using System.Diagnostics;
using System.Text.RegularExpressions;
using VoiceCat.Interop;

namespace VoiceCat.Interop.Tests;

/// <summary>
/// Exercises the full connect -> TOFU event -> confirm -> guest auth -> list channels flow
/// purely through the P/Invoke layer (NativeMethods/VoiceCatClient), against a real
/// `voicecat-server.exe` (the same binary the C++ ctest suite uses) — this is the same flow
/// tests/test_tofu_flow.cpp already proves at the C++ level, now proven reachable through
/// P/Invoke specifically: marshaling bugs, callback-lifetime bugs, and calling-convention
/// mistakes are all P/Invoke-specific failure modes ctest alone cannot catch.
/// </summary>
public sealed class VoiceCatClientSmokeTests : IDisposable
{
    private readonly string _tempDir;
    private readonly Process _server;
    private readonly ushort _port;

    public VoiceCatClientSmokeTests()
    {
        _tempDir = Path.Combine(Path.GetTempPath(), "vc_csharp_smoke_" + Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(_tempDir);

        string serverExe = Path.Combine(FindRepoRoot(), "build", "m1-dev", "bin", "voicecat-server.exe");
        Assert.True(File.Exists(serverExe),
            $"voicecat-server.exe not found at '{serverExe}' — build the m1-dev preset first " +
            "(cmake --preset m1-dev && cmake --build --preset m1-dev).");

        var psi = new ProcessStartInfo(serverExe)
        {
            Arguments = $"--port 0 --data-dir \"{_tempDir}\" --name CSharpSmokeTest",
            RedirectStandardOutput = true,
            RedirectStandardError = true,
            UseShellExecute = false,
        };
        _server = Process.Start(psi) ?? throw new InvalidOperationException("failed to start voicecat-server.exe");

        // "[voicecat-server] <name> — TCP :<port>  UDP :<port>" — see server/src/server.cpp.
        // ReadLineAsync()+timeout (not a bare blocking ReadLine() in a deadline loop) so a
        // server that never prints anything (crash, hang) can't hang this constructor forever
        // — the deadline check must apply to the read itself, not just the loop around it.
        ushort? port = null;
        var deadline = DateTime.UtcNow.AddSeconds(10);
        while (port is null && DateTime.UtcNow < deadline)
        {
            var readTask = _server.StandardOutput.ReadLineAsync();
            var remaining = deadline - DateTime.UtcNow;
            if (remaining <= TimeSpan.Zero || !readTask.Wait(remaining)) break;
            string? line = readTask.Result;
            if (line is null) break;
            var m = Regex.Match(line, @"TCP :(\d+)");
            if (m.Success) port = ushort.Parse(m.Groups[1].Value);
        }
        Assert.True(port is not null, "voicecat-server.exe did not report a bound TCP port within 10s.");
        _port = port!.Value;
    }

    public void Dispose()
    {
        try { if (!_server.HasExited) _server.Kill(entireProcessTree: true); } catch { /* best effort */ }
        try { Directory.Delete(_tempDir, recursive: true); } catch { /* best effort */ }
    }

    private static string FindRepoRoot()
    {
        var dir = new DirectoryInfo(AppContext.BaseDirectory);
        while (dir is not null && !File.Exists(Path.Combine(dir.FullName, "CMakePresets.json")))
            dir = dir.Parent;
        return dir?.FullName ?? throw new InvalidOperationException("Could not find repo root (CMakePresets.json) above " + AppContext.BaseDirectory);
    }

    private static bool PumpUntil(VoiceCatClient client, Func<bool> predicate, int timeoutMs)
    {
        var deadline = DateTime.UtcNow.AddMilliseconds(timeoutMs);
        while (DateTime.UtcNow < deadline)
        {
            client.PumpEvents();
            if (predicate()) return true;
            Thread.Sleep(20);
        }
        client.PumpEvents();
        return predicate();
    }

    [Fact]
    public void VersionString_IsNonEmpty()
    {
        Assert.False(string.IsNullOrEmpty(VoiceCatClient.VersionString));
    }

    [Fact]
    public void Connect_Tofu_Auth_ListChannels_RoundTrips()
    {
        var events = new List<VoiceCatEvent>();
        using var client = new VoiceCatClient("vc-csharp-smoke", "0.1", VcLogLevel.Off,
            tofuStorePath: Path.Combine(_tempDir, "tofu_pins.txt"));
        client.EventReceived += events.Add;

        Assert.Equal(VcResult.Ok, client.Connect("127.0.0.1", _port));
        Assert.Equal(VcResult.Ok, client.AuthenticateGuest("CSharpSmoke"));

        Assert.True(PumpUntil(client, () => events.Any(e => e.Type == VcEventType.ServerIdentity), 5000),
            "did not receive VC_EVENT_SERVER_IDENTITY");
        var identityEvent = events.First(e => e.Type == VcEventType.ServerIdentity);
        Assert.Equal((uint)VcTofuStatus.FirstConnect, identityEvent.U32a);
        Assert.NotNull(identityEvent.Text);
        Assert.Equal(64, identityEvent.Text!.Length); // SHA-256 hex, no separators

        // Auth must NOT complete before the identity is confirmed.
        Assert.False(PumpUntil(client, () => events.Any(e => e.Type == VcEventType.AuthResult), 800));

        Assert.Equal(VcResult.Ok, client.ConfirmServerIdentity(accept: true));

        Assert.True(PumpUntil(client, () => events.Any(e => e.Type == VcEventType.AuthResult), 5000),
            "did not receive VC_EVENT_AUTH_RESULT after confirming identity");
        var authEvent = events.First(e => e.Type == VcEventType.AuthResult);
        Assert.Equal(VcResult.Ok, authEvent.Result);

        Assert.True(PumpUntil(client, () => events.Any(e => e.Type == VcEventType.ChannelList), 3000),
            "did not receive VC_EVENT_CHANNEL_LIST");

        var channels = client.ListChannels();
        Assert.Contains(channels, c => c.Id == 1 && c.Name == "Lobby");

        client.Disconnect();
    }
}