using Akka.Actor;
using Akka.TestKit.Xunit2;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Commons.Messages.Deploy;
using ZB.MOM.WW.OtOpcUa.Commons.Types;
using ZB.MOM.WW.OtOpcUa.Runtime.Communication;
using ZB.MOM.WW.OtOpcUa.Runtime.Drivers;
using Serilog;
using ZB.MOM.WW.OtOpcUa.Commons.OpcUa;
using ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
using ZB.MOM.WW.OtOpcUa.Runtime.ScriptedAlarms;
using ZB.MOM.WW.OtOpcUa.Runtime.Tests.Harness;
using ZB.MOM.WW.OtOpcUa.Core.Scripting;

namespace ZB.MOM.WW.OtOpcUa.Runtime.Tests.Communication;

/// <summary>
///     Proves the Phase 2 node-side leg joins up: a command handed to
///     <see cref="NodeCommunicationActor"/> reaches the <b>real</b> <see cref="DriverHostActor"/>,
///     not just a test probe.
/// </summary>
/// <remarks>
///     <para>
///         The unit tests either side of this seam both pass with the wiring broken.
///         <c>NodeCommunicationActorTests</c> asserts a probe subscribed to the EventStream receives
///         the message; the driver-host tests drive the actor by direct <c>Tell</c>. Neither notices
///         if <c>DriverHostActor.PreStart</c> never subscribes. That gap is why this file exists.
///     </para>
///     <para>
///         <b>Ordering matters, and it bit this test first time out.</b> <c>ActorOf</c> returns
///         before <c>PreStart</c> has run, and an <c>EventStream.Publish</c> with no subscriber is
///         dropped silently — there is no buffering and no dead-letter. Relaying immediately after
///         spawning therefore fails intermittently. The warm-up below is not ceremony: it is the
///         only available proof that <c>PreStart</c> has completed. (In production the driver host
///         is spawned at startup, long before any deployment, so the same race does not arise.)
///     </para>
/// </remarks>
public class EventStreamCommandDeliveryTests : RuntimeActorTestBase
{
    private static DispatchDeployment NewDispatch() => new(
        new DeploymentId(Guid.NewGuid()),
        new RevisionHash("rev-does-not-exist"),
        new CorrelationId(Guid.NewGuid()));

    [Fact]
    public void A_dispatch_relayed_by_the_comm_actor_reaches_the_real_driver_host()
    {
        var ackRouter = CreateTestProbe();
        var driverHost = Sys.ActorOf(
            DriverHostActor.Props(NewInMemoryDbFactory(), new NodeId("127.0.0.1:4053"), ackRouter: ackRouter.Ref),
            "driver-host");
        var comm = Sys.ActorOf(NodeCommunicationActor.Props(centralClient: null), "node-communication");

        // Warm-up: a direct Tell whose ack proves PreStart has completed, and with it the
        // EventStream subscription. Without this the relay below races the subscription.
        var warmup = NewDispatch();
        driverHost.Tell(warmup);
        ackRouter.ExpectMsg<ApplyAck>(TimeSpan.FromSeconds(15)).DeploymentId.ShouldBe(warmup.DeploymentId);

        // Now the real assertion — relayed exactly as central would send it. The comm actor only
        // publishes node-locally, so the host must be subscribed for this to arrive at all.
        var relayed = NewDispatch();
        comm.Tell(relayed);

        // The deployment id does not exist, so the host answers Failed. That is the stronger
        // assertion, not a weaker one: an ack at all proves the command was received and handled,
        // and only PreStart's EventStream subscription can have delivered it.
        ackRouter.ExpectMsg<ApplyAck>(TimeSpan.FromSeconds(15)).DeploymentId.ShouldBe(relayed.DeploymentId);
    }

