using ErsatzTV.Core.Domain;
using GraphicsElement = ErsatzTV.Core.Domain.GraphicsElement;
using ErsatzTV.Core.Graphics;
using ErsatzTV.FFmpeg.State;
using ErsatzTV.Infrastructure.Data;
using ErsatzTV.Infrastructure.Streaming.Graphics;
using ErsatzTV.Tests.Support;
using Microsoft.EntityFrameworkCore;
using System.IO.Abstractions;
using Microsoft.Extensions.Logging.Abstractions;
using Testably.Abstractions.Testing;
using ErsatzTV.Core;
using NUnit.Framework;
using Shouldly;

namespace ErsatzTV.Tests.Infrastructure;

/// <summary>
/// #732 part 2: the On Now / Next overlay is a default rather than an opt-in. Channels that predate
/// that decision are backfilled once -- and only once, so a channel an operator deliberately clears
/// is never silently re-attached on the next restart.
/// </summary>
[TestFixture]
public class GraphicsElementDefaultAttachTests
{
    private InMemoryTvContext _db = null!;

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

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

    private static async Task<int> SeedBuiltInElement(TvContext context)
    {
        var element = new GraphicsElement
        {
            Path = $"/templates/text/{GraphicsElementDefaults.OnNowNextFileName}",
            Name = "On Now / Next",
            Kind = GraphicsElementKind.Text
        };

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

    private static async Task<Channel> SeedChannel(
        TvContext context,
        string number,
        StreamingMode mode = StreamingMode.HttpLiveStreamingSegmenter)
    {
        var channel = new Channel(Guid.NewGuid())
        {
            Name = $"Channel {number}",
            Number = number,
            StreamingMode = mode,
            ChannelGraphicsElements = []
        };

        await context.Channels.AddAsync(channel);
        await context.SaveChangesAsync();
        return channel;
    }

    private static async Task<List<int>> AttachedElementIds(TvContext context, int channelId) =>
        await context.Set<ChannelGraphicsElement>()
            .AsNoTracking()
            .Where(cge => cge.ChannelId == channelId)
            .Select(cge => cge.GraphicsElementId)
            .ToListAsync();

    [Test]
    public async Task Attaches_The_Built_In_Element_To_Existing_Channels()
    {
        await using TvContext context = _db.CreateContext();
        int elementId = await SeedBuiltInElement(context);
        Channel one = await SeedChannel(context, "1");
        Channel two = await SeedChannel(context, "2");

        await GraphicsElementSeeder.AttachOnNowNextByDefault(context, CancellationToken.None);

        (await AttachedElementIds(context, one.Id)).ShouldBe([elementId]);
        (await AttachedElementIds(context, two.Id)).ShouldBe([elementId]);
    }

    [Test]
    public async Task Skips_Hls_Direct_Channels_Where_The_Overlay_Cannot_Render()
    {
        await using TvContext context = _db.CreateContext();
        await SeedBuiltInElement(context);
        Channel direct = await SeedChannel(context, "1", StreamingMode.HttpLiveStreamingDirect);

        await GraphicsElementSeeder.AttachOnNowNextByDefault(context, CancellationToken.None);

        (await AttachedElementIds(context, direct.Id)).ShouldBeEmpty();
    }

    [Test]
    public async Task Does_Not_Duplicate_An_Existing_Attachment()
    {
        await using TvContext context = _db.CreateContext();
        int elementId = await SeedBuiltInElement(context);
        Channel channel = await SeedChannel(context, "1");

        await context.AddAsync(
            new ChannelGraphicsElement { ChannelId = channel.Id, GraphicsElementId = elementId });
        await context.SaveChangesAsync();

        await GraphicsElementSeeder.AttachOnNowNextByDefault(context, CancellationToken.None);

        (await AttachedElementIds(context, channel.Id)).Count.ShouldBe(1);
    }

    // The load-bearing property: a default must not fight the operator.
    [Test]
    public async Task Does_Not_Re_Attach_After_An_Operator_Clears_It()
    {
        await using TvContext context = _db.CreateContext();
        await SeedBuiltInElement(context);
        Channel channel = await SeedChannel(context, "1");

        await GraphicsElementSeeder.AttachOnNowNextByDefault(context, CancellationToken.None);
        (await AttachedElementIds(context, channel.Id)).Count.ShouldBe(1);

