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 FocasToolingOffsetsFixedTreeTests
{
    private const string Host = "focas://10.0.0.7:8193";

    /// <summary>
    ///     Variant of <see cref="FakeFocasClient"/> that returns configurable
    ///     <see cref="FocasToolingInfo"/> + <see cref="FocasWorkOffsetsInfo"/> snapshots
    ///     for the F1-d Tooling/CurrentTool + Offsets/ fixed-tree (issue #260).
    /// </summary>
    private sealed class ToolingAwareFakeFocasClient : FakeFocasClient, IFocasClient
    {
        public FocasToolingInfo? Tooling { get; set; }
        public FocasWorkOffsetsInfo? WorkOffsets { get; set; }

        Task<FocasToolingInfo?> IFocasClient.GetToolingAsync(CancellationToken ct) =>
            Task.FromResult(Tooling);

        Task<FocasWorkOffsetsInfo?> IFocasClient.GetWorkOffsetsAsync(CancellationToken ct) =>
            Task.FromResult(WorkOffsets);
    }

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

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

        builder.Folders.ShouldContain(f => f.BrowseName == "Tooling" && f.DisplayName == "Tooling");
        var toolingVars = builder.Variables.Where(v =>
            v.Info.FullName.Contains("::Tooling/")).ToList();
        toolingVars.Count.ShouldBe(1);
        var node = toolingVars.Single();
        node.BrowseName.ShouldBe("CurrentTool");
        node.Info.DriverDataType.ShouldBe(DriverDataType.Int16);
        node.Info.SecurityClass.ShouldBe(SecurityClassification.ViewOnly);
        node.Info.FullName.ShouldBe($"{Host}::Tooling/CurrentTool");
    }

    [Fact]
    public async Task DiscoverAsync_emits_Offsets_folder_with_G54_to_G59_each_with_3_axes()
    {
        // Six standard slots (G54..G59) * three axes (X/Y/Z) = 18 Float64 nodes per
        // device. Extended G54.1 P1..P48 deferred per the F1-d plan.
        var builder = new RecordingBuilder();
        var drv = new FocasDriver(new FocasDriverOptions
        {
            Devices = [new FocasDeviceOptions(Host, DeviceName: "Mill-1")],
            Tags = [],
            Probe = new FocasProbeOptions { Enabled = false },
        }, "drv-offsets", new FakeFocasClientFactory());
        await drv.InitializeAsync("{}", CancellationToken.None);

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

        builder.Folders.ShouldContain(f => f.BrowseName == "Offsets");
        string[] expectedSlots = ["G54", "G55", "G56", "G57", "G58", "G59"];
        foreach (var slot in expectedSlots)
            builder.Folders.ShouldContain(f => f.BrowseName == slot);
        var offsetVars = builder.Variables.Where(v =>
            v.Info.FullName.Contains("::Offsets/")).ToList();
        offsetVars.Count.ShouldBe(6 * 3);
        foreach (var slot in expectedSlots)
        foreach (var axis in new[] { "X", "Y", "Z" })
        {
            var fullRef = $"{Host}::Offsets/{slot}/{axis}";
            var node = offsetVars.SingleOrDefault(v => v.Info.FullName == fullRef);
            node.Info.DriverDataType.ShouldBe(DriverDataType.Float64);
            node.Info.SecurityClass.ShouldBe(SecurityClassification.ViewOnly);
        }
    }

    [Fact]
    public async Task ReadAsync_serves_Tooling_and_Offsets_fields_from_cached_snapshot()
    {
        var fake = new ToolingAwareFakeFocasClient
        {
            Tooling = new FocasToolingInfo(CurrentTool: 17),
            WorkOffsets = new FocasWorkOffsetsInfo(
            [
                new FocasWorkOffset("G54", X: 100.5, Y: 200.25, Z: -50.0),
                new FocasWorkOffset("G55", X: 0,     Y: 0,      Z: 0),
                new FocasWorkOffset("G56", X: 0,     Y: 0,      Z: 0),
                new FocasWorkOffset("G57", X: 0,     Y: 0,      Z: 0),
                new FocasWorkOffset("G58", X: 0,     Y: 0,      Z: 0),
                new FocasWorkOffset("G59", X: 1,     Y: 2,      Z: 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(50) },
        }, "drv-tooling-read", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);

