using System.Threading.Channels;
using ErsatzTV.Application;
using ErsatzTV.Application.Artworks;
using ErsatzTV.Application.Channels;
using ErsatzTV.Application.Playouts;
using ErsatzTV.Core;
using ErsatzTV.Core.Api.Channels;
using ErsatzTV.Core.Api.LibraryBrowse;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Domain.Filler;
using ErsatzTV.Core.Errors;
using ErsatzTV.Core.Graphics;
using ErsatzTV.Core.Interfaces.Images;
using ErsatzTV.Core.Interfaces.Search;
using ErsatzTV.Core.Scheduling;
using ErsatzTV.FFmpeg.State;
using ErsatzTV.Infrastructure.Data;
using ErsatzTV.Tests.Support;
using LanguageExt;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging.Abstractions;
using NSubstitute;
using NUnit.Framework;
using Shouldly;
using static LanguageExt.Prelude;
using DomainChannel = ErsatzTV.Core.Domain.Channel;
using DomainPlaylistItem = ErsatzTV.Core.Domain.PlaylistItem;

namespace ErsatzTV.Tests.Application.Channels;

[TestFixture]
public class CreateChannelFromLineupHandlerTests
{
    private Channel<IBackgroundServiceRequest> _background = null!;
    private InMemoryTvContext _db = null!;
    private ISearchTargets _searchTargets = null!;
    private IRemoteLogoCacher _remoteLogoCacher = null!;

    [SetUp]
    public async Task SetUp()
    {
        _background = System.Threading.Channels.Channel.CreateUnbounded<IBackgroundServiceRequest>();
        _db = await InMemoryTvContext.CreateAsync();
        _searchTargets = Substitute.For<ISearchTargets>();
        _remoteLogoCacher = Substitute.For<IRemoteLogoCacher>();
    }

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

    [Test]
    public async Task Should_Create_Single_Media_Item_Directly_Without_Playlist()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(), CancellationToken.None);

        CreateChannelFromLineupResponseModel response = RightOf(result);
        response.ChannelId.ShouldBeGreaterThan(0);
        response.PlaylistId.ShouldBeNull();
        response.ProgramScheduleId.ShouldBeGreaterThan(0);
        response.PlayoutId.ShouldBeGreaterThan(0);

        await using TvContext context = _db.CreateContext();

        // No generated playlist or collection for a single-item lineup.
        (await context.Playlists.CountAsync()).ShouldBe(0);
        (await context.Collections.CountAsync()).ShouldBe(0);

        DomainChannel channel = await context.Channels.SingleAsync();
        channel.Name.ShouldBe("Movies");
        channel.Number.ShouldBe("12");
        channel.Group.ShouldBe("Kids");
        channel.FFmpegProfileId.ShouldBe(1);
        channel.FallbackFillerId.ShouldBe(5);
        channel.StreamingMode.ShouldBe(StreamingMode.HttpLiveStreamingSegmenter);
        channel.ShowInEpg.ShouldBeTrue();
        channel.Origin.ShouldBe(ChannelOrigin.AutoTuned);

        ProgramSchedule schedule = await context.ProgramSchedules.Include(ps => ps.Items).SingleAsync();
        schedule.Name.ShouldBe("12 Movies Schedule");
        schedule.ShuffleScheduleItems.ShouldBeTrue();
        schedule.RandomStartPoint.ShouldBeTrue();
        schedule.FixedStartTimeBehavior.ShouldBe(FixedStartTimeBehavior.Strict);

        ProgramScheduleItem item = schedule.Items.Single();
        item.ShouldBeOfType<ProgramScheduleItemFlood>();
        item.CollectionType.ShouldBe(CollectionType.Movie);
        item.MediaItemId.ShouldBe(42);
        item.CollectionId.ShouldBeNull();
        item.PlaylistId.ShouldBeNull();
        item.PlaybackOrder.ShouldBe(PlaybackOrder.Shuffle);
        item.PreRollFillerId.ShouldBe(2);
        item.MidRollFillerId.ShouldBe(3);
        item.PostRollFillerId.ShouldBe(4);
        item.FallbackFillerId.ShouldBe(5);

        Playout playout = await context.Playouts.SingleAsync();
        playout.ChannelId.ShouldBe(channel.Id);
        playout.ProgramScheduleId.ShouldBe(schedule.Id);
        playout.ScheduleKind.ShouldBe(PlayoutScheduleKind.Classic);

        _background.Reader.TryRead(out IBackgroundServiceRequest? buildRequest).ShouldBeTrue();
        BuildPlayout buildPlayout = buildRequest.ShouldBeOfType<BuildPlayout>();
        buildPlayout.PlayoutId.ShouldBe(playout.Id);
        buildPlayout.Mode.ShouldBe(PlayoutBuildMode.Reset);

