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>Gitea #645 / #314 — PLC state / task-cycle facts on the optional IDriverDiagnostics bag.</summary>
[Trait("Category", "Unit")]
public sealed class TwinCATDiagnosticsTests
{
    private const string Host1 = "ads://5.23.91.23.1.1:851";
    private const string Host2 = "ads://5.23.91.24.1.1:851";

    private static TwinCATDriver NewDriver(FakeTwinCATClientFactory factory, bool probe, bool diagnostics, params (string host, string? name)[] devices) =>
        new(new TwinCATDriverOptions
        {
            Devices = [.. devices.Select(d => new TwinCATDeviceOptions(d.host, d.name))],
            Probe = new TwinCATProbeOptions { Enabled = probe, Interval = TimeSpan.FromMilliseconds(20) },
            DiagnosticsEnabled = diagnostics,
        }, "drv-diag", factory);

    private static FakeTwinCATClient PlcClient() => new()
    {
        AdsStateText = "Run",
        Values =
        {
            [TwinCATDriver.SymAppName] = "Plc30 App",
            [TwinCATDriver.SymOnlineChangeCnt] = 7u,
            [TwinCATDriver.SymCycleTime] = 100_000u,   // 10.0 ms
            [TwinCATDriver.SymLastExecTime] = 25_000u, // 2.5 ms
        },
    };

    private static async Task Sample(TwinCATDriver drv, FakeTwinCATClient client, string host)
    {
        var state = drv.GetDeviceState(host)!;
        await drv.SampleDeviceDiagnosticsAsync(state, client, CancellationToken.None);
    }

    /// <summary>Verifies the driver advertises the optional capability and is empty before any sample.</summary>
    [Fact]
    public async Task Bag_is_empty_before_the_first_sample()
    {
        var drv = NewDriver(new FakeTwinCATClientFactory(), false, true, (Host1, null));
        await drv.InitializeAsync("{}", CancellationToken.None);

        var diag = drv.ShouldBeAssignableTo<IDriverDiagnostics>()!;
        diag.GetDiagnostics().ShouldBeEmpty();
    }

    /// <summary>Verifies a single-device driver publishes flat keys with state, app, cycle, exec and headroom.</summary>
    [Fact]
    public async Task Single_device_publishes_flat_keys()
    {
        var drv = NewDriver(new FakeTwinCATClientFactory(), false, true, (Host1, null));
        await drv.InitializeAsync("{}", CancellationToken.None);
        await Sample(drv, PlcClient(), Host1);

        var bag = ((IDriverDiagnostics)drv).GetDiagnostics();

        bag["TwinCAT.AdsState"].ShouldBe("Run");
        bag["TwinCAT.AppName"].ShouldBe("Plc30 App");
        bag["TwinCAT.OnlineChangeCnt"].ShouldBe("7");
        bag["TwinCAT.CycleTimeMs"].ShouldBe("10.0");
        bag["TwinCAT.LastExecTimeMs"].ShouldBe("2.5");
        bag["TwinCAT.HeadroomMs"].ShouldBe("7.5");
        DriverDiagnostics.Bound(bag).Count.ShouldBe(bag.Count); // within the host's 16-entry cap
    }

    /// <summary>Verifies several devices are told apart by device name, falling back to host address.</summary>
    [Fact]
    public async Task Multiple_devices_are_prefixed()
    {
        var drv = NewDriver(new FakeTwinCATClientFactory(), false, true, (Host1, "Elma01"), (Host2, null));
        await drv.InitializeAsync("{}", CancellationToken.None);
        await Sample(drv, PlcClient(), Host1);
        await Sample(drv, PlcClient(), Host2);

        var bag = ((IDriverDiagnostics)drv).GetDiagnostics();

        bag["TwinCAT.Elma01"].ShouldBe("Run; Plc30 App; online-changes 7; cycle 10.0 ms; exec 2.5 ms; headroom 7.5 ms");
        bag[$"TwinCAT.{Host2}"].ShouldContain("cycle 10.0 ms");
        bag.ContainsKey("TwinCAT.AdsState").ShouldBeFalse();
    }

