// SPDX-License-Identifier: GPL-3.0-or-later

pragma solidity ^0.8.0;

interface IMiddleLayer {
    /**
     * @dev Handle syn package
     */
    function handleSynPackage(uint8 channelId, bytes calldata msgBytes) external returns (bytes memory responsePayload);

    /**
     * @dev Handle ack package
     */
    function handleAckPackage(
        uint8 channelId,
        uint64 sequence,
        bytes calldata msgBytes,
        uint256 _callbackGasLimit
    ) external returns (uint256 remainingGas, address refundAddress);

    /**
     * @dev Handle fail ack package
     */
    function handleFailAckPackage(
        uint8 channelId,
        uint64 sequence,
        bytes calldata msgBytes,
        uint256 _callbackGasLimit
    ) external returns (uint256 remainingGas, address refundAddress);
}