Contract 0xf23a700171e97de22ce6c4a39dc9c715f6286e25

/**
 *Submitted for verification at PolygonScan.com on 2022-07-14
*/

// File: Utils.sol


pragma solidity 0.8.9;

contract Utils {
    function getChainID() internal view returns (uint256) {
        uint256 chainID;
        assembly {
            chainID := chainid()
        }
        return chainID;
    }

    function max(uint a, uint b) internal pure returns (uint) {
        return a > b ? a : b;
    }

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

    function round(uint a, uint m) internal pure returns (uint ) {
        return ((a + m - 1) / m) * m;
    }
}
// File: @openzeppelin/contracts/security/ReentrancyGuard.sol


// OpenZeppelin Contracts v4.4.1 (security/ReentrancyGuard.sol)

pragma solidity ^0.8.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// File: Ownable.sol


pragma solidity 0.8.9;

contract Ownable {
    address private _owner;

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

    function owner() public view returns (address) {
        return _owner;
    }

    modifier onlyOwner() {
        require(_owner == msg.sender || _owner == address(0x0), "Ownable: caller is not the owner");
        _;
    }

    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}
// File: interfaces/IUniswapV2Router.sol


pragma solidity 0.8.9;

interface IUniswapV2Router {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB, uint liquidity);
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountToken, uint amountETH);
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountToken, uint amountETH);
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);

    function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
    function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
    function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}

// File: interfaces/IHermesContract.sol


pragma solidity 0.8.9;

interface IHermesContract {
    enum Status { Active, Paused, Punishment, Closed }
    function initialize(address _token, address _operator, uint16 _hermesFee, uint256 _minStake, uint256 _maxStake, address payable _routerAddress) external;
    function openChannel(address _party, uint256 _amountToLend) external;
    function getOperator() external view returns (address);
    function getStake() external view returns (uint256);
    function getStatus() external view returns (Status);
}

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


// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

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

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool);
}

// File: interfaces/IERC20Token.sol


pragma solidity 0.8.9;


abstract contract IERC20Token is IERC20 {
    function upgrade(uint256 value) public virtual;
}

// File: FundsRecovery.sol


pragma solidity 0.8.9;




contract FundsRecovery is Ownable, ReentrancyGuard {
    address payable internal fundsDestination;
    IERC20Token public token;

    event DestinationChanged(address indexed previousDestination, address indexed newDestination);

    /**
     * Setting new destination of funds recovery.
     */
    function setFundsDestination(address payable _newDestination) public virtual onlyOwner {
        require(_newDestination != address(0));
        emit DestinationChanged(fundsDestination, _newDestination);
        fundsDestination = _newDestination;
    }

    /**
     * Getting funds destination address.
     */
    function getFundsDestination() public view returns (address) {
        return fundsDestination;
    }

    /**
     * Possibility to recover funds in case they were sent to this address before smart contract deployment
     */
    function claimNativeCoin() public nonReentrant {
        require(fundsDestination != address(0));
        fundsDestination.transfer(address(this).balance);
    }

    /**
       Transfers selected tokens into owner address.
    */
    function claimTokens(address _token) public nonReentrant {
        require(fundsDestination != address(0));
        require(_token != address(token), "native token funds can't be recovered");
        uint256 _amount = IERC20Token(_token).balanceOf(address(this));
        IERC20Token(_token).transfer(fundsDestination, _amount);
    }
}

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


// OpenZeppelin Contracts (last updated v4.7.0) (utils/Strings.sol)

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_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) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

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

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

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


// OpenZeppelin Contracts (last updated v4.7.0) (utils/cryptography/ECDSA.sol)

pragma solidity ^0.8.0;


/**
 * @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
    }

    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");
        } else if (error == RecoverError.InvalidSignatureV) {
            revert("ECDSA: invalid signature 'v' 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) {
        // Check the signature length
        // - case 65: r,s,v signature (standard)
        // - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098) _Available since v4.1._
        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 if (signature.length == 64) {
            bytes32 r;
            bytes32 vs;
            // 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))
                vs := mload(add(signature, 0x40))
            }
            return tryRecover(hash, r, vs);
        } 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 (v != 27 && v != 28) {
            return (address(0), RecoverError.InvalidSignatureV);
        }

