EthFiddle - Solidity IDE in the Browser. Powered By Loom Network

pragma solidity 0.8.10;

interface IAugustus {
    function getTokenTransferProxy() external view returns (address);
}

interface IERC20 {
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(address from, address to, uint256 amount) external returns (bool);
    function transfer(address to, uint256 amount) external returns (bool);
    function balanceOf(address account) external view returns (uint256);
}

/*
 *  1/ some scenario is broken
 *  2/ not secure
 *  3/ not gas efficient
 */
contract BrokenSwapper {
    IAugustus immutable augustus;

constructor(IAugustus _augustus) {
        augustus = _augustus;
    }
    
  	// this should allow swaps with ERC20 tokens and native
    function swapTokensWithParaSwap(
        IERC20 srcToken, 
        IERC20 destToken, 
        uint256 amount, 
        bytes memory augustusCalldata // trusted data to pass down to augutus contract
    ) external {
        srcToken.transferFrom(msg.sender, address(this), amount);

srcToken.approve(augustus.getTokenTransferProxy(), amount);

address(augustus).delegatecall{value: msg.value}(augustusCalldata); // swap ERC20 and pure ETH
        
        destToken.transfer(msg.sender, destToken.balanceOf(address(this)));
    }
}