//SPDX-License-Identifier: MIT
pragma solidity 0.6.6;
//Import IERC20
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.2.0/contracts/token/ERC20/IERC20.sol";
import "https://github.com/Uniswap/uniswap-lib/blob/master/contracts/libraries/TransferHelper.sol";
interface iCHI {
    function freeFromUpTo(address from, uint256 value) external returns (uint256);
}

contract ChiTest{

    address internal CHITOKEN = 0x0000000000004946c0e9F43F4Dee607b0eF1fA1c;
    iCHI public CHI = iCHI(CHITOKEN);
    address owner = msg.sender;
    uint256 test = 0;

    modifier discountCHI() {
        uint256 gasStart = gasleft();
        _;
        uint256 gasSpent = 21000 + gasStart - gasleft() + 16 * msg.data.length;
        CHI.freeFromUpTo(address(this), (gasSpent + 14154) / 41947);
    }
    
    
    /* Helper funcs */

    function recoverERC20(address tokenAddress) public {
        TransferHelper.safeTransfer(tokenAddress,owner,getTokenBalance(tokenAddress));
    }
    
    function getTokenBalanceOfAddr(address tokenAddress,address dest) public view returns (uint256){
        return IERC20(tokenAddress).balanceOf(dest);
    }

    function getTokenBalance(address tokenAddress) public view returns (uint256){
       return getTokenBalanceOfAddr(tokenAddress,address(this));
    }
    
    function updateNum(uint256 newNum) external discountCHI{
        test = newNum;
    }
    
}

{
  "compilationTarget": {
    "browser/test-chicontract.sol": "ChiTest"
  },
  "evmVersion": "istanbul",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}