    /// <summary>Verifies a runtime without _TaskInfo (older TwinCAT 2) still yields the facts it has, and
    /// the missing symbols are asked for once, not on every probe tick.</summary>
    [Fact]
    public async Task Missing_task_info_gives_a_partial_bag_and_is_not_re_asked()
    {
        var drv = NewDriver(new FakeTwinCATClientFactory(), false, true, (Host1, null));
        await drv.InitializeAsync("{}", CancellationToken.None);
        var client = new FakeTwinCATClient { AdsStateText = "Run" };
        client.Values[TwinCATDriver.SymAppName] = "Plc1";
        client.ReadStatuses[TwinCATDriver.SymCycleTime] = TwinCATStatusMapper.BadNodeIdUnknown;
        client.ReadStatuses[TwinCATDriver.SymLastExecTime] = TwinCATStatusMapper.BadNodeIdUnknown;
        client.ReadStatuses[TwinCATDriver.SymOnlineChangeCnt] = TwinCATStatusMapper.BadNodeIdUnknown;
        // ...and the TwinCAT 2 equivalents are absent too.
        client.ReadStatuses[TwinCATDriver.SymTc2CycleTime] = TwinCATStatusMapper.BadNodeIdUnknown;
        client.ReadStatuses[TwinCATDriver.SymTc2LastExecTime] = TwinCATStatusMapper.BadNodeIdUnknown;
        client.ReadStatuses[TwinCATDriver.SymTc2OnlineChangeCount] = TwinCATStatusMapper.BadNodeIdUnknown;

        await Sample(drv, client, Host1);
        var readsAfterFirst = client.SingleReadCount;
        await Sample(drv, client, Host1);

        var bag = ((IDriverDiagnostics)drv).GetDiagnostics();
        bag["TwinCAT.AdsState"].ShouldBe("Run");
        bag["TwinCAT.AppName"].ShouldBe("Plc1");
        bag.Keys.ShouldNotContain("TwinCAT.CycleTimeMs");
        bag.Keys.ShouldNotContain("TwinCAT.HeadroomMs");
        client.SingleReadCount.ShouldBe(readsAfterFirst + 1); // only AppName is read again
    }

    /// <summary>hw2 live gate (TC2 2.11 Elma Z34834): a TwinCAT 2 runtime has no TwinCAT_SystemInfoVarList but
    /// serves the same facts as `.SYSTEMINFO` / `.SYSTEMTASKINFOARR[1]`; the bag must be filled from those, and
    /// after the first tick only the TC2 names are read (4 reads, not 8).</summary>
    [Fact]
    public async Task TwinCAT2_system_globals_fill_the_bag_when_the_TC3_names_are_absent()
    {
        var drv = NewDriver(new FakeTwinCATClientFactory(), false, true, (Host1, null));
        await drv.InitializeAsync("{}", CancellationToken.None);
        var client = new FakeTwinCATClient { AdsStateText = "Run" };
        foreach (var tc3 in new[] { TwinCATDriver.SymAppName, TwinCATDriver.SymOnlineChangeCnt, TwinCATDriver.SymCycleTime, TwinCATDriver.SymLastExecTime })
            client.ReadStatuses[tc3] = TwinCATStatusMapper.BadNodeIdUnknown;
        client.Values[TwinCATDriver.SymTc2ProjectName] = "ELMA_5STAGE";
        client.Values[TwinCATDriver.SymTc2OnlineChangeCount] = (ushort)3;
        client.Values[TwinCATDriver.SymTc2CycleTime] = 100_000u;  // 10.0 ms
        client.Values[TwinCATDriver.SymTc2LastExecTime] = 40_000u; // 4.0 ms

        await Sample(drv, client, Host1);
        var readsAfterFirst = client.SingleReadCount;
        await Sample(drv, client, Host1);

        var bag = ((IDriverDiagnostics)drv).GetDiagnostics();
        bag["TwinCAT.AppName"].ShouldBe("ELMA_5STAGE");
        bag["TwinCAT.OnlineChangeCnt"].ShouldBe("3");
        bag["TwinCAT.CycleTimeMs"].ShouldBe("10.0");
        bag["TwinCAT.LastExecTimeMs"].ShouldBe("4.0");
        bag["TwinCAT.HeadroomMs"].ShouldBe("6.0");
        readsAfterFirst.ShouldBe(8);
        client.SingleReadCount.ShouldBe(readsAfterFirst + 4);
    }

    /// <summary>A TC3 target that serves TwinCAT_SystemInfoVarList is never asked for the TC2 names.</summary>
    [Fact]
    public async Task A_TC3_target_never_reads_the_TwinCAT2_names()
    {
        var drv = NewDriver(new FakeTwinCATClientFactory(), false, true, (Host1, null));
        await drv.InitializeAsync("{}", CancellationToken.None);
        var client = PlcClient();

        await Sample(drv, client, Host1);

        client.SingleReadCount.ShouldBe(4);
    }

    /// <summary>Verifies a failed sample keeps the previous snapshot rather than blanking the bag.</summary>
    [Fact]
    public async Task Failed_sample_keeps_the_last_values()
    {
        var drv = NewDriver(new FakeTwinCATClientFactory(), false, true, (Host1, null));
        await drv.InitializeAsync("{}", CancellationToken.None);
        var client = PlcClient();
        await Sample(drv, client, Host1);

        client.ThrowOnRead = true;
        client.AdsStateText = null;
        await Sample(drv, client, Host1);

        var bag = ((IDriverDiagnostics)drv).GetDiagnostics();
        bag["TwinCAT.CycleTimeMs"].ShouldBe("10.0");
        bag["TwinCAT.AdsState"].ShouldBe("Run");
    }

