using System;
using System.Linq;
using Nito.AsyncEx;
using Realms;
using Xunit;

namespace osu.Game.Tests
{
    public class BacklinkViaQueryBugTests
    {
        [Fact]
        public void TestBacklinkViaQuery()
        {
            AsyncContext.Run(() =>
            {
                // test with no backlinks
                using (var realm = Realm.GetInstance(new InMemoryConfiguration("a")))
                {
                    using (var transaction = realm.BeginWrite())
                    {
                        realm.Add(new TestFile { Hash = "1" });
                        transaction.Commit();
                    }

                    var filesList = realm.All<TestFile>().ToList(); // non-queryable so we can linq access BacklinksCount.

                    Assert.Equal(0, filesList.Count(f => f.BacklinksCount > 0));
                    Assert.Equal(0, realm.All<TestFile>().Count(f => f.Usages.Any()));
                }
            });
        }

        public class TestThingUsingFile : RealmObject
        {
            public TestFile File { get; set; } = null!;
        }

        public class TestFile : RealmObject
        {
            [PrimaryKey]
            public string Hash { get; set; } = String.Empty;

            [Backlink(nameof(TestThingUsingFile.File))]
            public IQueryable<TestThingUsingFile> Usages { get; } = null!; // TODO: check efficiency (ie. do we need to cache this to a count still?)
        }
    }
}