using System;
using System.Collections.Generic;
using System.Collections.Concurrent;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Threading.Tasks;
using Codely.Newtonsoft.Json;
using Codely.Newtonsoft.Json.Linq;
using UnityEditor;
using UnityEngine;
using UnityTcp.Editor.Helpers;
using UnityTcp.Editor.Tools;

namespace UnityTcp.Editor
{
    /// <summary>
    /// Command structure for JSON deserialization
    /// </summary>
    public class Command
    {
        public string type { get; set; }
        public JObject @params { get; set; }
    }

    [InitializeOnLoad]
    public static partial class UnityTcpBridge
    {
        private static TcpListener listener;
        private static bool isRunning = false;
        private static readonly object lockObj = new();
        private static readonly object startStopLock = new();
        private static readonly object clientsLock = new();
        private static readonly HashSet<TcpClient> activeClients = new();
        // Thread-safe mapping of clients to their platform types
        private static readonly ConcurrentDictionary<TcpClient, string> clientPlatforms = new();
        // Callback to notify about client platform changes
        public static event System.Action OnClientPlatformsChanged;
        // Single-writer outbox for framed responses
        private class Outbound
        {
            public byte[] Payload;
            public string Tag;
            public int? ReqId;
        }
        private static readonly BlockingCollection<Outbound> _outbox = new(new ConcurrentQueue<Outbound>());
        private static CancellationTokenSource cts;
        private static Task listenerTask;
        private static int processingCommands = 0;
        private static bool initScheduled = false;
        private static bool ensureUpdateHooked = false;
        private static bool isStarting = false;
        private static double nextStartAt = 0.0f;
        private static double nextHeartbeatAt = 0.0f;
        private static string serverVer = "1.0.0-beta.1";
        private static int heartbeatSeq = 0;
        private const string ManualStopSessionKey = "UnityTcp.ManuallyStoppedThisSession";
        private static Dictionary<
            string,
            (string commandJson, TaskCompletionSource<string> tcs)
        > commandQueue = new();
        private static int currentUnityPort = 25916; // Dynamic port, starts with default
        private static bool isAutoConnectMode = false;
        private const ulong MaxFrameBytes = 64UL * 1024 * 1024; // 64 MiB hard cap for framed payloads
        private const int FrameIOTimeoutMs = 30000; // Per-read timeout to avoid stalled clients

        // IO diagnostics
        private static long _ioSeq = 0;
        private static void IoInfo(string s) { TcpLog.Info(s, always: false); }

        // Debug helpers
        private static bool IsDebugEnabled()
        {
            try { return EditorPrefs.GetBool("UnityTcp.DebugLogs", false); } catch { return false; }
        }

        private static void LogBreadcrumb(string stage)
        {
            if (IsDebugEnabled())
            {
                TcpLog.Info($"[{stage}]", always: false);
            }
        }

        public static bool IsRunning => isRunning;
        public static int GetCurrentPort() => currentUnityPort;
        public static bool IsAutoConnectMode() => isAutoConnectMode;

        /// <summary>
        /// Get all connected clients with their platform types
        /// </summary>
        public static Dictionary<string, string> GetConnectedClients()
        {
            var result = new Dictionary<string, string>();
            lock (clientsLock)
            {
                foreach (var client in activeClients)
                {
                    var endpoint = client.Client?.RemoteEndPoint?.ToString() ?? "unknown";
                    var platform = clientPlatforms.TryGetValue(client, out var p) ? p : "unknown";
                    result[endpoint] = platform;
                }
            }
            return result;
        }

        /// <summary>
        /// Start with Auto-Connect mode - discovers new port and saves it
        /// </summary>
        public static void StartAutoConnect()
        {
            Stop(); // Stop current connection

            try
            {
                // Auto-connect mode also gets a fresh port - no reuse
                // Note: Start() will call DiscoverNewPort() internally, so we don't need to set currentUnityPort here
                Start();
                isAutoConnectMode = true;

                // Record telemetry for bridge startup
                TelemetryHelper.RecordBridgeStartup();
            }
            catch (Exception ex)
            {
                Debug.LogError($"Auto-connect failed: {ex.Message}");

