ILightClient.sol

// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.9;

import "../../proto/Client.sol";

/**
 * @dev This defines an interface for Light Client contract can be integrated with ibc-solidity.
 * You can register the Light Client contract that implements this through `registerClient` on IBCHandler.
 */
interface ILightClient {
    /**
     * @dev createClient creates a new client with the given state.
     * If succeeded, it returns a commitment for the initial state.
     */
    function createClient(string calldata clientId, bytes calldata clientStateBytes, bytes calldata consensusStateBytes)
        external
        returns (bytes32 clientStateCommitment, ConsensusStateUpdate memory update, bool ok);

    /**
     * @dev getTimestampAtHeight returns the timestamp of the consensus state at the given height.
     *      The timestamp is nanoseconds since unix epoch.
     */
    function getTimestampAtHeight(string calldata clientId, Height.Data calldata height)
        external
        view
        returns (uint64, bool);

    /**
     * @dev getLatestHeight returns the latest height of the client state corresponding to `clientId`.
     */
    function getLatestHeight(string calldata clientId) external view returns (Height.Data memory, bool);

    /**
     * @dev getStatus returns the status of the client corresponding to `clientId`.
     */
    function getStatus(string calldata clientId) external view returns (ClientStatus);

    /**
     * @dev updateClient updates the client corresponding to `clientId`.
     * If succeeded, it returns a commitment for the updated state.
     * If there is no update for client state, this function should returns bytes32(0) as `clientStateCommitment`
     * If there are no updates for consensus state, this function should returns an empty array as `updates`.
     *
     * NOTE: updateClient is intended to perform the followings:
     * 1. verify a given client message(e.g. header)
     * 2. check misbehaviour such like duplicate block height
     * 3. if misbehaviour is found, update state accordingly and return
     * 4. update state(s) with the client message
     * 5. persist the state(s) on the host
     */
    function updateClient(string calldata clientId, bytes calldata clientMessageBytes)
        external
        returns (bytes32 clientStateCommitment, ConsensusStateUpdate[] memory updates, bool ok);

    /**
     * @dev verifyMembership is a generic proof verification method which verifies a proof of the existence of a value at a given CommitmentPath at the specified height.
     * The caller is expected to construct the full CommitmentPath from a CommitmentPrefix and a standardized path (as defined in ICS 24).
     */
    function verifyMembership(
        string calldata clientId,
        Height.Data calldata height,
        uint64 delayTimePeriod,
        uint64 delayBlockPeriod,
        bytes calldata proof,
        bytes calldata prefix,
        bytes calldata path,
        bytes calldata value
    ) external returns (bool);

    /**
     * @dev verifyNonMembership is a generic proof verification method which verifies the absence of a given CommitmentPath at a specified height.
     * The caller is expected to construct the full CommitmentPath from a CommitmentPrefix and a standardized path (as defined in ICS 24).
     */
    function verifyNonMembership(
        string calldata clientId,
        Height.Data calldata height,
        uint64 delayTimePeriod,
        uint64 delayBlockPeriod,
        bytes calldata proof,
        bytes calldata prefix,
        bytes calldata path
    ) external returns (bool);

    /**
     * @dev getClientState returns the clientState corresponding to `clientId`.
     *      If it's not found, the function returns false.
     */
    function getClientState(string calldata clientId) external view returns (bytes memory, bool);

    /**
     * @dev getConsensusState returns the consensusState corresponding to `clientId` and `height`.
     *      If it's not found, the function returns false.
     */
    function getConsensusState(string calldata clientId, Height.Data calldata height)
        external
        view
        returns (bytes memory, bool);
}

/**
 * @dev ConsensusStateUpdate represents a consensus state update.
 */
struct ConsensusStateUpdate {
    // commitment for updated consensusState
    bytes32 consensusStateCommitment;
    // updated height
    Height.Data height;
}

/**
 * @dev ClientStatus represents the status of a client.
 */
enum ClientStatus {
    Active,
    Expired,
    Frozen
}