using Akka.Actor;
using Akka.TestKit.Xunit2;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using NSubstitute;
using ScadaLink.Commons.Entities.Instances;
using ScadaLink.Commons.Entities.Sites;
using ScadaLink.Commons.Interfaces.Repositories;
using ScadaLink.Communication;
using ScadaLink.Communication.Actors;
using ScadaLink.Communication.Grpc;

namespace ScadaLink.Communication.Tests;

/// <summary>
/// Tests for DebugStreamService session lifecycle.
/// </summary>
public class DebugStreamServiceTests : TestKit
{
    [Fact]
    public async Task StartStreamAsync_StreamTerminatesBeforeSnapshot_ThrowsMeaningfulException()
    {
        // Regression test for Communication-001. When the debug stream terminates before
        // the initial snapshot arrives, StartStreamAsync used to let the raw
        // InvalidOperationException from onTerminatedWrapper escape its
        // OperationCanceledException-only catch — the caller saw an untranslated exception
        // and the failure path did not deterministically tear the bridge actor down.
        // The fix catches any failure, tells the bridge actor StopDebugStream, and throws
        // a descriptive exception that names the instance and wraps the underlying cause.
        var instance = new Instance("Site1.Pump01") { Id = 7, SiteId = 3 };
        var site = new Site("Site One", "site-1")
        {
            Id = 3,
            GrpcNodeAAddress = "http://localhost:5100",
            GrpcNodeBAddress = "http://localhost:5200"
        };

        var instanceRepo = Substitute.For<ITemplateEngineRepository>();
        instanceRepo.GetInstanceByIdAsync(7, Arg.Any<CancellationToken>()).Returns(instance);
        var siteRepo = Substitute.For<ISiteRepository>();
        siteRepo.GetSiteByIdAsync(3, Arg.Any<CancellationToken>()).Returns(site);

        var services = new ServiceCollection();
        services.AddScoped(_ => instanceRepo);
        services.AddScoped(_ => siteRepo);
        using var provider = services.BuildServiceProvider();

        var commProbe = CreateTestProbe();
        var commService = new CommunicationService(
            Options.Create(new CommunicationOptions()),
            NullLogger<CommunicationService>.Instance);
        commService.SetCommunicationActor(commProbe.Ref);

        using var grpcFactory = new SiteStreamGrpcClientFactory(NullLoggerFactory.Instance);
        var service = new DebugStreamService(
            commService, provider, grpcFactory, NullLogger<DebugStreamService>.Instance);
        service.SetActorSystem(Sys);

        // Act — start the stream; it blocks awaiting the initial snapshot.
        var startTask = service.StartStreamAsync(instanceId: 7, onEvent: _ => { }, onTerminated: () => { });

        // The bridge actor's PreStart sends SubscribeDebugViewRequest to the comm actor;
        // the envelope's sender is the bridge actor itself.
        commProbe.ExpectMsg<SiteEnvelope>(TimeSpan.FromSeconds(5));
        var bridgeActor = commProbe.LastSender;

        // Simulate the site terminating the stream before any snapshot is delivered.
        bridgeActor.Tell(new DebugStreamTerminated("site-1", "corr"));

        // Assert — a descriptive exception that names the instance and wraps the cause,
        // not the raw "terminated before snapshot received" InvalidOperationException.
        var ex = await Assert.ThrowsAsync<InvalidOperationException>(() => startTask);
        Assert.Contains("Site1.Pump01", ex.Message);
        Assert.NotNull(ex.InnerException);
    }
}