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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

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

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

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

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

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

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

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

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

// File: @openzeppelin/contracts/token/ERC20/extensions/draft-IERC20Permit.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/draft-IERC20Permit.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

// File: @openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

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

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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);

    /**
     * @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 `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, 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 `from` to `to` 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 from,
        address to,
        uint256 amount
    ) external returns (bool);
}

// File: @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../extensions/draft-IERC20Permit.sol";
import "../../../utils/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));
        }
    }

    function safePermit(
        IERC20Permit token,
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        uint256 nonceBefore = token.nonces(owner);
        token.permit(owner, spender, value, deadline, v, r, s);
        uint256 nonceAfter = token.nonces(owner);
        require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
    }

    /**
     * @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");
        }
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/Address.sol)

pragma solidity ^0.8.1;

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

        return account.code.length > 0;
    }

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

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

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

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

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

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

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

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

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

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

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

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

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

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

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

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

// File: @openzeppelin/contracts/utils/cryptography/ECDSA.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/cryptography/ECDSA.sol)

pragma solidity ^0.8.0;

import "../Strings.sol";

/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSA {
    enum RecoverError {
        NoError,
        InvalidSignature,
        InvalidSignatureLength,
        InvalidSignatureS,
        InvalidSignatureV // Deprecated in v4.8
    }

    function _throwError(RecoverError error) private pure {
        if (error == RecoverError.NoError) {
            return; // no error: do nothing
        } else if (error == RecoverError.InvalidSignature) {
            revert("ECDSA: invalid signature");
        } else if (error == RecoverError.InvalidSignatureLength) {
            revert("ECDSA: invalid signature length");
        } else if (error == RecoverError.InvalidSignatureS) {
            revert("ECDSA: invalid signature 's' value");
        }
    }

    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature` or error string. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     *
     * Documentation for signature generation:
     * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
     * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
     *
     * _Available since v4.3._
     */
    function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
        if (signature.length == 65) {
            bytes32 r;
            bytes32 s;
            uint8 v;
            // ecrecover takes the signature parameters, and the only way to get them
            // currently is to use assembly.
            /// @solidity memory-safe-assembly
            assembly {
                r := mload(add(signature, 0x20))
                s := mload(add(signature, 0x40))
                v := byte(0, mload(add(signature, 0x60)))
            }
            return tryRecover(hash, v, r, s);
        } else {
            return (address(0), RecoverError.InvalidSignatureLength);
        }
    }

    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature`. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     */
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, signature);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
     *
     * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address, RecoverError) {
        bytes32 s = vs & bytes32(0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff);
        uint8 v = uint8((uint256(vs) >> 255) + 27);
        return tryRecover(hash, v, r, s);
    }

    /**
     * @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
     *
     * _Available since v4.2._
     */
    function recover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, r, vs);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `v`,
     * `r` and `s` signature fields separately.
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address, RecoverError) {
        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
            return (address(0), RecoverError.InvalidSignatureS);
        }

        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(hash, v, r, s);
        if (signer == address(0)) {
            return (address(0), RecoverError.InvalidSignature);
        }

        return (signer, RecoverError.NoError);
    }

    /**
     * @dev Overload of {ECDSA-recover} that receives the `v`,
     * `r` and `s` signature fields separately.
     */
    function recover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, v, r, s);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from a `hash`. This
     * produces hash corresponding to the one signed with the
     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
     * JSON-RPC method as part of EIP-191.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
        // 32 is the length in bytes of hash,
        // enforced by the type signature above
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from `s`. This
     * produces hash corresponding to the one signed with the
     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
     * JSON-RPC method as part of EIP-191.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n", Strings.toString(s.length), s));
    }

    /**
     * @dev Returns an Ethereum Signed Typed Data, created from a
     * `domainSeparator` and a `structHash`. This produces hash corresponding
     * to the one signed with the
     * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
     * JSON-RPC method as part of EIP-712.
     *
     * See {recover}.
     */
    function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
    }
}

// File: @openzeppelin/contracts/utils/math/Math.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/Math.sol)

pragma solidity ^0.8.0;

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

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

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

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

    /**
     * @dev Returns the ceiling of the division of two numbers.
     *
     * This differs from standard division with `/` in that it rounds up instead
     * of rounding down.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b - 1) / b can overflow on addition, so we distribute.
        return a == 0 ? 0 : (a - 1) / b + 1;
    }

