ersatztv/ErsatzTV.Tests/Application/MediaCollections/MultiCollectionWeightValidationTests.cs

using ErsatzTV.Application.MediaCollections;
using ErsatzTV.Core;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Interfaces.Repositories;
using ErsatzTV.Tests.Support;
using LanguageExt;
using NSubstitute;
using NUnit.Framework;
using Shouldly;

namespace ErsatzTV.Tests.Application.MediaCollections;

/// <summary>
///     Pins the per-source <c>Weight</c> bounds (#70) on BOTH write paths, driven from one shared case list.
///     <para>
///         The bug this guards against was create and update <i>disagreeing</i>, not either one being wrong on its
///         own: EF's <c>HasDefaultValue(1)</c> substitutes 1 for a <c>0</c> on INSERT (0 reads as "not set") while an
///         UPDATE writes the 0 through, so the same request body landed differently depending on the verb. Testing the
///         two paths against the same inputs is the point — a per-path test would have passed while they diverged.
///     </para>
/// </summary>
[TestFixture]
public class MultiCollectionWeightValidationTests : MediaCollectionHandlerTestBase
{
    private const int CollectionId = 1;
    private const int SmartCollectionId = 2;

    private static readonly int[] RejectedWeights = [0, -1, -5, MultiCollectionItemWeight.Maximum + 1, int.MaxValue];
    private static readonly int[] AcceptedWeights =
        [MultiCollectionItemWeight.Minimum, 2, 500, MultiCollectionItemWeight.Maximum];

    [SetUp]
    public async Task SetUp()
    {
        await SeedCollection(CollectionId);
        await SeedSmartCollection(SmartCollectionId);
    }

    private CreateMultiCollectionHandler CreateHandler() => new(Db.Factory, SearchTargets);

    private UpdateMultiCollectionHandler UpdateHandler()
    {
        var repo = Substitute.For<IMediaCollectionRepository>();

        // the handler enqueues a playout rebuild for every playout using the collection once a real change
        // lands; an unstubbed mock returns null there and the NRE looks like a product bug
        repo.PlayoutIdsUsingMultiCollection(Arg.Any<int>()).Returns([]);

        return new UpdateMultiCollectionHandler(Db.Factory, repo, Worker, SearchTargets);
    }

    private static CreateMultiCollection CreateCommand(string name, int weight) =>
        new(name, [new CreateMultiCollectionItem(CollectionId, null, true, PlaybackOrder.WeightedShuffle, weight)]);

    private static CreateMultiCollection CreateSmartCommand(string name, int weight) =>
        new(
            name,
            [new CreateMultiCollectionItem(null, SmartCollectionId, true, PlaybackOrder.WeightedShuffle, weight)]);

    private async Task<int> SeedMultiCollection(string name)
    {
        Either<BaseError, MultiCollectionViewModel> created =
            await CreateHandler().Handle(CreateCommand(name, MultiCollectionItemWeight.Minimum), CancellationToken.None);
        created.IsRight.ShouldBeTrue();
        return created.RightToSeq().Head().Id;
    }

    [Test]
    public async Task Create_Rejects_Out_Of_Range_Weight([ValueSource(nameof(RejectedWeights))] int weight)
    {
        Either<BaseError, MultiCollectionViewModel> result =
            await CreateHandler().Handle(CreateCommand($"create-{weight}", weight), CancellationToken.None);

        result.IsLeft.ShouldBeTrue($"weight {weight} must be rejected");
        result.LeftToSeq().Head().Value.ShouldContain("Weight must be between");
    }

    [Test]
    public async Task Update_Rejects_Out_Of_Range_Weight([ValueSource(nameof(RejectedWeights))] int weight)
    {
        // the path that actually persisted a 0 before #402 -- EF's INSERT default masked it on create
        int id = await SeedMultiCollection($"update-{weight}");

        Either<BaseError, Unit> result = await UpdateHandler().Handle(
            new UpdateMultiCollection(
                id,
                $"update-{weight}",
                [new UpdateMultiCollectionItem(CollectionId, null, true, PlaybackOrder.WeightedShuffle, weight)]),
            CancellationToken.None);

        result.IsLeft.ShouldBeTrue($"weight {weight} must be rejected");
        result.LeftToSeq().Head().Value.ShouldContain("Weight must be between");
    }

    [Test]
    public async Task Create_Accepts_In_Range_Weight([ValueSource(nameof(AcceptedWeights))] int weight)
    {
        Either<BaseError, MultiCollectionViewModel> result =
            await CreateHandler().Handle(CreateCommand($"ok-create-{weight}", weight), CancellationToken.None);

        result.IsRight.ShouldBeTrue($"weight {weight} must be accepted");
    }

    [Test]
    public async Task Update_Accepts_In_Range_Weight([ValueSource(nameof(AcceptedWeights))] int weight)
    {
        int id = await SeedMultiCollection($"ok-update-{weight}");

        Either<BaseError, Unit> result = await UpdateHandler().Handle(
            new UpdateMultiCollection(
                id,
                $"ok-update-{weight}",
                [new UpdateMultiCollectionItem(CollectionId, null, true, PlaybackOrder.WeightedShuffle, weight)]),
            CancellationToken.None);

        result.IsRight.ShouldBeTrue($"weight {weight} must be accepted");
    }

    [Test]
    public async Task Create_Rejects_Out_Of_Range_Weight_On_A_Smart_Item()
    {
        // the smart mirror is the half that gets forgotten; the gate must cover it too
        Either<BaseError, MultiCollectionViewModel> result =
            await CreateHandler().Handle(CreateSmartCommand("smart-bad", 0), CancellationToken.None);

        result.IsLeft.ShouldBeTrue();
        result.LeftToSeq().Head().Value.ShouldContain("Weight must be between");
    }

    [Test]
    public async Task Update_And_Create_Agree_On_Every_Case()
    {
        // the regression that started B2: same input, different verb, different outcome. Asserted directly
        // rather than inferred from the two suites above passing.
        foreach (int weight in RejectedWeights.Concat(AcceptedWeights))
        {
            Either<BaseError, MultiCollectionViewModel> created = await CreateHandler()
                .Handle(CreateCommand($"agree-{weight}", weight), CancellationToken.None);

            int id = await SeedMultiCollection($"agree-base-{weight}");
            Either<BaseError, Unit> updated = await UpdateHandler().Handle(
                new UpdateMultiCollection(
                    id,
                    $"agree-base-{weight}",
                    [new UpdateMultiCollectionItem(CollectionId, null, true, PlaybackOrder.WeightedShuffle, weight)]),
                CancellationToken.None);

            updated.IsRight.ShouldBe(
                created.IsRight,
                $"create and update disagreed on weight {weight}");
        }
    }
}