using System.Collections.Concurrent;
using System.Reflection;
using Opc.Ua;
using ZB.MOM.WW.ScadaBridge.Commons.Types.Alarms;
using ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Adapters;

namespace ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests.Adapters;

/// <summary>
/// Review 2026-10-21 02/L3: the per-condition (active, acked) memory behind
/// <c>DeriveKind</c> must not grow for the life of a session. A condition that returns to
/// inactive + acknowledged is indistinguishable from one never seen (the default prior state), so
/// its key is dropped — otherwise a server whose condition names carry a per-occurrence component
/// (batch, lot, counter) adds a key per occurrence until the next reconnect.
/// </summary>
public class RealOpcUaAlarmLastStateTests
{
    private const string Handle = "h1";

    private static readonly MethodInfo Handler =
        typeof(RealOpcUaClient).GetMethod("HandleAlarmEvent", BindingFlags.Instance | BindingFlags.NonPublic)!;

    private static Dictionary<string, (bool Active, bool Acked)> SeedLastState(RealOpcUaClient client)
    {
        var field = typeof(RealOpcUaClient).GetField("_alarmLastState", BindingFlags.Instance | BindingFlags.NonPublic)!;
        var map = (ConcurrentDictionary<string, Dictionary<string, (bool Active, bool Acked)>>)field.GetValue(client)!;
        var perHandle = new Dictionary<string, (bool Active, bool Acked)>(StringComparer.Ordinal);
        map[Handle] = perHandle;
        return perHandle;
    }

    private static void Emit(RealOpcUaClient client, string condition, bool active, bool acked, List<NativeAlarmTransition> sink)
    {
        var fields = new VariantCollection
        {
            new(ObjectTypeIds.AlarmConditionType), // 0 EventType
            new(new NodeId("Tank01", 2)),          // 1 SourceNode
            new("Tank01"),                         // 2 SourceName
            new(DateTime.UtcNow),                  // 3 Time
            new(new LocalizedText("msg")),         // 4 Message
            new((ushort)500),                      // 5 Severity
            new(active),                           // 6 ActiveState/Id
            new(acked),                            // 7 AckedState/Id
            Variant.Null,                          // 8 ConfirmedState/Id
            new(false),                            // 9 SuppressedOrShelved
            Variant.Null,                          // 10 ShelvingState
            new(condition),                        // 11 ConditionName
        };
        Handler.Invoke(client, [Handle, "ns=2;s=Tank01", new EventFieldList { EventFields = fields },
            (Action<NativeAlarmTransition>)sink.Add]);
    }

    /// <summary>A per-occurrence condition that clears and is acknowledged leaves no key behind.</summary>
    [Fact]
    public void ReturnToNormal_DropsTheConditionKey()
    {
        var client = new RealOpcUaClient();
        var lastState = SeedLastState(client);
        var sink = new List<NativeAlarmTransition>();

        for (var lot = 1; lot <= 50; lot++)
        {
            Emit(client, $"Hi.Lot{lot}", active: true, acked: false, sink);
            Emit(client, $"Hi.Lot{lot}", active: false, acked: true, sink);
        }

        Assert.Empty(lastState);
        Assert.Equal(100, sink.Count);
    }

    /// <summary>
    /// Dropping the key does not change the transition kinds derived for a condition that comes
    /// back — the dropped state equals the default prior state.
    /// </summary>
    [Fact]
    public void ReRaiseAfterReturnToNormal_StillDerivesARaise()
    {
        var client = new RealOpcUaClient();
        var lastState = SeedLastState(client);
        var sink = new List<NativeAlarmTransition>();

        Emit(client, "Hi", active: true, acked: false, sink);
        Emit(client, "Hi", active: false, acked: true, sink);
        Emit(client, "Hi", active: true, acked: false, sink);

        Assert.Equal(sink[0].Kind, sink[2].Kind);
        Assert.Single(lastState); // the re-raised condition is tracked again
    }
}