pragma solidity 0.5.17;

/**
 * @title Keep interface
 */

interface ITBTCSystem {
    // expected behavior:
    // return the price of 1 sat in wei
    // these are the native units of the deposit contract
    function fetchBitcoinPrice() external view returns (uint256);

    // passthrough requests for the oracle
    function fetchRelayCurrentDifficulty() external view returns (uint256);

    function fetchRelayPreviousDifficulty() external view returns (uint256);

    function getNewDepositFeeEstimate() external view returns (uint256);

    function getAllowNewDeposits() external view returns (bool);

    function isAllowedLotSize(uint64 _requestedLotSizeSatoshis)
        external
        view
        returns (bool);

    function requestNewKeep(
        uint64 _requestedLotSizeSatoshis,
        uint256 _maxSecuredLifetime
    ) external payable returns (address);

    function getSignerFeeDivisor() external view returns (uint16);

    function getInitialCollateralizedPercent() external view returns (uint16);

    function getUndercollateralizedThresholdPercent()
        external
        view
        returns (uint16);

    function getSeverelyUndercollateralizedThresholdPercent()
        external
        view
        returns (uint16);
}