// SPDX-FileCopyrightText: 2023 Lido <info@lido.fi>
// SPDX-License-Identifier: GPL-3.0
pragma solidity 0.4.24;

import "@aragon/os/contracts/common/UnstructuredStorage.sol";

/**
 * @title Adapted code of /contracts/0.8.9/utils/Versioned.sol
 *
 * This contract contains only core part of original Versioned.sol
 * to reduce contract size
 */
contract Versioned {
    using UnstructuredStorage for bytes32;

    event ContractVersionSet(uint256 version);

    /// @dev Storage slot: uint256 version
    /// Version of the initialized contract storage.
    /// The version stored in CONTRACT_VERSION_POSITION equals to:
    /// - 0 right after the deployment, before an initializer is invoked (and only at that moment);
    /// - N after calling initialize(), where N is the initially deployed contract version;
    /// - N after upgrading contract by calling finalizeUpgrade_vN().
    bytes32 internal constant CONTRACT_VERSION_POSITION =
        0x4dd0f6662ba1d6b081f08b350f5e9a6a7b15cf586926ba66f753594928fa64a6; // keccak256("lido.Versioned.contractVersion");

    uint256 internal constant PETRIFIED_VERSION_MARK = uint256(-1);

    constructor() public {
        // lock version in the implementation's storage to prevent initialization
        CONTRACT_VERSION_POSITION.setStorageUint256(PETRIFIED_VERSION_MARK);
    }

    /// @notice Returns the current contract version.
    function getContractVersion() public view returns (uint256) {
        return CONTRACT_VERSION_POSITION.getStorageUint256();
    }

    function _checkContractVersion(uint256 version) internal view {
        require(version == getContractVersion(), "UNEXPECTED_CONTRACT_VERSION");
    }

    function _setContractVersion(uint256 version) internal {
        CONTRACT_VERSION_POSITION.setStorageUint256(version);
        emit ContractVersionSet(version);
    }
}