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.IntegrationTests;

/// <summary>
///     PR 3.2 / issue #314 — wire-level coverage for the cycle-time / jitter / online-change
///     diagnostics surfaced through the probe loop. Skipped via <see cref="TwinCATFactAttribute"/>
///     when the XAR VM isn't reachable. The four well-known system symbols
///     (<c>TwinCAT_SystemInfoVarList._AppInfo.OnlineChangeCnt</c>, <c>_AppInfo.AppName</c>,
///     <c>_TaskInfo[1].CycleTime</c>, <c>_TaskInfo[1].LastExecTime</c>) are always exported by
///     a live TC3 PLC runtime — no extra fixture state required beyond the existing
///     <c>GVL_Fixture</c> / <c>MAIN</c> setup documented in <c>TwinCatProject/README.md</c>.
/// </summary>
[Collection("TwinCATXar")]
[Trait("Category", "Integration")]
[Trait("Simulator", "TwinCAT-XAR")]
public sealed class TwinCATDiagnosticsIntegrationTests(TwinCATXarFixture sim)
{
    [TwinCATFact]
    public async Task Probe_loop_surfaces_cycle_time_and_online_change_count()
    {
        if (sim.SkipReason is not null) Assert.Skip(sim.SkipReason);

        // Probe interval kept tight (250 ms) so the test doesn't have to wait the default 5 s
        // between probe ticks. The four system symbols are scalar UDINTs / a STRING(80), so
        // the diagnostics sample completes well within the 250 ms budget on any healthy
        // runtime.
        var options = new TwinCATDriverOptions
        {
            Devices = [
                new TwinCATDeviceOptions(
                    HostAddress: $"ads://{sim.TargetNetId}:{sim.AmsPort}",
                    DeviceName: "XAR-VM"),
            ],
            // No Tags — diagnostics doesn't need any user-declared symbols.
            Tags = [],
            UseNativeNotifications = false,
            Timeout = TimeSpan.FromSeconds(5),
            Probe = new TwinCATProbeOptions
            {
                Enabled = true,
                Interval = TimeSpan.FromMilliseconds(250),
            },
        };

        await using var drv = new TwinCATDriver(options, driverInstanceId: "tc3-diag-probe");
        await drv.InitializeAsync("{}", TestContext.Current.CancellationToken);

        // Wait up to 5 s for the probe loop to fire at least once + populate the snapshot.
        // 250 ms cycle × 20 attempts ≈ 5 s budget — generous enough for AMS handshake on a
        // freshly-restarted runtime.
        var hostAddress = $"ads://{sim.TargetNetId}:{sim.AmsPort}";
        TwinCATDeviceDiagnostics? snap = null;
        for (var i = 0; i < 20 && snap is null; i++)
        {
            await Task.Delay(250, TestContext.Current.CancellationToken);
            snap = drv.GetDeviceDiagnostics(hostAddress);
        }

        snap.ShouldNotBeNull(
            "probe loop must populate TwinCATDeviceDiagnostics within ~5 s on a reachable XAR runtime");
        snap.CycleTimeMs.ShouldBeGreaterThan(0,
            "TwinCAT_SystemInfoVarList._TaskInfo[1].CycleTime is non-zero on every running PLC task");
        snap.OnlineChangeCnt.ShouldBeGreaterThanOrEqualTo(0u,
            "OnlineChangeCnt is a UDINT counter — non-negative by type, present on every TC3 runtime");
        // AppName is best-effort but on a project-loaded runtime it should be non-empty.
        snap.AppName.ShouldNotBeNull("running PLC project always reports an AppName");

        // The cross-driver DriverHealth.Diagnostics dictionary should also reflect the same
        // values so the driver-diagnostics RPC has a consistent surface.
        var dict = drv.GetHealth().DiagnosticsOrEmpty;
        dict["TwinCAT.CycleTimeMs"].ShouldBe(snap.CycleTimeMs);
        dict["TwinCAT.OnlineChangeCnt"].ShouldBe(snap.OnlineChangeCnt);
    }
}