pragma solidity ^0.5.0;

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

contract IKToken is IERC20 {

    event Mint(address minter, uint256 tokenAmount, uint256 kTokenAmount);
    event Redeem(address redeemer, uint256 tokenAmount, uint256 kTokenAmount);

    /*
     * PUBLIC STATE CHANGING
     */

    function redeem(uint256 kTokenAmount)
    external
    returns (bool);

    function redeemUnderlying(uint256 tokenAmount)
    external
    returns (bool);

    function mintInternal(uint256 amount)
    internal
    returns (bool);

    function redeemInternal(uint256 tokenAmount, uint256 kTokenAmount)
    internal
    returns (bool);

    /*
     * INVOKER STATE-CHANGING HOOKS
    */

    function transferUnderlying(address to, uint256 amount)
    external
    returns (bool);

    function transferUnderlyingInternal(address to, uint256 amount) internal returns (bool);

    /* Lock automatically clears after block in case of any unintended locking attacks */
    function lock()
    external;

    function unlock()
    external;

    /* Adds unlimited allowance functionality to standard transferFrom implementation */
    function transferFrom(address sender, address recipient, uint256 amount) public returns (bool);

    /*
     * VIEWS
     */

    function tokenAmountToKTokenAmount(uint256 tokenAmount, bool ceiling) public view returns (uint256);

    function tokenAmountToKTokenAmountInternal(uint256 tokenAmount, bool ceiling, bool alreadyDeposited)
    internal
    view
    returns (uint256);

    function kTokenAmountToTokenAmount(uint256 kTokenAmount) public view returns (uint256);

    function isKEther() public view returns (bool);

    function totalReserve() public view returns (uint256);

    function balanceOfUnderlying(address owner) public view returns (uint256);

    function tokenAddress() external view returns (address);

    function invokerAddress() external view returns (address);

    /*
     * ADMIN FUNCTIONS
     */

    /* KToken ownership will be relinquished before public launch. */
    function setInvokerAddress(address invokerAddress) external;
}