using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;
using Emby.Server.Implementations.ScheduledTasks.Tasks;
using MediaBrowser.Controller.ScheduledTasks;
using MediaBrowser.Model.Tasks;
using Xunit;

namespace Jellyfin.Server.Implementations.Tests.ScheduledTasks;

public class ScanLeaderOptionsTests
{
    /// <summary>
    /// A gated key that matches no registered task silently stops gating anything, so the default
    /// set is pinned to the task keys that actually exist in the build.
    /// </summary>
    [Fact]
    public void DefaultGatedTaskKeys_Should_MatchRegisteredScheduledTasks()
    {
        var registeredKeys = DiscoverScheduledTaskKeys();

        Assert.NotEmpty(registeredKeys);
        Assert.Empty(new ScanLeaderOptions().GatedTaskKeys.Except(registeredKeys, StringComparer.Ordinal));
    }

    private static HashSet<string> DiscoverScheduledTaskKeys()
    {
        var keys = new HashSet<string>(StringComparer.Ordinal);
        var assemblies = new[]
        {
            typeof(DeleteTranscodeFileTask).Assembly,
            typeof(Jellyfin.MediaEncoding.Hls.ScheduledTasks.KeyframeExtractionScheduledTask).Assembly
        };

        foreach (var type in assemblies.SelectMany(a => a.GetTypes()))
        {
            if (type.IsAbstract || type.IsInterface || !typeof(IScheduledTask).IsAssignableFrom(type))
            {
                continue;
            }

            // Task keys are constant expressions, so an uninitialised instance is enough to read
            // them without standing up each task's dependency graph.
            var task = (IScheduledTask)RuntimeHelpers.GetUninitializedObject(type);
            keys.Add(task.Key);
        }

        return keys;
    }
}