ersatztv/ErsatzTV.Tests/Application/Paging/PagedQueryTotalCountTests.cs

using ErsatzTV.Application.MediaCollections;
using ErsatzTV.Application.Playouts;
using ErsatzTV.Application.ProgramSchedules;
using ErsatzTV.Core.Domain;
using ErsatzTV.Infrastructure.Data;
using ErsatzTV.Tests.Support;
using NUnit.Framework;
using Shouldly;
using DomainChannel = ErsatzTV.Core.Domain.Channel;

namespace ErsatzTV.Tests.Application.Paging;

/// <summary>
///     Every paged handler whose page query applies a filter must compute its TotalCount from the SAME
///     query, or a filtered page reports the unfiltered total and the SPA paginates to pages that can
///     never contain anything (issues #690, #758).
///     Expected counts here are PINNED LITERALS derived from the seeded set by hand — never recomputed
///     by re-applying the handler's own predicate, which would pass whatever the handler happens to do.
/// </summary>
[TestFixture]
public class PagedQueryTotalCountTests
{
    // 5 seeded rows, of which exactly these 2 contain "Alpha"
    private const int SeededRows = 5;
    private const int MatchingAlpha = 2;

    private InMemoryTvContext _db = null!;

    [SetUp]
    public async Task SetUp() => _db = await InMemoryTvContext.CreateAsync();

    [TearDown]
    public async Task TearDown() => await _db.DisposeAsync();

    private static readonly string[] Names =
        ["Alpha One", "Beta", "Alpha Two", "Gamma", "Delta"];

    [Test]
    public async Task GetPagedCollections_Filtered_Count_Should_Match_Filter()
    {
        await using (TvContext context = _db.CreateContext())
        {
            for (var i = 0; i < Names.Length; i++)
            {
                context.Collections.Add(new Collection { Id = i + 1, Name = Names[i], MediaItems = [] });
            }

            await context.SaveChangesAsync();
        }

        var handler = new GetPagedCollectionsHandler(_db.Factory);

        PagedMediaCollectionsViewModel unfiltered =
            await handler.Handle(new GetPagedCollections(string.Empty, 0, 10), CancellationToken.None);
        unfiltered.TotalCount.ShouldBe(SeededRows);

        PagedMediaCollectionsViewModel filtered =
            await handler.Handle(new GetPagedCollections("Alpha", 0, 10), CancellationToken.None);

        filtered.TotalCount.ShouldBe(MatchingAlpha);
        filtered.Page.Select(c => c.Name).ShouldBe(["Alpha One", "Alpha Two"]);
    }

    [Test]
    public async Task GetPagedMultiCollections_Filtered_Count_Should_Match_Filter()
    {
        await using (TvContext context = _db.CreateContext())
        {
            for (var i = 0; i < Names.Length; i++)
            {
                context.MultiCollections.Add(new MultiCollection { Id = i + 1, Name = Names[i] });
            }

            // channel-owned rows are excluded from BOTH the page and the count, filter or no filter
            context.MultiCollections.Add(
                new MultiCollection { Id = 99, Name = "Alpha Owned", OwnedByChannelId = 7 });
            await context.SaveChangesAsync();
        }

        var handler = new GetPagedMultiCollectionsHandler(_db.Factory);

        PagedMultiCollectionsViewModel unfiltered =
            await handler.Handle(new GetPagedMultiCollections(string.Empty, 0, 10), CancellationToken.None);
        unfiltered.TotalCount.ShouldBe(SeededRows);

        PagedMultiCollectionsViewModel filtered =
            await handler.Handle(new GetPagedMultiCollections("Alpha", 0, 10), CancellationToken.None);

        filtered.TotalCount.ShouldBe(MatchingAlpha);
        filtered.Page.Select(mc => mc.Name).ShouldBe(["Alpha One", "Alpha Two"]);
    }

