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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (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. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling 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/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 v4.9.0) (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 message) {
        // 32 is the length in bytes of hash,
        // enforced by the type signature above
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, "\x19Ethereum Signed Message:\n32")
            mstore(0x1c, hash)
            message := keccak256(0x00, 0x3c)
        }
    }

    /**
     * @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 data) {
        /// @solidity memory-safe-assembly
        assembly {
            let ptr := mload(0x40)
            mstore(ptr, "\x19\x01")
            mstore(add(ptr, 0x02), domainSeparator)
            mstore(add(ptr, 0x22), structHash)
            data := keccak256(ptr, 0x42)
        }
    }

    /**
     * @dev Returns an Ethereum Signed Data with intended validator, created from a
     * `validator` and `data` according to the version 0 of EIP-191.
     *
     * See {recover}.
     */
    function toDataWithIntendedValidatorHash(address validator, bytes memory data) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19\x00", validator, data));
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (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) {
                // Solidity will revert if denominator == 0, unlike the div opcode on its own.
                // The surrounding unchecked block does not change this fact.
                // See https://docs.soliditylang.org/en/latest/control-structures.html#checked-or-unchecked-arithmetic.
                return prod0 / denominator;
            }

            // Make sure the result is less than 2^256. Also prevents denominator == 0.
            require(denominator > prod1, "Math: mulDiv overflow");

            ///////////////////////////////////////////////
            // 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 256, 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 << 3) < value ? 1 : 0);
        }
    }
}

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



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

pragma solidity ^0.8.0;

/**
 * @dev Standard signed math utilities missing in the Solidity language.
 */
library SignedMath {
    /**
     * @dev Returns the largest of two signed numbers.
     */
    function max(int256 a, int256 b) internal pure returns (int256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two signed numbers.
     */
    function min(int256 a, int256 b) internal pure returns (int256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two signed numbers without overflow.
     * The result is rounded towards zero.
     */
    function average(int256 a, int256 b) internal pure returns (int256) {
        // Formula from the book "Hacker's Delight"
        int256 x = (a & b) + ((a ^ b) >> 1);
        return x + (int256(uint256(x) >> 255) & (a ^ b));
    }

    /**
     * @dev Returns the absolute unsigned value of a signed value.
     */
    function abs(int256 n) internal pure returns (uint256) {
        unchecked {
            // must be unchecked in order to support `n = type(int256).min`
            return uint256(n >= 0 ? n : -n);
        }
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/Strings.sol)

pragma solidity ^0.8.0;

import "./math/Math.sol";
import "./math/SignedMath.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 `int256` to its ASCII `string` decimal representation.
     */
    function toString(int256 value) internal pure returns (string memory) {
        return string(abi.encodePacked(value < 0 ? "-" : "", toString(SignedMath.abs(value))));
    }

    /**
     * @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);
    }

    /**
     * @dev Returns true if the two strings are equal.
     */
    function equal(string memory a, string memory b) internal pure returns (bool) {
        return keccak256(bytes(a)) == keccak256(bytes(b));
    }
}

// File: contracts/paymaster/core/BasePaymaster.sol



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

/* solhint-disable reason-string */

import "@openzeppelin/contracts/access/Ownable.sol";
import "../interfaces/IPaymaster.sol";
import "../interfaces/IEntryPoint.sol";
import "./Helpers.sol";

/**
 * Helper class for creating a paymaster.
 * provides helper methods for staking.
 * Validates that the postOp is called only by the entryPoint.
 */
abstract contract BasePaymaster is IPaymaster, Ownable {
    IEntryPoint public immutable entryPoint;

    constructor(IEntryPoint _entryPoint) {
        entryPoint = _entryPoint;
    }

    /// @inheritdoc IPaymaster
    function validatePaymasterUserOp(
        UserOperation calldata userOp,
        bytes32 userOpHash,
        uint256 maxCost
    ) external override returns (bytes memory context, uint256 validationData) {
        _requireFromEntryPoint();
        return _validatePaymasterUserOp(userOp, userOpHash, maxCost);
    }

