using System.Collections.Concurrent;
using Shouldly;
using ZB.MOM.NatsNet.Server;

namespace ZB.MOM.NatsNet.Server.Tests.ImplBacklog;

public sealed partial class ConcurrencyTests1
{
    [Fact] // T:2452
    public void NoRaceFileStoreStreamMaxAgePerformance_ShouldSucceed()
    {
        WithStore((fs, _) =>
        {
            Parallel.For(0, 200, i => fs.StoreMsg($"age.{i % 4}", null, new[] { (byte)(i % 255) }, 0));

            var state = fs.State();
            state.Msgs.ShouldBeGreaterThan(0UL);
            state.LastSeq.ShouldBeGreaterThanOrEqualTo(state.Msgs);

            var (total, validThrough, err) = fs.NumPending(1, ">", false);
            err.ShouldBeNull();
            total.ShouldBeGreaterThan(0UL);
            validThrough.ShouldBeGreaterThan(0UL);
        }, DefaultStreamConfig(maxAge: TimeSpan.FromMilliseconds(20)));
    }

    [Fact] // T:2453
    public void NoRaceFileStoreFilteredStateWithLargeDeletes_ShouldSucceed()
    {
        WithStore((fs, _) =>
        {
            for (var i = 0; i < 240; i++)
                fs.StoreMsg("fd", null, new[] { (byte)(i % 255) }, 0);

            Parallel.For(1L, 240L, i =>
            {
                if (i % 3 == 0)
                    fs.RemoveMsg((ulong)i);
            });

            var filtered = fs.FilteredState(1, "fd");
            filtered.Msgs.ShouldBeGreaterThan(0UL);
            filtered.Last.ShouldBeGreaterThanOrEqualTo(filtered.First);

            fs.SubjectsTotals(">")["fd"].ShouldBeGreaterThan(0UL);
        });
    }

    [Fact] // T:2462
    public void NoRaceFileStoreNumPending_ShouldSucceed()
    {
        WithStore((fs, _) =>
        {
            for (var i = 0; i < 100; i++)
                fs.StoreMsg($"np.{i % 5}", null, "x"u8.ToArray(), 0);

            var errors = new ConcurrentQueue<Exception>();
            var workers = Enumerable.Range(0, 8).Select(_ => Task.Run(() =>
            {
                try
                {
                    for (var i = 0; i < 40; i++)
                    {
                        var (_, _, err1) = fs.NumPending(1, ">", false);
                        if (err1 != null)
                            throw err1;

                        var (_, _, err2) = fs.NumPendingMulti(1, new[] { "np.1", "np.*" }, false);
                        if (err2 != null)
                            throw err2;
                    }
                }
                catch (Exception ex)
                {
                    errors.Enqueue(ex);
                }
            })).ToArray();

            Task.WaitAll(workers);
            errors.ShouldBeEmpty();
        });
    }

    private static void WithStore(Action<JetStreamFileStore, string> action, StreamConfig? cfg = null)
    {
        var root = NewRoot();
        Directory.CreateDirectory(root);
        JetStreamFileStore? fs = null;

        try
        {
            fs = JetStreamFileStore.NewFileStore(new FileStoreConfig { StoreDir = root }, cfg ?? DefaultStreamConfig());
            action(fs, root);
        }
        finally
        {
            fs?.Stop();
            if (Directory.Exists(root))
                Directory.Delete(root, recursive: true);
        }
    }

    private static StreamConfig DefaultStreamConfig(TimeSpan? maxAge = null)
    {
        return new StreamConfig
        {
            Name = "TEST",
            Storage = StorageType.FileStorage,
            Subjects = ["test.>"],
            MaxMsgs = -1,
            MaxBytes = -1,
            MaxAge = maxAge ?? TimeSpan.Zero,
            MaxMsgsPer = -1,
            Discard = DiscardPolicy.DiscardOld,
            Retention = RetentionPolicy.LimitsPolicy,
        };
    }

    private static string NewRoot() => Path.Combine(Path.GetTempPath(), $"impl-fs-c1-{Guid.NewGuid():N}");
}