CEtherRedeamer

pragma solidity ^0.6.0;

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);
}
interface ICEther is IERC20
{
    function redeem(uint redeemTokens) external returns (uint);
    function redeemUnderlying(uint redeemAmount) external returns (uint);
}


contract CEtherRedeamer
{
    ICEther public immutable cether;
    
    constructor(address _cether)
    public
    {
        cether = ICEther(_cether);
    }
    
    receive()
    external payable
    {}
    
    function redeem(uint redeemTokens) external returns (uint)
    {
        uint result = cether.redeem(redeemTokens);
        (bool success, bytes memory returndata) = msg.sender.call{value: address(this).balance}("");
        require(success, string(returndata));
        cether.transfer(msg.sender, cether.balanceOf(address(this)));
        return result;
    }
    
    function redeemUnderlying(uint redeemAmount) external returns (uint)
    {
        uint result = cether.redeemUnderlying(redeemAmount);
        (bool success, bytes memory returndata) = msg.sender.call{value: address(this).balance}("");
        require(success, string(returndata));
        cether.transfer(msg.sender, cether.balanceOf(address(this)));
        return result;
    }

}