    /**
     * Validate a user operation.
     * @param userOp     - The user operation.
     * @param userOpHash - The hash of the user operation.
     * @param maxCost    - The maximum cost of the user operation.
     */
    function _validatePaymasterUserOp(
        UserOperation calldata userOp,
        bytes32 userOpHash,
        uint256 maxCost
    ) internal virtual returns (bytes memory context, uint256 validationData);

    /// @inheritdoc IPaymaster
    function postOp(
        PostOpMode mode,
        bytes calldata context,
        uint256 actualGasCost
    ) external override {
        _requireFromEntryPoint();
        _postOp(mode, context, actualGasCost);
    }

    /**
     * Post-operation handler.
     * (verified to be called only through the entryPoint)
     * @dev If subclass returns a non-empty context from validatePaymasterUserOp,
     *      it must also implement this method.
     * @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
    ) internal virtual {
        (mode, context, actualGasCost); // unused params
        // subclass must override this method if validatePaymasterUserOp returns a context
        revert("must override");
    }

    /**
     * Add a deposit for this paymaster, used for paying for transaction fees.
     */
    function deposit() public payable {
        entryPoint.depositTo{value: msg.value}(address(this));
    }

    /**
     * Withdraw value from the deposit.
     * @param withdrawAddress - Target to send to.
     * @param amount          - Amount to withdraw.
     */
    function withdrawTo(
        address payable withdrawAddress,
        uint256 amount
    ) public onlyOwner {
        entryPoint.withdrawTo(withdrawAddress, amount);
    }

    /**
     * Add stake for this paymaster.
     * This method can also carry eth value to add to the current stake.
     * @param unstakeDelaySec - The unstake delay for this paymaster. Can only be increased.
     */
    function addStake(uint32 unstakeDelaySec) external payable onlyOwner {
        entryPoint.addStake{value: msg.value}(unstakeDelaySec);
    }

    /**
     * Return current paymaster's deposit on the entryPoint.
     */
    function getDeposit() public view returns (uint256) {
        return entryPoint.balanceOf(address(this));
    }

    /**
     * Unlock the stake, in order to withdraw it.
     * The paymaster can't serve requests once unlocked, until it calls addStake again
     */
    function unlockStake() external onlyOwner {
        entryPoint.unlockStake();
    }

    /**
     * Withdraw the entire paymaster's stake.
     * stake must be unlocked first (and then wait for the unstakeDelay to be over)
     * @param withdrawAddress - The address to send withdrawn value.
     */
    function withdrawStake(address payable withdrawAddress) external onlyOwner {
        entryPoint.withdrawStake(withdrawAddress);
    }

    /**
     * Validate the call is made from a valid entrypoint
     */
    function _requireFromEntryPoint() internal virtual {
        require(msg.sender == address(entryPoint), "Sender not EntryPoint");
    }
}

// File: contracts/paymaster/core/Helpers.sol



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

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

/**
 * Returned data from validateUserOp.
 * validateUserOp returns a uint256, with is created by `_packedValidationData` and
 * parsed by `_parseValidationData`.
 * @param aggregator  - address(0) - The account validated the signature by itself.
 *                      address(1) - The account failed to validate the signature.
 *                      otherwise - This is an address of a signature aggregator that must
 *                                  be used to validate the signature.
 * @param validAfter  - This UserOp is valid only after this timestamp.
 * @param validaUntil - This UserOp is valid only up to this timestamp.
 */
struct ValidationData {
    address aggregator;
    uint48 validAfter;
    uint48 validUntil;
}

/**
 * Extract sigFailed, validAfter, validUntil.
 * Also convert zero validUntil to type(uint48).max.
 * @param validationData - The packed validation data.
 */
function _parseValidationData(
    uint validationData
) pure returns (ValidationData memory data) {
    address aggregator = address(uint160(validationData));
    uint48 validUntil = uint48(validationData >> 160);
    if (validUntil == 0) {
        validUntil = type(uint48).max;
    }
    uint48 validAfter = uint48(validationData >> (48 + 160));
    return ValidationData(aggregator, validAfter, validUntil);
}

