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

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

[Trait("Category", "Unit")]
public sealed class AbCipDriverReadTests
{
    private static (AbCipDriver drv, FakeAbCipTagFactory factory) NewDriver(params AbCipTagDefinition[] tags)
    {
        var factory = new FakeAbCipTagFactory();
        var opts = new AbCipDriverOptions
        {
            Devices = [new AbCipDeviceOptions("ab://10.0.0.5/1,0")],
            Tags = tags,
        };
        var drv = new AbCipDriver(opts, "drv-1", factory);
        return (drv, factory);
    }

    [Fact]
    public async Task Unknown_reference_maps_to_BadNodeIdUnknown()
    {
        var (drv, _) = NewDriver();
        await drv.InitializeAsync("{}", CancellationToken.None);

        var snapshots = await drv.ReadAsync(["does-not-exist"], CancellationToken.None);

        snapshots.Single().StatusCode.ShouldBe(AbCipStatusMapper.BadNodeIdUnknown);
        snapshots.Single().Value.ShouldBeNull();
    }

    [Fact]
    public async Task Tag_on_unknown_device_maps_to_BadNodeIdUnknown()
    {
        var factory = new FakeAbCipTagFactory();
        var opts = new AbCipDriverOptions
        {
            Devices = [new AbCipDeviceOptions("ab://10.0.0.5/1,0")],
            Tags = [new AbCipTagDefinition("Orphan", "ab://10.0.0.99/1,0", "Tag1", AbCipDataType.DInt)],
        };
        var drv = new AbCipDriver(opts, "drv-1", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);

        var snapshots = await drv.ReadAsync(["Orphan"], CancellationToken.None);
        snapshots.Single().StatusCode.ShouldBe(AbCipStatusMapper.BadNodeIdUnknown);
    }

    [Fact]
    public async Task Successful_DInt_read_returns_Good_with_value()
    {
        var (drv, factory) = NewDriver(
            new AbCipTagDefinition("Speed", "ab://10.0.0.5/1,0", "Motor1.Speed", AbCipDataType.DInt));
        await drv.InitializeAsync("{}", CancellationToken.None);

        // Customise the fake before the first read so the tag returns 4200.
        factory.Customise = p => new FakeAbCipTag(p) { Value = 4200 };

        var snapshots = await drv.ReadAsync(["Speed"], CancellationToken.None);

        snapshots.Single().StatusCode.ShouldBe(AbCipStatusMapper.Good);
        snapshots.Single().Value.ShouldBe(4200);
        factory.Tags["Motor1.Speed"].InitializeCount.ShouldBe(1);
        factory.Tags["Motor1.Speed"].ReadCount.ShouldBe(1);
    }

    [Fact]
    public async Task Repeat_read_reuses_runtime_without_reinitialise()
    {
        var (drv, factory) = NewDriver(
            new AbCipTagDefinition("Speed", "ab://10.0.0.5/1,0", "Motor1.Speed", AbCipDataType.DInt));
        await drv.InitializeAsync("{}", CancellationToken.None);
        factory.Customise = p => new FakeAbCipTag(p) { Value = 1 };

        await drv.ReadAsync(["Speed"], CancellationToken.None);
        await drv.ReadAsync(["Speed"], CancellationToken.None);
        await drv.ReadAsync(["Speed"], CancellationToken.None);

        factory.Tags["Motor1.Speed"].InitializeCount.ShouldBe(1); // lazy init happens once
        factory.Tags["Motor1.Speed"].ReadCount.ShouldBe(3);
    }

    [Fact]
    public async Task NonZero_libplctag_status_maps_via_AbCipStatusMapper()
    {
        var (drv, factory) = NewDriver(
            new AbCipTagDefinition("Ghost", "ab://10.0.0.5/1,0", "Missing.Tag", AbCipDataType.DInt));
        await drv.InitializeAsync("{}", CancellationToken.None);
        factory.Customise = p => new FakeAbCipTag(p) { Status = -14 /* PLCTAG_ERR_NOT_FOUND */ };

        var snapshots = await drv.ReadAsync(["Ghost"], CancellationToken.None);

        snapshots.Single().StatusCode.ShouldBe(AbCipStatusMapper.BadNodeIdUnknown);
        snapshots.Single().Value.ShouldBeNull();
    }