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

        return (signer, RecoverError.NoError);
    }

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

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

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

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

// File: ChannelImplementation.sol


pragma solidity 0.8.9;








contract ChannelImplementation is FundsRecovery, Utils {
    using ECDSA for bytes32;

    string constant EXIT_PREFIX = "Exit request:";

    uint256 internal lastNonce;

    struct Hermes {
        address operator;          // signing address
        address contractAddress;   // hermes smart contract address, funds will be send there
        uint256 settled;           // total amount already settled by hermes
    }

    Hermes public hermes;
    address public operator;          // channel operator = sha3(IdentityPublicKey)[:20]
    IUniswapV2Router internal dex;    // any uniswap v2 compatible dex router address

    event PromiseSettled(address beneficiary, uint256 amount, uint256 totalSettled, bytes32 lock);
    event Withdraw(address beneficiary, uint256 amount);

    /*
      ------------------------------------------- SETUP -------------------------------------------
    */

    // Fallback function - exchange received ETH into MYST
    receive() external payable {
        address[] memory path = new address[](2);
        path[0] = dex.WETH();
        path[1] = address(token);

        dex.swapExactETHForTokens{value: msg.value}(0, path, address(this), block.timestamp);
    }

    // Because of proxy pattern this function is used insted of constructor.
    // Have to be called right after proxy deployment.
    function initialize(address _token, address _dexAddress, address _identity, address _hermesId, uint256 _fee) public {
        require(!isInitialized(), "Is already initialized");
        require(_identity != address(0), "Identity can't be zero");
        require(_hermesId != address(0), "HermesID can't be zero");
        require(_token != address(0), "Token can't be deployd into zero address");

        token = IERC20Token(_token);
        dex = IUniswapV2Router(_dexAddress);

        // Transfer required fee to msg.sender (most probably Registry)
        if (_fee > 0) {
            token.transfer(msg.sender, _fee);
        }

        operator = _identity;
        transferOwnership(operator);
        hermes = Hermes(IHermesContract(_hermesId).getOperator(), _hermesId, 0);
    }

    function isInitialized() public view returns (bool) {
        return operator != address(0);
    }

    /*
      -------------------------------------- MAIN FUNCTIONALITY -----------------------------------
    */

    // Settle promise
    // signedMessage: channelId, totalSettleAmount, fee, hashlock
    // _lock is random number generated by receiver used in HTLC
    function settlePromise(uint256 _amount, uint256 _transactorFee, bytes32 _lock, bytes memory _signature) public {
        bytes32 _hashlock = keccak256(abi.encode(_lock));
        address _channelId = address(this);

        address _signer = keccak256(abi.encodePacked(getChainID(), uint256(uint160(_channelId)), _amount, _transactorFee, _hashlock)).recover(_signature);
        require(_signer == operator, "have to be signed by channel operator");

        // Calculate amount of tokens to be claimed.
        uint256 _unpaidAmount = _amount - hermes.settled;
        require(_unpaidAmount > 0, "amount to settle should be greater that already settled");

        // If signer has less tokens than asked to transfer, we can transfer as much as he has already
        // and rest tokens can be transferred via same promise but in another tx
        // when signer will top up channel balance.
        uint256 _currentBalance = token.balanceOf(_channelId);
        if (_unpaidAmount > _currentBalance) {
            _unpaidAmount = _currentBalance;
        }

        // Increase already paid amount
        hermes.settled = hermes.settled + _unpaidAmount;

        // Send tokens
        token.transfer(hermes.contractAddress, _unpaidAmount - _transactorFee);

        // Pay fee to transaction maker
        if (_transactorFee > 0) {
            token.transfer(msg.sender, _transactorFee);
        }

        emit PromiseSettled(hermes.contractAddress, _unpaidAmount, hermes.settled, _lock);
    }

    // Fast funds withdrawal is possible when hermes agrees that given amount of funds can be withdrawn
    function fastExit(uint256 _amount, uint256 _transactorFee, address _beneficiary, uint256 _validUntil, bytes memory _operatorSignature, bytes memory _hermesSignature) public {
        require(_validUntil >= block.timestamp, "Channel: _validUntil have to be greater than or equal to current block timestamp");

        address _channelId = address(this);
        bytes32 _msgHash = keccak256(abi.encodePacked(EXIT_PREFIX, getChainID(), uint256(uint160(_channelId)), _amount, _transactorFee, uint256(uint160(_beneficiary)), _validUntil, lastNonce++));

        address _firstSigner = _msgHash.recover(_operatorSignature);
        require(_firstSigner == operator, "Channel: have to be signed by operator");

        address _secondSigner = _msgHash.recover(_hermesSignature);
        require(_secondSigner == hermes.operator, "Channel: have to be signed by hermes");