        _background.Reader.TryRead(out IBackgroundServiceRequest? refreshRequest).ShouldBeTrue();
        refreshRequest.ShouldBeOfType<RefreshChannelList>();
        _searchTargets.Received(1).SearchTargetsChanged();
    }

    [Test]
    public async Task Should_Create_Single_Collection_Item_Directly()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedCollection(7);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(lineup: [CollectionItem(7)]), CancellationToken.None);

        RightOf(result).PlaylistId.ShouldBeNull();

        await using TvContext context = _db.CreateContext();
        (await context.Playlists.CountAsync()).ShouldBe(0);
        ProgramScheduleItem item = await context.ProgramScheduleItems.SingleAsync();
        item.CollectionType.ShouldBe(CollectionType.Collection);
        item.CollectionId.ShouldBe(7);
    }

    [Test]
    public async Task Should_Create_Single_Playlist_Item_Directly()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedExistingPlaylist(9);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(lineup: [PlaylistEntry(9)]), CancellationToken.None);

        // The generated-playlist id is null for a single-item lineup, even when it references a playlist.
        RightOf(result).PlaylistId.ShouldBeNull();

        await using TvContext context = _db.CreateContext();
        ProgramScheduleItem item = await context.ProgramScheduleItems.SingleAsync();
        item.CollectionType.ShouldBe(CollectionType.Playlist);
        item.PlaylistId.ShouldBe(9);
    }

    [Test]
    public async Task Should_Create_Single_Rerun_Collection_As_First_Run()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedRerunCollection(11);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(lineup: [RerunItem(11)]), CancellationToken.None);

        RightOf(result).PlaylistId.ShouldBeNull();

        await using TvContext context = _db.CreateContext();
        ProgramScheduleItem item = await context.ProgramScheduleItems.SingleAsync();
        item.CollectionType.ShouldBe(CollectionType.RerunFirstRun);
        item.RerunCollectionId.ShouldBe(11);
    }

    [Test]
    public async Task Should_Create_Multi_Item_Lineup_As_Generated_System_Playlist()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);
        await SeedShow(43);
        await SeedCollection(7);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(
                MakeRequest(lineup: [MovieItem(42), ShowItem(43), CollectionItem(7)]),
                CancellationToken.None);

        CreateChannelFromLineupResponseModel response = RightOf(result);
        response.PlaylistId.ShouldNotBeNull();

        await using TvContext context = _db.CreateContext();

        PlaylistGroup group = await context.PlaylistGroups.SingleAsync();
        group.Name.ShouldBe("Channel Lineups");
        group.IsSystem.ShouldBeTrue();

        Playlist playlist = await context.Playlists.Include(p => p.Items).SingleAsync();
        playlist.Id.ShouldBe(response.PlaylistId!.Value);
        playlist.Name.ShouldBe("12 Movies Lineup");
        playlist.IsSystem.ShouldBeTrue();
        playlist.PlaylistGroupId.ShouldBe(group.Id);

        List<DomainPlaylistItem> items = playlist.Items.OrderBy(i => i.Index).ToList();
        items.Count.ShouldBe(3);
        items.ShouldAllBe(i => i.PlayAll);
        items.ShouldAllBe(i => i.IncludeInProgramGuide);
        items.ShouldAllBe(i => i.PlaybackOrder == PlaybackOrder.Shuffle);

        items[0].Index.ShouldBe(1);
        items[0].CollectionType.ShouldBe(CollectionType.Movie);
        items[0].MediaItemId.ShouldBe(42);

        items[1].Index.ShouldBe(2);
        items[1].CollectionType.ShouldBe(CollectionType.TelevisionShow);
        items[1].MediaItemId.ShouldBe(43);

        items[2].Index.ShouldBe(3);
        items[2].CollectionType.ShouldBe(CollectionType.Collection);
        items[2].CollectionId.ShouldBe(7);

        // Exactly one flood schedule item, referencing the generated playlist.
        ProgramScheduleItem scheduleItem = await context.ProgramScheduleItems.SingleAsync();
        scheduleItem.ShouldBeOfType<ProgramScheduleItemFlood>();
        scheduleItem.CollectionType.ShouldBe(CollectionType.Playlist);
        scheduleItem.PlaylistId.ShouldBe(playlist.Id);
    }

    [Test]
    public async Task Should_Reject_Rerun_Collection_In_Multi_Item_Lineup()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);
        await SeedRerunCollection(11);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(
                MakeRequest(lineup: [MovieItem(42), RerunItem(11)]),
                CancellationToken.None);

