// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (crosschain/optimism/CrossChainEnabledOptimism.sol)

pragma solidity ^0.8.4;

import "../CrossChainEnabledUpgradeable.sol";
import "./LibOptimismUpgradeable.sol";
import "../../proxy/utils/Initializable.sol";

/**
 * @dev https://www.optimism.io/[Optimism] specialization or the
 * {CrossChainEnabled} abstraction.
 *
 * The messenger (`CrossDomainMessenger`) contract is provided and maintained by
 * the optimism team. You can find the address of this contract on mainnet and
 * kovan in the https://github.com/ethereum-optimism/optimism/tree/develop/packages/contracts/deployments[deployments section of Optimism monorepo].
 *
 * _Available since v4.6._
 */
abstract contract CrossChainEnabledOptimismUpgradeable is Initializable, CrossChainEnabledUpgradeable {
    /// @custom:oz-upgrades-unsafe-allow state-variable-immutable
    address private immutable _messenger;

    /// @custom:oz-upgrades-unsafe-allow constructor
    constructor(address messenger) {
        _messenger = messenger;
    }

    /**
     * @dev see {CrossChainEnabled-_isCrossChain}
     */
    function _isCrossChain() internal view virtual override returns (bool) {
        return LibOptimismUpgradeable.isCrossChain(_messenger);
    }

    /**
     * @dev see {CrossChainEnabled-_crossChainSender}
     */
    function _crossChainSender() internal view virtual override onlyCrossChain returns (address) {
        return LibOptimismUpgradeable.crossChainSender(_messenger);
    }

    /**
     * @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;
}