                // Record telemetry for connection failure
                TelemetryHelper.RecordBridgeConnection(false, ex.Message);
                throw;
            }
        }

        public static bool FolderExists(string path)
        {
            if (string.IsNullOrEmpty(path))
            {
                return false;
            }

            if (path.Equals("Assets", StringComparison.OrdinalIgnoreCase))
            {
                return true;
            }

            string fullPath = Path.Combine(
                Application.dataPath,
                path.StartsWith("Assets/") ? path[7..] : path
            );
            return Directory.Exists(fullPath);
        }

        static UnityTcpBridge()
        {
            // Initialize main thread ID for safe thread checks
            MainThreadHelper.InitializeMainThreadId();
            
            // Register the FindObjectByInstruction delegate for UnityEngineObjectConverter
            UnityTcp.Editor.Serialization.UnityEngineObjectConverter.FindObjectByInstruction = ManageGameObject.FindObjectByInstruction;
            // Start single writer thread for framed responses
            try
            {
                var writerThread = new Thread(() =>
                {
                    foreach (var item in _outbox.GetConsumingEnumerable())
                    {
                        try
                        {
                            long seq = Interlocked.Increment(ref _ioSeq);
                            IoInfo($"[IO] ➜ write start seq={seq} tag={item.Tag} len={(item.Payload?.Length ?? 0)} reqId={(item.ReqId?.ToString() ?? "?")}");
                            var sw = System.Diagnostics.Stopwatch.StartNew();
                            // Note: We currently have a per-connection 'stream' in the client handler. For simplicity,
                            // writes are performed inline there. This outbox provides single-writer semantics; if a shared
                            // stream is introduced, redirect here accordingly.
                            // No-op: actual write happens in client loop using WriteFrameAsync
                            sw.Stop();
                            IoInfo($"[IO] ✓ write end   tag={item.Tag} len={(item.Payload?.Length ?? 0)} reqId={(item.ReqId?.ToString() ?? "?")} durMs={sw.Elapsed.TotalMilliseconds:F1}");
                        }
                        catch (Exception ex)
                        {
                            IoInfo($"[IO] ✗ write FAIL  tag={item.Tag} reqId={(item.ReqId?.ToString() ?? "?")} {ex.GetType().Name}: {ex.Message}");
                        }
                    }
                })
                { IsBackground = true, Name = "TCP-Writer" };
                writerThread.Start();
            }
            catch { }

            // Skip bridge in headless/batch environments (CI/builds) unless explicitly allowed via env
            // CI override: set UNITY_TCP_ALLOW_BATCH=1 to allow the bridge in batch mode
            if (Application.isBatchMode && string.IsNullOrWhiteSpace(Environment.GetEnvironmentVariable("UNITY_TCP_ALLOW_BATCH")))
            {
                return;
            }
            // Defer start until the editor is idle and not compiling
            ScheduleInitRetry();
            // Add a safety net update hook in case delayCall is missed during reload churn
            if (!ensureUpdateHooked)
            {
                ensureUpdateHooked = true;
                EditorApplication.update += EnsureStartedOnEditorIdle;
            }
            EditorApplication.quitting += Stop;
            AssemblyReloadEvents.beforeAssemblyReload += OnBeforeAssemblyReload;
            AssemblyReloadEvents.afterAssemblyReload += OnAfterAssemblyReload;
            // Also coalesce play mode transitions into a deferred init
            EditorApplication.playModeStateChanged += _ => ScheduleInitRetry();
        }

        /// <summary>
        /// Initialize the bridge after Unity is fully loaded and compilation is complete.
        /// This prevents repeated restarts during script compilation that cause port hopping.
        /// </summary>
        private static void InitializeAfterCompilation()
        {
            Debug.Log($"InitializeAfterCompilation()");
            // Don't auto-start if manually stopped this session (persists across domain reloads)
            if (SessionState.GetBool(ManualStopSessionKey, false))   
            {
                return;
            }
            initScheduled = false;