    [Test]
    public async Task GetPagedSmartCollections_Filtered_Count_Should_Match_Filter()
    {
        await using (TvContext context = _db.CreateContext())
        {
            for (var i = 0; i < Names.Length; i++)
            {
                context.SmartCollections.Add(
                    new SmartCollection { Id = i + 1, Name = Names[i], Query = "tag:family" });
            }

            context.SmartCollections.Add(
                new SmartCollection
                {
                    Id = 99,
                    Name = "Alpha Owned",
                    Query = "tag:family",
                    OwnedByChannelId = 7
                });
            await context.SaveChangesAsync();
        }

        var handler = new GetPagedSmartCollectionsHandler(_db.Factory);

        PagedSmartCollectionsViewModel unfiltered =
            await handler.Handle(new GetPagedSmartCollections(string.Empty, 0, 10), CancellationToken.None);
        unfiltered.TotalCount.ShouldBe(SeededRows);

        PagedSmartCollectionsViewModel filtered =
            await handler.Handle(new GetPagedSmartCollections("Alpha", 0, 10), CancellationToken.None);

        filtered.TotalCount.ShouldBe(MatchingAlpha);
        filtered.Page.Select(sc => sc.Name).ShouldBe(["Alpha One", "Alpha Two"]);
    }

    [Test]
    public async Task GetPagedRerunCollections_Filtered_Count_Should_Match_Filter()
    {
        await using (TvContext context = _db.CreateContext())
        {
            for (var i = 0; i < Names.Length; i++)
            {
                context.RerunCollections.Add(
                    new RerunCollection
                    {
                        Id = i + 1,
                        Name = Names[i],
                        CollectionType = CollectionType.Collection,
                        CollectionId = i + 1
                    });
                context.Collections.Add(new Collection { Id = i + 1, Name = Names[i], MediaItems = [] });
            }

            await context.SaveChangesAsync();
        }

        var handler = new GetPagedRerunCollectionsHandler(_db.Factory);

        PagedRerunCollectionsViewModel unfiltered =
            await handler.Handle(new GetPagedRerunCollections(string.Empty, 0, 10), CancellationToken.None);
        unfiltered.TotalCount.ShouldBe(SeededRows);

        PagedRerunCollectionsViewModel filtered =
            await handler.Handle(new GetPagedRerunCollections("Alpha", 0, 10), CancellationToken.None);

        filtered.TotalCount.ShouldBe(MatchingAlpha);
        filtered.Page.Select(rc => rc.Name).ShouldBe(["Alpha One", "Alpha Two"]);

        // the selection graph still loads for the page — moving IncludeSelectionDetails off the
        // counted query must not stop the page from projecting it (issue #671)
        filtered.Page.Select(rc => rc.Collection?.Name).ShouldBe(["Alpha One", "Alpha Two"]);
    }

    [Test]
    public async Task GetPagedProgramSchedules_Filtered_Count_Should_Match_Filter()
    {
        await using (TvContext context = _db.CreateContext())
        {
            for (var i = 0; i < Names.Length; i++)
            {
                context.ProgramSchedules.Add(new ProgramSchedule { Id = i + 1, Name = Names[i] });
            }

            await context.SaveChangesAsync();
        }

        var handler = new GetPagedProgramSchedulesHandler(_db.Factory);

        PagedProgramSchedulesViewModel unfiltered =
            await handler.Handle(new GetPagedProgramSchedules(string.Empty, 0, 10), CancellationToken.None);
        unfiltered.TotalCount.ShouldBe(SeededRows);

        PagedProgramSchedulesViewModel filtered =
            await handler.Handle(new GetPagedProgramSchedules("Alpha", 0, 10), CancellationToken.None);

        filtered.TotalCount.ShouldBe(MatchingAlpha);
        filtered.Page.Select(ps => ps.Name).ShouldBe(["Alpha One", "Alpha Two"]);
    }

