using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Driver.FOCAS;

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

[Trait("Category", "Unit")]
public sealed class FocasFigureScalingDiagnosticsTests
{
    private const string Host = "focas://10.0.0.7:8193";

    /// <summary>
    ///     Variant of <see cref="FakeFocasClient"/> that returns configurable
    ///     per-axis figure scaling for the F1-f cache + diagnostics surface
    ///     (issue #262).
    /// </summary>
    private sealed class FigureAwareFakeFocasClient : FakeFocasClient, IFocasClient
    {
        public IReadOnlyDictionary<string, int>? Scaling { get; set; }

        Task<IReadOnlyDictionary<string, int>?> IFocasClient.GetFigureScalingAsync(CancellationToken ct) =>
            Task.FromResult(Scaling);
    }

    [Fact]
    public async Task DiscoverAsync_emits_Diagnostics_subtree_with_five_counters()
    {
        var builder = new RecordingBuilder();
        var drv = new FocasDriver(new FocasDriverOptions
        {
            Devices = [new FocasDeviceOptions(Host, DeviceName: "Mill-1")],
            Tags = [],
            Probe = new FocasProbeOptions { Enabled = false },
        }, "drv-diag", new FakeFocasClientFactory());
        await drv.InitializeAsync("{}", CancellationToken.None);

        await drv.DiscoverAsync(builder, CancellationToken.None);

        builder.Folders.ShouldContain(f => f.BrowseName == "Diagnostics" && f.DisplayName == "Diagnostics");
        var diagVars = builder.Variables.Where(v =>
            v.Info.FullName.Contains("::Diagnostics/")).ToList();
        diagVars.Count.ShouldBe(5);

        // Verify per-field types match the documented surface (Int64 counters,
        // String error message, DateTime last-success timestamp).
        diagVars.Single(v => v.BrowseName == "ReadCount")
            .Info.DriverDataType.ShouldBe(DriverDataType.Int64);
        diagVars.Single(v => v.BrowseName == "ReadFailureCount")
            .Info.DriverDataType.ShouldBe(DriverDataType.Int64);
        diagVars.Single(v => v.BrowseName == "ReconnectCount")
            .Info.DriverDataType.ShouldBe(DriverDataType.Int64);
        diagVars.Single(v => v.BrowseName == "LastErrorMessage")
            .Info.DriverDataType.ShouldBe(DriverDataType.String);
        diagVars.Single(v => v.BrowseName == "LastSuccessfulRead")
            .Info.DriverDataType.ShouldBe(DriverDataType.DateTime);

        foreach (var v in diagVars)
            v.Info.SecurityClass.ShouldBe(SecurityClassification.ViewOnly);
    }

    [Fact]
    public async Task ReadAsync_publishes_diagnostics_counters_after_probe_ticks()
    {
        // Probe enabled — successful ticks bump ReadCount + LastSuccessfulRead;
        // ReconnectCount bumps once on the initial connect (issue #262).
        var fake = new FakeFocasClient { ProbeResult = true };
        var factory = new FakeFocasClientFactory { Customise = () => fake };
        var drv = new FocasDriver(new FocasDriverOptions
        {
            Devices = [new FocasDeviceOptions(Host)],
            Tags = [],
            Probe = new FocasProbeOptions { Enabled = true, Interval = TimeSpan.FromMilliseconds(30) },
        }, "drv-diag-read", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);

        // Wait for at least 2 successful probe ticks so ReadCount > 0 deterministically.
        await WaitForAsync(async () =>
        {
            var snap = (await drv.ReadAsync(
                [$"{Host}::Diagnostics/ReadCount"], CancellationToken.None)).Single();
            return snap.Value is long n && n >= 2;
        }, TimeSpan.FromSeconds(3));

        var refs = new[]
        {
            $"{Host}::Diagnostics/ReadCount",
            $"{Host}::Diagnostics/ReadFailureCount",
            $"{Host}::Diagnostics/ReconnectCount",
            $"{Host}::Diagnostics/LastErrorMessage",
            $"{Host}::Diagnostics/LastSuccessfulRead",
        };
        var snaps = await drv.ReadAsync(refs, CancellationToken.None);

