// SPDX-License-Identifier: MIT
pragma solidity >=0.7.6 <0.9;

interface IICleanable {
    /**
     * Set the contract that is allowed to call history cleaning methods.
     */
    function setCleanerContract(address _cleanerContract) external;
    
    /**
     * Set the cleanup block number.
     * Historic data for the blocks before `cleanupBlockNumber` can be erased,
     * history before that block should never be used since it can be inconsistent.
     * In particular, cleanup block number must be before current vote power block.
     * @param _blockNumber The new cleanup block number.
     */
    function setCleanupBlockNumber(uint256 _blockNumber) external;
    
    /**
     * Set the contract that is allowed to set cleanupBlockNumber.
     * Usually this will be an instance of CleanupBlockNumberManager.
     */
    function setCleanupBlockNumberManager(address _cleanupBlockNumberManager) external;
    
    /**
     * Get the current cleanup block number.
     */
    function cleanupBlockNumber() external view returns (uint256);
}