namespace ZB.MOM.WW.OtOpcUa.Core.Abstractions;

/// <summary>
///     Driver capability for alarm events. Optional — only drivers whose backends expose
///     alarm conditions implement this. Currently: Galaxy (MxAccess alarms), FOCAS
///     (CNC alarms), OPC UA Client (A&amp;C events from upstream server), MTConnect
///     (CONDITION data items, Gitea #626).
/// </summary>
public interface IAlarmSource
{
    /// <summary>
    ///     Subscribe to alarm events for a node-set (typically: a folder or equipment subtree).
    ///     The driver fires <see cref="OnAlarmEvent"/> for every alarm transition.
    /// </summary>
    /// <param name="sourceNodeIds">The driver node IDs to subscribe to.</param>
    /// <param name="cancellationToken">Cancellation token for the operation.</param>
    /// <returns>A handle identifying the created subscription.</returns>
    Task<IAlarmSubscriptionHandle> SubscribeAlarmsAsync(
        IReadOnlyList<string> sourceNodeIds,
        CancellationToken cancellationToken);

    /// <summary>Cancel an alarm subscription returned by <see cref="SubscribeAlarmsAsync"/>.</summary>
    /// <param name="handle">The subscription handle returned from <see cref="SubscribeAlarmsAsync"/>.</param>
    /// <param name="cancellationToken">Cancellation token for the operation.</param>
    /// <returns>A task that represents the asynchronous operation.</returns>
    Task UnsubscribeAlarmsAsync(IAlarmSubscriptionHandle handle, CancellationToken cancellationToken);

    /// <summary>Acknowledge one or more active alarms by source node ID + condition ID.</summary>
    /// <param name="acknowledgements">The batch of alarm acknowledgement requests.</param>
    /// <param name="cancellationToken">Cancellation token for the operation.</param>
    /// <returns>A task that represents the asynchronous operation.</returns>
    Task AcknowledgeAsync(
        IReadOnlyList<AlarmAcknowledgeRequest> acknowledgements,
        CancellationToken cancellationToken);

    /// <summary>Server-pushed alarm transition (raise / clear / change).</summary>
    event EventHandler<AlarmEventArgs>? OnAlarmEvent;
}

/// <summary>Opaque alarm-subscription identity returned by <see cref="IAlarmSource.SubscribeAlarmsAsync"/>.</summary>
public interface IAlarmSubscriptionHandle
{
    /// <summary>Driver-internal subscription identifier (for diagnostics + post-mortem).</summary>
    string DiagnosticId { get; }
}

/// <summary>One alarm acknowledgement in a batch.</summary>
/// <param name="SourceNodeId">Driver-side identifier for the alarm source.</param>
/// <param name="ConditionId">Stable id correlating raise / ack / clear of the same condition.</param>
/// <param name="Comment">Operator-supplied comment forwarded to the upstream alarm system.</param>
/// <param name="OperatorUser">Authenticated principal performing the ack; null on the raw/non-OPC-UA path.</param>
public sealed record AlarmAcknowledgeRequest(
    string SourceNodeId,
    string ConditionId,
    string? Comment,
    string? OperatorUser = null);