        ((long)snaps[0].Value!).ShouldBeGreaterThanOrEqualTo(2);
        ((long)snaps[1].Value!).ShouldBe(0); // no failures on a healthy probe
        ((long)snaps[2].Value!).ShouldBe(1); // one initial connect
        snaps[3].Value.ShouldBe(string.Empty);
        ((DateTime)snaps[4].Value!).ShouldBeGreaterThan(DateTime.MinValue);

        foreach (var s in snaps) s.StatusCode.ShouldBe(FocasStatusMapper.Good);

        await drv.ShutdownAsync(CancellationToken.None);
    }

    [Fact]
    public async Task ReadAsync_increments_ReadFailureCount_when_probe_returns_false()
    {
        // ProbeResult=false → success branch is skipped, ReadFailureCount bumps each
        // tick. The connect itself succeeded so ReconnectCount is 1.
        var fake = new FakeFocasClient { ProbeResult = false };
        var factory = new FakeFocasClientFactory { Customise = () => fake };
        var drv = new FocasDriver(new FocasDriverOptions
        {
            Devices = [new FocasDeviceOptions(Host)],
            Tags = [],
            Probe = new FocasProbeOptions { Enabled = true, Interval = TimeSpan.FromMilliseconds(30) },
        }, "drv-diag-fail", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);

        await WaitForAsync(async () =>
        {
            var snap = (await drv.ReadAsync(
                [$"{Host}::Diagnostics/ReadFailureCount"], CancellationToken.None)).Single();
            return snap.Value is long n && n >= 2;
        }, TimeSpan.FromSeconds(3));

        var snaps = await drv.ReadAsync(
            [$"{Host}::Diagnostics/ReadCount", $"{Host}::Diagnostics/ReadFailureCount"],
            CancellationToken.None);
        ((long)snaps[0].Value!).ShouldBe(0);
        ((long)snaps[1].Value!).ShouldBeGreaterThanOrEqualTo(2);

        await drv.ShutdownAsync(CancellationToken.None);
    }

    [Fact]
    public async Task ApplyFigureScaling_divides_raw_position_by_ten_to_the_decimal_places()
    {
        // Cache populated via probe-tick GetFigureScalingAsync. ApplyFigureScaling
        // default is true → rawValue / 10^dec for the named axis (issue #262).
        var fake = new FigureAwareFakeFocasClient
        {
            Scaling = new Dictionary<string, int>(StringComparer.OrdinalIgnoreCase)
            {
                ["axis1"] = 3,  // X-axis: 3 decimal places (mm * 1000)
                ["axis2"] = 4,  // Y-axis: 4 decimal places
            },
        };
        var factory = new FakeFocasClientFactory { Customise = () => fake };
        var drv = new FocasDriver(new FocasDriverOptions
        {
            Devices = [new FocasDeviceOptions(Host)],
            Tags = [],
            Probe = new FocasProbeOptions { Enabled = true, Interval = TimeSpan.FromMilliseconds(30) },
        }, "drv-fig", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);

        // Wait for the probe-tick path to populate the cache (one successful tick is
        // enough — the figure-scaling read happens whenever the cache is null).
        await WaitForAsync(async () =>
        {
            var snap = (await drv.ReadAsync(
                [$"{Host}::Diagnostics/ReadCount"], CancellationToken.None)).Single();
            return snap.Value is long n && n >= 1;
        }, TimeSpan.FromSeconds(3));