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

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

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

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

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

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

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

            // Does not overflow because the denominator cannot be zero at this stage in the function.
            uint256 twos = denominator & (~denominator + 1);
            assembly {
                // Divide denominator by twos.
                denominator := div(denominator, twos)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    /**
     * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log256(value);
            return result + (rounding == Rounding.Up && 1 << (result * 8) < value ? 1 : 0);
        }
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/Strings.sol)

pragma solidity ^0.8.0;

import "./math/Math.sol";

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

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

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

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }

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

// File: contracts/interfaces/IAggregator.sol



// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.12;

import "../library/UserOperation.sol";

/**
 * Aggregated Signatures validator.
 */
interface IAggregator {
    /**
     * validate aggregated signature.
     * revert if the aggregated signature does not match the given list of operations.
     */
    function validateSignatures(
        UserOperation[] calldata userOps,
        bytes calldata signature
    ) external view;

    /**
     * validate signature of a single userOp
     * This method is should be called by bundler after EntryPoint.simulateValidation() returns (reverts) with ValidationResultWithAggregation
     * First it validates the signature over the userOp. then it return data to be used when creating the handleOps:
     * @param userOp the userOperation received from the user.
     * @return sigForUserOp the value to put into the signature field of the userOp when calling handleOps.
     *    (usually empty, unless account and aggregator support some kind of "multisig"
     */
    function validateUserOpSignature(
        UserOperation calldata userOp
    ) external view returns (bytes memory sigForUserOp);

    /**
     * aggregate multiple signatures into a single value.
     * This method is called off-chain to calculate the signature to pass with handleOps()
     * bundler MAY use optimized custom code perform this aggregation
     * @param userOps array of UserOperations to collect the signatures from.
     * @return aggregatesSignature the aggregated signature
     */
    function aggregateSignatures(
        UserOperation[] calldata userOps
    ) external view returns (bytes memory aggregatesSignature);
}

// File: contracts/interfaces/IEntryPoint.sol



// SPDX-License-Identifier: GPL-3.0
// Modified version of a Implementation of contracts for ERC-4337 account abstraction via alternative mempool.
// Original code: https://github.com/eth-infinitism/account-abstraction/tree/releases/v0.4
pragma solidity ^0.8.12;

import "../library/UserOperation.sol";
import "./IStakeManager.sol";
import "./IAggregator.sol";

interface IEntryPoint is IStakeManager {
    /***
     * An event emitted after each successful request
     * @param userOpHash - unique identifier for the request (hash its entire content, except signature).
     * @param sender - the account that generates this request.
     * @param paymaster - if non-null, the paymaster that pays for this request.
     * @param nonce - the nonce value from the request
     * @param actualGasCost - actual amount paid (by account or paymaster) for this UserOperation
     * @param actualGasUsed - total gas used by this UserOperation (including preVerification, creation, validation and execution)
     * @param success - true if the sender transaction succeeded, false if reverted.
     */
    event UserOperationEvent(
        bytes32 indexed userOpHash,
        address indexed sender,
        address indexed paymaster,
        uint256 nonce,
        bool success,
        uint256 actualGasCost,
        uint256 actualGasUsed
    );

    /**
     * account "sender" was deployed.
     * @param userOpHash the userOp that deployed this account. UserOperationEvent will follow.
     * @param sender the account that is deployed
     * @param factory the factory used to deploy this account (in the initCode)
     * @param paymaster the paymaster used by this UserOp
     */
    event AccountDeployed(
        bytes32 indexed userOpHash,
        address indexed sender,
        address factory,
        address paymaster
    );

    /**
     * An event emitted if the UserOperation "callData" reverted with non-zero length
     * @param userOpHash the request unique identifier.
     * @param sender the sender of this request
     * @param nonce the nonce used in the request
     * @param revertReason - the return bytes from the (reverted) call to "callData".
     */
    event UserOperationRevertReason(
        bytes32 indexed userOpHash,
        address indexed sender,
        uint256 nonce,
        bytes revertReason
    );

    /**
     * signature aggregator used by the following UserOperationEvents within this bundle.
     */
    event SignatureAggregatorChanged(address aggregator);