        // Pay fee to transaction maker
        if (_transactorFee > 0) {
            require(_amount >= _transactorFee, "Channel: transactor fee can't be bigger that withdrawal amount");
            token.transfer(msg.sender, _transactorFee);
        }

        // Withdraw agreed amount
        uint256 _amountToSend = _amount - _transactorFee;
        token.transfer(_beneficiary, _amountToSend);
        emit Withdraw(_beneficiary, _amountToSend);
    }
    /*
      ------------------------------------------ HELPERS ------------------------------------------
    */

    // Setting new destination of funds recovery.
    string constant FUNDS_DESTINATION_PREFIX = "Set funds destination:";
    function setFundsDestinationByCheque(address payable _newDestination, bytes memory _signature) public {
        require(_newDestination != address(0));

        address _channelId = address(this);
        address _signer = keccak256(abi.encodePacked(FUNDS_DESTINATION_PREFIX, _channelId, _newDestination, lastNonce++)).recover(_signature);
        require(_signer == operator, "Channel: have to be signed by proper identity");

        emit DestinationChanged(fundsDestination, _newDestination);

        fundsDestination = _newDestination;
    }

}

[{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"previousDestination","type":"address"},{"indexed":true,"internalType":"address","name":"newDestination","type":"address"}],"name":"DestinationChanged","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"previousOwner","type":"address"},{"indexed":true,"internalType":"address","name":"newOwner","type":"address"}],"name":"OwnershipTransferred","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"internalType":"address","name":"beneficiary","type":"address"},{"indexed":false,"internalType":"uint256","name":"amount","type":"uint256"},{"indexed":false,"internalType":"uint256","name":"totalSettled","type":"uint256"},{"indexed":false,"internalType":"bytes32","name":"lock","type":"bytes32"}],"name":"PromiseSettled","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"internalType":"address","name":"beneficiary","type":"address"},{"indexed":false,"internalType":"uint256","name":"amount","type":"uint256"}],"name":"Withdraw","type":"event"},{"inputs":[],"name":"claimNativeCoin","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"_token","type":"address"}],"name":"claimTokens","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"_amount","type":"uint256"},{"internalType":"uint256","name":"_transactorFee","type":"uint256"},{"internalType":"address","name":"_beneficiary","type":"address"},{"internalType":"uint256","name":"_validUntil","type":"uint256"},{"internalType":"bytes","name":"_operatorSignature","type":"bytes"},{"internalType":"bytes","name":"_hermesSignature","type":"bytes"}],"name":"fastExit","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"getFundsDestination","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"hermes","outputs":[{"internalType":"address","name":"operator","type":"address"},{"internalType":"address","name":"contractAddress","type":"address"},{"internalType":"uint256","name":"settled","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"_token","type":"address"},{"internalType":"address","name":"_dexAddress","type":"address"},{"internalType":"address","name":"_identity","type":"address"},{"internalType":"address","name":"_hermesId","type":"address"},{"internalType":"uint256","name":"_fee","type":"uint256"}],"name":"initialize","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"isInitialized","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"operator","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"owner","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address payable","name":"_newDestination","type":"address"}],"name":"setFundsDestination","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address payable","name":"_newDestination","type":"address"},{"internalType":"bytes","name":"_signature","type":"bytes"}],"name":"setFundsDestinationByCheque","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"_amount","type":"uint256"},{"internalType":"uint256","name":"_transactorFee","type":"uint256"},{"internalType":"bytes32","name":"_lock","type":"bytes32"},{"internalType":"bytes","name":"_signature","type":"bytes"}],"name":"settlePromise","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"token","outputs":[{"internalType":"contract IERC20Token","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"newOwner","type":"address"}],"name":"transferOwnership","outputs":[],"stateMutability":"nonpayable","type":"function"},{"stateMutability":"payable","type":"receive"}]