using Microsoft.Extensions.Hosting;
using Moq;
using OwnerNumberMigration.Migrations;
using OwnerNumberMigrationTest.TestDataFactories;

namespace OwnerNumberMigrationTest.Migrations;

public class MigrationManagerTest
{
    private readonly IMigrationManager _manager;

    private readonly Mock<IHostApplicationLifetime> _lifetime = new();

    public MigrationManagerTest()
    {
        _manager = new MigrationManager(_lifetime.Object);
    }

    [SetUp]
    public void SetUp()
    {
        _lifetime.Reset();
    }

    [Test]
    public async Task Start_OneTaskThatFinishes_EndsApplication()
    {
        var applicationStopped = new SemaphoreSlim(0);
        _lifetime
            .Setup(l => l.StopApplication())
            .Callback(() => applicationStopped.Release());
        var task = Task.CompletedTask;

        _manager.Start(task);

        await applicationStopped.WaitAsync(TimeSpan.FromMilliseconds(50));
        _lifetime.Verify(l => l.StopApplication(), Times.AtLeastOnce);
    }

    [Test]
    public async Task Start_OneTaskThatCancels_EndsApplication()
    {
        var applicationStopped = new SemaphoreSlim(0);
        _lifetime
            .Setup(l => l.StopApplication())
            .Callback(() => applicationStopped.Release());
        var task = Task.FromCanceled(new CancellationToken(true));

        _manager.Start(task);

        await applicationStopped.WaitAsync(TimeSpan.FromMilliseconds(50));
        _lifetime.Verify(l => l.StopApplication(), Times.AtLeastOnce);
    }

    [Test]
    public async Task Start_OneTaskThatErrors_EndsApplication()
    {
        var applicationStopped = new SemaphoreSlim(0);
        _lifetime
            .Setup(l => l.StopApplication())
            .Callback(() => applicationStopped.Release());
        _lifetime
            .Setup(l => l.StopApplication())
            .Callback(() => applicationStopped.Release());
        var task = Task.FromException(new Exception());

        _manager.Start(task);

        await applicationStopped.WaitAsync(TimeSpan.FromMilliseconds(50));
        _lifetime.Verify(l => l.StopApplication(), Times.AtLeastOnce);
    }

    [Test]
    public async Task Start_MultipleTasksThatFinish_EndsApplicationAfterAll()
    {
        var applicationStopped = new SemaphoreSlim(0);
        _lifetime
            .Setup(l => l.StopApplication())
            .Callback(() => applicationStopped.Release());
        var semaphores = EnumerableDataSeriesFactory
            .CreateSeries(() => new SemaphoreSlim(0), 5)
            .ToArray();
        var tasks = semaphores
            .Select(s => Task.Run(async () => await s.WaitAsync()))
            .ToArray();

        foreach(var task in tasks) _manager.Start(task);

        _lifetime.Verify(l => l.StopApplication(), Times.Never);
        foreach (var semaphore in semaphores[..^1])
        {
            semaphore.Release();
            _lifetime.Verify(l => l.StopApplication(), Times.Never);
        }
        foreach (var semaphore in semaphores[^1..])
        {
            semaphore.Release();
        }
        await applicationStopped.WaitAsync(TimeSpan.FromMilliseconds(50));
        _lifetime.Verify(l => l.StopApplication(), Times.AtLeastOnce);
    }
}