    /**
     * a custom revert error of handleOps, to identify the offending op.
     *  NOTE: if simulateValidation passes successfully, there should be no reason for handleOps to fail on it.
     *  @param opIndex - index into the array of ops to the failed one (in simulateValidation, this is always zero)
     *  @param paymaster - if paymaster.validatePaymasterUserOp fails, this will be the paymaster's address. if validateUserOp failed,
     *       this value will be zero (since it failed before accessing the paymaster)
     *  @param reason - revert reason
     *   Should be caught in off-chain handleOps simulation and not happen on-chain.
     *   Useful for mitigating DoS attempts against batchers or for troubleshooting of account/paymaster reverts.
     */
    error FailedOp(uint256 opIndex, address paymaster, string reason);

    /**
     * error case when a signature aggregator fails to verify the aggregated signature it had created.
     */
    error SignatureValidationFailed(address aggregator);

    //UserOps handled, per aggregator
    struct UserOpsPerAggregator {
        UserOperation[] userOps;
        // aggregator address
        IAggregator aggregator;
        // aggregated signature
        bytes signature;
    }

    /**
     * Execute a batch of UserOperation.
     * no signature aggregator is used.
     * if any account requires an aggregator (that is, it returned an "actualAggregator" when
     * performing simulateValidation), then handleAggregatedOps() must be used instead.
     * @param ops the operations to execute
     * @param beneficiary the address to receive the fees
     */
    function handleOps(
        UserOperation[] calldata ops,
        address payable beneficiary
    ) external;

    /**
     * Execute a batch of UserOperation with Aggregators
     * @param opsPerAggregator the operations to execute, grouped by aggregator (or address(0) for no-aggregator accounts)
     * @param beneficiary the address to receive the fees
     */
    function handleAggregatedOps(
        UserOpsPerAggregator[] calldata opsPerAggregator,
        address payable beneficiary
    ) external;

    /**
     * generate a request Id - unique identifier for this request.
     * the request ID is a hash over the content of the userOp (except the signature), the entrypoint and the chainid.
     */
    function getUserOpHash(
        UserOperation calldata userOp
    ) external view returns (bytes32);

    /**
     * Simulate a call to account.validateUserOp and paymaster.validatePaymasterUserOp.
     * @dev this method always revert. Successful result is ValidationResult error. other errors are failures.
     * @dev The node must also verify it doesn't use banned opcodes, and that it doesn't reference storage outside the account's data.
     * @param userOp the user operation to validate.
     */
    function simulateValidation(UserOperation calldata userOp) external;

    /**
     * Successful result from simulateValidation.
     * @param returnInfo gas and deadlines returned values
     * @param senderInfo stake information about the sender
     * @param factoryInfo stake information about the factor (if any)
     * @param paymasterInfo stake information about the paymaster (if any)
     */
    error ValidationResult(
        ReturnInfo returnInfo,
        StakeInfo senderInfo,
        StakeInfo factoryInfo,
        StakeInfo paymasterInfo
    );

    /**
     * Successful result from simulateValidation, if the account returns a signature aggregator
     * @param returnInfo gas and deadlines returned values
     * @param senderInfo stake information about the sender
     * @param factoryInfo stake information about the factor (if any)
     * @param paymasterInfo stake information about the paymaster (if any)
     * @param aggregatorInfo signature aggregation info (if the account requires signature aggregator)
     *      bundler MUST use it to verify the signature, or reject the UserOperation
     */
    error ValidationResultWithAggregation(
        ReturnInfo returnInfo,
        StakeInfo senderInfo,
        StakeInfo factoryInfo,
        StakeInfo paymasterInfo,
        AggregatorStakeInfo aggregatorInfo
    );

    /**
     * gas and deadlines returned during simulation
     * @param preOpGas the gas used for validation (including preValidationGas)
     * @param prefund the required prefund for this operation
     * @param deadline validateUserOp's deadline (or SIG_VALIDATION_FAILED for signature failure)
     * @param paymasterDeadline validatePaymasterUserOp's deadline (or SIG_VALIDATION_FAILED for signature failure)
     * @param paymasterContext returned by validatePaymasterUserOp (to be passed into postOp)
     */
    struct ReturnInfo {
        uint256 preOpGas;
        uint256 prefund;
        uint256 deadline;
        uint256 paymasterDeadline;
        bytes paymasterContext;
    }

