// File: samples/VerifyingPaymaster.sol



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

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

import "../core/BasePaymaster.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 VALID_TIMESTAMP_OFFSET = 20;

    uint256 private constant SIGNATURE_OFFSET = 84;

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

    mapping(address => uint256) public senderNonce;

    function pack(UserOperation calldata userOp) internal pure returns (bytes memory ret) {
        // lighter signature scheme. must match UserOp.ts#packUserOp
        bytes calldata pnd = userOp.paymasterAndData;
        // copy directly the userOp from calldata up to (but not including) the paymasterAndData.
        // this encoding depends on the ABI encoding of calldata, but is much lighter to copy
        // than referencing each field separately.
        assembly {
            let ofs := userOp
            let len := sub(sub(pnd.offset, ofs), 32)
            ret := mload(0x40)
            mstore(0x40, add(ret, add(len, 32)))
            mstore(ret, len)
            calldatacopy(add(ret, 32), ofs, len)
        }
    }

    /**
     * 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, uint48 validUntil, uint48 validAfter)
    public view returns (bytes32) {
        //can't use userOp.hash(), since it contains also the paymasterAndData itself.

        return keccak256(abi.encode(
                pack(userOp),
                block.chainid,
                address(this),
                senderNonce[userOp.getSender()],
                validUntil,
                validAfter
            ));
    }

    /**
     * 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[20:84] : abi.encode(validUntil, validAfter)
     * paymasterAndData[84:] : signature
     */
    function _validatePaymasterUserOp(UserOperation calldata userOp, bytes32 /*userOpHash*/, uint256 requiredPreFund)
    internal override returns (bytes memory context, uint256 validationData) {
        (requiredPreFund);

        (uint48 validUntil, uint48 validAfter, 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, validUntil, validAfter));
        senderNonce[userOp.getSender()]++;

        //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 ("",_packValidationData(false,validUntil,validAfter));
    }

    function parsePaymasterAndData(bytes calldata paymasterAndData) public pure returns(uint48 validUntil, uint48 validAfter, bytes calldata signature) {
        (validUntil, validAfter) = abi.decode(paymasterAndData[VALID_TIMESTAMP_OFFSET:SIGNATURE_OFFSET],(uint48, uint48));
        signature = paymasterAndData[SIGNATURE_OFFSET:];
    }
}

// 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: 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 immutable public 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);
    }

    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 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: 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
    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.
    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: 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.
     */
    event SignatureAggregatorChanged(address indexed 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 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.
     *   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.
     */
    error FailedOp(uint256 opIndex, string reason);

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

    /**
     * Successful result from simulateValidation.
     * @param returnInfo gas and time-range returned values
     * @param senderInfo stake information about the sender
     * @param factoryInfo stake information about the factory (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 time-range returned values
     * @param senderInfo stake information about the sender
     * @param factoryInfo stake information about the factory (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);

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

    /**
     * return value of simulateHandleOp
     */
    error ExecutionResult(uint256 preOpGas, uint256 paid, uint48 validAfter, uint48 validUntil, bool targetSuccess, bytes targetResult);

    //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 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.
     */
    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;

    /**
     * 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;


    /**
     * simulate full execution of a UserOperation (including both validation and target execution)
     * this method will always revert with "ExecutionResult".
     * it performs full validation of the UserOperation, but ignores signature error.
     * an optional target address is called after the userop succeeds, and its value is returned
     * (before the entire call is reverted)
     * 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.
     * @param op the UserOperation to simulate
     * @param target if nonzero, a target address to call after userop simulation. If called, the targetSuccess and targetResult
     *        are set to the return from that call.
     * @param targetCallData callData to pass to target address
     */
    function simulateHandleOp(UserOperation calldata op, address target, bytes calldata targetCallData) external;
}


// File: interfaces/IPaymaster.sol



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

import "./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 {

    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 it's a 2nd call, after user's op was deliberately reverted.
    }

    /**
     * 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: @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/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: interfaces/UserOperation.sol



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

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

import {calldataKeccak} from "../core/Helpers.sol";

/**
 * 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;
    }

/**
 * Utility functions helpful when working with UserOperation structs.
 */
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 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: 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: 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.
     */
    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: 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;
    }

    /// @return info - full deposit information of given account
    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;

    /**
     * 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: @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/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/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;
    }
}