    [Test]
    public async Task GetPagedPlayouts_Filtered_Count_Should_Match_Filter()
    {
        await using (TvContext context = _db.CreateContext())
        {
            for (var i = 0; i < Names.Length; i++)
            {
                context.Channels.Add(NewChannel(i + 1, $"{i + 1}", Names[i]));
                context.Playouts.Add(
                    new Playout
                    {
                        Id = i + 1,
                        ChannelId = i + 1,
                        ScheduleKind = PlayoutScheduleKind.Classic
                    });
            }

            // a playout whose channel row does not exist: excluded from the page by the
            // `Channel != null` filter, so it must be excluded from the count too
            context.Playouts.Add(
                new Playout { Id = 99, ChannelId = 4242, ScheduleKind = PlayoutScheduleKind.Classic });
            await context.SaveChangesAsync();
        }

        var handler = new GetPagedPlayoutsHandler(_db.Factory);

        PagedPlayoutsViewModel unfiltered =
            await handler.Handle(new GetPagedPlayouts(string.Empty, 0, 10), CancellationToken.None);

        // 5, NOT 6 — the orphaned playout is filtered out of the page, so it is not part of the total
        unfiltered.TotalCount.ShouldBe(SeededRows);
        unfiltered.Page.Count.ShouldBe(SeededRows);

        PagedPlayoutsViewModel filtered =
            await handler.Handle(new GetPagedPlayouts("Alpha", 0, 10), CancellationToken.None);

        filtered.TotalCount.ShouldBe(MatchingAlpha);
        filtered.Page.Select(p => p.ChannelName).ShouldBe(["Alpha One", "Alpha Two"]);
    }

    [Test]
    public async Task Filtered_Count_Should_Drive_A_Second_Page()
    {
        await using (TvContext context = _db.CreateContext())
        {
            for (var i = 0; i < Names.Length; i++)
            {
                context.Collections.Add(new Collection { Id = i + 1, Name = Names[i], MediaItems = [] });
            }

            await context.SaveChangesAsync();
        }

        var handler = new GetPagedCollectionsHandler(_db.Factory);

        // pageSize 1 over the 2 matching rows: this is the property the issues are about — the count
        // is what tells the client a SECOND page exists, and each page holds exactly its own row
        PagedMediaCollectionsViewModel first =
            await handler.Handle(new GetPagedCollections("Alpha", 0, 1), CancellationToken.None);
        first.TotalCount.ShouldBe(MatchingAlpha);
        first.Page.Select(c => c.Name).ShouldBe(["Alpha One"]);

        PagedMediaCollectionsViewModel second =
            await handler.Handle(new GetPagedCollections("Alpha", 1, 1), CancellationToken.None);
        second.TotalCount.ShouldBe(MatchingAlpha);
        second.Page.Select(c => c.Name).ShouldBe(["Alpha Two"]);

        // and the page AFTER the last matching row is empty — with the pre-fix count of 5 the client
        // would have been told to fetch three more pages that can never contain anything
        PagedMediaCollectionsViewModel past =
            await handler.Handle(new GetPagedCollections("Alpha", 2, 1), CancellationToken.None);
        past.TotalCount.ShouldBe(MatchingAlpha);
        past.Page.ShouldBeEmpty();
    }

    private static DomainChannel NewChannel(int id, string number, string name) =>
        new(Guid.NewGuid())
        {
            Id = id,
            Number = number,
            SortNumber = id,
            Name = name,
            Group = "ErsatzTV",
            Categories = string.Empty,
            FFmpegProfileId = 1,
            StreamSelector = string.Empty,
            PreferredAudioLanguageCode = string.Empty,
            PreferredAudioTitle = string.Empty,
            PreferredSubtitleLanguageCode = string.Empty,
            MusicVideoCreditsTemplate = string.Empty,
            StreamingMode = StreamingMode.TransportStreamHybrid,
            PlayoutSource = ChannelPlayoutSource.Generated,
            PlayoutMode = ChannelPlayoutMode.Continuous
        };
}