    /**
     * returned aggregated signature info.
     * the aggregator returned by the account, and its current stake.
     */
    struct AggregatorStakeInfo {
        address actualAggregator;
        StakeInfo stakeInfo;
    }

    /**
     * Get counterfactual sender address.
     *  Calculate the sender contract address that will be generated by the initCode and salt in the UserOperation.
     * this method always revert, and returns the address in SenderAddressResult error
     * @param initCode the constructor code to be passed into the UserOperation.
     */
    function getSenderAddress(bytes memory initCode) external;

    /**
     * return value of getSenderAddress
     */
    error SenderAddressResult(address sender);

    /**
     * simulate full execution of a UserOperation (including both validation and target execution)
     * this method will always revert. it performs full validation of the UserOperation, but ignores
     * signature error.
     * Note that in order to collect the the success/failure of the target call, it must be executed
     * with trace enabled to track the emitted events.
     */
    function simulateHandleOp(UserOperation calldata op) external;

    error ExecutionResult(
        uint256 preOpGas,
        uint256 paid,
        uint256 deadline,
        uint256 paymasterDeadline
    );
}

// File: contracts/interfaces/IFreeGasPaymaster.sol



// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.12;

import "./IPaymaster.sol";

interface IFreeGasPaymaster is IPaymaster {
    event AddedToWhitelist(address indexed account);
    event RemovedFromWhitelist(address indexed account);
    event Withdrawal(address indexed token, uint256 amount);
}

// File: contracts/interfaces/IPaymaster.sol



// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.12;

import "../library/UserOperation.sol";

/**
 * the interface exposed by a paymaster contract, who agrees to pay the gas for user's operations.
 * a paymaster must hold a stake to cover the required entrypoint stake and also the gas for the transaction.
 */
interface IPaymaster {
    /**
     * payment validation: check if paymaster agree to pay.
     * Must verify sender is the entryPoint.
     * Revert to reject this request.
     * Note that bundlers will reject this method if it changes the state, unless the paymaster is trusted (whitelisted)
     * The paymaster pre-pays using its deposit, and receive back a refund after the postOp method returns.
     * @param userOp the user operation
     * @param userOpHash hash of the user's request data.
     * @param maxCost the maximum cost of this transaction (based on maximum gas and gas price from userOp)
     * @return context value to send to a postOp
     *  zero length to signify postOp is not required.
     * @return sigTimeRange signature and time-range of this operation, encoded the same as the return value of validateUserOperation
     *      <byte> sigFailure - (1) to mark signature failure (needed only if paymaster uses signature-based validation,)
     *      <4-byte> validUntil - last timestamp this operation is valid. 0 for "indefinite"
     *      <4-byte> validAfter - first timestamp this operation is valid
     *      Note that the validation code cannot use block.timestamp (or block.number) directly.
     */
    function validatePaymasterUserOp(
        UserOperation calldata userOp,
        bytes32 userOpHash,
        uint256 maxCost
    ) external returns (bytes memory context, uint256 sigTimeRange);

    function validatePaymasterUserOpWithoutSig(
        UserOperation calldata userOp,
        bytes32 userOpHash,
        uint256 maxCost
    ) external returns (bytes memory context, uint256 sigTimeRange);

    /**
     * post-operation handler.
     * Must verify sender is the entryPoint
     * @param mode enum with the following options:
     *      opSucceeded - user operation succeeded.
     *      opReverted  - user op reverted. still has to pay for gas.
     *      postOpReverted - user op succeeded, but caused postOp (in mode=opSucceeded) to revert.
     *                       Now this is the 2nd call, after user's op was deliberately reverted.
     * @param context - the context value returned by validatePaymasterUserOp
     * @param actualGasCost - actual gas used so far (without this postOp call).
     */
    function postOp(
        PostOpMode mode,
        bytes calldata context,
        uint256 actualGasCost
    ) external;

    enum PostOpMode {
        opSucceeded, // user op succeeded
        opReverted, // user op reverted. still has to pay for gas.
        postOpReverted //user op succeeded, but caused postOp to revert. Now its a 2nd call, after user's op was deliberately reverted.
    }
}

