/*
    Copyright 2020 Set Labs Inc.

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.

    SPDX-License-Identifier: Apache License, Version 2.0
*/

pragma solidity 0.6.10;

import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";


/**
 * @title ICEth
 * @author Set Protocol
 *
 * Interface for interacting with Compound Ether
 */
interface ICEth is IERC20 {

    /**
     * Calculates the exchange rate from the underlying to the CToken
     *
     * @notice Accrue interest then return the up-to-date exchange rate
     * @return Calculated exchange rate scaled by 1e18
     */
    function exchangeRateCurrent() external returns (uint256);

    function exchangeRateStored() external view returns (uint256);

    /**
     * @notice Sender supplies assets into the market and receives cTokens in exchange
     * @dev Reverts upon any failure
     */
    function mint() external payable;

    /**
     * @notice Sender redeems cTokens in exchange for the underlying asset
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param _redeemTokens The number of cTokens to redeem into underlying
     * @return uint256 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function redeem(uint256 _redeemTokens) external returns (uint256);

    /**
     * @notice Sender redeems cTokens in exchange for a specified amount of underlying asset
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param _redeemAmount The amount of underlying to redeem
     * @return uint256 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function redeemUnderlying(uint256 _redeemAmount) external returns (uint256);

    /**
      * @notice Sender borrows assets from the protocol to their own address
      * @param _borrowAmount The amount of the underlying asset to borrow
      * @return uint256 0=success, otherwise a failure (see ErrorReporter.sol for details)
      */
    function borrow(uint256 _borrowAmount) external returns (uint256);

    /**
     * @notice Sender repays their own borrow
     * @dev Reverts upon any failure
     */
    function repayBorrow() external payable;
}