using System.Collections.Generic;
using Jellyfin.Server.Extensions;
using MediaBrowser.Controller.MediaEncoding;
using MediaBrowser.Controller.Session;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging.Abstractions;
using Moq;
using StackExchange.Redis;
using Xunit;

namespace Jellyfin.Server.Tests.HighAvailability;

/// <summary>
/// The directory and the bus are two halves of one mechanism: a shared directory paired with a bus that
/// reaches nobody advertises sessions from every instance and then fails every command sent to one.
/// </summary>
public static class SessionDirectoryRegistrationTests
{
    [Fact]
    public static void AddSessionDirectory_WithoutARedisConnection_RegistersNeitherHalf()
    {
        var services = Build(configured: false);

        Assert.IsType<NullSessionDirectory>(services.GetRequiredService<ISessionDirectory>());
        Assert.IsType<NullPodMessageBus>(services.GetRequiredService<IPodMessageBus>());
    }

    [Fact]
    public static void AddSessionDirectory_WhenOneHalfCannotBeBuilt_FallsBackOnBoth()
    {
        // A connection that can serve the directory but not the bus: taking the directory on its own
        // would advertise every instance's sessions and then fail every command sent to one.
        var redis = new Mock<IConnectionMultiplexer>();
        redis.Setup(i => i.GetDatabase(It.IsAny<int>(), It.IsAny<object>())).Returns(Mock.Of<IDatabase>());
        redis.Setup(i => i.GetSubscriber(It.IsAny<object>())).Throws(new RedisConnectionException(ConnectionFailureType.UnableToConnect, "unreachable"));

        var services = Build(configured: true, redis.Object);

        Assert.IsType<NullSessionDirectory>(services.GetRequiredService<ISessionDirectory>());
        Assert.IsType<NullPodMessageBus>(services.GetRequiredService<IPodMessageBus>());
    }

    private static ServiceProvider Build(bool configured, IConnectionMultiplexer? redis = null)
    {
        var settings = new Dictionary<string, string?>();
        if (configured)
        {
            settings[TranscodeStoreOptions.RedisConnectionStringKey] = "127.0.0.1:6379";
        }

        var configuration = new ConfigurationBuilder().AddInMemoryCollection(settings).Build();
        var serviceCollection = new ServiceCollection().AddLogging();

        if (redis is not null)
        {
            serviceCollection.AddSingleton(redis);
        }

        return serviceCollection
            .AddSessionDirectory(configuration, NullLogger.Instance)
            .BuildServiceProvider();
    }
}