using Akka.Actor;
using Akka.TestKit.Xunit2;
using Microsoft.Extensions.DependencyInjection;
using NSubstitute;
using ScadaLink.Commons.Entities.Sites;
using ScadaLink.Commons.Interfaces.Repositories;
using ScadaLink.Commons.Messages.Communication;
using ScadaLink.Commons.Messages.Deployment;
using ScadaLink.Commons.Messages.DebugView;
using ScadaLink.Commons.Messages.Health;
using ScadaLink.Communication.Actors;

namespace ScadaLink.Communication.Tests;

/// <summary>
/// Tests for CentralCommunicationActor with database-driven site addressing.
/// WP-4: Message routing via site address cache loaded from DB.
/// WP-5: Connection failure and failover handling.
/// </summary>
public class CentralCommunicationActorTests : TestKit
{
    public CentralCommunicationActorTests() : base(@"akka.loglevel = DEBUG") { }

    private (IActorRef actor, ISiteRepository mockRepo) CreateActorWithMockRepo(IEnumerable<Site>? sites = null)
    {
        var mockRepo = Substitute.For<ISiteRepository>();
        mockRepo.GetAllSitesAsync(Arg.Any<CancellationToken>())
            .Returns(sites?.ToList() ?? new List<Site>());

        var services = new ServiceCollection();
        services.AddScoped(_ => mockRepo);
        var sp = services.BuildServiceProvider();

        var actor = Sys.ActorOf(Props.Create(() => new CentralCommunicationActor(sp)));
        return (actor, mockRepo);
    }

    private Site CreateSite(string identifier, string? nodeAPath, string? nodeBPath = null) =>
        new("Test Site", identifier) { NodeAAddress = nodeAPath, NodeBAddress = nodeBPath };

    [Fact]
    public void DatabaseDrivenRouting_RoutesToConfiguredSite()
    {
        var probe = CreateTestProbe();
        var site = CreateSite("site1", probe.Ref.Path.ToString());
        var (actor, _) = CreateActorWithMockRepo(new[] { site });

        // Send explicit refresh and wait for async DB load + PipeTo
        actor.Tell(new RefreshSiteAddresses());
        Thread.Sleep(1000);

        var command = new DeployInstanceCommand(
            "dep1", "inst1", "hash1", "{}", "admin", DateTimeOffset.UtcNow);
        actor.Tell(new SiteEnvelope("site1", command));

        probe.ExpectMsg<DeployInstanceCommand>(msg => msg.DeploymentId == "dep1");
    }

    [Fact]
    public void UnconfiguredSite_MessageIsDropped()
    {
        var (actor, _) = CreateActorWithMockRepo();

        actor.Tell(new RefreshSiteAddresses());
        Thread.Sleep(1000);

        var command = new DeployInstanceCommand(
            "dep1", "inst1", "hash1", "{}", "admin", DateTimeOffset.UtcNow);
        actor.Tell(new SiteEnvelope("unknown-site", command));

        ExpectNoMsg(TimeSpan.FromMilliseconds(200));
    }

    [Fact]
    public void ConnectionLost_DebugStreamsKilled()
    {
        var siteProbe = CreateTestProbe();
        var site = CreateSite("site1", siteProbe.Ref.Path.ToString());
        var (actor, _) = CreateActorWithMockRepo(new[] { site });

        actor.Tell(new RefreshSiteAddresses());
        Thread.Sleep(1000);

        // Subscribe to debug view (tracks the subscription)
        var subscriberProbe = CreateTestProbe();
        var subRequest = new SubscribeDebugViewRequest("inst1", "corr-123");
        actor.Tell(new SiteEnvelope("site1", subRequest), subscriberProbe.Ref);

        // Simulate site disconnection
        actor.Tell(new ConnectionStateChanged("site1", false, DateTimeOffset.UtcNow));

        // The subscriber should receive a DebugStreamTerminated notification
        subscriberProbe.ExpectMsg<DebugStreamTerminated>(
            msg => msg.SiteId == "site1" && msg.CorrelationId == "corr-123");
    }

    [Fact]
    public void Heartbeat_ForwardedToParent()
    {
        // Actor still needs IServiceProvider even though this test doesn't use routing
        var mockRepo = Substitute.For<ISiteRepository>();
        mockRepo.GetAllSitesAsync(Arg.Any<CancellationToken>())
            .Returns(new List<Site>());

        var services = new ServiceCollection();
        services.AddScoped(_ => mockRepo);
        var sp = services.BuildServiceProvider();

        var parentProbe = CreateTestProbe();
        var centralActor = parentProbe.ChildActorOf(
            Props.Create(() => new CentralCommunicationActor(sp)));

        var heartbeat = new HeartbeatMessage("site1", "host1", true, DateTimeOffset.UtcNow);
        centralActor.Tell(heartbeat);

        parentProbe.ExpectMsg<HeartbeatMessage>(msg => msg.SiteId == "site1");
    }

    [Fact]
    public void RefreshSiteAddresses_UpdatesCache()
    {
        var probe1 = CreateTestProbe();
        var probe2 = CreateTestProbe();

        var site1 = CreateSite("site1", probe1.Ref.Path.ToString());
        var (actor, mockRepo) = CreateActorWithMockRepo(new[] { site1 });

        // Wait for initial load, then send explicit refresh
        actor.Tell(new RefreshSiteAddresses());
        Thread.Sleep(1000);

        // Verify routing to site1 works
        var cmd1 = new DeployInstanceCommand(
            "dep1", "inst1", "hash1", "{}", "admin", DateTimeOffset.UtcNow);
        actor.Tell(new SiteEnvelope("site1", cmd1));
        probe1.ExpectMsg<DeployInstanceCommand>(msg => msg.DeploymentId == "dep1");

        // Update mock repo to return both sites
        var site2 = CreateSite("site2", probe2.Ref.Path.ToString());
        mockRepo.GetAllSitesAsync(Arg.Any<CancellationToken>())
            .Returns(new List<Site> { site1, site2 });

        // Refresh again
        actor.Tell(new RefreshSiteAddresses());
        Thread.Sleep(1000);

        // Verify routing to site2 now works
        var cmd2 = new DeployInstanceCommand(
            "dep2", "inst2", "hash2", "{}", "admin", DateTimeOffset.UtcNow);
        actor.Tell(new SiteEnvelope("site2", cmd2));
        probe2.ExpectMsg<DeployInstanceCommand>(msg => msg.DeploymentId == "dep2");
    }

    [Fact]
    public void NodeBFallback_WhenNodeANotConfigured()
    {
        var probe = CreateTestProbe();
        var site = CreateSite("site1", null, probe.Ref.Path.ToString());
        var (actor, _) = CreateActorWithMockRepo(new[] { site });

        actor.Tell(new RefreshSiteAddresses());
        Thread.Sleep(1000);

        var command = new DeployInstanceCommand(
            "dep1", "inst1", "hash1", "{}", "admin", DateTimeOffset.UtcNow);
        actor.Tell(new SiteEnvelope("site1", command));

        probe.ExpectMsg<DeployInstanceCommand>(msg => msg.DeploymentId == "dep1");
    }
}