// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;
import "@openzeppelin/contracts/access/AccessControl.sol";
import "@openzeppelin/contracts/utils/structs/EnumerableSet.sol";

abstract contract Moderatable is AccessControl {
    using EnumerableSet for EnumerableSet.AddressSet;
    EnumerableSet.AddressSet private _moderators;

    bytes32 public constant ROLE_MODERATOR = keccak256("MODERATOR");

    event ModeratorAdded(address indexed moderator, uint timestamp);

    event ModeratorRemoved(address indexed moderator, uint timestamp);

    constructor() {
        _moderators.add(_msgSender());
        _setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
        grantRole(ROLE_MODERATOR, _msgSender());
    }

    function addModerator(
        address moderator
    ) public onlyRole(DEFAULT_ADMIN_ROLE) {
        _moderators.add(moderator);
        grantRole(ROLE_MODERATOR, moderator);
        emit ModeratorAdded(moderator, block.timestamp);
    }

    function removeModerator(
        address moderator
    ) public onlyRole(DEFAULT_ADMIN_ROLE) {
        renounceRole(ROLE_MODERATOR, moderator);
        _moderators.remove(moderator);
        emit ModeratorRemoved(moderator, block.timestamp);
    }

    function getModerators() public view returns (address[] memory moderators) {
        return _moderators.values();
    }

    function getModeratorsCount() public view returns (uint256 moderatorCount) {
        return _moderators.length();
    }

    function isModerator(address moderator) public view returns (bool) {
        return _moderators.contains(moderator);
    }
}