UpgradeableContract.sol

// SPDX-License-Identifier: CC0-1.0

/// @title Upgradeable Contract with Access Control

/**
 *        ><<    ><<<<< ><<    ><<      ><<
 *      > ><<          ><<      ><<      ><<
 *     >< ><<         ><<       ><<      ><<
 *   ><<  ><<        ><<        ><<      ><<
 *  ><<<< >< ><<     ><<        ><<      ><<
 *        ><<        ><<       ><<<<    ><<<<
 */

pragma solidity ^0.8.17;

import "openzeppelin-upgradeable/proxy/utils/Initializable.sol";
import "openzeppelin-upgradeable/access/AccessControlUpgradeable.sol";
import "openzeppelin-upgradeable/access/OwnableUpgradeable.sol";
import "openzeppelin-upgradeable/proxy/utils/UUPSUpgradeable.sol";

contract UpgradeableContract is Initializable, AccessControlUpgradeable, OwnableUpgradeable, UUPSUpgradeable {
    bytes32 public constant UPGRADER_ROLE = keccak256("UPGRADER_ROLE");
    bytes32 public constant WITHDRAW_ROLE = keccak256("WITHDRAW_ROLE");

    /// @custom:oz-upgrades-unsafe-allow constructor
    constructor() {
        _disableInitializers();
    }

    function initialize(address admin) public initializer {
        __AccessControl_init();
        __UUPSUpgradeable_init();

        _grantRole(DEFAULT_ADMIN_ROLE, admin);
        _grantRole(UPGRADER_ROLE, admin);
        _grantRole(WITHDRAW_ROLE, admin);
        _transferOwnership(admin);
    }

    function transferOwnership(address newOwner) public virtual override onlyRole(DEFAULT_ADMIN_ROLE) {
        _transferOwnership(newOwner);
    }

    function _authorizeUpgrade(address newImplementation) internal override onlyRole(UPGRADER_ROLE) {}

    function withdraw() external onlyRole(WITHDRAW_ROLE) {
        payable(msg.sender).transfer(address(this).balance);
    }

    /**
     * @dev This empty reserved space is put in place to allow future versions to add new
     * variables without shifting down storage in the inheritance chain.
     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
     */
    uint256[50] private __gap;
}