using System.Threading.Channels;
using Akka.Actor;
using Akka.TestKit.Xunit2;
using Google.Protobuf.WellKnownTypes;
using ZB.MOM.WW.ScadaBridge.Commons.Messages.Streaming;
using ZB.MOM.WW.ScadaBridge.Communication.Actors;
using ZB.MOM.WW.ScadaBridge.Communication.Grpc;

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

/// <summary>
/// Flow Debugger (design 2026-09-05 §5.3/§5.4): <c>AttributeValueUpdate</c> fields 7/8 —
/// <see cref="StreamRelayActor"/> stamps <c>source_execution_id</c>/<c>trace</c> on the way
/// out and <see cref="SiteStreamGrpcClient"/> parses them back; an unstamped change (and an
/// older site's frame) round-trips to null/false.
/// </summary>
public class StreamRelayTraceStampTests : TestKit
{
    private static SiteStreamEvent Relay(AttributeValueChanged change, ActorSystem sys)
    {
        var channel = Channel.CreateUnbounded<SiteStreamEvent>();
        var actor = sys.ActorOf(Props.Create(() => new StreamRelayActor("corr", channel.Writer)));
        actor.Tell(change);
        SiteStreamEvent? evt = null;
        for (var i = 0; i < 40 && !channel.Reader.TryRead(out evt); i++) Thread.Sleep(50);
        Assert.NotNull(evt);
        return evt!;
    }

    /// <summary>Verifies that a traced change is stamped on the wire and parsed back.</summary>
    [Fact]
    public void TracedChange_IsStampedOnTheWire_AndParsedBack()
    {
        var source = Guid.NewGuid();
        var now = new DateTimeOffset(2026, 9, 5, 12, 0, 0, TimeSpan.Zero);
        var change = new AttributeValueChanged("P1", "Status", "Status", "Running", "Good", now, SourceExecutionId: source, Trace: true);

        var evt = Relay(change, Sys);
        Assert.Equal(source.ToString("D"), evt.AttributeChanged.SourceExecutionId);
        Assert.True(evt.AttributeChanged.Trace);

        var back = Assert.IsType<AttributeValueChanged>(SiteStreamGrpcClient.ConvertToDomainEvent(evt));
        Assert.Equal(source, back.SourceExecutionId);
        Assert.True(back.Trace);
    }

    /// <summary>Verifies that an unstamped change round-trips to null and false.</summary>
    [Fact]
    public void UnstampedChange_RoundTripsToNullAndFalse()
    {
        var change = new AttributeValueChanged("P1", "Status", "Status", "Idle", "Good", DateTimeOffset.UtcNow);

        var evt = Relay(change, Sys);
        Assert.Equal(string.Empty, evt.AttributeChanged.SourceExecutionId);
        Assert.False(evt.AttributeChanged.Trace);

        var back = Assert.IsType<AttributeValueChanged>(SiteStreamGrpcClient.ConvertToDomainEvent(evt));
        Assert.Null(back.SourceExecutionId);
        Assert.False(back.Trace);
    }

    /// <summary>Verifies that an older site frame without the trace fields parses to null and false.</summary>
    [Fact]
    public void OlderSiteFrame_WithoutTheFields_ParsesToNullAndFalse()
    {
        var evt = new SiteStreamEvent
        {
            CorrelationId = "c",
            AttributeChanged = new AttributeValueUpdate
            {
                InstanceUniqueName = "P1", AttributePath = "A", AttributeName = "A", Value = "1",
                Quality = Quality.Good, Timestamp = Timestamp.FromDateTimeOffset(DateTimeOffset.UtcNow),
            },
        };
        var back = Assert.IsType<AttributeValueChanged>(SiteStreamGrpcClient.ConvertToDomainEvent(evt));
        Assert.Null(back.SourceExecutionId);
        Assert.False(back.Trace);
    }
}