pragma solidity ^0.5.17;


interface IClock {
    /**
    * @dev Ensure that the current term of the clock is up-to-date
    * @return Identification number of the current term
    */
    function ensureCurrentTerm() external returns (uint64);

    /**
    * @dev Transition up to a certain number of terms to leave the clock up-to-date
    * @param _maxRequestedTransitions Max number of term transitions allowed by the sender
    * @return Identification number of the term ID after executing the heartbeat transitions
    */
    function heartbeat(uint64 _maxRequestedTransitions) external returns (uint64);

    /**
    * @dev Ensure that a certain term has its randomness set
    * @return Randomness of the current term
    */
    function ensureCurrentTermRandomness() external returns (bytes32);

    /**
    * @dev Tell the last ensured term identification number
    * @return Identification number of the last ensured term
    */
    function getLastEnsuredTermId() external view returns (uint64);

    /**
    * @dev Tell the current term identification number. Note that there may be pending term transitions.
    * @return Identification number of the current term
    */
    function getCurrentTermId() external view returns (uint64);

    /**
    * @dev Tell the number of terms the clock should transition to be up-to-date
    * @return Number of terms the clock should transition to be up-to-date
    */
    function getNeededTermTransitions() external view returns (uint64);

    /**
    * @dev Tell the information related to a term based on its ID
    * @param _termId ID of the term being queried
    * @return startTime Term start time
    * @return randomnessBN Block number used for randomness in the requested term
    * @return randomness Randomness computed for the requested term
    */
    function getTerm(uint64 _termId) external view returns (uint64 startTime, uint64 randomnessBN, bytes32 randomness);

    /**
    * @dev Tell the randomness of a term even if it wasn't computed yet
    * @param _termId Identification number of the term being queried
    * @return Randomness of the requested term
    */
    function getTermRandomness(uint64 _termId) external view returns (bytes32);
}