/// <summary>Event payload for <see cref="IAlarmSource.OnAlarmEvent"/>.</summary>
/// <param name="SubscriptionHandle">Subscription this event belongs to.</param>
/// <param name="SourceNodeId">Driver-side identifier for the alarm source.</param>
/// <param name="ConditionId">Stable id correlating raise / ack / clear of the same condition.</param>
/// <param name="AlarmType">Driver-defined alarm type name (e.g. AnalogLimitAlarm.HiHi).</param>
/// <param name="Message">Human-readable alarm description.</param>
/// <param name="Severity">Four-bucket severity ladder.</param>
/// <param name="SourceTimestampUtc">When this transition occurred.</param>
/// <param name="OperatorComment">
///     Operator-supplied comment recorded by the upstream alarm system on Acknowledge
///     transitions. Null on raise / clear, or when the upstream path can't surface
///     the comment (the Galaxy sub-attribute fallback path collapses comments into a
///     single string write — null on that path; the driver-native gateway path
///     populates this).
/// </param>
/// <param name="OriginalRaiseTimestampUtc">
///     When the alarm originally entered the active state. Preserved across
///     Acknowledge transitions so OPC UA Part 9 conditions keep the original raise
///     time in <c>Time</c>. Null when the upstream path doesn't surface it.
/// </param>
/// <param name="AlarmCategory">
///     Upstream alarm taxonomy bucket (e.g. <c>Process</c> / <c>Safety</c> /
///     <c>Diagnostics</c>). Maps to OPC UA <c>ConditionClassName</c> downstream when
///     a class mapping is configured. Null when the upstream path doesn't carry it.
/// </param>
/// <param name="Kind">
///     The alarm transition kind (raise / acknowledge / clear / retrigger). Lets a
///     consumer derive OPC UA Part 9 active/ack state without inferring it from
///     other fields. <see cref="AlarmTransitionKind.Unspecified"/> when the upstream
///     path doesn't surface a distinct kind.
/// </param>
/// <param name="OpcUaSeverity">
///     Optional exact OPC UA severity (1..1000) for a source whose own scale is finer than the four
///     <see cref="AlarmSeverity"/> buckets (Gitea #626: MTConnect Warning = 500, Fault = 800). When set it
///     supersedes the bucket on the projected Part 9 condition (clamped to 1..1000); <c>null</c> — every
///     pre-#626 source — keeps the bucket mapping. <see cref="Severity"/> must still carry the nearest
///     bucket for consumers that only read the bucket.
/// </param>
/// <param name="QualityStatusCode">
///     Optional status code of the condition's SOURCE data (Part 9 <c>ConditionType.Quality</c>), for a
///     source that can report "no value for this condition" per alarm rather than per connection (Gitea
///     #626: MTConnect <c>Unavailable</c>). <c>null</c> keeps the pre-#626 behaviour (projected Good;
///     driver-wide comms loss is annotated separately by the host). An event whose <see cref="Kind"/> is
///     <see cref="AlarmTransitionKind.Unspecified"/> and which carries a quality is a
///     <b>quality-only annotation</b> (<see cref="IsQualityOnly"/>): the host updates (via its Quality-only node path) the condition's
///     Quality without touching its Active/Acked state and publishes no <c>alerts</c> row for it.
/// </param>
/// <param name="IsRestatement">
///     Gitea #656 — true when the source is RE-STATING upstream's current state rather than reporting a transition it
///     watched happen: a reconnect snapshot entry (Galaxy) or the first event for a condition after a driver start or
///     deploy respawn (OpcUaClient). It governs <b>history only, never node state</b>: the host still projects the
///     state, but writes no <c>alerts</c> row when the re-statement changes nothing the condition shows (a Retrigger on
///     an Active+unacked condition with the same message and severity; a Clear on an already-inactive condition; an
///     Acknowledge on an already-acknowledged condition) — or
///     when a flagged <see cref="AlarmTransitionKind.Unspecified"/> update moves the message/severity of an
///     already-active condition (node updated, one condition event, active/acked kept, no row). AbCip ALMA sets the
///     flag for the last shape (the governing limit changed, no new occurrence). OpcUaClient (Gitea #657) re-states a
///     first-seen inactive+acked condition as a flagged Clear then a flagged Acknowledge, so a host already showing
///     that writes nothing and a host retaining it Active gets a real "Cleared". <c>false</c> (the default, every source that does not
///     opt in) keeps every transition's row.
/// </param>
public sealed record AlarmEventArgs(
    IAlarmSubscriptionHandle SubscriptionHandle,
    string SourceNodeId,
    string ConditionId,
    string AlarmType,
    string Message,
    AlarmSeverity Severity,
    DateTime SourceTimestampUtc,
    string? OperatorComment = null,
    DateTime? OriginalRaiseTimestampUtc = null,
    string? AlarmCategory = null,
    AlarmTransitionKind Kind = AlarmTransitionKind.Unspecified,
    int? OpcUaSeverity = null,
    uint? QualityStatusCode = null,
    bool IsRestatement = false)
{
    /// <summary>
    ///     True when this event only re-annotates the condition's source-data quality — a
    ///     <see cref="QualityStatusCode"/> with an <see cref="AlarmTransitionKind.Unspecified"/> kind. No
    ///     alarm-state change happened, so the host must not publish it as an alarm transition.
    /// </summary>
    public bool IsQualityOnly => Kind == AlarmTransitionKind.Unspecified && QualityStatusCode is not null;
}

/// <summary>Mirrors the <c>NodePermissions</c> alarm-severity enum in <c>docs/v2/acl-design.md</c>.</summary>
public enum AlarmSeverity { Low, Medium, High, Critical }

/// <summary>
///     Kind of alarm state change carried by <see cref="AlarmEventArgs.Kind"/>, letting a
///     consumer derive OPC UA Part 9 active/ack state. Mirrors the driver-side
///     transition-kind enums (e.g. Galaxy's <c>GalaxyAlarmTransitionKind</c>).
///     <see cref="ActiveAcknowledged"/> (Gitea #656) means "the condition is active AND acknowledged", applied by the
///     host as ONE projection — never Raise-then-Acknowledge, which would show clients an Active+unacked intermediate.
///     <see cref="InactiveUnacknowledged"/> (Gitea #657) is its mirror: "the condition is inactive AND unacknowledged"
///     (it went active and cleared unacknowledged), applied as ONE projection — never Raise-then-Clear, which showed
///     clients the condition Active again for an instant. The host writes rows only for what actually changed:
///     "Activated" + "Cleared" when the condition was acknowledged (a new occurrence must have happened), "Cleared"
///     alone when it was Active+unacked, none when it already showed inactive+unacked.
///     Members are append-only: their numeric values must not move.
/// </summary>
public enum AlarmTransitionKind { Unspecified = 0, Raise, Acknowledge, Clear, Retrigger, ActiveAcknowledged, InactiveUnacknowledged }