        // 100000 / 10^3 = 100.0 mm
        drv.ApplyFigureScaling(Host, "axis1", 100000).ShouldBe(100.0);
        // 250000 / 10^4 = 25.0 mm
        drv.ApplyFigureScaling(Host, "axis2", 250000).ShouldBe(25.0);
        // Unknown axis → raw value passes through.
        drv.ApplyFigureScaling(Host, "axis3", 42).ShouldBe(42.0);

        await drv.ShutdownAsync(CancellationToken.None);
    }

    [Fact]
    public async Task ApplyFigureScaling_returns_raw_when_FixedTreeApplyFigureScaling_is_false()
    {
        // ApplyFigureScaling=false short-circuits before the cache lookup so the raw
        // integer is published unchanged. Migration parity for deployments that already
        // surfaced raw values from older drivers (issue #262).
        var fake = new FigureAwareFakeFocasClient
        {
            Scaling = new Dictionary<string, int> { ["axis1"] = 3 },
        };
        var factory = new FakeFocasClientFactory { Customise = () => fake };
        var drv = new FocasDriver(new FocasDriverOptions
        {
            Devices = [new FocasDeviceOptions(Host)],
            Tags = [],
            Probe = new FocasProbeOptions { Enabled = true, Interval = TimeSpan.FromMilliseconds(30) },
            FixedTree = new FocasFixedTreeOptions { ApplyFigureScaling = false },
        }, "drv-fig-off", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);

        await WaitForAsync(async () =>
        {
            var snap = (await drv.ReadAsync(
                [$"{Host}::Diagnostics/ReadCount"], CancellationToken.None)).Single();
            return snap.Value is long n && n >= 1;
        }, TimeSpan.FromSeconds(3));

        // Even though the cache has axis1 → 3 decimal places, ApplyFigureScaling=false
        // means the raw value passes through unchanged.
        drv.ApplyFigureScaling(Host, "axis1", 100000).ShouldBe(100000.0);

        await drv.ShutdownAsync(CancellationToken.None);
    }

    [Fact]
    public async Task FwlibFocasClient_GetFigureScaling_returns_null_when_disconnected()
    {
        // Construction is licence-safe (no DLL load); the unconnected client must
        // short-circuit before P/Invoke so the driver leaves the cache untouched.
        var client = new FwlibFocasClient();
        (await client.GetFigureScalingAsync(CancellationToken.None)).ShouldBeNull();
    }

    [Fact]
    public void DecodeFigureScaling_extracts_per_axis_decimal_places_from_buffer()
    {
        // Build an IODBAXIS-shaped buffer: 3 axes, decimal places = 3, 4, 0. Per
        // fwlib32.h each axis entry is { short dec, short unit, short reserved,
        // short reserved2 } = 8 bytes; we only read dec.
        var buf = new byte[FwlibNative.MAX_AXIS * 8];
        // Axis 1: dec=3
        buf[0] = 3; buf[1] = 0;
        // Axis 2: dec=4
        buf[8] = 4; buf[9] = 0;
        // Axis 3: dec=0 (already zero)

        var map = FwlibFocasClient.DecodeFigureScaling(buf, count: 3);
        map.Count.ShouldBe(3);
        map["axis1"].ShouldBe(3);
        map["axis2"].ShouldBe(4);
        map["axis3"].ShouldBe(0);

        // Out-of-range count clamps to MAX_AXIS so a malformed CNC reply doesn't
        // overrun the buffer.
        var clamped = FwlibFocasClient.DecodeFigureScaling(buf, count: 99);
        clamped.Count.ShouldBe(FwlibNative.MAX_AXIS);
    }

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

    private sealed class RecordingBuilder : IAddressSpaceBuilder
    {
        public List<(string BrowseName, string DisplayName)> Folders { get; } = new();
        public List<(string BrowseName, DriverAttributeInfo Info)> Variables { get; } = new();

        public IAddressSpaceBuilder Folder(string browseName, string displayName)
        { Folders.Add((browseName, displayName)); return this; }

        public IVariableHandle Variable(string browseName, string displayName, DriverAttributeInfo info)
        { Variables.Add((browseName, info)); return new Handle(info.FullName); }

        public void AddProperty(string _, DriverDataType __, object? ___) { }

        private sealed class Handle(string fullRef) : IVariableHandle
        {
            public string FullReference => fullRef;
            public IAlarmConditionSink MarkAsAlarmCondition(AlarmConditionInfo info) => new NullSink();
        }
        private sealed class NullSink : IAlarmConditionSink { public void OnTransition(AlarmEventArgs args) { } }
    }
}