        // operator turns the overlay off for this channel
        context.Set<ChannelGraphicsElement>()
            .RemoveRange(context.Set<ChannelGraphicsElement>().Where(cge => cge.ChannelId == channel.Id));
        await context.SaveChangesAsync();

        // ...and the app restarts
        await GraphicsElementSeeder.AttachOnNowNextByDefault(context, CancellationToken.None);

        (await AttachedElementIds(context, channel.Id)).ShouldBeEmpty();
    }

    // The upgrade population this backfill exists for -- an install seeding the template for the
    // first time on this boot -- must not be stranded. The GraphicsElement row is normally created
    // by RefreshGraphicsElements, which runs long after startup, so the seeder ensures it itself.
    // Without that, the marker would be written against an unresolved element and every pre-existing
    // channel would go permanently unattached.
    [Test]
    public async Task Backfills_On_The_Same_Boot_That_First_Seeds_The_Template()
    {
        var fs = new MockFileSystem();
        await using TvContext context = _db.CreateContext();
        Channel channel = await SeedChannel(context, "1");

        // no ConfigElement markers and no GraphicsElement row: a pre-#74 install meeting #732
        await GraphicsElementSeeder.SeedOnNowNext(context, fs, NullLogger.Instance, CancellationToken.None);
        await GraphicsElementSeeder.AttachOnNowNextByDefault(context, CancellationToken.None);

        (await AttachedElementIds(context, channel.Id)).Count.ShouldBe(1);
    }

    // Filename alone is ambiguous: the five template folders are separate namespaces, so an element
    // of another kind may legitimately carry the same filename.
    [Test]
    public async Task Ignores_A_Same_Named_Element_Of_A_Different_Kind()
    {
        await using TvContext context = _db.CreateContext();
        await context.GraphicsElements.AddAsync(
            new GraphicsElement
            {
                Path = $"/templates/image/{GraphicsElementDefaults.OnNowNextFileName}",
                Kind = GraphicsElementKind.Image
            });
        await context.SaveChangesAsync();

        Channel channel = await SeedChannel(context, "1");

        await GraphicsElementSeeder.AttachOnNowNextByDefault(context, CancellationToken.None);

        (await AttachedElementIds(context, channel.Id)).ShouldBeEmpty();
    }

    [Test]
    public async Task Ignores_A_Non_Built_In_Element_With_A_Different_Filename()
    {
        await using TvContext context = _db.CreateContext();
        await context.GraphicsElements.AddAsync(
            new GraphicsElement { Path = "/templates/text/something-else.yml", Kind = GraphicsElementKind.Text });
        await context.SaveChangesAsync();

        Channel channel = await SeedChannel(context, "1");

        await GraphicsElementSeeder.AttachOnNowNextByDefault(context, CancellationToken.None);

        (await AttachedElementIds(context, channel.Id)).ShouldBeEmpty();
    }

    // The marker is permanent, so writing it with nothing resolved would strand every channel. Stay
    // armed instead and pick the work up once the element exists.
    [Test]
    public async Task Stays_Armed_When_There_Is_No_Built_In_Element_To_Attach()
    {
        await using TvContext context = _db.CreateContext();
        Channel channel = await SeedChannel(context, "1");

        await GraphicsElementSeeder.AttachOnNowNextByDefault(context, CancellationToken.None);

        (await context.ConfigElements
            .AnyAsync(c => c.Key == ConfigElementKey.GraphicsOnNowNextDefaultAttached.Key))
            .ShouldBeFalse("the marker was written with nothing to attach");

        // the element turns up later; the backfill must still do its job
        await SeedBuiltInElement(context);
        await GraphicsElementSeeder.AttachOnNowNextByDefault(context, CancellationToken.None);