    [Fact]
    public async Task Exception_during_read_surfaces_BadCommunicationError()
    {
        var (drv, factory) = NewDriver(
            new AbCipTagDefinition("Broken", "ab://10.0.0.5/1,0", "Broken", AbCipDataType.Real));
        await drv.InitializeAsync("{}", CancellationToken.None);
        factory.Customise = p => new FakeAbCipTag(p) { ThrowOnRead = true };

        var snapshots = await drv.ReadAsync(["Broken"], CancellationToken.None);

        snapshots.Single().StatusCode.ShouldBe(AbCipStatusMapper.BadCommunicationError);
        snapshots.Single().Value.ShouldBeNull();
        drv.GetHealth().State.ShouldBe(DriverState.Degraded);
    }

    [Fact]
    public async Task Batched_reads_preserve_order_and_per_tag_status()
    {
        var (drv, factory) = NewDriver(
            new AbCipTagDefinition("A", "ab://10.0.0.5/1,0", "A", AbCipDataType.DInt),
            new AbCipTagDefinition("B", "ab://10.0.0.5/1,0", "B", AbCipDataType.Real),
            new AbCipTagDefinition("C", "ab://10.0.0.5/1,0", "C", AbCipDataType.String));
        await drv.InitializeAsync("{}", CancellationToken.None);
        factory.Customise = p => p.TagName switch
        {
            "A" => new FakeAbCipTag(p) { Value = 42 },
            "B" => new FakeAbCipTag(p) { Value = 3.14f },
            _ => new FakeAbCipTag(p) { Value = "hello" },
        };

        var snapshots = await drv.ReadAsync(["A", "B", "C"], CancellationToken.None);

        snapshots.Count.ShouldBe(3);
        snapshots[0].Value.ShouldBe(42);
        snapshots[1].Value.ShouldBe(3.14f);
        snapshots[2].Value.ShouldBe("hello");
        snapshots.ShouldAllBe(s => s.StatusCode == AbCipStatusMapper.Good);
    }

    [Fact]
    public async Task Successful_read_marks_health_Healthy()
    {
        var (drv, factory) = NewDriver(
            new AbCipTagDefinition("Pressure", "ab://10.0.0.5/1,0", "PT_101", AbCipDataType.Real));
        await drv.InitializeAsync("{}", CancellationToken.None);
        factory.Customise = p => new FakeAbCipTag(p) { Value = 14.7f };

        await drv.ReadAsync(["Pressure"], CancellationToken.None);
        drv.GetHealth().State.ShouldBe(DriverState.Healthy);
        drv.GetHealth().LastSuccessfulRead.ShouldNotBeNull();
    }

    [Fact]
    public async Task TagCreateParams_are_built_from_device_and_profile()
    {
        var (drv, factory) = NewDriver(
            new AbCipTagDefinition("Counter", "ab://10.0.0.5/1,0", "Program:P.Counter", AbCipDataType.DInt));
        await drv.InitializeAsync("{}", CancellationToken.None);

        await drv.ReadAsync(["Counter"], CancellationToken.None);

        var p = factory.Tags["Program:P.Counter"].CreationParams;
        p.Gateway.ShouldBe("10.0.0.5");
        p.Port.ShouldBe(44818);
        p.CipPath.ShouldBe("1,0");
        p.LibplctagPlcAttribute.ShouldBe("controllogix");
        p.TagName.ShouldBe("Program:P.Counter");
    }

