using Akka.Actor;
using Akka.TestKit.Xunit2;
using NSubstitute;
using ScadaLink.Commons.Interfaces.Protocol;
using ScadaLink.Commons.Messages.DataConnection;
using ScadaLink.Commons.Types.Enums;
using ScadaLink.DataConnectionLayer.Actors;
using ScadaLink.HealthMonitoring;

namespace ScadaLink.DataConnectionLayer.Tests;

/// <summary>
/// WP-34: Tests for DataConnectionManagerActor routing and lifecycle.
/// </summary>
public class DataConnectionManagerActorTests : TestKit
{
    private readonly IDataConnectionFactory _mockFactory;
    private readonly DataConnectionOptions _options;
    private readonly ISiteHealthCollector _mockHealthCollector;

    public DataConnectionManagerActorTests()
        : base(@"akka.loglevel = DEBUG")
    {
        _mockFactory = Substitute.For<IDataConnectionFactory>();
        _mockHealthCollector = Substitute.For<ISiteHealthCollector>();
        _options = new DataConnectionOptions
        {
            ReconnectInterval = TimeSpan.FromMilliseconds(100),
            TagResolutionRetryInterval = TimeSpan.FromMilliseconds(200)
        };
    }

    [Fact]
    public void WriteToUnknownConnection_ReturnsError()
    {
        var manager = Sys.ActorOf(Props.Create(() =>
            new DataConnectionManagerActor(_mockFactory, _options, _mockHealthCollector)));

        manager.Tell(new WriteTagRequest(
            "corr1", "nonexistent", "tag1", 42, DateTimeOffset.UtcNow));

        var response = ExpectMsg<WriteTagResponse>();
        Assert.False(response.Success);
        Assert.Contains("Unknown connection", response.ErrorMessage);
    }

    [Fact]
    public void SubscribeToUnknownConnection_ReturnsError()
    {
        var manager = Sys.ActorOf(Props.Create(() =>
            new DataConnectionManagerActor(_mockFactory, _options, _mockHealthCollector)));

        manager.Tell(new SubscribeTagsRequest(
            "corr1", "inst1", "nonexistent", ["tag1"], DateTimeOffset.UtcNow));

        var response = ExpectMsg<SubscribeTagsResponse>();
        Assert.False(response.Success);
        Assert.Contains("Unknown connection", response.ErrorMessage);
    }

    [Fact]
    public async Task DCL002_ConnectionActorCrash_PreservesSubscriptionState()
    {
        // Regression test for DataConnectionLayer-002. The supervisor used
        // Directive.Restart, which discards the connection actor's in-memory
        // subscription registry — breaking the design doc's "transparent
        // re-subscribe" guarantee (subscribers are never re-subscribed and sit at
        // stale quality forever). After the fix the supervisor uses Resume, which
        // keeps the actor instance and its state across a transient exception.
        var mockAdapter = Substitute.For<IDataConnection>();
        mockAdapter.ConnectAsync(Arg.Any<IDictionary<string, string>>(), Arg.Any<CancellationToken>())
            .Returns(Task.CompletedTask);
        mockAdapter.Status.Returns(ConnectionHealth.Connected);
        mockAdapter.SubscribeAsync(Arg.Any<string>(), Arg.Any<SubscriptionCallback>(), Arg.Any<CancellationToken>())
            .Returns("sub-001");
        mockAdapter.ReadAsync(Arg.Any<string>(), Arg.Any<CancellationToken>())
            .Returns(new ReadResult(false, null, null));
        // A write throws synchronously, escaping the message handler and crashing
        // the connection actor — exercising the supervisor strategy.
        mockAdapter.WriteAsync(Arg.Any<string>(), Arg.Any<object?>(), Arg.Any<CancellationToken>())
            .Returns<Task<WriteResult>>(_ => throw new InvalidOperationException("boom"));

        _mockFactory.Create("OpcUa", Arg.Any<IDictionary<string, string>>()).Returns(mockAdapter);

        var manager = Sys.ActorOf(Props.Create(() =>
            new DataConnectionManagerActor(_mockFactory, _options, _mockHealthCollector)));

        manager.Tell(new CreateConnectionCommand("conn1", "OpcUa", new Dictionary<string, string>(), null, 3));
        await Task.Delay(300); // connection actor reaches Connected

        // Register a subscription.
        manager.Tell(new SubscribeTagsRequest("c1", "inst1", "conn1", ["tag1"], DateTimeOffset.UtcNow));
        ExpectMsg<SubscribeTagsResponse>(TimeSpan.FromSeconds(3));

        // Crash the connection actor via a synchronously-throwing write.
        manager.Tell(new WriteTagRequest("c2", "conn1", "tag1", 42, DateTimeOffset.UtcNow));
        await Task.Delay(300); // supervisor handles the failure

        // After the crash the subscription state must survive: the health report
        // still shows the subscribed/resolved tag. With Restart it would be 0.
        manager.Tell(new GetAllHealthReports());
        var report = ExpectMsg<DataConnectionHealthReport>(TimeSpan.FromSeconds(3));
        Assert.Equal(1, report.TotalSubscribedTags);
        Assert.Equal(1, report.ResolvedTags);
    }

    [Fact]
    public void CreateConnection_UsesFactory()
    {
        var mockAdapter = Substitute.For<IDataConnection>();
        mockAdapter.ConnectAsync(Arg.Any<IDictionary<string, string>>(), Arg.Any<CancellationToken>())
            .Returns(Task.CompletedTask);
        _mockFactory.Create("OpcUa", Arg.Any<IDictionary<string, string>>())
            .Returns(mockAdapter);

        var manager = Sys.ActorOf(Props.Create(() =>
            new DataConnectionManagerActor(_mockFactory, _options, _mockHealthCollector)));

        manager.Tell(new CreateConnectionCommand(
            "conn1", "OpcUa", new Dictionary<string, string>(), null, 3));

        // Factory should have been called
        AwaitCondition(() =>
            _mockFactory.ReceivedCalls().Any(c => c.GetMethodInfo().Name == "Create"),
            TimeSpan.FromSeconds(2));
    }
}
