namespace ZB.MOM.WW.OtOpcUa.Commons.OpcUa;

/// <summary>
///     Wrapper <see cref="IOpcUaAddressSpaceSink"/> that defers to an inner sink swapped in at
///     runtime. Needed because the production sink (<c>SdkAddressSpaceSink</c>) wraps an
///     <c>OtOpcUaNodeManager</c> that only exists after the SDK <c>StandardServer</c> has
///     started — but Akka actors resolve their sink dependency at construction time, before
///     the hosted service has booted the SDK.
///
///     Bound as a singleton in DI on driver-role hosts; the OPC UA hosted service calls
///     <see cref="SetSink"/> once the server is up. Until that swap happens, every call is a
///     no-op against <see cref="NullOpcUaAddressSpaceSink"/>, so the actor stays safe to
///     receive messages from the moment it boots.
/// </summary>
public sealed class DeferredAddressSpaceSink : IOpcUaAddressSpaceSink, ISurgicalAddressSpaceSink
{
    private volatile IOpcUaAddressSpaceSink _inner = NullOpcUaAddressSpaceSink.Instance;

    /// <summary>Swap in the production sink. Pass <c>null</c> to revert to the null sink
    /// (used during graceful shutdown so post-stop writes don't hit a half-disposed manager).</summary>
    /// <param name="sink">The sink implementation to use, or null to use the null sink.</param>
    public void SetSink(IOpcUaAddressSpaceSink? sink) =>
        _inner = sink ?? NullOpcUaAddressSpaceSink.Instance;

    /// <inheritdoc />
    public void WriteValue(string nodeId, object? value, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm)
        => _inner.WriteValue(nodeId, value, quality, sourceTimestampUtc, realm);

    /// <inheritdoc />
    public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm)
        => _inner.WriteAlarmCondition(alarmNodeId, state, sourceTimestampUtc, realm);

    /// <inheritdoc />
    public void MaterialiseAlarmCondition(string alarmNodeId, string equipmentNodeId, string displayName, string alarmType, int severity, AddressSpaceRealm realm, bool isNative = false)
        => _inner.MaterialiseAlarmCondition(alarmNodeId, equipmentNodeId, displayName, alarmType, severity, realm, isNative);

    /// <inheritdoc />
    // Forward the WP4 multi-notifier wiring to the inner sink. Without this the native-alarm fan-out to the
    // referencing equipment folders ships INERT on every driver-role host (actors inject THIS wrapper, not the
    // inner SdkAddressSpaceSink) — the F10b / PR#423 forwarding trap the reflection guard exists to catch.
    public void WireAlarmNotifiers(string alarmNodeId, AddressSpaceRealm alarmRealm, IReadOnlyList<string> notifierFolderNodeIds, AddressSpaceRealm notifierFolderRealm)
        => _inner.WireAlarmNotifiers(alarmNodeId, alarmRealm, notifierFolderNodeIds, notifierFolderRealm);

    /// <inheritdoc />
    public void EnsureFolder(string folderNodeId, string? parentNodeId, string displayName, AddressSpaceRealm realm)
        => _inner.EnsureFolder(folderNodeId, parentNodeId, displayName, realm);

    /// <inheritdoc />
    public void EnsureVariable(string variableNodeId, string? parentFolderNodeId, string displayName, string dataType, bool writable, AddressSpaceRealm realm, string? historianTagname = null, bool isArray = false, uint? arrayLength = null)
        => _inner.EnsureVariable(variableNodeId, parentFolderNodeId, displayName, dataType, writable, realm, historianTagname, isArray, arrayLength);

    /// <inheritdoc />
    public void RebuildAddressSpace() => _inner.RebuildAddressSpace();

    /// <inheritdoc />
    public void RaiseNodesAddedModelChange(string affectedNodeId, AddressSpaceRealm realm) => _inner.RaiseNodesAddedModelChange(affectedNodeId, realm);

    /// <inheritdoc />
    public void AddReference(string sourceNodeId, AddressSpaceRealm sourceRealm, string targetNodeId, AddressSpaceRealm targetRealm, string referenceType = "Organizes")
        => _inner.AddReference(sourceNodeId, sourceRealm, targetNodeId, targetRealm, referenceType);

    /// <inheritdoc />
    // Forwards to the inner sink when it supports the surgical capability; returns false otherwise —
    // before the real SdkAddressSpaceSink is swapped in (inner is still the null sink), or any inner
    // sink that isn't surgical — so the caller (AddressSpaceApplier) falls back to a full rebuild.
    // Without this forward the surgical optimization is inert on every driver-role host, because
    // actors inject THIS wrapper, not the inner sink. ALL six args (including the DataType/array-shape
    // ones) MUST be forwarded — a partial forward silently drops the shape update on every driver-role host.
    public bool UpdateTagAttributes(string variableNodeId, bool writable, string? historianTagname, string dataType, bool isArray, uint? arrayLength, AddressSpaceRealm realm)
        => _inner is ISurgicalAddressSpaceSink surgical
           && surgical.UpdateTagAttributes(variableNodeId, writable, historianTagname, dataType, isArray, arrayLength, realm);

    /// <inheritdoc />
    // Forwards to the inner sink when it supports the surgical capability; returns false otherwise —
    // before the real SdkAddressSpaceSink is swapped in (inner is still the null sink), or any inner
    // sink that isn't surgical — so the caller (AddressSpaceApplier) falls back to a full rebuild.
    // Without this forward the rename-refresh optimization is inert on every driver-role host, because
    // actors inject THIS wrapper, not the inner sink.
    public bool UpdateFolderDisplayName(string folderNodeId, string displayName, AddressSpaceRealm realm)
        => _inner is ISurgicalAddressSpaceSink surgical
           && surgical.UpdateFolderDisplayName(folderNodeId, displayName, realm);

    // R2-07 T7 — surgical remove forwards. Same capability-sniffing pattern as UpdateTagAttributes /
    // UpdateFolderDisplayName: forward when the inner sink supports the surgical capability; return false
    // otherwise (before the real SdkAddressSpaceSink is swapped in, or any non-surgical inner) so the caller
    // (AddressSpaceApplier) falls back to a full rebuild. Without these forwards the surgical remove path is
    // inert on every driver-role host — the F10b / PR#423 trap the reflection guard exists to catch.
    /// <inheritdoc />
    public bool RemoveVariableNode(string variableNodeId, AddressSpaceRealm realm)
        => _inner is ISurgicalAddressSpaceSink surgical && surgical.RemoveVariableNode(variableNodeId, realm);

    /// <inheritdoc />
    public bool RemoveAlarmConditionNode(string alarmNodeId, AddressSpaceRealm realm)
        => _inner is ISurgicalAddressSpaceSink surgical && surgical.RemoveAlarmConditionNode(alarmNodeId, realm);

    /// <inheritdoc />
    public bool RemoveEquipmentSubtree(string equipmentNodeId, AddressSpaceRealm realm)
        => _inner is ISurgicalAddressSpaceSink surgical && surgical.RemoveEquipmentSubtree(equipmentNodeId, realm);
}