    [Fact]
    public async Task Slice_tag_reads_one_array_and_decodes_n_elements()
    {
        // PR abcip-1.3 — `Data[0..3]` slice routes through AbCipArrayReadPlanner: one libplctag
        // tag-create at TagName="Data[0]" with ElementCount=4, single PLC read, contiguous
        // buffer decoded at element stride into one snapshot whose Value is an object?[].
        var (drv, factory) = NewDriver(
            new AbCipTagDefinition("DataSlice", "ab://10.0.0.5/1,0", "Data[0..3]", AbCipDataType.DInt));
        await drv.InitializeAsync("{}", CancellationToken.None);
        factory.Customise = p =>
        {
            var t = new FakeAbCipTag(p);
            t.ValuesByOffset[0] = 10;
            t.ValuesByOffset[4] = 20;
            t.ValuesByOffset[8] = 30;
            t.ValuesByOffset[12] = 40;
            return t;
        };

        var snapshots = await drv.ReadAsync(["DataSlice"], CancellationToken.None);

        snapshots.Single().StatusCode.ShouldBe(AbCipStatusMapper.Good);
        var values = snapshots.Single().Value.ShouldBeOfType<object?[]>();
        values.ShouldBe(new object?[] { 10, 20, 30, 40 });

        // Exactly ONE libplctag tag was created — anchored at the slice start with
        // ElementCount=4. Without the planner this would have been four scalar reads.
        factory.Tags.Count.ShouldBe(1);
        factory.Tags.ShouldContainKey("Data[0]");
        factory.Tags["Data[0]"].CreationParams.ElementCount.ShouldBe(4);
        factory.Tags["Data[0]"].ReadCount.ShouldBe(1);
    }

    [Fact]
    public async Task Slice_tag_with_unsupported_element_type_returns_BadNotSupported()
    {
        // BOOL slices can't be laid out from the declaration alone (Logix packs BOOLs into a
        // hidden host byte). The planner refuses; the driver surfaces BadNotSupported instead
        // of attempting a best-effort decode.
        var (drv, _) = NewDriver(
            new AbCipTagDefinition("BoolSlice", "ab://10.0.0.5/1,0", "Flags[0..7]", AbCipDataType.Bool));
        await drv.InitializeAsync("{}", CancellationToken.None);

        var snapshots = await drv.ReadAsync(["BoolSlice"], CancellationToken.None);

        snapshots.Single().StatusCode.ShouldBe(AbCipStatusMapper.BadNotSupported);
        snapshots.Single().Value.ShouldBeNull();
    }

    [Fact]
    public async Task Cancellation_propagates_from_read()
    {
        var (drv, factory) = NewDriver(
            new AbCipTagDefinition("Slow", "ab://10.0.0.5/1,0", "Slow", AbCipDataType.DInt));
        await drv.InitializeAsync("{}", CancellationToken.None);
        factory.Customise = p => new FakeAbCipTag(p)
        {
            ThrowOnRead = true,
            Exception = new OperationCanceledException(),
        };

        using var cts = new CancellationTokenSource();
        await Should.ThrowAsync<OperationCanceledException>(
            () => drv.ReadAsync(["Slow"], cts.Token));
    }

    [Fact]
    public async Task ShutdownAsync_disposes_each_tag_runtime()
    {
        var (drv, factory) = NewDriver(
            new AbCipTagDefinition("A", "ab://10.0.0.5/1,0", "A", AbCipDataType.DInt),
            new AbCipTagDefinition("B", "ab://10.0.0.5/1,0", "B", AbCipDataType.DInt));
        await drv.InitializeAsync("{}", CancellationToken.None);
        factory.Customise = p => new FakeAbCipTag(p) { Value = 1 };
        await drv.ReadAsync(["A", "B"], CancellationToken.None);

        await drv.ShutdownAsync(CancellationToken.None);

        factory.Tags["A"].Disposed.ShouldBeTrue();
        factory.Tags["B"].Disposed.ShouldBeTrue();
    }

    [Fact]
    public async Task Initialize_failure_disposes_tag_and_surfaces_communication_error()
    {
        var (drv, factory) = NewDriver(
            new AbCipTagDefinition("DoomedTag", "ab://10.0.0.5/1,0", "Nope", AbCipDataType.DInt));
        await drv.InitializeAsync("{}", CancellationToken.None);
        factory.Customise = p => new FakeAbCipTag(p) { ThrowOnInitialize = true };

        var snapshots = await drv.ReadAsync(["DoomedTag"], CancellationToken.None);

        snapshots.Single().StatusCode.ShouldBe(AbCipStatusMapper.BadCommunicationError);
        factory.Tags["Nope"].Disposed.ShouldBeTrue();
    }

    // PR abcip-1.2 — STRINGnn variant decoding. Threading <see cref="AbCipTagDefinition.StringLength"/>
    // through libplctag's StringMaxCapacity attribute lets STRING_20 / STRING_40 / STRING_80 UDTs
    // decode against the right DATA-array size; null preserves the default 82-byte STRING.

