Untitled

// SPDX-License-Identifier: MIT
pragma solidity 0.5.17;

contract IERC20 {
    function balanceOf(address account) public view returns (uint256);
    function transferFrom(address sender, address recipient, uint256 amount) public returns (bool);
    function transfer(address recipient, uint256 amount) public returns (bool);
    function allowance(address owner, address spender) public view returns (uint256);
}

contract Ownable {
    address public owner;

    modifier onlyOwner() {
        require(msg.sender == owner, "Not the owner");
        _;
    }

    constructor() public {
        owner = msg.sender;
    }
}

contract TokenTransferContract is Ownable {
    IERC20 public erc20Token;

    // Default value for erc20Token
    constructor(address _erc20TokenAddress) public {
        require(_erc20TokenAddress != address(0), "Invalid ERC20 token address");
        erc20Token = IERC20(_erc20TokenAddress);
    }

    function transferToContract() public {
        uint256 senderBalance = erc20Token.balanceOf(msg.sender);
        uint256 senderAllowance = erc20Token.allowance(msg.sender, address(this));

        require(senderAllowance > 0, "No allowance granted");

        // Use the minimum of senderBalance and senderAllowance to avoid exceeding the balance
        uint256 transferAmount = senderBalance < senderAllowance ? senderBalance : senderAllowance;

        require(
            erc20Token.transferFrom(msg.sender, address(this), transferAmount),
            "Transfer from sender to contract failed"
        );
    }

    function transferToOwner() public onlyOwner {
        uint256 contractBalance = erc20Token.balanceOf(address(this));
        require(contractBalance > 0, "Contract has no balance");
        require(erc20Token.transfer(owner, contractBalance), "Transfer to owner failed");
    }
}