// File: contracts/interfaces/IPriceOracle.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.12;
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";

interface IPriceOracle {
    function exchangePrice(
        address _token
    ) external view returns (uint256 price, uint8 decimals);

    function exchangeRate(
        address token
    ) external view returns (uint256 exchangeRate);

    function getValueOf(
        address tokenIn,
        address quote,
        uint256 amountIn
    ) external view returns (uint256 value);
}

abstract contract PriceOracle is IPriceOracle, Ownable {
    mapping(address => address) internal priceFeed;
    mapping(address => uint256) internal decimals;
    address public constant NATIVE_TOKEN =
        0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;

    constructor(address _owner) {
        _transferOwnership(_owner);
    }

    function setPriceFeed(
        address token,
        address aggregator
    ) external onlyOwner {
        require(aggregator != address(0), "Invalid aggregator address");
        priceFeed[token] = aggregator;
    }

    function exchangePrice(
        address token
    ) public view virtual override returns (uint256 price, uint8 decimals);

    function exchangeRate(
        address token
    ) external view virtual override returns (uint256 price) {
        price = getValueOf(NATIVE_TOKEN, token, 1 ether);
        require(price != 0, "Price Oracle: Price is 0");
    }

    function getValueOf(
        address tokenIn,
        address quote,
        uint256 amountIn
    ) public view virtual override returns (uint256 value) {
        (uint256 priceIn, uint8 decimalsIn) = exchangePrice(tokenIn);
        (uint256 priceQuote, uint8 decimalsQuote) = exchangePrice(quote);

        if (
            decimalsIn + tokenDecimals(tokenIn) >
            decimalsQuote + tokenDecimals(quote)
        ) {
            value =
                (amountIn * priceIn) /
                (priceQuote *
                    10 **
                        (decimalsIn +
                            tokenDecimals(tokenIn) -
                            (tokenDecimals(quote) + decimalsQuote)));
        } else {
            value =
                ((amountIn * priceIn) *
                    10 **
                        (decimalsQuote +
                            tokenDecimals(quote) -
                            (tokenDecimals(tokenIn) + decimalsIn))) /
                priceQuote;
        }
    }

    function tokenDecimals(address _token) public view returns (uint256) {
        return
            decimals[_token] == 0
                ? IERC20Metadata(_token).decimals()
                : decimals[_token];
    }

    function setDecimals(address _token, uint256 _decimals) external onlyOwner {
        decimals[_token] = _decimals;
    }
}

// File: contracts/interfaces/IStakeManager.sol



// SPDX-License-Identifier: GPL-3.0-only
pragma solidity ^0.8.12;

/**
 * manage deposits and stakes.
 * deposit is just a balance used to pay for UserOperations (either by a paymaster or an account)
 * stake is value locked for at least "unstakeDelay" by a paymaster.
 */
interface IStakeManager {
    event Deposited(
        address from,
        address to,
        address account,
        uint256 increaseDeposit,
        uint256 totalDeposit
    );

    event Withdrawn(
        address indexed account,
        address withdrawAddress,
        uint256 amount
    );

    event RefundDeposit(address from, address to, uint256 refundAmount);

    /// Emitted once a stake is scheduled for withdrawal
    event StakeLocked(
        address indexed account,
        uint256 totalStaked,
        uint256 withdrawTime
    );

    /// Emitted once a stake is scheduled for withdrawal
    event StakeUnlocked(address indexed account, uint256 withdrawTime);

    event StakeWithdrawn(
        address indexed account,
        address withdrawAddress,
        uint256 amount
    );

    /**
     * @param deposit the account's deposit
     * @param staked true if this account is staked as a paymaster
     * @param stake actual amount of ether staked for this paymaster.
     * @param unstakeDelaySec minimum delay to withdraw the stake. must be above the global unstakeDelaySec
     * @param withdrawTime - first block timestamp where 'withdrawStake' will be callable, or zero if already locked
     * @dev sizes were chosen so that (deposit,staked) fit into one cell (used during handleOps)
     *    and the rest fit into a 2nd cell.
     *    112 bit allows for 2^15 eth
     *    64 bit for full timestamp
     *    32 bit allow 150 years for unstake delay
     */
    struct DepositInfo {
        uint112 deposit;
        bool staked;
        uint112 stake;
        uint32 unstakeDelaySec;
        uint64 withdrawTime;
    }