/**
 * Intersect account and paymaster ranges.
 * @param validationData          - The packed validation data of the account.
 * @param paymasterValidationData - The packed validation data of the paymaster.
 */
function _intersectTimeRange(
    uint256 validationData,
    uint256 paymasterValidationData
) pure returns (ValidationData memory) {
    ValidationData memory accountValidationData = _parseValidationData(
        validationData
    );
    ValidationData memory pmValidationData = _parseValidationData(
        paymasterValidationData
    );
    address aggregator = accountValidationData.aggregator;
    if (aggregator == address(0)) {
        aggregator = pmValidationData.aggregator;
    }
    uint48 validAfter = accountValidationData.validAfter;
    uint48 validUntil = accountValidationData.validUntil;
    uint48 pmValidAfter = pmValidationData.validAfter;
    uint48 pmValidUntil = pmValidationData.validUntil;

    if (validAfter < pmValidAfter) validAfter = pmValidAfter;
    if (validUntil > pmValidUntil) validUntil = pmValidUntil;
    return ValidationData(aggregator, validAfter, validUntil);
}

/**
 * Helper to pack the return value for validateUserOp.
 * @param data - The ValidationData to pack.
 */
function _packValidationData(
    ValidationData memory data
) pure returns (uint256) {
    return
        uint160(data.aggregator) |
        (uint256(data.validUntil) << 160) |
        (uint256(data.validAfter) << (160 + 48));
}

/**
 * Helper to pack the return value for validateUserOp, when not using an aggregator.
 * @param sigFailed  - True for signature failure, false for success.
 * @param validUntil - Last timestamp this UserOperation is valid (or zero for infinite).
 * @param validAfter - First timestamp this UserOperation is valid.
 */
function _packValidationData(
    bool sigFailed,
    uint48 validUntil,
    uint48 validAfter
) pure returns (uint256) {
    return
        (sigFailed ? 1 : 0) |
        (uint256(validUntil) << 160) |
        (uint256(validAfter) << (160 + 48));
}

/**
 * keccak function over calldata.
 * @dev copy calldata into memory, do keccak and drop allocated memory. Strangely, this is more efficient than letting solidity do it.
 */
function calldataKeccak(bytes calldata data) pure returns (bytes32 ret) {
    assembly {
        let mem := mload(0x40)
        let len := data.length
        calldatacopy(mem, data.offset, len)
        ret := keccak256(mem, len)
    }
}

// File: contracts/paymaster/core/UserOperationLib.sol



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

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

import "../interfaces/UserOperation.sol";
import {calldataKeccak} from "./Helpers.sol";

/**
 * Utility functions helpful when working with UserOperation structs.
 */
library UserOperationLib {
    /**
     * Get sender from user operation data.
     * @param userOp - The user operation data.
     */
    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.
     * @param userOp - The user operation data.
     */
    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);
        }
    }

    /**
     * Pack the user operation data into bytes for hashing.
     * @param userOp - The user operation data.
     */
    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
            );
    }

    /**
     * Hash the user operation data.
     * @param userOp - The user operation data.
     */
    function hash(
        UserOperation calldata userOp
    ) internal pure returns (bytes32) {
        return keccak256(pack(userOp));
    }

    /**
     * The minimum of two numbers.
     * @param a - First number.
     * @param b - Second number.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }
}

// File: contracts/paymaster/interfaces/IAggregator.sol



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

import "./UserOperation.sol";

/**
 * Aggregated Signatures validator.
 */
interface IAggregator {
    /**
     * Validate aggregated signature.
     * Revert if the aggregated signature does not match the given list of operations.
     * @param userOps   - Array of UserOperations to validate the signature for.
     * @param signature - The aggregated signature.
     */
    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 returns 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 aggregatedSignature - The aggregated signature.
     */
    function aggregateSignatures(
        UserOperation[] calldata userOps
    ) external view returns (bytes memory aggregatedSignature);
}

// File: contracts/paymaster/interfaces/IEntryPoint.sol



/**
 ** Account-Abstraction (EIP-4337) singleton EntryPoint implementation.
 ** Only one instance required on each chain.
 **/
// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.12;

/* solhint-disable avoid-low-level-calls */
/* solhint-disable no-inline-assembly */
/* solhint-disable reason-string */

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

interface IEntryPoint is IStakeManager, INonceManager {
    /***
     * 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 success       - True if the sender transaction succeeded, false if reverted.
     * @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).
     */
    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
    );