        BaseError error = LeftOf(result);
        error.ShouldNotBeOfType<NotFoundError>();
        error.Value.ShouldContain("single-item");
    }

    [Test]
    public async Task Should_Reject_Playlist_In_Multi_Item_Lineup()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);
        await SeedExistingPlaylist(9);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(
                MakeRequest(lineup: [MovieItem(42), PlaylistEntry(9)]),
                CancellationToken.None);

        BaseError error = LeftOf(result);
        error.ShouldNotBeOfType<NotFoundError>();
        error.Value.ShouldContain("single-item");
    }

    [Test]
    public async Task Advanced_Overrides_Should_Beat_Template_Defaults()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);

        await using (TvContext context = _db.CreateContext())
        {
            context.FFmpegProfiles.Add(new FFmpegProfile { Id = 2, Name = "advanced-profile" });
            context.ChannelWatermarks.Add(new ChannelWatermark { Id = 21, Name = "wm", Image = "wm.png" });
            context.FillerPresets.AddRange(
                MakeFiller(6, FillerKind.Fallback),
                MakeFiller(7, FillerKind.PreRoll));
            await context.SaveChangesAsync();
        }

        var advanced = new CreateChannelFromLineupAdvancedOptions(
            PlaybackOrder: PlaybackOrder.Shuffle,
            FFmpegProfileId: 2,
            WatermarkId: 21,
            FallbackFillerId: 6,
            PreRollFillerId: 7,
            StreamingMode: StreamingMode.TransportStream);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(advanced: advanced), CancellationToken.None);

        RightOf(result);

        await using TvContext assert = _db.CreateContext();
        DomainChannel channel = await assert.Channels.SingleAsync();

        // Advanced wins over the template's values (template = profile 1, no watermark, HLS, fallback 5).
        channel.FFmpegProfileId.ShouldBe(2);
        channel.WatermarkId.ShouldBe(21);
        channel.StreamingMode.ShouldBe(StreamingMode.TransportStream);
        channel.FallbackFillerId.ShouldBe(6);

        ProgramScheduleItem item = await assert.ProgramScheduleItems.SingleAsync();
        item.PlaybackOrder.ShouldBe(PlaybackOrder.Shuffle);
        item.PreRollFillerId.ShouldBe(7);
        item.FallbackFillerId.ShouldBe(6);

        // Not overridden in Advanced -> falls through to the template value.
        item.MidRollFillerId.ShouldBe(3);
    }

    [Test]
    public async Task Clear_Should_Force_Template_Inherited_Values_To_None()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);

        // Give the template a watermark + preferred audio language so "clear" has something to drop
        // (the base template has fillers 2-5 but no watermark / audio language).
        await using (TvContext context = _db.CreateContext())
        {
            context.ChannelWatermarks.Add(new ChannelWatermark { Id = 21, Name = "wm", Image = "wm.png" });
            ChannelTemplate template = await context.ChannelTemplates.SingleAsync();
            template.WatermarkId = 21;
            template.PreferredAudioLanguageCode = "eng";
            await context.SaveChangesAsync();
        }

        var advanced = new CreateChannelFromLineupAdvancedOptions(
            PlaybackOrder: PlaybackOrder.Shuffle,
            Clear:
            [
                CreateChannelFromLineupClearField.Watermark,
                CreateChannelFromLineupClearField.FallbackFiller,
                CreateChannelFromLineupClearField.PreRollFiller,
                CreateChannelFromLineupClearField.MidRollFiller,
                CreateChannelFromLineupClearField.PostRollFiller,
                CreateChannelFromLineupClearField.PreferredAudioLanguage
            ]);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(advanced: advanced), CancellationToken.None);
        RightOf(result);

        await using TvContext assert = _db.CreateContext();
        DomainChannel channel = await assert.Channels.SingleAsync();

        // Cleared -> none, even though the template supplies a value.
        channel.WatermarkId.ShouldBeNull();
        channel.FallbackFillerId.ShouldBeNull();
        channel.PreferredAudioLanguageCode.ShouldBe(string.Empty);

        ProgramScheduleItem item = await assert.ProgramScheduleItems.SingleAsync();
        item.PreRollFillerId.ShouldBeNull();
        item.MidRollFillerId.ShouldBeNull();
        item.PostRollFillerId.ShouldBeNull();
        item.FallbackFillerId.ShouldBeNull();
        item.PreferredAudioLanguageCode.ShouldBe(string.Empty);
    }

    [Test]
    public async Task Clear_And_Set_Same_Field_Should_Be_Validation_Error()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);

        await using (TvContext context = _db.CreateContext())
        {
            context.FillerPresets.Add(MakeFiller(6, FillerKind.Fallback));
            await context.SaveChangesAsync();
        }

        var advanced = new CreateChannelFromLineupAdvancedOptions(
            PlaybackOrder: PlaybackOrder.Shuffle,
            FallbackFillerId: 6,
            Clear: [CreateChannelFromLineupClearField.FallbackFiller]);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(advanced: advanced), CancellationToken.None);