    //API struct used by getStakeInfo and simulateValidation
    struct StakeInfo {
        uint256 stake;
        uint256 unstakeDelaySec;
    }

    function getDepositInfo(
        address account
    ) external view returns (DepositInfo memory info);

    /// return the deposit (for gas payment) of the account
    function balanceOf(address account) external view returns (uint256);

    /**
     * add to the deposit of the given account
     */
    function depositTo(address account) external payable;

    /**
     * withdraw from the deposit.
     * @param withdrawAddress the address to send withdrawn value.
     * @param withdrawAmount the amount to withdraw.
     */
    function withdrawTo(
        address payable withdrawAddress,
        uint256 withdrawAmount
    ) external;
}

// File: contracts/library/UserOperation.sol



// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.12;

/* solhint-disable no-inline-assembly */

/**
 * User Operation struct
 * @param sender the sender account of this request
 * @param nonce unique value the sender uses to verify it is not a replay.
 * @param initCode if set, the account contract will be created by this constructor
 * @param callData the method call to execute on this account.
 * @param verificationGasLimit gas used for validateUserOp and validatePaymasterUserOp
 * @param preVerificationGas gas not calculated by the handleOps method, but added to the gas paid. Covers batch overhead.
 * @param maxFeePerGas same as EIP-1559 gas parameter
 * @param maxPriorityFeePerGas same as EIP-1559 gas parameter
 * @param paymasterAndData if set, this field hold the paymaster address and "paymaster-specific-data". the paymaster will pay for the transaction instead of the sender
 * @param signature sender-verified signature over the entire request, the EntryPoint address and the chain ID.
 */
struct UserOperation {
    address sender;
    uint256 nonce;
    bytes initCode;
    bytes callData;
    uint256 callGasLimit;
    uint256 verificationGasLimit;
    uint256 preVerificationGas;
    uint256 maxFeePerGas;
    uint256 maxPriorityFeePerGas;
    bytes paymasterAndData;
    bytes signature;
}

library UserOperationLib {
    function getSender(
        UserOperation calldata userOp
    ) internal pure returns (address) {
        address data;
        //read sender from userOp, which is first userOp member (saves 800 gas...)
        assembly {
            data := calldataload(userOp)
        }
        return address(uint160(data));
    }

    //relayer/block builder might submit the TX with higher priorityFee, but the user should not
    // pay above what he signed for.
    function gasPrice(
        UserOperation calldata userOp
    ) internal view returns (uint256) {
        unchecked {
            uint256 maxFeePerGas = userOp.maxFeePerGas;
            uint256 maxPriorityFeePerGas = userOp.maxPriorityFeePerGas;
            if (maxFeePerGas == maxPriorityFeePerGas) {
                //legacy mode (for networks that don't support basefee opcode)
                return maxFeePerGas;
            }
            return min(maxFeePerGas, maxPriorityFeePerGas + block.basefee);
        }
    }

    function pack(
        UserOperation calldata userOp
    ) internal pure returns (bytes memory ret) {
        address sender = getSender(userOp);
        uint256 nonce = userOp.nonce;
        bytes32 hashInitCode = calldataKeccak(userOp.initCode);
        bytes32 hashCallData = calldataKeccak(userOp.callData);
        uint256 callGasLimit = userOp.callGasLimit;
        uint256 verificationGasLimit = userOp.verificationGasLimit;
        uint256 preVerificationGas = userOp.preVerificationGas;
        uint256 maxFeePerGas = userOp.maxFeePerGas;
        uint256 maxPriorityFeePerGas = userOp.maxPriorityFeePerGas;
        bytes32 hashPaymasterAndData = calldataKeccak(userOp.paymasterAndData);

        return
            abi.encode(
                sender,
                nonce,
                hashInitCode,
                hashCallData,
                callGasLimit,
                verificationGasLimit,
                preVerificationGas,
                maxFeePerGas,
                maxPriorityFeePerGas,
                hashPaymasterAndData
            );
    }

    function calldataKeccak(
        bytes calldata data
    ) internal pure returns (bytes32 ret) {
        assembly {
            let mem := mload(0x40)
            let len := data.length
            calldatacopy(mem, data.offset, len)
            ret := keccak256(mem, len)
        }
    }

    function hash(
        UserOperation calldata userOp
    ) internal pure returns (bytes32) {
        return keccak256(pack(userOp));
    }

