pragma solidity ^0.5.2;

import "@openzeppelin/upgrades/contracts/Initializable.sol";

import "../../GSN/Context.sol";
import "../Roles.sol";

/**
 * @title WhitelistAdminRole
 * @dev WhitelistAdmins are responsible for assigning and removing Whitelisted accounts.
 */
contract WhitelistAdminRole is Initializable, Context {
    using Roles for Roles.Role;

    event WhitelistAdminAdded(address indexed account);
    event WhitelistAdminRemoved(address indexed account);

    Roles.Role private _whitelistAdmins;

    function initialize(address sender) public initializer {
        if (!isWhitelistAdmin(sender)) {
            _addWhitelistAdmin(sender);
        }
    }

    modifier onlyWhitelistAdmin() {
        require(isWhitelistAdmin(_msgSender()), "WhitelistAdminRole: caller does not have the WhitelistAdmin role");
        _;
    }

    function isWhitelistAdmin(address account) public view returns (bool) {
        return _whitelistAdmins.has(account);
    }

    function addWhitelistAdmin(address account) public onlyWhitelistAdmin {
        _addWhitelistAdmin(account);
    }

    function renounceWhitelistAdmin() public {
        _removeWhitelistAdmin(_msgSender());
    }

    function _addWhitelistAdmin(address account) internal {
        _whitelistAdmins.add(account);
        emit WhitelistAdminAdded(account);
    }

    function _removeWhitelistAdmin(address account) internal {
        _whitelistAdmins.remove(account);
        emit WhitelistAdminRemoved(account);
    }

    uint256[50] private ______gap;
}