        BaseError error = LeftOf(result);
        error.ShouldNotBeOfType<NotFoundError>();
        error.Value.ShouldContain("cannot be both set and cleared");
    }

    [Test]
    public async Task Clear_And_Set_String_Field_Conflicts_But_Empty_String_Is_Redundant()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);

        // A real value + clear on the same string field is contradictory.
        var conflicting = new CreateChannelFromLineupAdvancedOptions(
            PlaybackOrder: PlaybackOrder.Shuffle,
            PreferredAudioLanguageCode: "eng",
            Clear: [CreateChannelFromLineupClearField.PreferredAudioLanguage]);

        BaseError error = LeftOf(
            await MakeHandler().Handle(MakeRequest(advanced: conflicting), CancellationToken.None));
        error.Value.ShouldContain("cannot be both set and cleared");

        // An empty string + clear is redundant, not conflicting -> the create still succeeds. (This
        // runs second: the conflicting request above returned Left without persisting, so number "12"
        // is still free.)
        var redundant = new CreateChannelFromLineupAdvancedOptions(
            PlaybackOrder: PlaybackOrder.Shuffle,
            PreferredAudioLanguageCode: "",
            Clear: [CreateChannelFromLineupClearField.PreferredAudioLanguage]);

        RightOf(await MakeHandler().Handle(MakeRequest(advanced: redundant), CancellationToken.None));
    }

    [Test]
    public async Task Should_Return_Validation_Error_When_Not_Exactly_One_Id_Provided()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();

        var item = new CreateChannelFromLineupItem(
            LibraryBrowseMediaType.Movie, CollectionType.Movie, null, null, null, null, null, null);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(lineup: [item]), CancellationToken.None);

        LeftOf(result).Value.ShouldContain("exactly one typed id");
    }

    [Test]
    public async Task Should_Return_Validation_Error_When_Media_Type_Does_Not_Match_Collection_Type()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);

        var item = new CreateChannelFromLineupItem(
            LibraryBrowseMediaType.Movie, CollectionType.Playlist, null, null, null, null, 42, null);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(lineup: [item]), CancellationToken.None);

        BaseError error = LeftOf(result);
        error.ShouldNotBeOfType<NotFoundError>();
        error.Value.ShouldContain("does not match");
    }

    [Test]
    public async Task Should_Reject_MultiCollection_With_Non_Shuffle_Playback_Order()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMultiCollection(15);

        var advanced = new CreateChannelFromLineupAdvancedOptions(PlaybackOrder: PlaybackOrder.Chronological);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(
                MakeRequest(advanced: advanced, lineup: [MultiCollectionItem(15)]),
                CancellationToken.None);

        LeftOf(result).Value.ShouldContain("Invalid playback order for multi collection");
    }

    [Test]
    public async Task Should_Reject_WeightedShuffle_For_A_Multi_Item_Lineup()
    {
        // regression (#70, PR #402): a 2+ entry lineup is persisted as a
        // Playlist, and PlaylistEnumerator has no default arm -- an order it doesn't know leaves the
        // enumerator null and the items vanish from the playlist with nothing reported. This handler is the
        // THIRD writer of PlaylistItem.PlaybackOrder and was missed when the other two were gated.
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedCollection(21);
        await SeedCollection(22);

        var advanced = new CreateChannelFromLineupAdvancedOptions(PlaybackOrder: PlaybackOrder.WeightedShuffle);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(
                MakeRequest(advanced: advanced, lineup: [CollectionItem(21), CollectionItem(22)]),
                CancellationToken.None);

        LeftOf(result).Value.ShouldContain("not supported for a multi-item lineup");
    }

    [Test]
    public async Task Should_Allow_WeightedShuffle_For_A_MultiCollection_Lineup()
    {
        // the mirror of PlayoutModeMustBeValid: a multi collection is WeightedShuffle's intended home, and a
        // single-entry lineup goes to a flood item on the Classic engine, which handles the order
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMultiCollection(16);

        var advanced = new CreateChannelFromLineupAdvancedOptions(PlaybackOrder: PlaybackOrder.WeightedShuffle);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(
                MakeRequest(advanced: advanced, lineup: [MultiCollectionItem(16)]),
                CancellationToken.None);

        result.IsRight.ShouldBeTrue();
    }

    [Test]
    public async Task Should_Reject_Mirror_Playout_Source()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);

        var advanced = new CreateChannelFromLineupAdvancedOptions(
            PlaybackOrder: PlaybackOrder.Shuffle,
            PlayoutSource: ChannelPlayoutSource.Mirror);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(advanced: advanced), CancellationToken.None);

