InstaContract/contracts/v2/DAI2ETH.sol

pragma solidity ^0.5.0;

interface IERC20 {
    function balanceOf(address who) external view returns (uint256);
    function approve(address spender, uint256 value) external returns (bool);
}

interface AddressRegistry {
    function getAddr(string calldata name) external view returns (address);
}

interface Kyber {
    function trade(
        address src,
        uint srcAmount,
        address dest,
        address destAddress,
        uint maxDestAmount,
        uint minConversionRate,
        address walletId
    ) external payable returns (uint);

    function getExpectedRate(address src, address dest, uint srcQty) external view returns (uint, uint);
}

contract Registry {
    address public addressRegistry;
    modifier onlyAdmin() {
        require(msg.sender == getAddress("admin"), "Permission Denied");
        _;
    }
    function getAddress(string memory name) internal view returns (address) {
        AddressRegistry addrReg = AddressRegistry(addressRegistry);
        return addrReg.getAddr(name);
    }
}

contract Trade is Registry {
    event KyberTrade(address src, uint srcAmt, address dest, uint destAmt, address beneficiary, uint minConversionRate);

    function approveDAIKyber() public {
        IERC20 tokenFunctions = IERC20(getAddress("dai"));
        tokenFunctions.approve(getAddress("kyber"), 2 ** 255);
    }

    function expectedETH(uint srcDAI) public view returns (uint, uint) {
        Kyber kyberFunctions = Kyber(getAddress("kyber"));
        return kyberFunctions.getExpectedRate(getAddress("dai"), getAddress("eth"), srcDAI);
    }

    function dai2eth(uint srcDAI) public returns (uint destAmt) {
        address src = getAddress("dai");
        address dest = getAddress("eth");
        uint minConversionRate;
        (, minConversionRate) = expectedETH(srcDAI);

        // Interacting with Kyber Proxy Contract
        Kyber kyberFunctions = Kyber(getAddress("kyber"));
        destAmt = kyberFunctions.trade.value(0)(src, srcDAI, dest, msg.sender, 2 ** 255, minConversionRate, getAddress("admin"));

        emit KyberTrade(src, srcDAI, dest, destAmt, msg.sender, minConversionRate);

    }

}

contract DAI2ETH is Trade {
    constructor(address rAddr) public {
        addressRegistry = rAddr;
        approveDAIKyber();
    }

    function() external payable {}

}