            // Play-mode friendly: allow starting in play mode; only defer while compiling
            if (CompilationHelper.IsCompiling())
            {
                ScheduleInitRetry();
                return;
            }

            if (!isRunning)
            {
                Start();
                if (!isRunning)
                {
                    // If a race prevented start, retry later
                    ScheduleInitRetry();
                }
            }
        }

        private static void ScheduleInitRetry()
        {
            if (SessionState.GetBool(ManualStopSessionKey, false))   
            {
                return;
            }
            if (initScheduled) 
            {
                return;
            }
            initScheduled = true;
            // Debounce: start ~200ms after the last trigger
            nextStartAt = EditorApplication.timeSinceStartup + 0.20f;
            // Ensure the update pump is active
            if (!ensureUpdateHooked)
            {
                ensureUpdateHooked = true;
                EditorApplication.update += EnsureStartedOnEditorIdle;
            }
            // Keep the original delayCall as a secondary path
            EditorApplication.delayCall += InitializeAfterCompilation;
        }

        // Safety net: ensure the bridge starts shortly after domain reload when editor is idle
        private static void EnsureStartedOnEditorIdle()
        {
            if (SessionState.GetBool(ManualStopSessionKey, false))   
            {
                EditorApplication.update -= EnsureStartedOnEditorIdle;
                ensureUpdateHooked = false;
                return;
            }
            // Do nothing while compiling
            if (CompilationHelper.IsCompiling())
            {
                return;
            }
            // If already running, remove the hook
            if (isRunning)
            {
                EditorApplication.update -= EnsureStartedOnEditorIdle;
                ensureUpdateHooked = false;
                return;
            }

            // Debounced start: wait until the scheduled time
            if (nextStartAt > 0 && EditorApplication.timeSinceStartup < nextStartAt)
            {
                return;
            }

            if (isStarting)
            {
                return;
            }

            isStarting = true;
            try
            {
                // Attempt start; if it succeeds, remove the hook to avoid overhead
                Start();
            }
            finally
            {
                isStarting = false;
            }
            if (isRunning)
            {
                EditorApplication.update -= EnsureStartedOnEditorIdle;
                ensureUpdateHooked = false;
            }
        }


        public static void Start()
        {
            // Reset manual stop flag when manually starting (persists across domain reloads)
            SessionState.SetBool(ManualStopSessionKey, false);

            lock (startStopLock)
            {
                // Don't restart if already running on a working port
                if (isRunning && listener != null)
                {
                    if (IsDebugEnabled())
                    {
                        Debug.Log($"<b><color=#2EA3FF>Codely-Bridge</color></b>: UnityTcpBridge already running on port {currentUnityPort}");
                    }
                    return;
                }

                Stop();

                // Always discover a completely new port - no reuse to ensure instance isolation
                try
                {
                    // Discover fresh port for this instance - no reuse of stored ports
                    currentUnityPort = PortManager.DiscoverNewPort();
                    if (IsDebugEnabled()) Debug.Log($"<b><color=#2EA3FF>Codely Bridge</color></b>: Using fresh port {currentUnityPort} for this instance");

                    // Breadcrumb: Start
                    LogBreadcrumb("Start");

                    const int maxImmediateRetries = 5;
                    const int retrySleepMs = 150;
                    int attempt = 0;
                    for (; ; )
                    {
                        try
                        {
                            listener = new TcpListener(IPAddress.IPv6Any, currentUnityPort);
                            
                            // Configure socket options for port isolation / fast reuse behavior
#if UNITY_EDITOR_WIN
                            try
                            {
                                listener.Server.SetSocketOption(
                                    SocketOptionLevel.Socket,
                                    SocketOptionName.ReuseAddress,
                                    false  // Disable port reuse on Windows to ensure complete isolation between instances
                                );
                            }
                            catch { }
                            try
                            {
                                // On Windows: Force exclusive access
                                listener.ExclusiveAddressUse = true;
                            }
                            catch { }
#else
                            try
                            {
                                listener.Server.SetSocketOption(
                                    SocketOptionLevel.Socket,
                                    SocketOptionName.ReuseAddress,
                                    false  // Disable port reuse
                                );
                            }
                            catch { }
#endif
                            // Minimize TIME_WAIT by sending RST on close
                            try
                            {
                                listener.Server.LingerState = new LingerOption(true, 0);
                            }
                            catch (Exception)
                            {
                                // Ignore if not supported on platform
                            }
                            listener.Start();
                            break;
                        }
                        catch (SocketException se) when (se.SocketErrorCode == SocketError.AddressAlreadyInUse && attempt < maxImmediateRetries)
                        {
                            attempt++;
                            if (IsDebugEnabled())
                            {
                                var (inUse, description) = PortManager.CheckPortConflict(currentUnityPort);
                                Debug.LogWarning($"<b><color=#2EA3FF>Codely Bridge</color></b>: Port {currentUnityPort} bind failed (attempt {attempt}/{maxImmediateRetries}): {description}");
                            }
                            Thread.Sleep(retrySleepMs);
                            continue;
                        }
                        catch (SocketException se) when (se.SocketErrorCode == SocketError.AddressAlreadyInUse && attempt >= maxImmediateRetries)
                        {
                            // Report the port conflict before switching
                            var (inUse, description) = PortManager.CheckPortConflict(currentUnityPort);
                            if (IsDebugEnabled()) Debug.LogWarning($"<b><color=#2EA3FF>Codely Bridge</color></b>: Port {currentUnityPort} persistently busy: {description}");
                            
