// SPDX-License-Identifier: MIT
pragma solidity >=0.8;

import { UUPSUtils } from "@superfluid-finance/ethereum-contracts/contracts/upgradability/UUPSUtils.sol";
import { Initializable } from "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";

/**
 * @title UUPS (Universal Upgradeable Proxy Standard) Proxiable contract.
 * @dev Modified for SuperGoodDollar
 * 1. use upgradeable Initializable for compatability with usage of other openzep upgradeablaes contracts
 */
abstract contract UUPSProxiable is Initializable {
	/**
	 * @dev Get current implementation code address.
	 */
	function getCodeAddress() public view returns (address codeAddress) {
		return UUPSUtils.implementation();
	}

	function updateCode(address newAddress) external virtual;

	// allows to mark logic contracts as initialized in order to reduce the attack surface
	// solhint-disable-next-line no-empty-blocks
	function castrate() external initializer {}

	/**
	 * @dev Proxiable UUID marker function, this would help to avoid wrong logic
	 *      contract to be used for upgrading.
	 *
	 * NOTE: The semantics of the UUID deviates from the actual UUPS standard,
	 *       where it is equivalent of _IMPLEMENTATION_SLOT.
	 */
	function proxiableUUID() public view virtual returns (bytes32);

	/**
	 * @dev Update code address function.
	 *      It is internal, so the derived contract could setup its own permission logic.
	 */
	function _updateCodeAddress(address newAddress) internal {
		// require UUPSProxy.initializeProxy first
		require(
			UUPSUtils.implementation() != address(0),
			"UUPSProxiable: not upgradable"
		);
		require(
			proxiableUUID() == UUPSProxiable(newAddress).proxiableUUID(),
			"UUPSProxiable: not compatible logic"
		);
		require(address(this) != newAddress, "UUPSProxiable: proxy loop");
		UUPSUtils.setImplementation(newAddress);
		emit CodeUpdated(proxiableUUID(), newAddress);
	}

	event CodeUpdated(bytes32 uuid, address codeAddress);
}