using Akka.Actor;
using Akka.TestKit.Xunit2;
using NSubstitute;
using ZB.MOM.WW.ScadaBridge.Commons.Messages.DataConnection;
using ZB.MOM.WW.ScadaBridge.Commons.Messages.Deployment;
using ZB.MOM.WW.ScadaBridge.Commons.Messages.Health;
using ZB.MOM.WW.ScadaBridge.Commons.Messages.Lifecycle;
using ZB.MOM.WW.ScadaBridge.Commons.Messages.Management;
using ZB.MOM.WW.ScadaBridge.Commons.Messages.Notification;
using ZB.MOM.WW.ScadaBridge.Commons.Messages.RemoteQuery;
using ZB.MOM.WW.ScadaBridge.Communication.Actors;

namespace ZB.MOM.WW.ScadaBridge.Communication.Tests;

/// <summary>
/// WP-4: Tests for SiteCommunicationActor message routing to local actors.
/// </summary>
public class SiteCommunicationActorTests : TestKit
{
    private readonly CommunicationOptions _options = new();

    public SiteCommunicationActorTests()
        : base(@"akka.loglevel = DEBUG")
    {
    }

    [Fact]
    public void RefreshDeploymentCommand_ForwardedToDeploymentManager()
    {
        var dmProbe = CreateTestProbe();
        var siteActor = Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", _options, dmProbe.Ref)));

        var command = new RefreshDeploymentCommand(
            "dep1", "inst1", "hash1", "admin", DateTimeOffset.UtcNow,
            "https://central/", "tok1");
        siteActor.Tell(command);

        dmProbe.ExpectMsg<RefreshDeploymentCommand>(msg => msg.DeploymentId == "dep1");
    }

    [Fact]
    public void LifecycleCommands_ForwardedToDeploymentManager()
    {
        var dmProbe = CreateTestProbe();
        var siteActor = Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", _options, dmProbe.Ref)));

        siteActor.Tell(new DisableInstanceCommand("cmd1", "inst1", DateTimeOffset.UtcNow));
        dmProbe.ExpectMsg<DisableInstanceCommand>();

        siteActor.Tell(new EnableInstanceCommand("cmd2", "inst1", DateTimeOffset.UtcNow));
        dmProbe.ExpectMsg<EnableInstanceCommand>();

        siteActor.Tell(new DeleteInstanceCommand("cmd3", "inst1", DateTimeOffset.UtcNow));
        dmProbe.ExpectMsg<DeleteInstanceCommand>();
    }

    [Fact]
    public void DeploymentStateQuery_ForwardedToDeploymentManager()
    {
        // DeploymentManager-006: the site-before-redeploy query travels over the
        // ClusterClient command/control transport and is routed to the local
        // Deployment Manager, which owns the deployed-config store.
        var dmProbe = CreateTestProbe();
        var siteActor = Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", _options, dmProbe.Ref)));

        var request = new DeploymentStateQueryRequest("corr-q", "inst1", DateTimeOffset.UtcNow);
        siteActor.Tell(request);

        dmProbe.ExpectMsg<DeploymentStateQueryRequest>(msg => msg.CorrelationId == "corr-q");
    }

    // The site→central send-forwarding tests that used to live here (NotificationSubmit /
    // NotificationStatusQuery, with and without a registered central ClusterClient) were removed
    // with the Akka transport in the ClusterClient→gRPC migration's Phase 4: the actor no longer
    // owns the wire, it delegates to an injected ICentralTransport, and those seven sends (plus the
    // reply routing and the fail-loud fallback) are now covered by SiteCommunicationActorTransportTests.

    [Fact]
    public void EventLogQuery_WithoutHandler_ReturnsFailure()
    {
        var dmProbe = CreateTestProbe();
        var siteActor = Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", _options, dmProbe.Ref)));

        var request = new EventLogQueryRequest(
            "corr1", "site1", null, null, null, null, null, null, null, 25, DateTimeOffset.UtcNow);

        siteActor.Tell(request);

        ExpectMsg<EventLogQueryResponse>(msg => !msg.Success);
    }

    // ── Task 5 (#22): central→site Retry/Discard relay for parked cached calls ──

    [Fact]
    public void RetryParkedOperation_WithHandler_ForwardedToParkedMessageHandler()
    {
        var dmProbe = CreateTestProbe();
        var handlerProbe = CreateTestProbe();
        var siteActor = Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", _options, dmProbe.Ref)));

        siteActor.Tell(new RegisterLocalHandler(LocalHandlerType.ParkedMessages, handlerProbe.Ref));

        var id = Commons.Types.TrackedOperationId.New();
        siteActor.Tell(new RetryParkedOperation("corr-rp", id));

        handlerProbe.ExpectMsg<RetryParkedOperation>(msg =>
            msg.CorrelationId == "corr-rp" && msg.TrackedOperationId.Equals(id));
    }