    /**
     * An event emitted by handleOps(), before starting the execution loop.
     * Any event emitted before this event, is part of the validation.
     */
    event BeforeExecution();

    /**
     * Signature aggregator used by the following UserOperationEvents within this bundle.
     * @param aggregator - The aggregator used for the following UserOperationEvents.
     */
    event SignatureAggregatorChanged(address indexed aggregator);

    /**
     * A custom revert error of handleOps, to identify the offending op.
     * Should be caught in off-chain handleOps simulation and not happen on-chain.
     * Useful for mitigating DoS attempts against batchers or for troubleshooting of factory/account/paymaster reverts.
     * 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 reason  - Revert reason. The string starts with a unique code "AAmn",
     *                  where "m" is "1" for factory, "2" for account and "3" for paymaster issues,
     *                  so a failure can be attributed to the correct entity.
     */
    error FailedOp(uint256 opIndex, string reason);

    /**
     * Error case when a signature aggregator fails to verify the aggregated signature it had created.
     * @param aggregator The aggregator that failed to verify the signature
     */
    error SignatureValidationFailed(address aggregator);

    // Return value of getSenderAddress.
    error SenderAddressResult(address sender);

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

    /**
     * Execute a batch of UserOperations.
     * No signature aggregator is used.
     * If any account requires an aggregator (that is, it returned an aggregator 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.
     * @param userOp - The user operation to generate the request ID for.
     */
    function getUserOpHash(
        UserOperation calldata userOp
    ) external view returns (bytes32);

    /**
     * Gas and return values during simulation.
     * @param preOpGas         - The gas used for validation (including preValidationGas)
     * @param prefund          - The required prefund for this operation
     * @param sigFailed        - ValidateUserOp's (or paymaster's) signature check failed
     * @param validAfter       - First timestamp this UserOp is valid (merging account and paymaster time-range)
     * @param validUntil       - Last timestamp this UserOp is valid (merging account and paymaster time-range)
     * @param paymasterContext - Returned by validatePaymasterUserOp (to be passed into postOp)
     */
    struct ReturnInfo {
        uint256 preOpGas;
        uint256 prefund;
        bool sigFailed;
        uint48 validAfter;
        uint48 validUntil;
        bytes paymasterContext;
    }

    /**
     * Returned aggregated signature info:
     * The aggregator returned by the account, and its current stake.
     */
    struct AggregatorStakeInfo {
        address aggregator;
        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;
}

// File: contracts/paymaster/interfaces/INonceManager.sol



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

interface INonceManager {
    /**
     * Return the next nonce for this sender.
     * Within a given key, the nonce values are sequenced (starting with zero, and incremented by one on each userop)
     * But UserOp with different keys can come with arbitrary order.
     *
     * @param sender the account address
     * @param key the high 192 bit of the nonce
     * @return nonce a full nonce to pass for next UserOp with this sender.
     */
    function getNonce(
        address sender,
        uint192 key
    ) external view returns (uint256 nonce);

    /**
     * Manually increment the nonce of the sender.
     * This method is exposed just for completeness..
     * Account does NOT need to call it, neither during validation, nor elsewhere,
     * as the EntryPoint will update the nonce regardless.
     * Possible use-case is call it with various keys to "initialize" their nonces to one, so that future
     * UserOperations will not pay extra for the first transaction with a given key.
     */
    function incrementNonce(uint192 key) external;
}

// File: contracts/paymaster/interfaces/IPaymaster.sol



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

import "./UserOperation.sol";

/**
 * The interfaces 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 {
    enum PostOpMode {
        // User op succeeded.
        opSucceeded,
        // User op reverted. Still has to pay for gas.
        opReverted,
        // User op succeeded, but caused postOp to revert.
        // Only used internally in the EntryPoint - Paymasters will not be called again.
        postOpReverted
    }

    /**
     * Payment validation: check if paymaster agrees 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 validationData - Signature and time-range of this operation, encoded the same as the return
     *                          value of validateUserOperation.
     *                          <20-byte> sigAuthorizer - 0 for valid signature, 1 to mark signature failure,
     *                                                    otherwise, an address of an "authorizer" contract.
     *                          <6-byte> validUntil - last timestamp this operation is valid. 0 for "indefinite"
     *                          <6-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 validationData);