    /// <summary>Verifies the probe loop itself fills the bag — no manual sampling.</summary>
    [Fact]
    public async Task Probe_loop_populates_the_bag()
    {
        var factory = new FakeTwinCATClientFactory { Customise = PlcClient };
        var drv = NewDriver(factory, true, true, (Host1, null));
        await drv.InitializeAsync("{}", CancellationToken.None);
        try
        {
            IReadOnlyDictionary<string, string> bag = new Dictionary<string, string>();
            for (var i = 0; i < 100 && bag.Count == 0; i++)
            {
                await Task.Delay(50);
                bag = ((IDriverDiagnostics)drv).GetDiagnostics();
            }
            bag["TwinCAT.OnlineChangeCnt"].ShouldBe("7");
        }
        finally { await drv.ShutdownAsync(CancellationToken.None); }
    }

    /// <summary>Verifies a bag for the maximum number of devices fits the host's cap (one line per device).</summary>
    [Fact]
    public async Task Many_devices_all_fit_the_bag_cap()
    {
        var hosts = Enumerable.Range(1, 12).Select(i => ($"ads://5.23.91.{i}.1.1:851", (string?)$"D{i}")).ToArray();
        var drv = NewDriver(new FakeTwinCATClientFactory(), false, true, hosts);
        await drv.InitializeAsync("{}", CancellationToken.None);
        foreach (var (host, _) in hosts) await Sample(drv, PlcClient(), host);

        var bag = DriverDiagnostics.Bound(((IDriverDiagnostics)drv).GetDiagnostics());

        bag.Count.ShouldBe(12);
    }

    /// <summary>Verifies sampling is opt-in: with it off the probe loop adds no reads and the bag stays empty.</summary>
    [Fact]
    public async Task Disabled_by_default_adds_no_reads()
    {
        var factory = new FakeTwinCATClientFactory { Customise = PlcClient };
        var drv = NewDriver(factory, true, false, (Host1, null));
        await drv.InitializeAsync("{}", CancellationToken.None);
        try
        {
            for (var i = 0; i < 100 && drv.GetHostStatuses().All(h => h.State != HostState.Running); i++)
                await Task.Delay(20);
            await Task.Delay(100); // several more probe ticks
        }
        finally { await drv.ShutdownAsync(CancellationToken.None); }

        factory.Clients[0].SingleReadCount.ShouldBe(0);
        ((IDriverDiagnostics)drv).GetDiagnostics().ShouldBeEmpty();
    }

    /// <summary>Verifies a symbol the PLC did not export is asked for again once the client is rebuilt.</summary>
    [Fact]
    public async Task Unavailable_symbols_are_cleared_when_a_new_client_is_installed()
    {
        var factory = new FakeTwinCATClientFactory();
        var drv = new TwinCATDriver(new TwinCATDriverOptions
        {
            Devices = [new TwinCATDeviceOptions(Host1)],
            RawTags = TwinCATRawTags.Entries([new TwinCATTagDefinition("A", Host1, "MAIN.A", TwinCATDataType.DInt)]),
            Probe = new TwinCATProbeOptions { Enabled = false },
            DiagnosticsEnabled = true,
        }, "drv-diag", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);
        var first = new FakeTwinCATClient();
        first.ReadStatuses[TwinCATDriver.SymCycleTime] = TwinCATStatusMapper.BadNodeIdUnknown;
        factory.Customise = () => first;
        await drv.ReadAsync(["A"], CancellationToken.None); // installs the first client
        await Sample(drv, first, Host1);
        drv.GetDeviceState(Host1)!.UnavailableDiagSymbols.ContainsKey(TwinCATDriver.SymCycleTime).ShouldBeTrue();

        first.SimulateWireDrop();
        factory.Customise = () => new FakeTwinCATClient();
        await drv.ReadAsync(["A"], CancellationToken.None); // reconnect installs a new client

        drv.GetDeviceState(Host1)!.UnavailableDiagSymbols.ShouldBeEmpty();
    }
}