// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import {CheckpointStorage} from "../storage/CheckpointStorage.sol";
import {CheckpointLeaf} from "../libraries/CheckpointLeaf.sol";

/**
 * @title ICheckpointExtension
 * @notice Pluggable modules for unlimited extensibility (hub invokes via call; delegatecall optional per module).
 */
interface ICheckpointExtension {
    /// @dev Hook bitmasks — new hooks require implementation upgrade + gap only on hub
    function HOOK_BEFORE_SUBMIT() external pure returns (uint32);
    function HOOK_AFTER_SUBMIT() external pure returns (uint32);
    function HOOK_ON_CCIP() external pure returns (uint32);
    function HOOK_VERIFY_LEAF() external pure returns (uint32);

    function beforeSubmit(CheckpointStorage.CheckpointHeader calldata header, bytes calldata data) external;

    function afterSubmit(CheckpointStorage.CheckpointHeader calldata header, bytes calldata data) external;

    function onCCIPReceive(bytes calldata messageData) external;

    /// @notice Optional custom leaf verification (return true to accept, false to defer to core Merkle)
    function verifyLeaf(
        CheckpointStorage.CheckpointHeader calldata header,
        CheckpointLeaf.PaymentLeafV1 calldata leaf,
        bytes32[] calldata proof
    ) external view returns (bool);
}