        LeftOf(result).Value.ShouldContain("Mirror playout source");
    }

    [Test]
    public async Task OnDemand_Playout_Mode_Should_Queue_TimeShift_After_Build()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);

        var advanced = new CreateChannelFromLineupAdvancedOptions(
            PlaybackOrder: PlaybackOrder.Shuffle,
            PlayoutMode: ChannelPlayoutMode.OnDemand);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(advanced: advanced), CancellationToken.None);

        CreateChannelFromLineupResponseModel response = RightOf(result);

        _background.Reader.TryRead(out IBackgroundServiceRequest? first).ShouldBeTrue();
        first.ShouldBeOfType<BuildPlayout>();

        _background.Reader.TryRead(out IBackgroundServiceRequest? second).ShouldBeTrue();
        TimeShiftOnDemandPlayout timeShift = second.ShouldBeOfType<TimeShiftOnDemandPlayout>();
        timeShift.PlayoutId.ShouldBe(response.PlayoutId);
        timeShift.Force.ShouldBeFalse();

        _background.Reader.TryRead(out IBackgroundServiceRequest? third).ShouldBeTrue();
        third.ShouldBeOfType<RefreshChannelList>();
    }

    [Test]
    public async Task Should_Recreate_With_De_Collided_Names_After_Channel_Delete()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);
        await SeedShow(43);

        // First create builds "12 Movies Schedule" + "12 Movies Lineup".
        RightOf(await MakeHandler().Handle(
            MakeRequest(lineup: [MovieItem(42), ShowItem(43)]),
            CancellationToken.None));

        // Delete the channel + playout but leave the generated schedule/playlist rows behind.
        await using (TvContext context = _db.CreateContext())
        {
            context.Playouts.RemoveRange(await context.Playouts.ToListAsync());
            context.Channels.RemoveRange(await context.Channels.ToListAsync());
            await context.SaveChangesAsync();
        }

        // Second create with the same name must succeed via de-collided names.
        CreateChannelFromLineupResponseModel response = RightOf(await MakeHandler().Handle(
            MakeRequest(lineup: [MovieItem(42), ShowItem(43)]),
            CancellationToken.None));

        await using TvContext assert = _db.CreateContext();

        bool scheduleExists = await assert.ProgramSchedules.AnyAsync(ps => ps.Name == "12 Movies Schedule 2");
        scheduleExists.ShouldBeTrue();

        Playlist newPlaylist = await assert.Playlists.SingleAsync(p => p.Id == response.PlaylistId!.Value);
        newPlaylist.Name.ShouldBe("12 Movies Lineup 2");

        // Only one system playlist group is ever created.
        (await assert.PlaylistGroups.CountAsync(pg => pg.Name == "Channel Lineups")).ShouldBe(1);
    }

    [Test]
    public async Task Should_Return_NotFound_For_Missing_Advanced_References()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);

        await AssertNotFound(
            new CreateChannelFromLineupAdvancedOptions(FFmpegProfileId: 999),
            "FFmpegProfile 999");
        await AssertNotFound(
            new CreateChannelFromLineupAdvancedOptions(WatermarkId: 999),
            "Watermark 999");
        await AssertNotFound(
            new CreateChannelFromLineupAdvancedOptions(FallbackFillerId: 999),
            "Fallback filler 999");
        await AssertNotFound(
            new CreateChannelFromLineupAdvancedOptions(PreRollFillerId: 999),
            "Pre-roll filler 999");
        await AssertNotFound(
            new CreateChannelFromLineupAdvancedOptions(MidRollFillerId: 999),
            "Mid-roll filler 999");
        await AssertNotFound(
            new CreateChannelFromLineupAdvancedOptions(PostRollFillerId: 999),
            "Post-roll filler 999");
    }

    [Test]
    public async Task Should_Roll_Back_When_Save_Fails()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);
        await SeedShow(43);

        // A non-system group with the reserved name forces the handler's new system group insert
        // to violate the unique Name index at save time (multi-item lineup path).
        await using (TvContext context = _db.CreateContext())
        {
            context.PlaylistGroups.Add(new PlaylistGroup { Id = 99, Name = "Channel Lineups", IsSystem = false });
            await context.SaveChangesAsync();
        }

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(
                MakeRequest(lineup: [MovieItem(42), ShowItem(43)]),
                CancellationToken.None);

