using Shouldly;
using Xunit;

namespace ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests;

/// <summary>
///     Lane B review N4 — <see cref="VariableShape.TryFit"/> decides whether a value deferred during a plan window may
///     be replayed onto a node an in-place edit re-shaped: never an old-typed value the new DataType contradicts.
/// </summary>
public sealed class VariableShapeTests
{
    [Fact]
    public void A_value_of_the_new_type_fits_unchanged()
    {
        new VariableShape("Int32", false, null).TryFit(7, out var fitted).ShouldBeTrue();
        fitted.ShouldBe(7);
    }

    [Fact]
    public void A_convertible_old_typed_value_is_converted_to_the_new_type()
    {
        new VariableShape("Int32", false, null).TryFit(5.0f, out var fitted).ShouldBeTrue();
        fitted.ShouldBeOfType<int>().ShouldBe(5);
        new VariableShape("Double", false, null).TryFit((short)3, out var d).ShouldBeTrue();
        d.ShouldBeOfType<double>().ShouldBe(3d);
    }

    [Theory]
    [InlineData("Int32", "fast")]          // not a number
    [InlineData("Byte", 300)]              // overflow
    [InlineData("DateTime", 12)]           // no conversion
    public void A_value_the_new_type_cannot_hold_does_not_fit(string dataType, object value)
    {
        new VariableShape(dataType, false, null).TryFit(value, out var fitted).ShouldBeFalse();
        fitted.ShouldBeNull();
    }

    [Fact]
    public void Scalar_and_array_never_cross()
    {
        new VariableShape("Int32", false, null).TryFit(new[] { 1, 2 }, out _).ShouldBeFalse();
        new VariableShape("Int32", true, 2).TryFit(1, out _).ShouldBeFalse();
        new VariableShape("String", true, null).TryFit("ab", out _).ShouldBeFalse("a string is not an array of strings");
    }

    [Fact]
    public void An_array_is_converted_element_wise_and_its_fixed_length_enforced()
    {
        new VariableShape("Int16", true, 3).TryFit(new[] { 1, 2, 3 }, out var fitted).ShouldBeTrue();
        fitted.ShouldBeOfType<short[]>().ShouldBe(new short[] { 1, 2, 3 });
        new VariableShape("Int16", true, 4).TryFit(new[] { 1, 2, 3 }, out _).ShouldBeFalse("wrong length");
        new VariableShape("Int16", true, null).TryFit(new[] { 1, 2, 3 }, out _).ShouldBeTrue("no fixed length");
        new VariableShape("Byte", true, null).TryFit(new[] { 1, 999 }, out _).ShouldBeFalse("an element overflows");
    }

    [Fact]
    public void Null_and_unknown_types_always_fit()
    {
        new VariableShape("Int32", false, null).TryFit(null, out var n).ShouldBeTrue();
        n.ShouldBeNull();
        new VariableShape("Structure", false, null).TryFit("anything", out var any).ShouldBeTrue();
        any.ShouldBe("anything");
    }
}