using System.Net;
using System.Net.Http.Json;
using System.Net.Sockets;
using Microsoft.Extensions.Logging.Abstractions;
using NATS.Server.Monitoring;

namespace NATS.Server.Tests;

public class MonitorTests : IAsyncLifetime
{
    private readonly NatsServer _server;
    private readonly int _natsPort;
    private readonly int _monitorPort;
    private readonly CancellationTokenSource _cts = new();
    private readonly HttpClient _http = new();

    public MonitorTests()
    {
        _natsPort = GetFreePort();
        _monitorPort = GetFreePort();
        _server = new NatsServer(
            new NatsOptions { Port = _natsPort, MonitorPort = _monitorPort },
            NullLoggerFactory.Instance);
    }

    public async Task InitializeAsync()
    {
        _ = _server.StartAsync(_cts.Token);
        await _server.WaitForReadyAsync();
        // Give monitoring server time to start
        await Task.Delay(200);
    }

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

    [Fact]
    public async Task Healthz_returns_ok()
    {
        var response = await _http.GetAsync($"http://127.0.0.1:{_monitorPort}/healthz");
        response.StatusCode.ShouldBe(HttpStatusCode.OK);
    }

    [Fact]
    public async Task Varz_returns_server_identity()
    {
        var response = await _http.GetAsync($"http://127.0.0.1:{_monitorPort}/varz");
        response.StatusCode.ShouldBe(HttpStatusCode.OK);

        var varz = await response.Content.ReadFromJsonAsync<Varz>();
        varz.ShouldNotBeNull();
        varz.Id.ShouldNotBeNullOrEmpty();
        varz.Name.ShouldNotBeNullOrEmpty();
        varz.Version.ShouldBe("0.1.0");
        varz.Host.ShouldBe("0.0.0.0");
        varz.Port.ShouldBe(_natsPort);
        varz.MaxPayload.ShouldBe(1024 * 1024);
        varz.Uptime.ShouldNotBeNullOrEmpty();
        varz.Now.ShouldBeGreaterThan(DateTime.MinValue);
        varz.Mem.ShouldBeGreaterThan(0);
        varz.Cores.ShouldBeGreaterThan(0);
    }

    [Fact]
    public async Task Varz_tracks_connections_and_messages()
    {
        // Connect a client and send a message
        using var sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        await sock.ConnectAsync(new IPEndPoint(IPAddress.Loopback, _natsPort));

        var buf = new byte[4096];
        _ = await sock.ReceiveAsync(buf, SocketFlags.None); // Read INFO

        var cmd = "CONNECT {}\r\nSUB test 1\r\nPUB test 5\r\nhello\r\n"u8.ToArray();
        await sock.SendAsync(cmd, SocketFlags.None);
        await Task.Delay(200);

        var response = await _http.GetAsync($"http://127.0.0.1:{_monitorPort}/varz");
        var varz = await response.Content.ReadFromJsonAsync<Varz>();

        varz.ShouldNotBeNull();
        varz.Connections.ShouldBeGreaterThanOrEqualTo(1);
        varz.TotalConnections.ShouldBeGreaterThanOrEqualTo(1UL);
        varz.InMsgs.ShouldBeGreaterThanOrEqualTo(1L);
        varz.InBytes.ShouldBeGreaterThanOrEqualTo(5L);
    }

    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;
    }
}