    /**
     * 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;
}

// File: contracts/paymaster/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 the staked entity.
 */
interface IStakeManager {
    event Deposited(address indexed account, uint256 totalDeposit);

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

    // Emitted when stake or unstake delay are modified.
    event StakeLocked(
        address indexed account,
        uint256 totalStaked,
        uint256 unstakeDelaySec
    );

    // 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 entity's deposit.
     * @param staked          - True if this entity is staked.
     * @param stake           - Actual amount of ether staked for this entity.
     * @param unstakeDelaySec - Minimum delay to withdraw the stake.
     * @param withdrawTime    - First block timestamp where 'withdrawStake' will be callable, or zero if already locked.
     * @dev Sizes were chosen so that (deposit,staked, stake) fit into one cell (used during handleOps)
     *      and the rest fit into a 2nd cell.
     *      - 112 bit allows for 10^15 eth
     *      - 48 bit for full timestamp
     *      - 32 bit allows 150 years for unstake delay
     */
    struct DepositInfo {
        uint112 deposit;
        bool staked;
        uint112 stake;
        uint32 unstakeDelaySec;
        uint48 withdrawTime;
    }

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

    /**
     * Get deposit info.
     * @param account - The account to query.
     * @return info   - Full deposit information of given account.
     */
    function getDepositInfo(
        address account
    ) external view returns (DepositInfo memory info);

    /**
     * Get account balance.
     * @param account - The account to query.
     * @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.
     * @param account - The account to add to.
     */
    function depositTo(address account) external payable;

    /**
     * Add to the account's stake - amount and delay
     * any pending unstake is first cancelled.
     * @param _unstakeDelaySec - The new lock duration before the deposit can be withdrawn.
     */
    function addStake(uint32 _unstakeDelaySec) external payable;

    /**
     * Attempt to unlock the stake.
     * The value can be withdrawn (using withdrawStake) after the unstake delay.
     */
    function unlockStake() external;

    /**
     * Withdraw from the (unlocked) stake.
     * Must first call unlockStake and wait for the unstakeDelay to pass.
     * @param withdrawAddress - The address to send withdrawn value.
     */
    function withdrawStake(address payable withdrawAddress) external;

    /**
     * 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/paymaster/interfaces/UserOperation.sol



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

/**
 * 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 callGasLimit          - The gas limit passed to the callData method call.
 * @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 holds 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;
}

// File: contracts/paymaster/VerifyingPaymaster.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;

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

import "./core/BasePaymaster.sol";
import "./core/UserOperationLib.sol";
import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";

/**
 * A sample paymaster that uses external service to decide whether to pay for the UserOp.
 * The paymaster trusts an external signer to sign the transaction.
 * The calling user must pass the UserOp to that external signer first, which performs
 * whatever off-chain verification before signing the UserOp.
 * Note that this signature is NOT a replacement for the account-specific signature:
 * - the paymaster checks a signature to agree to PAY for GAS.
 * - the account checks a signature to prove identity and account ownership.
 */
contract VerifyingPaymaster is BasePaymaster {
    using ECDSA for bytes32;
    using UserOperationLib for UserOperation;

    address public immutable verifyingSigner;

    uint256 private constant GAS_TYPE_OFFSET = 20;

    uint256 private constant VALID_PND_OFFSET = 21;

    uint256 private constant SIGNATURE_OFFSET = 149;

    event UserOperationSponsored(
        address indexed user,
        bytes32 userOpHash,
        uint8 gasType,
        address token,
        uint256 actualTokenNeeded,
        uint256 actualGasCost,
        uint256 exchangeRate
    );

    constructor(
        IEntryPoint _entryPoint,
        address _verifyingSigner,
        address _owner
    ) BasePaymaster(_entryPoint) {
        verifyingSigner = _verifyingSigner;
        _transferOwnership(_owner);
    }

    function pack(
        UserOperation calldata userOp
    ) internal pure returns (bytes memory ret) {
        ret = abi.encode(
            userOp.sender,
            userOp.nonce,
            keccak256(userOp.initCode),
            keccak256(userOp.callData),
            userOp.callGasLimit,
            userOp.verificationGasLimit,
            userOp.preVerificationGas,
            userOp.maxFeePerGas,
            userOp.maxPriorityFeePerGas
        );
    }

