/*

    Copyright 2020 DODO ZOO.
    SPDX-License-Identifier: Apache-2.0

*/

pragma solidity 0.6.9;

import {SafeMath} from "../../lib/SafeMath.sol";
import {IERC20} from "../../intf/IERC20.sol";
import {SafeERC20} from "../../lib/SafeERC20.sol";

library UniversalERC20 {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    IERC20 private constant ETH_ADDRESS = IERC20(0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE);

    function universalTransfer(
        IERC20 token,
        address payable to,
        uint256 amount
    ) internal {
        if (amount > 0) {
            if (isETH(token)) {
                to.transfer(amount);
            } else {
                token.safeTransfer(to, amount);
            }
        }
    }

    function universalApproveMax(
        IERC20 token,
        address to,
        uint256 amount
    ) internal {
        uint256 allowance = token.allowance(address(this), to);
        if (allowance < amount) {
            if (allowance > 0) {
                token.safeApprove(to, 0);
            }
            token.safeApprove(to, uint256(-1));
        }
    }

    function universalBalanceOf(IERC20 token, address who) internal view returns (uint256) {
        if (isETH(token)) {
            return who.balance;
        } else {
            return token.balanceOf(who);
        }
    }

    function tokenBalanceOf(IERC20 token, address who) internal view returns (uint256) {
        return token.balanceOf(who);
    }

    function isETH(IERC20 token) internal pure returns (bool) {
        return token == ETH_ADDRESS;
    }
}