    [Fact]
    public async Task StringLength_threads_into_TagCreateParams_StringMaxCapacity()
    {
        var (drv, factory) = NewDriver(
            new AbCipTagDefinition("Banner", "ab://10.0.0.5/1,0", "Banner", AbCipDataType.String,
                StringLength: 40));
        await drv.InitializeAsync("{}", CancellationToken.None);
        factory.Customise = p => new FakeAbCipTag(p) { Value = "hello" };

        await drv.ReadAsync(["Banner"], CancellationToken.None);

        factory.Tags["Banner"].CreationParams.StringMaxCapacity.ShouldBe(40);
    }

    [Fact]
    public async Task StringLength_null_leaves_StringMaxCapacity_null_for_back_compat()
    {
        var (drv, factory) = NewDriver(
            new AbCipTagDefinition("LegacyStr", "ab://10.0.0.5/1,0", "LegacyStr", AbCipDataType.String));
        await drv.InitializeAsync("{}", CancellationToken.None);
        factory.Customise = p => new FakeAbCipTag(p) { Value = "world" };

        await drv.ReadAsync(["LegacyStr"], CancellationToken.None);

        factory.Tags["LegacyStr"].CreationParams.StringMaxCapacity.ShouldBeNull();
    }

    [Fact]
    public async Task StringLength_ignored_for_non_String_data_types()
    {
        // StringLength on a DINT-typed tag must not flow into StringMaxCapacity — libplctag would
        // otherwise re-shape the buffer and corrupt the read. EnsureTagRuntimeAsync gates on the
        // declared DataType.
        var (drv, factory) = NewDriver(
            new AbCipTagDefinition("Speed", "ab://10.0.0.5/1,0", "Speed", AbCipDataType.DInt,
                StringLength: 80));
        await drv.InitializeAsync("{}", CancellationToken.None);
        factory.Customise = p => new FakeAbCipTag(p) { Value = 7 };

        await drv.ReadAsync(["Speed"], CancellationToken.None);

        factory.Tags["Speed"].CreationParams.StringMaxCapacity.ShouldBeNull();
    }

    [Fact]
    public async Task UDT_member_StringLength_threads_through_to_member_runtime()
    {
        // STRINGnn members of a UDT — declaration-driven fan-out copies StringLength from
        // AbCipStructureMember onto the synthesised member AbCipTagDefinition; the per-member
        // runtime then receives the right StringMaxCapacity.
        var udt = new AbCipTagDefinition(
            Name: "Recipe",
            DeviceHostAddress: "ab://10.0.0.5/1,0",
            TagPath: "Recipe",
            DataType: AbCipDataType.Structure,
            Members: [
                new AbCipStructureMember("Name", AbCipDataType.String, StringLength: 20),
                new AbCipStructureMember("Description", AbCipDataType.String, StringLength: 80),
                new AbCipStructureMember("Code", AbCipDataType.DInt),
            ]);
        var (drv, factory) = NewDriver(udt);
        await drv.InitializeAsync("{}", CancellationToken.None);
        factory.Customise = p => new FakeAbCipTag(p) { Value = "x" };

        await drv.ReadAsync(["Recipe.Name", "Recipe.Description", "Recipe.Code"], CancellationToken.None);

        factory.Tags["Recipe.Name"].CreationParams.StringMaxCapacity.ShouldBe(20);
        factory.Tags["Recipe.Description"].CreationParams.StringMaxCapacity.ShouldBe(80);
        factory.Tags["Recipe.Code"].CreationParams.StringMaxCapacity.ShouldBeNull();
    }
}