        // Wait for at least one probe tick to populate both caches.
        await WaitForAsync(async () =>
        {
            var snap = (await drv.ReadAsync(
                [$"{Host}::Tooling/CurrentTool"], CancellationToken.None)).Single();
            return snap.StatusCode == FocasStatusMapper.Good;
        }, TimeSpan.FromSeconds(3));

        var refs = new[]
        {
            $"{Host}::Tooling/CurrentTool",
            $"{Host}::Offsets/G54/X",
            $"{Host}::Offsets/G54/Y",
            $"{Host}::Offsets/G54/Z",
            $"{Host}::Offsets/G59/X",
        };
        var snaps = await drv.ReadAsync(refs, CancellationToken.None);

        snaps[0].Value.ShouldBe((short)17);
        snaps[1].Value.ShouldBe(100.5);
        snaps[2].Value.ShouldBe(200.25);
        snaps[3].Value.ShouldBe(-50.0);
        snaps[4].Value.ShouldBe(1.0);
        foreach (var s in snaps) s.StatusCode.ShouldBe(FocasStatusMapper.Good);

        await drv.ShutdownAsync(CancellationToken.None);
    }

    [Fact]
    public async Task ReadAsync_returns_BadCommunicationError_when_caches_are_empty()
    {
        // Probe disabled — neither tooling nor offsets caches populate; the nodes
        // still resolve as known references but report Bad until the first poll.
        var drv = new FocasDriver(new FocasDriverOptions
        {
            Devices = [new FocasDeviceOptions(Host)],
            Tags = [],
            Probe = new FocasProbeOptions { Enabled = false },
        }, "drv-empty-tooling", new FakeFocasClientFactory());
        await drv.InitializeAsync("{}", CancellationToken.None);

        var snaps = await drv.ReadAsync(
            [$"{Host}::Tooling/CurrentTool", $"{Host}::Offsets/G54/X"], CancellationToken.None);
        snaps[0].StatusCode.ShouldBe(FocasStatusMapper.BadCommunicationError);
        snaps[1].StatusCode.ShouldBe(FocasStatusMapper.BadCommunicationError);
    }

    [Fact]
    public async Task FwlibFocasClient_GetTooling_and_GetWorkOffsets_return_null_when_disconnected()
    {
        // Construction is licence-safe (no DLL load); the unconnected client must
        // short-circuit before P/Invoke. Returns null → driver leaves the cache
        // untouched, matching the policy in f1a/f1b/f1c.
        var client = new FwlibFocasClient();
        (await client.GetToolingAsync(CancellationToken.None)).ShouldBeNull();
        (await client.GetWorkOffsetsAsync(CancellationToken.None)).ShouldBeNull();
    }

    [Fact]
    public void DecodeOfsbAxis_applies_decimal_point_count_like_macro_decode()
    {
        // Layout per fwlib32.h: int data, short dec, short unit, short disp = 10 bytes.
        // Three axes (X=12345 / dec=3 = 12.345; Y=-500 / dec=2 = -5.00; Z=0 / dec=0 = 0).
        var buf = new byte[80];
        WriteAxis(buf, 0, raw: 12345, dec: 3);
        WriteAxis(buf, 1, raw: -500,  dec: 2);
        WriteAxis(buf, 2, raw: 0,     dec: 0);

        FwlibFocasClient.DecodeOfsbAxis(buf, 0).ShouldBe(12.345, tolerance: 1e-9);
        FwlibFocasClient.DecodeOfsbAxis(buf, 1).ShouldBe(-5.0, tolerance: 1e-9);
        FwlibFocasClient.DecodeOfsbAxis(buf, 2).ShouldBe(0.0, tolerance: 1e-9);
    }

    private static void WriteAxis(byte[] buf, int axisIndex, int raw, short dec)
    {
        var offset = axisIndex * 10;
        System.Buffers.Binary.BinaryPrimitives.WriteInt32LittleEndian(buf.AsSpan(offset, 4), raw);
        System.Buffers.Binary.BinaryPrimitives.WriteInt16LittleEndian(buf.AsSpan(offset + 4, 2), dec);
    }

    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) { } }
    }
}