    [Fact]
    public void CONTROL_the_driver_host_acks_a_direct_tell()
    {
        // Falsifiability control. If the test above fails, this one says which half broke: green
        // here means the host is healthy and the EventStream relay is at fault; red here means the
        // host would not have acked either way and the relay is not implicated.
        var ackRouter = CreateTestProbe();
        var driverHost = Sys.ActorOf(
            DriverHostActor.Props(NewInMemoryDbFactory(), new NodeId("127.0.0.1:4053"), ackRouter: ackRouter.Ref),
            "driver-host-control");

        var dispatch = NewDispatch();
        driverHost.Tell(dispatch);

        ackRouter.ExpectMsg<ApplyAck>(TimeSpan.FromSeconds(15)).DeploymentId.ShouldBe(dispatch.DeploymentId);
    }

}

/// <summary>
///     The alarm leg of the same wiring proof, in its own ActorSystem because the shared
///     <see cref="RuntimeActorTestBase"/> harness pins <c>loglevel = WARNING</c> and the only
///     observable signal <c>ScriptedAlarmHostActor</c> gives for an unowned alarm is a Debug line.
/// </summary>
public class AlarmCommandEventStreamDeliveryTests : TestKit
{
    private static string DebugLevelHocon => @"
akka {
    loglevel = ""DEBUG""
    extensions = [
        ""Akka.Cluster.Tools.PublishSubscribe.DistributedPubSubExtensionProvider, Akka.Cluster.Tools""
    ]
    actor {
        provider = ""Akka.Cluster.ClusterActorRefProvider, Akka.Cluster""
    }
    remote.dot-netty.tcp {
        hostname = ""127.0.0.1""
        port = 0
    }
    cluster {
        seed-nodes = []
        roles = [""driver""]
        min-nr-of-members = 1
        run-coordinated-shutdown-when-down = off
    }
}";

    public AlarmCommandEventStreamDeliveryTests()
        : base(DebugLevelHocon)
    {
        var cluster = Akka.Cluster.Cluster.Get(Sys);
        cluster.Join(cluster.SelfAddress);
        AwaitCondition(
            () => cluster.State.Members.Any(m => m.Status == Akka.Cluster.MemberStatus.Up),
            TimeSpan.FromSeconds(5));
    }

    [Fact]
    public void An_alarm_command_relayed_by_the_comm_actor_reaches_the_real_scripted_alarm_host()
    {
        // Needed for the same reason as the deploy leg: the comm actor's unit test only proves a
        // probe receives it, and the alarm-host tests drive the actor by direct Tell. Neither
        // notices a missing PreStart subscription.
        var upstream = new DependencyMuxTagUpstreamSource();
        var logger = new LoggerConfiguration().CreateLogger();
        var engine = new ScriptedAlarmEngine(
            upstream, new InMemoryAlarmStateStore(), new ScriptLoggerFactory(logger), logger);

        var host = Sys.ActorOf(
            ScriptedAlarmHostActor.Props(
                CreateTestProbe().Ref, CreateTestProbe().Ref, upstream, engine, new NodeId("node-A")),
            "scripted-alarm-host");
        var comm = Sys.ActorOf(NodeCommunicationActor.Props(centralClient: null), "node-communication");

        var cmd = new AlarmCommand("alarm-unowned", "Acknowledge", "alice", "c", null);

        // Warm-up, OUTSIDE the real assertion: a direct Tell whose debug line proves PreStart has
        // completed and the EventStream subscription is registered. An earlier draft did the direct
        // Tell INSIDE the assertion window alongside the relay, which made the test vacuous — the
        // direct Tell alone produced the log the assertion was waiting for.
        EventFilter.Debug(contains: "ignoring AlarmCommand")
            .ExpectOne(TimeSpan.FromSeconds(15), () => host.Tell(cmd));

        // The real assertion: relayed ONLY through the comm actor, which publishes node-locally.
        // The host owns no alarms, so it logs and stops — still a positive delivery signal, because
        // that line is only reached if the message arrived.
        EventFilter.Debug(contains: "ignoring AlarmCommand")
            .ExpectOne(TimeSpan.FromSeconds(15), () => comm.Tell(cmd));
    }
}