using Shouldly;
using Xunit;

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

[Trait("Category", "Unit")]
public sealed class AbCipArrayReadPlannerTests
{
    private const string Device = "ab://10.0.0.5/1,0";

    private static AbCipTagCreateParams BaseParams(string tagName) => new(
        Gateway: "10.0.0.5",
        Port: 44818,
        CipPath: "1,0",
        LibplctagPlcAttribute: "controllogix",
        TagName: tagName,
        Timeout: TimeSpan.FromSeconds(5));

    [Fact]
    public void TryBuild_emits_single_tag_create_with_element_count()
    {
        var def = new AbCipTagDefinition("DataSlice", Device, "Data[0..15]", AbCipDataType.DInt);
        var parsed = AbCipTagPath.TryParse(def.TagPath)!;

        var plan = AbCipArrayReadPlanner.TryBuild(def, parsed, BaseParams("Data[0..15]"));

        plan.ShouldNotBeNull();
        plan.ElementType.ShouldBe(AbCipDataType.DInt);
        plan.Stride.ShouldBe(4);
        plan.Slice.Count.ShouldBe(16);
        plan.CreateParams.ElementCount.ShouldBe(16);
        // Anchored at the slice start; libplctag reads N consecutive elements from there.
        plan.CreateParams.TagName.ShouldBe("Data[0]");
    }

    [Fact]
    public void TryBuild_returns_null_when_path_has_no_slice()
    {
        var def = new AbCipTagDefinition("Plain", Device, "Data[3]", AbCipDataType.DInt);
        var parsed = AbCipTagPath.TryParse(def.TagPath)!;

        AbCipArrayReadPlanner.TryBuild(def, parsed, BaseParams("Data[3]")).ShouldBeNull();
    }

    [Theory]
    [InlineData(AbCipDataType.Bool)]
    [InlineData(AbCipDataType.String)]
    [InlineData(AbCipDataType.Structure)]
    public void TryBuild_returns_null_for_unsupported_element_types(AbCipDataType type)
    {
        var def = new AbCipTagDefinition("Slice", Device, "Data[0..3]", type);
        var parsed = AbCipTagPath.TryParse(def.TagPath)!;

        AbCipArrayReadPlanner.TryBuild(def, parsed, BaseParams("Data[0..3]")).ShouldBeNull();
    }

    [Theory]
    [InlineData(AbCipDataType.SInt, 1)]
    [InlineData(AbCipDataType.Int, 2)]
    [InlineData(AbCipDataType.DInt, 4)]
    [InlineData(AbCipDataType.Real, 4)]
    [InlineData(AbCipDataType.LInt, 8)]
    [InlineData(AbCipDataType.LReal, 8)]
    public void TryBuild_uses_natural_stride_per_element_type(AbCipDataType type, int expectedStride)
    {
        var def = new AbCipTagDefinition("Slice", Device, "Data[0..3]", type);
        var parsed = AbCipTagPath.TryParse(def.TagPath)!;

        var plan = AbCipArrayReadPlanner.TryBuild(def, parsed, BaseParams("Data[0..3]"))!;
        plan.Stride.ShouldBe(expectedStride);
    }

    [Fact]
    public void Decode_walks_buffer_at_element_stride()
    {
        var def = new AbCipTagDefinition("DataSlice", Device, "Data[0..3]", AbCipDataType.DInt);
        var parsed = AbCipTagPath.TryParse(def.TagPath)!;
        var plan = AbCipArrayReadPlanner.TryBuild(def, parsed, BaseParams("Data[0..3]"))!;

        var fake = new FakeAbCipTag(plan.CreateParams);
        // Stride == 4 for DInt, so offsets 0/4/8/12 hold the four element values.
        fake.ValuesByOffset[0] = 100;
        fake.ValuesByOffset[4] = 200;
        fake.ValuesByOffset[8] = 300;
        fake.ValuesByOffset[12] = 400;

        var decoded = AbCipArrayReadPlanner.Decode(plan, fake);

        decoded.Length.ShouldBe(4);
        decoded.ShouldBe(new object?[] { 100, 200, 300, 400 });
    }

    [Fact]
    public void Decode_preserves_slice_count_for_real_arrays()
    {
        var def = new AbCipTagDefinition("FloatSlice", Device, "Floats[2..5]", AbCipDataType.Real);
        var parsed = AbCipTagPath.TryParse(def.TagPath)!;
        var plan = AbCipArrayReadPlanner.TryBuild(def, parsed, BaseParams("Floats[2]"))!;

        var fake = new FakeAbCipTag(plan.CreateParams);
        fake.ValuesByOffset[0] = 1.5f;
        fake.ValuesByOffset[4] = 2.5f;
        fake.ValuesByOffset[8] = 3.5f;
        fake.ValuesByOffset[12] = 4.5f;

        var decoded = AbCipArrayReadPlanner.Decode(plan, fake);

        decoded.ShouldBe(new object?[] { 1.5f, 2.5f, 3.5f, 4.5f });
    }
}