// SPDX-License-Identifier: MIT
pragma solidity 0.8.17;

import {ChainGas, GasData} from "../libs/stack/GasData.sol";

interface InterfaceDestination {
    /**
     * @notice Attempts to pass a quarantined Agent Merkle Root to a local Light Manager.
     * @dev Will do nothing, if root optimistic period is not over.
     * @return rootPending  Whether there is a pending agent merkle root left
     */
    function passAgentRoot() external returns (bool rootPending);

    /**
     * @notice Accepts an attestation, which local `AgentManager` verified to have been signed
     * by an active Notary for this chain.
     * > Attestation is created whenever a Notary-signed snapshot is saved in Summit on Synapse Chain.
     * - Saved Attestation could be later used to prove the inclusion of message in the Origin Merkle Tree.
     * - Messages coming from chains included in the Attestation's snapshot could be proven.
     * - Proof only exists for messages that were sent prior to when the Attestation's snapshot was taken.
     * > Will revert if any of these is true:
     * > - Called by anyone other than local `AgentManager`.
     * > - Attestation payload is not properly formatted.
     * > - Attestation signer is in Dispute.
     * > - Attestation's snapshot root has been previously submitted.
     * Note: agentRoot and snapGas have been verified by the local `AgentManager`.
     * @param notaryIndex       Index of Attestation Notary in Agent Merkle Tree
     * @param sigIndex          Index of stored Notary signature
     * @param attPayload        Raw payload with Attestation data
     * @param agentRoot         Agent Merkle Root from the Attestation
     * @param snapGas           Gas data for each chain in the Attestation's snapshot
     * @return wasAccepted      Whether the Attestation was accepted
     */
    function acceptAttestation(
        uint32 notaryIndex,
        uint256 sigIndex,
        bytes memory attPayload,
        bytes32 agentRoot,
        ChainGas[] memory snapGas
    ) external returns (bool wasAccepted);

    // ═══════════════════════════════════════════════════ VIEWS ═══════════════════════════════════════════════════════

    /**
     * @notice Returns the total amount of Notaries attestations that have been accepted.
     */
    function attestationsAmount() external view returns (uint256);

    /**
     * @notice Returns a Notary-signed attestation with a given index.
     * > Index refers to the list of all attestations accepted by this contract.
     * @dev Attestations are created on Synapse Chain whenever a Notary-signed snapshot is accepted by Summit.
     * Will return an empty signature if this contract is deployed on Synapse Chain.
     * @param index             Attestation index
     * @return attPayload       Raw payload with Attestation data
     * @return attSignature     Notary signature for the reported attestation
     */
    function getAttestation(uint256 index) external view returns (bytes memory attPayload, bytes memory attSignature);

    /**
     * @notice Returns the gas data for a given chain from the latest accepted attestation with that chain.
     * @dev Will return empty values if there is no data for the domain,
     * or if the notary who provided the data is in dispute.
     * @param domain            Domain for the chain
     * @return gasData          Gas data for the chain
     * @return dataMaturity     Gas data age in seconds
     */
    function getGasData(uint32 domain) external view returns (GasData gasData, uint256 dataMaturity);

    /**
     * Returns status of Destination contract as far as snapshot/agent roots are concerned
     * @return snapRootTime     Timestamp when latest snapshot root was accepted
     * @return agentRootTime    Timestamp when latest agent root was accepted
     * @return notaryIndex      Index of Notary who signed the latest agent root
     */
    function destStatus() external view returns (uint40 snapRootTime, uint40 agentRootTime, uint32 notaryIndex);

    /**
     * Returns Agent Merkle Root to be passed to LightManager once its optimistic period is over.
     */
    function nextAgentRoot() external view returns (bytes32);

    /**
     * @notice Returns the nonce of the last attestation submitted by a Notary with a given agent index.
     * @dev Will return zero if the Notary hasn't submitted any attestations yet.
     */
    function lastAttestationNonce(uint32 notaryIndex) external view returns (uint32);
}