        BaseError error = LeftOf(result);
        error.ShouldNotBeOfType<NotFoundError>();
        error.Value.ShouldBe("Unable to create channel from lineup");

        await using TvContext assertContext = _db.CreateContext();
        (await assertContext.Channels.CountAsync()).ShouldBe(0);
        (await assertContext.Playlists.CountAsync()).ShouldBe(0);
        (await assertContext.ProgramSchedules.CountAsync()).ShouldBe(0);
        (await assertContext.Playouts.CountAsync()).ShouldBe(0);
        _background.Reader.TryRead(out _).ShouldBeFalse();
    }

    [Test]
    public async Task Should_Return_NotFound_When_Template_Is_Missing()
    {
        await SeedTemplateDependencies();
        await SeedMovie(42);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(templateId: 999), CancellationToken.None);

        LeftOf(result).ShouldBeOfType<NotFoundError>();
    }

    [Test]
    public async Task Should_Return_Validation_Error_When_Channel_Number_Already_Exists_After_Trim()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);
        await using (TvContext context = _db.CreateContext())
        {
            context.Channels.Add(new DomainChannel(Guid.NewGuid())
            {
                Number = "12",
                Name = "Existing",
                Group = "Kids",
                Categories = string.Empty,
                FFmpegProfileId = 1,
                StreamSelector = string.Empty,
                PreferredAudioLanguageCode = string.Empty,
                PreferredAudioTitle = string.Empty,
                PreferredSubtitleLanguageCode = string.Empty,
                MusicVideoCreditsTemplate = string.Empty
            });
            await context.SaveChangesAsync();
        }

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(number: " 12 "), CancellationToken.None);

        BaseError error = LeftOf(result);
        error.ShouldNotBeOfType<NotFoundError>();
        error.Value.ShouldContain("Channel number must be unique");
    }

    [Test]
    public async Task Should_Return_Validation_Error_When_Disabled_But_Shown_In_Epg()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(
                MakeRequest(isEnabled: false, showInEpg: true),
                CancellationToken.None);

        BaseError error = LeftOf(result);
        error.ShouldNotBeOfType<NotFoundError>();
        error.Value.ShouldContain("Disabled channels cannot be shown in EPG");
    }

    [Test]
    public async Task Should_Return_Validation_Error_For_Invalid_External_Logo()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);

        var logo = new ArtworkContentTypeModel("ftp://example.com/logo.png", string.Empty);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(logo: logo), CancellationToken.None);

        LeftOf(result).Value.ShouldContain("External logo url is invalid");
    }

    [Test]
    public async Task Should_Download_External_Url_Logo_And_Store_Cache_Name()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);
        _remoteLogoCacher.CacheFromUrl(Arg.Any<Uri>(), Arg.Any<CancellationToken>())
            .Returns(Right<BaseError, string>("cachedhash"));

        var logo = new ArtworkContentTypeModel("https://example.com/logo.png", string.Empty);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(logo: logo), CancellationToken.None);

        result.IsRight.ShouldBeTrue();
        await using TvContext context = _db.CreateContext();
        Artwork artwork = (await context.Channels.Include(c => c.Artwork).SingleAsync())
            .Artwork.Single(a => a.ArtworkKind == ArtworkKind.Logo);
        artwork.Path.ShouldBe("cachedhash");
        artwork.IsExternalUrl().ShouldBeFalse();
    }

    [Test]
    public async Task Should_Fail_The_Create_When_The_Logo_Download_Fails()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);
        _remoteLogoCacher.CacheFromUrl(Arg.Any<Uri>(), Arg.Any<CancellationToken>())
            .Returns(Left<BaseError, string>(BaseError.New("Could not download logo: host timed out")));

        var logo = new ArtworkContentTypeModel("https://example.com/logo.png", string.Empty);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(logo: logo), CancellationToken.None);

        LeftOf(result).Value.ShouldContain("Could not download logo");

        // nothing is persisted when the download fails (resolution runs before PersistAndDispatch)
        await using TvContext context = _db.CreateContext();
        (await context.Channels.CountAsync()).ShouldBe(0);
        (await context.Playouts.CountAsync()).ShouldBe(0);
    }

    [Test]
    public async Task Should_Not_Call_The_Cacher_For_An_Uploaded_Logo_Path()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);

        var logo = new ArtworkContentTypeModel("iptv/logos/deadbeef", string.Empty);

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(logo: logo), CancellationToken.None);

        result.IsRight.ShouldBeTrue();
        await _remoteLogoCacher.DidNotReceive().CacheFromUrl(Arg.Any<Uri>(), Arg.Any<CancellationToken>());

        await using TvContext context = _db.CreateContext();
        Artwork artwork = (await context.Channels.Include(c => c.Artwork).SingleAsync())
            .Artwork.Single(a => a.ArtworkKind == ArtworkKind.Logo);
        artwork.Path.ShouldBe("deadbeef");
    }

