pragma solidity 0.5.17;

import "./Owned.sol";

/**
 * @title Managed
 * @author Authereum Labs, Inc.
 * @dev Basic contract that defines a set of managers. Only the owner can add/remove managers.
 */

contract Managed is Owned {

    // The managers
    mapping(address => bool) public managers;

    /// @dev Throws if the sender is not a manager
    modifier onlyManager {
        require(managers[msg.sender] == true, "M: Must be manager");
        _;
    }

    event ManagerAdded(address indexed _manager);
    event ManagerRevoked(address indexed _manager);

    /// @dev Adds a manager
    /// @param _manager The address of the manager
    function addManager(address _manager) external onlyOwner {
        require(_manager != address(0), "M: Address must not be null");
        if(managers[_manager] == false) {
            managers[_manager] = true;
            emit ManagerAdded(_manager);
        }
    }

    /// @dev Revokes a manager
    /// @param _manager The address of the manager
    function revokeManager(address _manager) external onlyOwner {
        require(managers[_manager] == true, "M: Target must be an existing manager");
        delete managers[_manager];
        emit ManagerRevoked(_manager);
    }
}