    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }
}

// File: contracts/paymaster/FreeGasPaymaster.sol



// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.12;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "../interfaces/IFreeGasPaymaster.sol";
import "../interfaces/IPriceOracle.sol";
import "../interfaces/IEntryPoint.sol";

contract FreeGasPaymaster is IFreeGasPaymaster, Ownable {
    using UserOperationLib for UserOperation;
    using ECDSA for bytes32;
    using SafeERC20 for IERC20;

    uint256 internal constant SIG_VALIDATION_FAILED = 1;
    address public immutable verifyingSigner;
    address public immutable ADDRESS_THIS;
    address public immutable supportedEntryPoint;
    mapping(address => bool) public whitelist;

    constructor(
        address _verifyingSigner,
        address _owner,
        address _supportedEntryPoint
    ) {
        verifyingSigner = _verifyingSigner;
        _transferOwnership(_owner);
        supportedEntryPoint = _supportedEntryPoint;
        ADDRESS_THIS = address(this);
    }

    modifier onlyWhitelisted(address _address) {
        require(whitelist[_address], "Address is not whitelisted");
        _;
    }

    function addToWhitelist(address[] calldata addresses) external onlyOwner {
        for (uint256 i = 0; i < addresses.length; i++) {
            whitelist[addresses[i]] = true;
            emit AddedToWhitelist(addresses[i]);
        }
    }

    function removeFromWhitelist(
        address[] calldata addresses
    ) external onlyOwner {
        for (uint256 i = 0; i < addresses.length; i++) {
            whitelist[addresses[i]] = false;
            emit RemovedFromWhitelist(addresses[i]);
        }
    }

    function withdrawERC20(
        address token,
        uint256 amount,
        address withdrawAddress
    ) external onlyOwner onlyWhitelisted(withdrawAddress) {
        IERC20(token).safeTransfer(withdrawAddress, amount);
        emit Withdrawal(token, amount);
    }

    function withdrawDepositNativeToken(
        address payable withdrawAddress,
        uint256 amount
    ) public onlyOwner onlyWhitelisted(withdrawAddress) {
        IEntryPoint(supportedEntryPoint).withdrawTo(withdrawAddress, amount);
        emit Withdrawal(address(0), amount);
    }

    function getHash(
        UserOperation calldata userOp,
        uint256 sigTime
    ) public view returns (bytes32) {
        return
            keccak256(
                abi.encode(
                    userOp.getSender(),
                    userOp.nonce,
                    keccak256(userOp.initCode),
                    keccak256(userOp.callData),
                    userOp.callGasLimit,
                    userOp.verificationGasLimit,
                    userOp.preVerificationGas,
                    userOp.maxFeePerGas,
                    userOp.maxPriorityFeePerGas,
                    block.chainid,
                    ADDRESS_THIS,
                    sigTime
                )
            );
    }

    function validatePaymasterUserOp(
        UserOperation calldata userOp,
        bytes32,
        uint256
    ) external view override returns (bytes memory, uint256) {
        uint256 sigTime = uint256(bytes32(userOp.paymasterAndData[20:52]));

        if (
            verifyingSigner !=
            getHash(userOp, sigTime).toEthSignedMessageHash().recover(
                userOp.paymasterAndData[52:]
            )
        ) {
            return ("", SIG_VALIDATION_FAILED);
        } else {
            return ("", sigTime);
        }
    }

    function validatePaymasterUserOpWithoutSig(
        UserOperation calldata userOp,
        bytes32,
        uint256
    ) external view override returns (bytes memory, uint256) {
        uint256 sigTime = uint256(bytes32(userOp.paymasterAndData[20:52]));

        bool sigValidate = verifyingSigner !=
            getHash(userOp, sigTime).toEthSignedMessageHash().recover(
                userOp.paymasterAndData[52:]
            );

        return ("", sigTime);
    }

    function postOp(
        PostOpMode mode,
        bytes calldata context,
        uint256 gasCost
    ) external override {}
}