using Shouldly;
using TwinCAT.Ads;
using TwinCAT.Ads.SumCommand;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Driver.TwinCAT;

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

/// <summary>
///     hw2 live gate (2026-10-08, TC3 Z35474): every ADS sum-read chunk failed with
///     <see cref="InvalidCastException"/> thrown by Beckhoff's own <see cref="SumRead"/> constructor, because the
///     <c>IList&lt;IgIoSumReadEntity&gt;</c> overload casts its argument to <c>IList&lt;SumDataEntity&gt;</c> — which
///     works for an array (covariance) and not for a <c>List&lt;IgIoSumReadEntity&gt;</c>. The driver turned it into
///     <c>BadCommunicationError</c> for every batched tag on every poll. The fake client never builds a real
///     <see cref="SumRead"/>, so these tests construct one directly; the constructor does no I/O, so an unconnected
///     <see cref="AdsClient"/> is enough.
/// </summary>
[Trait("Category", "Unit")]
public sealed class TwinCATSumReadConstructionTests
{
    [Fact]
    public void CreateSumRead_builds_a_real_Beckhoff_sum_command_without_a_cast_failure()
    {
        using var client = new AdsClient();

        var sum = AdsTwinCATClient.CreateSumRead(client, [(0x4040u, 0x10u, 2), (0x4040u, 0x20u, 4), (0x4020u, 0x0u, 81)]);

        sum.ShouldNotBeNull();
    }

    [Fact]
    public void The_Beckhoff_list_overload_really_throws_for_a_List_which_is_why_CreateSumRead_passes_an_array()
    {
        // Falsifiability control: if a future Beckhoff release fixes the cast, this test goes red and the remark
        // on CreateSumRead can be retired — but the array form keeps working either way.
        using var client = new AdsClient();
        var list = new List<IgIoSumReadEntity> { new(0x4040, 0x10, 2), new(0x4040, 0x20, 4) };

        Should.Throw<InvalidCastException>(() => new SumRead(client, list, SumCommandErrorStrategy.Relaxed));
    }
}