// Copyright 2013-2026 The NATS Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

using System.Net;
using System.Text;
using Shouldly;
using ZB.MOM.NatsNet.Server;

namespace ZB.MOM.NatsNet.Server.IntegrationTests;

/// <summary>
/// End-to-end server boot tests that validate the full
/// Start() → AcceptLoop → client connection lifecycle.
/// </summary>
[Trait("Category", "Integration")]
public sealed class ServerBootTests : IDisposable
{
    private readonly string _storeDir;

    public ServerBootTests()
    {
        _storeDir = Path.Combine(Path.GetTempPath(), $"natsnet-test-{Guid.NewGuid():N}");
    }

    public void Dispose()
    {
        try { Directory.Delete(_storeDir, true); } catch { }
    }

    /// <summary>
    /// Validates that a server can boot, accept a TCP connection, and send
    /// a NATS protocol INFO line. This proves the full Start() → AcceptLoop
    /// → CreateClient pipeline works end-to-end.
    /// </summary>
    /// <summary>
    /// Validates that a server can boot, bind a port, and accept a TCP connection.
    /// Note: GenerateClientInfoJSON is currently a stub (returns empty), so we only
    /// verify the TCP handshake succeeds — not the INFO protocol line.
    /// </summary>
    [Fact]
    public async Task ServerBoot_AcceptsTcpConnection_ShouldSucceed()
    {
        // Arrange — create server with ephemeral port
        var opts = new ServerOptions
        {
            Host = "127.0.0.1",
            Port = 0, // ephemeral
        };

        var (server, err) = NatsServer.NewServer(opts);
        err.ShouldBeNull("NewServer should succeed");
        server.ShouldNotBeNull();

        try
        {
            // Act — start the server
            server!.Start();

            // Get the actual bound port
            var addr = server.Addr() as IPEndPoint;
            addr.ShouldNotBeNull("Server should have a listener address after Start()");
            addr!.Port.ShouldBeGreaterThan(0);

            // Connect a raw TCP client — proves AcceptLoop is working
            using var tcp = new System.Net.Sockets.TcpClient();
            using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(5));
            await tcp.ConnectAsync(addr.Address, addr.Port, cts.Token);

            tcp.Connected.ShouldBeTrue();

            // Verify the server registered the client
            await Task.Delay(100); // Give CreateClient a moment to run
            server.NumClients().ShouldBeGreaterThan(0);
        }
        finally
        {
            server!.Shutdown();
        }
    }

    /// <summary>
    /// Validates that Shutdown() after Start() completes cleanly.
    /// Uses DontListen to skip TCP binding — tests lifecycle only.
    /// </summary>
    [Fact]
    public void ServerBoot_StartAndShutdown_ShouldSucceed()
    {
        var opts = new ServerOptions
        {
            Host = "127.0.0.1",
            Port = 0,
            DontListen = true,
        };

        var (server, err) = NatsServer.NewServer(opts);
        err.ShouldBeNull();
        server.ShouldNotBeNull();

        server!.Start();
        server.Running().ShouldBeTrue();

        server.Shutdown();
        server.Running().ShouldBeFalse();
    }
}