    [Test]
    public async Task Should_Return_NotFound_When_Lineup_Target_Is_Missing()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(), CancellationToken.None);

        NotFoundError error = LeftOf(result).ShouldBeOfType<NotFoundError>();
        error.Value.ShouldContain("lineup[0]");
        error.Value.ShouldContain("Movie 42");
    }

    private async Task AssertNotFound(CreateChannelFromLineupAdvancedOptions advanced, string expectedFragment)
    {
        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(advanced: advanced), CancellationToken.None);

        NotFoundError error = LeftOf(result).ShouldBeOfType<NotFoundError>();
        error.Value.ShouldContain(expectedFragment);
    }

    private CreateChannelFromLineupHandler MakeHandler() =>
        new(
            _background.Writer,
            _db.Factory,
            _searchTargets,
            _remoteLogoCacher,
            NullLogger<CreateChannelFromLineupHandler>.Instance);

    private async Task SeedTemplateDependencies()
    {
        await using TvContext context = _db.CreateContext();
        context.FFmpegProfiles.Add(new FFmpegProfile { Id = 1, Name = "profile" });
        context.FillerPresets.AddRange(
            MakeFiller(2, FillerKind.PreRoll),
            MakeFiller(3, FillerKind.MidRoll),
            MakeFiller(4, FillerKind.PostRoll),
            MakeFiller(5, FillerKind.Fallback));
        await context.SaveChangesAsync();
    }

    private async Task SeedTemplate()
    {
        await using TvContext context = _db.CreateContext();
        context.ChannelTemplates.Add(new ChannelTemplate
        {
            Id = 10,
            Name = "Template",
            Description = string.Empty,
            FFmpegProfileId = 1,
            FallbackFillerId = 5,
            PreRollFillerId = 2,
            MidRollFillerId = 3,
            PostRollFillerId = 4,
            StreamSelectorMode = ChannelStreamSelectorMode.Default,
            StreamSelector = string.Empty,
            PreferredAudioLanguageCode = string.Empty,
            PreferredAudioTitle = string.Empty,
            PlayoutSource = ChannelPlayoutSource.Generated,
            PlayoutMode = ChannelPlayoutMode.Continuous,
            StreamingMode = StreamingMode.HttpLiveStreamingSegmenter,
            PreferredSubtitleLanguageCode = string.Empty,
            SubtitleMode = ChannelSubtitleMode.None,
            MusicVideoCreditsMode = ChannelMusicVideoCreditsMode.None,
            MusicVideoCreditsTemplate = string.Empty,
            SongVideoMode = ChannelSongVideoMode.Default,
            TranscodeMode = ChannelTranscodeMode.OnDemand,
            IdleBehavior = ChannelIdleBehavior.StopOnDisconnect,
            ShuffleScheduleItems = true,
            RandomStartPoint = true,
            FixedStartTimeBehavior = FixedStartTimeBehavior.Strict
        });
        await context.SaveChangesAsync();
    }

    private async Task SeedMovie(int id)
    {
        await using TvContext context = _db.CreateContext();
        context.Movies.Add(new Movie { Id = id });
        await context.SaveChangesAsync();
    }

    private async Task SeedShow(int id)
    {
        await using TvContext context = _db.CreateContext();
        context.Shows.Add(new Show { Id = id });
        await context.SaveChangesAsync();
    }

    private async Task SeedCollection(int id)
    {
        await using TvContext context = _db.CreateContext();
        context.Collections.Add(new Collection { Id = id, Name = $"Collection {id}" });
        await context.SaveChangesAsync();
    }

    private async Task SeedMultiCollection(int id)
    {
        await using TvContext context = _db.CreateContext();
        context.MultiCollections.Add(new MultiCollection { Id = id, Name = $"Multi {id}" });
        await context.SaveChangesAsync();
    }

    private async Task SeedRerunCollection(int id)
    {
        await using TvContext context = _db.CreateContext();
        context.RerunCollections.Add(new RerunCollection
        {
            Id = id,
            Name = $"Rerun {id}",
            CollectionType = CollectionType.Collection
        });
        await context.SaveChangesAsync();
    }

    private async Task SeedExistingPlaylist(int id)
    {
        await using TvContext context = _db.CreateContext();
        context.PlaylistGroups.Add(new PlaylistGroup { Id = 500, Name = "User Group", IsSystem = false });
        context.Playlists.Add(new Playlist { Id = id, Name = $"Playlist {id}", PlaylistGroupId = 500, IsSystem = false });
        await context.SaveChangesAsync();
    }