    [Fact]
    public void DiscardParkedOperation_WithHandler_ForwardedToParkedMessageHandler()
    {
        var dmProbe = CreateTestProbe();
        var handlerProbe = CreateTestProbe();
        var siteActor = Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", _options, dmProbe.Ref)));

        siteActor.Tell(new RegisterLocalHandler(LocalHandlerType.ParkedMessages, handlerProbe.Ref));

        var id = Commons.Types.TrackedOperationId.New();
        siteActor.Tell(new DiscardParkedOperation("corr-dp", id));

        handlerProbe.ExpectMsg<DiscardParkedOperation>(msg =>
            msg.CorrelationId == "corr-dp" && msg.TrackedOperationId.Equals(id));
    }

    [Fact]
    public void RetryParkedOperation_WithoutHandler_RepliesNotAppliedAck()
    {
        // No parked-message handler registered — the relay must get a definitive
        // non-applied ack, not silence (the SiteCallAuditActor's Ask must not
        // hang and then mis-report site-unreachable when the site IS reachable).
        var dmProbe = CreateTestProbe();
        var siteActor = Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", _options, dmProbe.Ref)));

        siteActor.Tell(new RetryParkedOperation("corr-no-handler", Commons.Types.TrackedOperationId.New()));

        var ack = ExpectMsg<ParkedOperationActionAck>();
        Assert.Equal("corr-no-handler", ack.CorrelationId);
        Assert.False(ack.Applied);
        Assert.NotNull(ack.ErrorMessage);
    }

    [Fact]
    public void DiscardParkedOperation_WithoutHandler_RepliesNotAppliedAck()
    {
        var dmProbe = CreateTestProbe();
        var siteActor = Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", _options, dmProbe.Ref)));

        siteActor.Tell(new DiscardParkedOperation("corr-no-handler", Commons.Types.TrackedOperationId.New()));

        var ack = ExpectMsg<ParkedOperationActionAck>();
        Assert.False(ack.Applied);
        Assert.NotNull(ack.ErrorMessage);
    }

    // ── M7 OPC UA cross-cluster routing: Search (T15), WriteTag (T14), Verify (T17) ──
    //
    // Regression guard for the M7 dead-letter defect. These three interactive
    // commands have downstream handlers in DataConnectionManagerActor but were NOT
    // forwarded through SiteCommunicationActor → Deployment Manager, so they
    // dead-lettered and the central Ask timed out in the real cluster. They must
    // forward to the Deployment Manager proxy exactly like BrowseNodeCommand, with
    // the original Ask sender preserved so the result routes straight back.

    [Fact]
    public void SearchAddressSpaceCommand_ForwardedToDeploymentManager_SenderPreserved()
    {
        var dmProbe = CreateTestProbe();
        var senderProbe = CreateTestProbe();
        var siteActor = Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", _options, dmProbe.Ref)));

        var command = new SearchAddressSpaceCommand("conn1", "Temp", 5, 100);
        siteActor.Tell(command, senderProbe.Ref);

        dmProbe.ExpectMsg<SearchAddressSpaceCommand>(msg => msg.ConnectionName == "conn1");
        Assert.Equal(senderProbe.Ref, dmProbe.LastSender);
    }

    [Fact]
    public void WriteTagRequest_ForwardedToDeploymentManager_SenderPreserved()
    {
        var dmProbe = CreateTestProbe();
        var senderProbe = CreateTestProbe();
        var siteActor = Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", _options, dmProbe.Ref)));

        var request = new WriteTagRequest(
            "corr-w", "conn1", "Channel1.Device1.Tag1", 42, DateTimeOffset.UtcNow);
        siteActor.Tell(request, senderProbe.Ref);

        dmProbe.ExpectMsg<WriteTagRequest>(msg => msg.CorrelationId == "corr-w");
        Assert.Equal(senderProbe.Ref, dmProbe.LastSender);
    }

    [Fact]
    public void VerifyEndpointCommand_ForwardedToDeploymentManager_SenderPreserved()
    {
        var dmProbe = CreateTestProbe();
        var senderProbe = CreateTestProbe();
        var siteActor = Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", _options, dmProbe.Ref)));

        var command = new VerifyEndpointCommand("conn1", "OpcUa", "{}");
        siteActor.Tell(command, senderProbe.Ref);

        dmProbe.ExpectMsg<VerifyEndpointCommand>(msg => msg.ConnectionName == "conn1");
        Assert.Equal(senderProbe.Ref, dmProbe.LastSender);
    }

