/**

Deployed by Ren Project, https://renproject.io

Commit hash: 9068f80
Repository: https://github.com/renproject/darknode-sol
Issues: https://github.com/renproject/darknode-sol/issues

Licenses
@openzeppelin/contracts: (MIT) https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/LICENSE
darknode-sol: (GNU GPL V3) https://github.com/renproject/darknode-sol/blob/master/LICENSE

*/

pragma solidity 0.5.16;


library SafeMath {
    
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        
        
        
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        
        require(b > 0, errorMessage);
        uint256 c = a / b;
        

        return c;
    }

    
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

contract Initializable {

  
  bool private initialized;

  
  bool private initializing;

  
  modifier initializer() {
    require(initializing || isConstructor() || !initialized, "Contract instance has already been initialized");

    bool isTopLevelCall = !initializing;
    if (isTopLevelCall) {
      initializing = true;
      initialized = true;
    }

    _;

    if (isTopLevelCall) {
      initializing = false;
    }
  }

  
  function isConstructor() private view returns (bool) {
    
    
    
    
    
    address self = address(this);
    uint256 cs;
    assembly { cs := extcodesize(self) }
    return cs == 0;
  }

  
  uint256[50] private ______gap;
}

contract Context is Initializable {
    
    
    constructor () internal { }
    

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; 
        return msg.data;
    }
}

interface IERC20 {
    
    function totalSupply() external view returns (uint256);

    
    function balanceOf(address account) external view returns (uint256);

    
    function transfer(address recipient, uint256 amount) external returns (bool);

    
    function allowance(address owner, address spender) external view returns (uint256);

    
    function approve(address spender, uint256 amount) external returns (bool);

    
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    
    event Transfer(address indexed from, address indexed to, uint256 value);

    
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

contract ERC20 is Initializable, Context, IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    
    function balanceOf(address account) public view returns (uint256) {
        return _balances[account];
    }

    
    function transfer(address recipient, uint256 amount) public returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    
    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowances[owner][spender];
    }

    
    function approve(address spender, uint256 amount) public returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    
    function transferFrom(address sender, address recipient, uint256 amount) public returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    
    function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    
    function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    
    function _transfer(address sender, address recipient, uint256 amount) internal {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    
    function _mint(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: mint to the zero address");

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

     
    function _burn(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: burn from the zero address");

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    
    function _approve(address owner, address spender, uint256 amount) internal {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    
    function _burnFrom(address account, uint256 amount) internal {
        _burn(account, amount);
        _approve(account, _msgSender(), _allowances[account][_msgSender()].sub(amount, "ERC20: burn amount exceeds allowance"));
    }

    uint256[50] private ______gap;
}

library Address {
    
    function isContract(address account) internal view returns (bool) {
        
        
        

        
        
        
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        
        assembly { codehash := extcodehash(account) }
        return (codehash != 0x0 && codehash != accountHash);
    }

    
    function toPayable(address account) internal pure returns (address payable) {
        return address(uint160(account));
    }

    
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

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

library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        
        
        
        
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    
    function callOptionalReturn(IERC20 token, bytes memory data) private {
        
        

        
        
        
        
        
        require(address(token).isContract(), "SafeERC20: call to non-contract");

        
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "SafeERC20: low-level call failed");

        if (returndata.length > 0) { 
            
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

contract Ownable is Initializable, Context {
    address private _owner;

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

    
    function initialize(address sender) public initializer {
        _owner = sender;
        emit OwnershipTransferred(address(0), _owner);
    }

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

    
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    
    function isOwner() public view returns (bool) {
        return _msgSender() == _owner;
    }

    
    function renounceOwnership() public onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }

    uint256[50] private ______gap;
}

contract Claimable is Initializable, Ownable {
    address public pendingOwner;

    function initialize(address _nextOwner) public initializer {
        Ownable.initialize(_nextOwner);
    }

    modifier onlyPendingOwner() {
        require(
            _msgSender() == pendingOwner,
            "Claimable: caller is not the pending owner"
        );
        _;
    }

    function transferOwnership(address newOwner) public onlyOwner {
        require(
            newOwner != owner() && newOwner != pendingOwner,
            "Claimable: invalid new owner"
        );
        pendingOwner = newOwner;
    }

    function claimOwnership() public onlyPendingOwner {
        _transferOwnership(pendingOwner);
        delete pendingOwner;
    }
}

library Math {
    
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

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

    
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        
        return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
    }
}

library ERC20WithFees {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    
    
    function safeTransferFromWithFees(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal returns (uint256) {
        uint256 balancesBefore = token.balanceOf(to);
        token.safeTransferFrom(from, to, value);
        uint256 balancesAfter = token.balanceOf(to);
        return Math.min(value, balancesAfter.sub(balancesBefore));
    }
}

contract DarknodePaymentStore is Claimable {
    using SafeMath for uint256;
    using SafeERC20 for ERC20;
    using ERC20WithFees for ERC20;

    string public VERSION; 

    
    address public constant ETHEREUM = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;

    
    mapping(address => mapping(address => uint256)) public darknodeBalances;

    
    mapping(address => uint256) public lockedBalances;

    
    
    
    constructor(string memory _VERSION) public {
        Claimable.initialize(msg.sender);
        VERSION = _VERSION;
    }

    
    function() external payable {}

    
    
    
    
    function totalBalance(address _token) public view returns (uint256) {
        if (_token == ETHEREUM) {
            return address(this).balance;
        } else {
            return ERC20(_token).balanceOf(address(this));
        }
    }

    
    
    
    
    
    
    function availableBalance(address _token) public view returns (uint256) {
        return
            totalBalance(_token).sub(
                lockedBalances[_token],
                "DarknodePaymentStore: locked balance exceed total balance"
            );
    }

    
    
    
    
    
    
    function incrementDarknodeBalance(
        address _darknode,
        address _token,
        uint256 _amount
    ) external onlyOwner {
        require(_amount > 0, "DarknodePaymentStore: invalid amount");
        require(
            availableBalance(_token) >= _amount,
            "DarknodePaymentStore: insufficient contract balance"
        );

        darknodeBalances[_darknode][_token] = darknodeBalances[_darknode][_token]
            .add(_amount);
        lockedBalances[_token] = lockedBalances[_token].add(_amount);
    }

    
    
    
    
    
    
    function transfer(
        address _darknode,
        address _token,
        uint256 _amount,
        address payable _recipient
    ) external onlyOwner {
        require(
            darknodeBalances[_darknode][_token] >= _amount,
            "DarknodePaymentStore: insufficient darknode balance"
        );
        darknodeBalances[_darknode][_token] = darknodeBalances[_darknode][_token]
            .sub(
            _amount,
            "DarknodePaymentStore: insufficient darknode balance for transfer"
        );
        lockedBalances[_token] = lockedBalances[_token].sub(
            _amount,
            "DarknodePaymentStore: insufficient token balance for transfer"
        );

        if (_token == ETHEREUM) {
            _recipient.transfer(_amount);
        } else {
            ERC20(_token).safeTransfer(_recipient, _amount);
        }
    }

}