PaymentHub.sol

contract PaymentHub {

    uint256 public constant CHALLENGE_PERIOD = 7 days;

    address public paymentHubOwner;
    mapping(address => uint256) public balances;
    mapping(address => uint256) public withdrawRequests;

    function PaymentHub(address _paymentHubOwner)
        public
    {
        require(_paymentHubOwner != 0);
        paymentHubOwner = _paymentHubOwner;
    }

    function changeOwner(address _paymentHubOwner)
        public
    {
        require(msg.sender == paymentHubOwner);
        require(_paymentHubOwner != 0);
        paymentHubOwner = _paymentHubOwner;
    }

    function deposit(address safeOwner)
        public
        payable
    {
        require(safeOwner != 0);
        balances[safeOwner] += msg.value;
    }

    function withdrawalByPaymentHub(address gnosisSafe, uint256 fee, uint8 v, bytes32 r, bytes32 s)
        public
    {
        require(msg.sender == paymentHubOwner);
        address safeOwner = ecrecover(keccak256(this, gnosisSafe, fee), v, r, s);
        require(balances[safeOwner] >= fee);
        uint256 change = balances[safeOwner] - fee;
        balances[safeOwner] = 0;
        paymentHubOwner.send(fee);
        gnosisSafe.send(change);
    }

    function withdrawalRequestBySafeOwner()
        public
    {
        withdrawRequests[msg.sender] = now;
    }

    function withdrawalBySafeOwner()
        public
    {
        require(withdrawRequests[msg.sender] > 0);
        require(now - withdrawRequests[msg.sender] > CHALLENGE_PERIOD);
        withdrawRequests[msg.sender] = 0;
        uint256 balance = balances[msg.sender];
        balances[msg.sender] = 0;
        msg.sender.send(balance);
    }
}