    // ── Communication-018: heartbeat IsActive reflects this node's cluster role ──

    [Theory]
    [InlineData(true)]
    [InlineData(false)]
    public void Heartbeat_StampsIsActive_FromInjectedCheck(bool isActive)
    {
        // Communication-018: HeartbeatMessage.IsActive must reflect the actual
        // active/standby role of this node, not a hard-coded `true`. The actor
        // now takes a Func<bool> override (defaulting to a real Akka.Cluster
        // leader check in production); tests inject a stub so they do not need
        // to bring up a full cluster in the TestKit ActorSystem.
        var dmProbe = CreateTestProbe();
        var transport = Substitute.For<ICentralTransport>();
        var fastHeartbeatOptions = new CommunicationOptions
        {
            ApplicationHeartbeatInterval = TimeSpan.FromMilliseconds(100)
        };

        Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", fastHeartbeatOptions, dmProbe.Ref, () => isActive, null, transport)));

        // The heartbeat now rides the injected ICentralTransport (SendHeartbeat), not a
        // ClusterClient. The captured message must carry the injected active/standby flag.
        AwaitAssert(
            () => transport.Received().SendHeartbeat(
                Arg.Is<HeartbeatMessage>(h => h.IsActive == isActive && h.SiteId == "site1"),
                Arg.Any<IActorRef>()),
            TimeSpan.FromSeconds(3));
    }

    // ---- Central→site failover relay (Task 10) ----------------------------------
    // The failover action is injected for the same reason isActiveCheck is: performing a
    // real Cluster.Leave would require Akka.Cluster in the TestKit ActorSystem. These
    // tests pin the ROUTING and GUARD logic; the actual Leave against a real two-node
    // site cluster is covered by SiteFailoverRelayTests in the integration suite.

    [Fact]
    public void TriggerSiteFailover_IssuesTheLeave_AndAcksWithTheTarget()
    {
        var dmProbe = CreateTestProbe();
        string? roleAskedFor = null;
        Func<string, string?> failOver = role =>
        {
            roleAskedFor = role;
            return "akka.tcp://scadabridge@site1-a:8082";
        };
        var siteActor = Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", _options, dmProbe.Ref, null, failOver)));

        siteActor.Tell(new TriggerSiteFailover("corr-1", "site1"));

        var ack = ExpectMsg<SiteFailoverAck>();
        Assert.True(ack.Accepted);
        Assert.Equal("corr-1", ack.CorrelationId);
        Assert.Equal("akka.tcp://scadabridge@site1-a:8082", ack.TargetAddress);
        Assert.Null(ack.ErrorMessage);
        // Site singletons are scoped to the site-specific role, not the base "Site" role;
        // failing over the wrong scope would move the wrong node.
        Assert.Equal("site-site1", roleAskedFor);
    }

    [Fact]
    public void TriggerSiteFailover_RefusesWhenThereIsNoPeer()
    {
        var dmProbe = CreateTestProbe();
        Func<string, string?> failOver = _ => null;
        var siteActor = Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", _options, dmProbe.Ref, null, failOver)));

        siteActor.Tell(new TriggerSiteFailover("corr-2", "site1"));

        var ack = ExpectMsg<SiteFailoverAck>();
        Assert.False(ack.Accepted);
        Assert.Null(ack.TargetAddress);
        Assert.NotNull(ack.ErrorMessage);
    }

    [Fact]
    public void TriggerSiteFailover_RefusesACommandAddressedToAnotherSite()
    {
        // A misrouted command must be refused, not silently acted on — acting would fail
        // over a site the operator never selected.
        var dmProbe = CreateTestProbe();
        var invoked = false;
        Func<string, string?> failOver = _ =>
        {
            invoked = true;
            return "addr";
        };
        var siteActor = Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", _options, dmProbe.Ref, null, failOver)));

        siteActor.Tell(new TriggerSiteFailover("corr-3", "site2"));

        var ack = ExpectMsg<SiteFailoverAck>();
        Assert.False(ack.Accepted);
        Assert.Contains("site2", ack.ErrorMessage);
        Assert.False(invoked);
    }

    [Fact]
    public void TriggerSiteFailover_FaultInTheLeave_IsReportedNotThrown()
    {
        var dmProbe = CreateTestProbe();
        Func<string, string?> failOver = _ => throw new InvalidOperationException("cluster unavailable");
        var siteActor = Sys.ActorOf(Props.Create(() =>
            new SiteCommunicationActor("site1", _options, dmProbe.Ref, null, failOver)));

        siteActor.Tell(new TriggerSiteFailover("corr-4", "site1"));

        var ack = ExpectMsg<SiteFailoverAck>();
        Assert.False(ack.Accepted);
        Assert.Contains("cluster unavailable", ack.ErrorMessage);
    }
}