using System.Net;
using System.Net.Sockets;
using System.Text;
using Microsoft.Extensions.Logging.Abstractions;
using NATS.Client.Core;
using NATS.Server;

namespace NATS.Server.Tests;

public class IntegrationTests : IAsyncDisposable
{
    private readonly NatsServer _server;
    private readonly int _port;
    private readonly CancellationTokenSource _cts = new();
    private readonly Task _serverTask;

    public IntegrationTests()
    {
        _port = GetFreePort();
        _server = new NatsServer(new NatsOptions { Port = _port }, NullLoggerFactory.Instance);
        _serverTask = _server.StartAsync(_cts.Token);
        Thread.Sleep(200); // Let server start
    }

    public async ValueTask DisposeAsync()
    {
        await _cts.CancelAsync();
        _server.Dispose();
    }

    private static int GetFreePort()
    {
        using var sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        sock.Bind(new IPEndPoint(IPAddress.Loopback, 0));
        return ((IPEndPoint)sock.LocalEndPoint!).Port;
    }

    private NatsConnection CreateClient()
    {
        var opts = new NatsOpts { Url = $"nats://127.0.0.1:{_port}" };
        return new NatsConnection(opts);
    }

    [Fact]
    public async Task PubSub_basic()
    {
        await using var pub = CreateClient();
        await using var sub = CreateClient();

        await pub.ConnectAsync();
        await sub.ConnectAsync();

        var received = new TaskCompletionSource<string>();

        var subscription = Task.Run(async () =>
        {
            await foreach (var msg in sub.SubscribeAsync<string>("test.subject"))
            {
                received.TrySetResult(msg.Data!);
                break;
            }
        });

        await Task.Delay(100); // let subscription register

        await pub.PublishAsync("test.subject", "Hello NATS!");

        var result = await received.Task.WaitAsync(TimeSpan.FromSeconds(5));
        result.ShouldBe("Hello NATS!");
    }

    [Fact]
    public async Task PubSub_wildcard_star()
    {
        await using var pub = CreateClient();
        await using var sub = CreateClient();

        await pub.ConnectAsync();
        await sub.ConnectAsync();

        var received = new TaskCompletionSource<string>();

        var subscription = Task.Run(async () =>
        {
            await foreach (var msg in sub.SubscribeAsync<string>("test.*"))
            {
                received.TrySetResult(msg.Subject);
                break;
            }
        });

        await Task.Delay(100);
        await pub.PublishAsync("test.hello", "data");

        var result = await received.Task.WaitAsync(TimeSpan.FromSeconds(5));
        result.ShouldBe("test.hello");
    }

    [Fact]
    public async Task PubSub_wildcard_gt()
    {
        await using var pub = CreateClient();
        await using var sub = CreateClient();

        await pub.ConnectAsync();
        await sub.ConnectAsync();

        var received = new TaskCompletionSource<string>();

        var subscription = Task.Run(async () =>
        {
            await foreach (var msg in sub.SubscribeAsync<string>("test.>"))
            {
                received.TrySetResult(msg.Subject);
                break;
            }
        });

        await Task.Delay(100);
        await pub.PublishAsync("test.foo.bar.baz", "data");

        var result = await received.Task.WaitAsync(TimeSpan.FromSeconds(5));
        result.ShouldBe("test.foo.bar.baz");
    }

    [Fact]
    public async Task PubSub_fan_out()
    {
        await using var pub = CreateClient();
        await using var sub1 = CreateClient();
        await using var sub2 = CreateClient();

        await pub.ConnectAsync();
        await sub1.ConnectAsync();
        await sub2.ConnectAsync();

        var count1 = 0;
        var count2 = 0;
        var done = new TaskCompletionSource();

        var s1 = Task.Run(async () =>
        {
            await foreach (var msg in sub1.SubscribeAsync<string>("fanout"))
            {
                Interlocked.Increment(ref count1);
                if (Volatile.Read(ref count1) + Volatile.Read(ref count2) >= 2)
                    done.TrySetResult();
                break;
            }
        });

        var s2 = Task.Run(async () =>
        {
            await foreach (var msg in sub2.SubscribeAsync<string>("fanout"))
            {
                Interlocked.Increment(ref count2);
                if (Volatile.Read(ref count1) + Volatile.Read(ref count2) >= 2)
                    done.TrySetResult();
                break;
            }
        });

        await Task.Delay(100);
        await pub.PublishAsync("fanout", "hello");

        await done.Task.WaitAsync(TimeSpan.FromSeconds(5));
        count1.ShouldBe(1);
        count2.ShouldBe(1);
    }

    [Fact]
    public async Task PingPong()
    {
        await using var client = CreateClient();
        await client.ConnectAsync();

        // If we got here, the connection is alive and PING/PONG works
        await client.PingAsync();
    }
}