner of `vaultId`
     *
     */
    function payInterest(uint256 vaultId) external {
        uint amount = totalInterest(vaultId);
        if(amount == 0) revert INVALID_AMOUNT();

        vaults[vaultId].lastPaymentTimestamp = block.timestamp;
        vaults[vaultId].accumulatedInterest = 0;

        AMERG.transferFrom(msg.sender, _cold, amount);

        emit InterestPaid(vaultId, amount, block.timestamp);
    }

    /**
     * @notice Reimburse portion of borrowed amerG tokens
     * @param vaultId id of vault to reimburse
     * @param amount amount of amerG to reimburse
     *
     * Requirements:
     *
     * - Caller must be owner of `vaultId`
     * - `amount` must be non zero and less than or equal to initially borrowed amount
     * - `amount` of amerG must have been approved beforehand
     *
     */
    function reimburse(uint256 vaultId, uint256 amount) external { 
        Vault storage vault = vaults[vaultId];
        if(msg.sender != vault.creator) revert INVALID_CALLER();

        if(amount == 0 || amount > vault.amountAmerG) revert INVALID_AMOUNT();

        vault.accumulatedInterest = totalInterest(vaultId);
        vault.lastPaymentTimestamp = block.timestamp;
        
        unchecked {
            vault.amountAmerG = vault.amountAmerG - amount;
        }

        AMERG.burn(msg.sender, amount);
    }

    /**
     * @notice Refinance an active vault
     * @param vaultId id of vault to refinance
     * @param collateralPercentage new collateral percentage for vault
     *
     * Requirements:
     *
     * - Caller must be owner of `vaultId`
     * - `collateralPercentage` must be within specified range
     * - Caller must have approved refinance fee beforehand
     *
     */
    function refinance(uint256 vaultId, uint256 collateralPercentage) external {
        Vault storage vault = vaults[vaultId];
        if(msg.sender != vault.creator) revert INVALID_CALLER();

        if(collateralPercentage < minimumCollateralPercentage || collateralPercentage > maximumCollateralPercentage) {
            revert INVALID_COLLATERAL();
        }

        uint256 total = (_getRate() * vault.amountCollateral * 10000) / collateralPercentage;
        uint256 fee;
        uint256 claimable;

        unchecked {
            fee = (vault.amountAmerG * refinanceFeePercentage) / 100;
            claimable = total - vault.amountAmerG - fee;
        }
        
        if(claimable == 0) revert INVALID_AMOUNT();

        vault.accumulatedInterest = totalInterest(vaultId);
        vault.lastPaymentTimestamp = block.timestamp;
        vault.collateralPercentage = collateralPercentage;

        unchecked {
            vault.amountAmerG = vault.amountAmerG + claimable;
        }


        AMERG.transferFrom(msg.sender, _cold, fee);
        
        AMERG.mint(msg.sender, claimable);
    }
    

    // =============================================================
    //                          CHAINLINK 
    // =============================================================

    function _getRate() private view returns (uint256) {
        ( ,int price, , , ) = _BTC_PRICE_FEED.latestRoundData();
        return uint256(price);
    }


    // =============================================================
    //                       GETTER FUNCTIONS 
    // =============================================================

    /**
     * @notice Returns current unpaid interest for `vaultId`
     *
     */
    function totalInterest(uint vaultId) public view returns (uint256) {
        Vault storage vault = vaults[vaultId];
        uint256 perAnnum = (
            vault.amountAmerG * _findInterestRate(vault.collateralPercentage)
        ) / 10000;

        uint256 currentInterest = (perAnnum * (block.timestamp - vault.lastPaymentTimestamp)) / 365 days;

        unchecked { return currentInterest + vault.accumulatedInterest; }
    }

    function btcExchangeRate() external view returns (uint256) {
        return _getRate() / 1e8; 
    }

    function totalVaults() external view returns (uint256) {
        return _counter;

    }

    function vaultsOf(address creator) external view returns (uint256[] memory) {
        return _vaultIds[creator];
    }
    
    
    // =============================================================
    //                       PRIVATE HELPERS
    // =============================================================

    function _findInterestRate(uint256 collateral) private view returns (uint256) {
        if(collateral >= 401 && collateral <= 500)
            return interestRates[0];
        else if(collateral >= 301 && collateral < 401)
            return interestRates[1];
        else if(collateral >= 251 && collateral < 301)
            return interestRates[2];
        else if(collateral >= 201 && collateral < 251)
            return interestRates[3];
        else if(collateral >= 171 && collateral < 201)
            return interestRates[4];
        else 
            return interestRates[5];
    }

    // =============================================================
    //                          ADMIN ONLY
    // =============================================================

    /**
     * @notice Transfers total accumulated interest in BTC to cold wallet
     *
     */
    function collectInterest(uint256[] calldata vaultIds) external payable onlyOwner {
        uint256 total;

        for(uint256 i; i < vaultIds.length; ) {
            uint256 id = vaultIds[i];
            if(block.timestamp - vaults[id].lastPaymentTimestamp > 90 days) {
                uint amountCollateral = totalInterest(id) / (_getRate() * 100);
           
                vaults[id].lastPaymentTimestamp = block.timestamp;
                vaults[id].accumulatedInterest = 0;

                unchecked{ 
                    vaults[id].amountCollateral = vaults[id].amountCollateral - amountCollateral;
                    total =  total + amountCollateral;
                }
            }

            unchecked { ++i; }
        }
        
        BTC.transfer(_cold, total);

    }

    /**
     * @notice Change interest rates
     * @param newInterestRates list containing new interest rates for each of the 6 collateral ranges sequentially
     *
     * Requirements:
     *
     * - Passed array must have 6 elements
     *
     */
    function setInterestRates(uint256[6] calldata newInterestRates) external payable onlyOwner {
        interestRates = newInterestRates;
    }

    /**
     * @notice Change cold wallet address
     * @param newColdWallet address of new cold wallet
     *
     */
    function setColdWallet(address newColdWallet) external payable onlyOwner {
        _cold = newColdWallet;
    }

    /**
     * @notice Change collateral percentage limits
     * @param minimum new minimum collateral percentage
     * @param maximum new maximum collateral percentage
     *
     */
    function setCollateralPercentages(uint256 minimum, uint256 maximum) external payable onlyOwner {
        minimumCollateralPercentage = minimum;
        maximumCollateralPercentage = maximum;
    }

    /**
     * @notice Change refinance fee percentage
     * @param newRefinanceFeePercentage new refinance fee percentage
     *
     */
    function setRefinanceFee(uint256 newRefinanceFeePercentage) external payable onlyOwner {
        refinanceFeePercentage = newRefinanceFeePercentage;
    }

    /**
     * @notice Sends `amount` of `token` to cold wallet
     * Can be used to withdraw tokens in case they get stuck in the contract
     *
     */
    function withdrawTokens(address token, uint256 amount) external payable onlyOwner {
        IERC20(token).transfer(_cold, amount);
    }

    /**
     * @notice Refund wrapped BTC for `vaultId`
     *
     */
    function refundCollateral(uint256 vaultId) external payable onlyOwner {
        uint256 currentBalance = vaults[vaultId].amountCollateral;
        if(currentBalance == 0) {
            revert INVALID_AMOUNT();
        }

        vaults[vaultId].amountCollateral = 0;
    
        BTC.transfer(vaults[vaultId].creator, currentBalance);
    }

}