        (await AttachedElementIds(context, channel.Id)).Count.ShouldBe(1);
    }

    // The already-seeded branch of SeedOnNowNext has its own EnsureBuiltInElementRow call. Removing
    // it reddened nothing until this test existed -- the other tests all exercise a FRESH seed.
    [Test]
    public async Task An_Already_Seeded_Install_Missing_Its_Element_Row_Gets_One()
    {
        var fs = new MockFileSystem();
        fs.Directory.CreateDirectory(FileSystemLayout.GraphicsElementsTextTemplatesFolder);
        string target = Path.Combine(
            FileSystemLayout.GraphicsElementsTextTemplatesFolder,
            GraphicsElementDefaults.OnNowNextFileName);
        await fs.File.WriteAllTextAsync(target, "name: On Now / Next\n");

        await using TvContext context = _db.CreateContext();
        context.ConfigElements.Add(
            new ConfigElement { Key = ConfigElementKey.GraphicsOnNowNextSeeded.Key, Value = "true" });
        await context.SaveChangesAsync();

        (await context.GraphicsElements.CountAsync()).ShouldBe(0);

        await GraphicsElementSeeder.SeedOnNowNext(context, fs, NullLogger.Instance, CancellationToken.None);

        // Assert the ROW, not just that one exists: a lookup-only assertion is satisfied by a row
        // with a null Name, which sorts the built-in element into the unnamed bucket in the SPA.
        List<GraphicsElement> rows = await context.GraphicsElements.ToListAsync();
        rows.Count.ShouldBe(1);
        rows[0].Path.ShouldBe(target);
        rows[0].Kind.ShouldBe(GraphicsElementKind.Text);
        rows[0].Name.ShouldBe(GraphicsElementDefaults.OnNowNextName);

        (await GraphicsElementSeeder.GetBuiltInElementId(context, CancellationToken.None)).IsSome.ShouldBeTrue();
    }

    // The armed path is a real, reachable state: an operator deletes the template, refresh reaps the
    // row, and the backfill then has nothing to resolve. Pin what happens when the element comes
    // back -- a single global marker cannot both avoid stranding and avoid re-adding, and this is
    // the half we accept. See graphics.on-now-next-on-by-default.
    [Test]
    public async Task While_Armed_A_Restored_Element_Is_Attached_To_Every_Eligible_Channel()
    {
        await using TvContext context = _db.CreateContext();
        Channel kept = await SeedChannel(context, "1");
        Channel cleared = await SeedChannel(context, "2");

        // nothing to resolve yet -> stays armed, no marker
        await GraphicsElementSeeder.AttachOnNowNextByDefault(context, CancellationToken.None);
        (await context.ConfigElements
            .AnyAsync(c => c.Key == ConfigElementKey.GraphicsOnNowNextDefaultAttached.Key))
            .ShouldBeFalse();

        // The element reappears and is attached to BOTH channels; the operator then clears `cleared`.
        // Doing the attach-then-remove for real matters: seeding `cleared` with no join at all would
        // only prove an untouched channel gets backfilled, which is not the claim.
        int elementId = await SeedBuiltInElement(context);
        await context.AddAsync(new ChannelGraphicsElement { ChannelId = kept.Id, GraphicsElementId = elementId });
        await context.AddAsync(new ChannelGraphicsElement { ChannelId = cleared.Id, GraphicsElementId = elementId });
        await context.SaveChangesAsync();

        (await AttachedElementIds(context, cleared.Id)).Count.ShouldBe(1);

        context.Set<ChannelGraphicsElement>()
            .RemoveRange(context.Set<ChannelGraphicsElement>().Where(cge => cge.ChannelId == cleared.Id));
        await context.SaveChangesAsync();
        (await AttachedElementIds(context, cleared.Id)).ShouldBeEmpty();

        await GraphicsElementSeeder.AttachOnNowNextByDefault(context, CancellationToken.None);

        // documented consequence: the still-armed backfill cannot see that deliberate clear
        (await AttachedElementIds(context, kept.Id)).Count.ShouldBe(1);
        (await AttachedElementIds(context, cleared.Id)).Count.ShouldBe(1);

        // ...but it is now marked, so it never fires again
        (await context.ConfigElements
            .AnyAsync(c => c.Key == ConfigElementKey.GraphicsOnNowNextDefaultAttached.Key))
            .ShouldBeTrue();
    }
}