pragma solidity ^0.5.0;

import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "../Invoker.sol";
import "../KToken.sol";

contract KollateralInvokable {
    using SafeMath for uint256;

    function currentKTokenAddress() internal view returns (address) {
        return Invoker(msg.sender).currentKTokenAddress();
    }

    function currentTokenAddress() internal view returns (address) {
        return Invoker(msg.sender).currentTokenAddress();
    }

    function currentTokenAmount() internal view returns (uint256) {
        return Invoker(msg.sender).currentTokenAmount();
    }

    function currentExpectedBalance() internal view returns (uint256) {
        return Invoker(msg.sender).currentExpectedBalance();
    }

    function currentKTokenTotalReserve() internal view returns (uint256) {
        return KToken(currentKTokenAddress()).totalReserve();
    }

    function currentOutstandingTokenAmount() internal view returns (uint256) {
        return currentExpectedBalance().sub(currentKTokenTotalReserve());
    }

    function isKTokenKEther() internal view returns (bool) {
        return KToken(currentKTokenAddress()).isKEther();
    }

    function repay() internal returns (bool) {
        return repayAmount(currentOutstandingTokenAmount());
    }

    function repayAmount(uint256 amount) internal returns (bool) {
        if (isKTokenKEther()) {
            address payable kEtherAddress = address(uint160(currentKTokenAddress()));
            require(address(this).balance >= amount, "KollateralInvokable: not enough ether balance");
            kEtherAddress.transfer(amount);
            return true;
        } else {
            IERC20 token = IERC20(currentTokenAddress());
            require(token.balanceOf(address(this)) >= amount, "KollateralInvokable: not enough token balance");
            return token.transfer(currentKTokenAddress(), amount);
        }
    }
}