using System.Collections.Concurrent;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Driver.TwinCAT;

namespace ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Tests;

/// <summary>
///     #739 / R02:P1 — TwinCAT is an <see cref="IBatchSubscribable"/>. DriverInstanceActor subscribes ONLY the
///     batch event of a batch-capable driver, so every data change — poll cycle AND native push, including the
///     Bad snapshots the native path publishes itself — must reach <c>OnDataChangeBatch</c>; the per-tag event
///     keeps firing for legacy consumers (the CLI).
/// </summary>
[Trait("Category", "Unit")]
public sealed class TwinCATBatchSubscribeTests
{
    private const string Host = "ads://5.23.91.23.1.1:851";

    private static TwinCATDriver NewDriver(FakeTwinCATClientFactory factory, bool native) =>
        new(new TwinCATDriverOptions
        {
            Devices = [new TwinCATDeviceOptions(Host)],
            RawTags = TwinCATRawTags.Entries(
            [
                new TwinCATTagDefinition("A", Host, "MAIN.A", TwinCATDataType.DInt),
                new TwinCATTagDefinition("B", Host, "MAIN.B", TwinCATDataType.DInt),
            ]),
            Probe = new TwinCATProbeOptions { Enabled = false },
            UseNativeNotifications = native,
        }, "drv-1", factory);

    /// <summary>The driver advertises the batch capability.</summary>
    [Fact]
    public void Driver_is_batch_subscribable() =>
        NewDriver(new FakeTwinCATClientFactory(), native: false).ShouldBeAssignableTo<IBatchSubscribable>();

    /// <summary>A poll cycle that changes two tags raises ONE batch carrying both, and the per-tag event twice.</summary>
    [Fact]
    public async Task A_poll_cycle_raises_one_batch_with_every_changed_tag()
    {
        var factory = new FakeTwinCATClientFactory
        {
            Customise = () => new FakeTwinCATClient { Values = { ["MAIN.A"] = 1, ["MAIN.B"] = 2 } },
        };
        var drv = NewDriver(factory, native: false);
        await drv.InitializeAsync("{}", TestContext.Current.CancellationToken);
        var batches = new ConcurrentQueue<DataChangeBatchEventArgs>();
        var single = new ConcurrentQueue<DataChangeEventArgs>();
        drv.OnDataChangeBatch += (_, e) => batches.Enqueue(e);
        drv.OnDataChange += (_, e) => single.Enqueue(e);

        var handle = await drv.SubscribeAsync(["A", "B"], TimeSpan.FromMilliseconds(100), TestContext.Current.CancellationToken);
        await WaitForAsync(() => !batches.IsEmpty, TimeSpan.FromSeconds(3));
        await drv.UnsubscribeAsync(handle, TestContext.Current.CancellationToken);

        var first = batches.First();
        first.SubscriptionHandle.ShouldBe(handle);
        first.Items.Select(i => i.FullReference).ShouldBe(["A", "B"], ignoreOrder: true);
        single.Count(e => e.FullReference is "A" or "B").ShouldBeGreaterThanOrEqualTo(2);
    }

    /// <summary>A native push and the native path's own Bad snapshot both reach the batch event.</summary>
    [Fact]
    public async Task Native_pushes_and_native_bad_snapshots_reach_the_batch_event()
    {
        var fake = new FakeTwinCATClient();
        var drv = NewDriver(new FakeTwinCATClientFactory { Customise = () => fake }, native: true);
        await drv.InitializeAsync("{}", TestContext.Current.CancellationToken);
        var batches = new ConcurrentQueue<DataChangeBatchEventArgs>();
        drv.OnDataChangeBatch += (_, e) => batches.Enqueue(e);

        _ = await drv.SubscribeAsync(["A", "Ghost"], TimeSpan.FromMilliseconds(100), TestContext.Current.CancellationToken);
        fake.FireNotification("MAIN.A", 42);

        var items = batches.SelectMany(b => b.Items).ToList();
        items.Single(i => i.FullReference == "Ghost").Snapshot.StatusCode.ShouldBe(TwinCATStatusMapper.BadNodeIdUnknown);
        var a = items.Single(i => i.FullReference == "A");
        a.Snapshot.StatusCode.ShouldBe(TwinCATStatusMapper.Good);
        a.Snapshot.Value.ShouldBe(42);
    }

    private static async Task WaitForAsync(Func<bool> condition, TimeSpan timeout)
    {
        var deadline = DateTime.UtcNow + timeout;
        while (!condition() && DateTime.UtcNow < deadline)
            await Task.Delay(20);
    }
}