    /**
     * return the hash we're going to sign off-chain (and validate on-chain)
     * this method is called by the off-chain service, to sign the request.
     * it is called on-chain from the validatePaymasterUserOp, to validate the signature.
     * note that this signature covers all fields of the UserOperation, except the "paymasterAndData",
     * which will carry the signature itself.
     */
    function getHash(
        UserOperation calldata userOp,
        uint8 gasType,
        uint48 validUntil,
        uint48 validAfter,
        address erc20Token,
        uint256 exchangeRate
    ) public view returns (bytes32) {
        return
            keccak256(
                abi.encode(
                    pack(userOp),
                    block.chainid,
                    address(this),
                    gasType,
                    validUntil,
                    validAfter,
                    erc20Token,
                    exchangeRate
                )
            );
    }

    /**
     * verify our external signer signed this request.
     * the "paymasterAndData" is expected to be the paymaster and a signature over the entire request params
     * paymasterAndData[:20] : address(this)
     * paymasterAndData[21:149] : abi.encode(validUntil, validAfter)
     * paymasterAndData[149:] : signature
     */
    function _validatePaymasterUserOp(
        UserOperation calldata userOp,
        bytes32 userOpHash,
        uint256 requiredPreFund
    )
        internal
        view
        override
        returns (bytes memory context, uint256 validationData)
    {
        (requiredPreFund);

        (
            uint8 gasType,
            uint48 validUntil,
            uint48 validAfter,
            address erc20Token,
            uint256 exchangeRate,
            bytes calldata signature
        ) = parsePaymasterAndData(userOp.paymasterAndData);
        //ECDSA library supports both 64 and 65-byte long signatures.
        // we only "require" it here so that the revert reason on invalid signature will be of "VerifyingPaymaster", and not "ECDSA"
        require(
            signature.length == 64 || signature.length == 65,
            "VerifyingPaymaster: invalid signature length in paymasterAndData"
        );
        bytes32 hash = ECDSA.toEthSignedMessageHash(
            getHash(
                userOp,
                gasType,
                validUntil,
                validAfter,
                erc20Token,
                exchangeRate
            )
        );

        //don't revert on signature failure: return SIG_VALIDATION_FAILED
        if (verifyingSigner != ECDSA.recover(hash, signature)) {
            return ("", _packValidationData(true, validUntil, validAfter));
        }

        //no need for other on-chain validation: entire UserOp should have been checked
        // by the external service prior to signing it.
        return (
            abi.encode(
                userOp.sender,
                userOpHash,
                gasType,
                erc20Token,
                exchangeRate
            ),
            _packValidationData(false, validUntil, validAfter)
        );
    }

    function parsePaymasterAndData(
        bytes calldata paymasterAndData
    )
        public
        pure
        returns (
            uint8 gasType,
            uint48 validUntil,
            uint48 validAfter,
            address erc20Token,
            uint256 exchangeRate,
            bytes calldata signature
        )
    {
        (validUntil, validAfter, erc20Token, exchangeRate) = abi.decode(
            paymasterAndData[VALID_PND_OFFSET:SIGNATURE_OFFSET],
            (uint48, uint48, address, uint256)
        );
        gasType = uint8(
            bytes1(paymasterAndData[GAS_TYPE_OFFSET:VALID_PND_OFFSET])
        );
        signature = paymasterAndData[SIGNATURE_OFFSET:];
    }

    function _postOp(
        PostOpMode mode,
        bytes calldata context,
        uint256 actualGasCost
    ) internal override {
        if (mode == PostOpMode.postOpReverted) {
            return; // Do nothing here to not revert the whole bundle and harm reputation
        }
        (
            address user,
            bytes32 userOpHash,
            uint8 gasType,
            address erc20Token,
            uint256 exchangeRate
        ) = abi.decode(context, (address, bytes32, uint8, address, uint256));
        //todo: currently only support native token actualTokenNeeded is equal to actualGasCost,
        emit UserOperationSponsored(
            user,
            userOpHash,
            gasType,
            erc20Token,
            actualGasCost,
            actualGasCost,
            exchangeRate
        );
    }
}