    private static FillerPreset MakeFiller(int id, FillerKind kind) =>
        new()
        {
            Id = id,
            Name = $"filler-{id}",
            FillerKind = kind,
            FillerMode = FillerMode.Count,
            Count = 1,
            CollectionType = CollectionType.Collection
        };

    private static CreateChannelFromLineupItem MovieItem(int id) =>
        new(LibraryBrowseMediaType.Movie, CollectionType.Movie, null, null, null, null, id, null);

    private static CreateChannelFromLineupItem ShowItem(int id) =>
        new(LibraryBrowseMediaType.TelevisionShow, CollectionType.TelevisionShow, null, null, null, null, id, null);

    private static CreateChannelFromLineupItem CollectionItem(int id) =>
        new(LibraryBrowseMediaType.Collection, CollectionType.Collection, id, null, null, null, null, null);

    private static CreateChannelFromLineupItem MultiCollectionItem(int id) =>
        new(LibraryBrowseMediaType.MultiCollection, CollectionType.MultiCollection, null, id, null, null, null, null);

    private static CreateChannelFromLineupItem RerunItem(int id) =>
        new(LibraryBrowseMediaType.RerunCollection, CollectionType.RerunFirstRun, null, null, null, id, null, null);

    private static CreateChannelFromLineupItem PlaylistEntry(int id) =>
        new(LibraryBrowseMediaType.Playlist, CollectionType.Playlist, null, null, null, null, null, id);

    private static CreateChannelFromLineup MakeRequest(
        string number = "12",
        string name = "Movies",
        int templateId = 10,
        bool isEnabled = true,
        bool showInEpg = true,
        ArtworkContentTypeModel logo = null,
        CreateChannelFromLineupAdvancedOptions advanced = null,
        List<CreateChannelFromLineupItem> lineup = null) =>
        new(
            name,
            number,
            "Kids",
            string.Empty,
            logo ?? ArtworkContentTypeModel.None,
            isEnabled,
            showInEpg,
            templateId,
            advanced ?? new CreateChannelFromLineupAdvancedOptions(PlaybackOrder.Shuffle),
            lineup ?? [MovieItem(42)]);

    private static BaseError LeftOf<TR>(Either<BaseError, TR> either) =>
        either.Match(Left: e => e, Right: _ => throw new AssertionException("Expected a Left result"));

    private static TR RightOf<TR>(Either<BaseError, TR> either) =>
        either.Match(Left: e => throw new AssertionException($"Expected a Right result, got {e.Value}"), Right: r => r);

    // #732: this is the SPA's primary "Add Channel" flow and the one Auto-Tune bulk-creates through.
    // It was the channel-creation site the default attach originally missed, so a channel made here
    // would silently never get the overlay once the one-time backfill marker had landed.
    [Test]
    public async Task Should_Attach_The_Built_In_On_Now_Next_Element()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);
        int elementId = await SeedBuiltInGraphicsElement();

        Either<BaseError, CreateChannelFromLineupResponseModel> result =
            await MakeHandler().Handle(MakeRequest(), CancellationToken.None);

        CreateChannelFromLineupResponseModel response = RightOf(result);

        await using TvContext context = _db.CreateContext();
        DomainChannel channel = await context.Channels
            .Include(c => c.ChannelGraphicsElements)
            .SingleAsync(c => c.Id == response.ChannelId);

        channel.ChannelGraphicsElements.Select(x => x.GraphicsElementId).ShouldBe([elementId]);
    }

    [Test]
    public async Task Should_Not_Attach_The_Overlay_To_An_Hls_Direct_Channel()
    {
        await SeedTemplateDependencies();
        await SeedTemplate();
        await SeedMovie(42);
        await SeedBuiltInGraphicsElement();

        Either<BaseError, CreateChannelFromLineupResponseModel> result = await MakeHandler().Handle(
            MakeRequest(advanced: new CreateChannelFromLineupAdvancedOptions(
                PlaybackOrder.Shuffle,
                StreamingMode: StreamingMode.HttpLiveStreamingDirect)),
            CancellationToken.None);

        CreateChannelFromLineupResponseModel response = RightOf(result);

        await using TvContext context = _db.CreateContext();
        DomainChannel channel = await context.Channels
            .Include(c => c.ChannelGraphicsElements)
            .SingleAsync(c => c.Id == response.ChannelId);

        channel.ChannelGraphicsElements.ShouldBeEmpty();
    }

    private async Task<int> SeedBuiltInGraphicsElement()
    {
        await using TvContext context = _db.CreateContext();
        var element = new GraphicsElement
        {
            Path = $"/templates/text/{GraphicsElementDefaults.OnNowNextFileName}",
            Kind = GraphicsElementKind.Text
        };

        context.GraphicsElements.Add(element);
        await context.SaveChangesAsync();
        return element.Id;
    }
}