SimulatedKyber.sol

SimulatedKyber.sol

pragma solidity 0.5.7;
pragma experimental ABIEncoderV2;

import { IERC20 } from "openzeppelin-solidity/contracts/token/ERC20/IERC20.sol";
import { SafeMath } from "openzeppelin-solidity/contracts/math/SafeMath.sol";

contract SimulatedKyber {
    using SafeMath for uint256;
    
    IERC20 public dai;
    uint256 public daiPerEth;
    
    constructor(IERC20 _dai, uint256 _daiPerEth) public {
        dai = _dai;
        daiPerEth = _daiPerEth; // Exchange rate
    }
    
    function exchangeEthToDai() public payable {
        require(
            msg.value > 0,
            "Ether value must be more than zero"
        );
        uint256 daiResult = msg.value.mul(daiPerEth);
        require(
            dai.balanceOf(address(this)) >= daiResult,
            "Insufficient DAI liquidity in Simulated Kyber"
        );
        dai.transfer(msg.sender, daiResult);
    }
    
    function exchangeDaiToEth(uint256 _daiValue) public {
        require(
            _daiValue > 0,
            "_daiValue must be more than zero"
        );
        require(
            dai.allowance(msg.sender, address(this)) >= _daiValue,
            "SimulatedKyber DAI allowance is insufficient, please increase this contract's DAI allowance to facilitate the DAI -> ETH exchange"
        );
        uint256 ethResult = _daiValue.div(daiPerEth);
        require(
            address(this).balance >= ethResult,
            "Insufficient DAI liquidity in Simulated Kyber"
        );
        require(
            ethResult.mul(daiPerEth) == _daiValue,
            "Trade would cause precision loss"
        );
        dai.transferFrom(msg.sender, address(this), _daiValue);
        msg.sender.transfer(ethResult);
    }
    
}