                            // Force discovery of a new port since the current one is persistently busy
                            try
                            {
                                currentUnityPort = PortManager.DiscoverNewPort();
                                if (IsDebugEnabled()) Debug.Log($"<b><color=#2EA3FF>Codely Bridge</color></b>: Switched to new port {currentUnityPort} after retries failed");
                            }
                            catch (Exception ex)
                            {
                                Debug.LogError($"Failed to discover new port after retries: {ex.Message}");
                                throw new Exception($"Unable to find any available ports: {ex.Message}");
                            }
                            
                            // Try to bind to the newly discovered port with a final retry attempt
                            bool newPortBound = false;
                            for (int finalAttempt = 0; finalAttempt < 2; finalAttempt++)
                            {
                                try
                                {
                                    listener = new TcpListener(IPAddress.IPv6Any, currentUnityPort);
                                    
                                    // Configure socket options for port isolation / fast reuse behavior
#if UNITY_EDITOR_WIN
                                    try
                                    {
                                        listener.Server.SetSocketOption(
                                            SocketOptionLevel.Socket,
                                            SocketOptionName.ReuseAddress,
                                            false  // Disable port reuse on Windows to ensure complete isolation between instances
                                        );
                                    }
                                    catch { }
                                    try
                                    {
                                        // On Windows: Force exclusive access
                                        listener.ExclusiveAddressUse = true;
                                    }
                                    catch { }
#else
                                    try
                                    {
                                        listener.Server.SetSocketOption(
                                            SocketOptionLevel.Socket,
                                            SocketOptionName.ReuseAddress,
                                            false  // Disable port reuse
                                        );
                                    }
                                    catch { }
#endif
                                    try
                                    {
                                        listener.Server.LingerState = new LingerOption(true, 0);
                                    }
                                    catch (Exception)
                                    {
                                    }
                                    listener.Start();
                                    newPortBound = true;
                                    break;
                                }
                                catch (SocketException bindEx) when (bindEx.SocketErrorCode == SocketError.AddressAlreadyInUse && finalAttempt == 0)
                                {
                                    // Race condition: newly discovered port became busy, try one more new port
                                    if (IsDebugEnabled()) Debug.LogWarning($"<b><color=#2EA3FF>Codely Bridge</color></b>: Newly discovered port {currentUnityPort} also became busy, trying another...");
                                    currentUnityPort = PortManager.DiscoverNewPort();
                                    continue;
                                }
                            }
                            
                            if (newPortBound)
                            {
                                break;
                            }
                            else
                            {
                                throw new Exception($"Failed to bind to any discovered ports, including fallback attempts");
                            }
                        }
                    }

                    isRunning = true;
                    isAutoConnectMode = false;
                    string platform = Application.platform.ToString();
                    Debug.Log($"<b><color=#2EA3FF>Codely-Bridge</color></b>: Codely Bridge started on port {currentUnityPort}. (OS={platform}, server={serverVer})");
                    // Start background listener with cooperative cancellation
                    cts = new CancellationTokenSource();
                    listenerTask = Task.Run(() => ListenerLoopAsync(cts.Token));
                    EditorApplication.update += ProcessCommands;
                    // Ensure lifecycle events are (re)subscribed in case Stop() removed them earlier in-domain
                    try { AssemblyReloadEvents.beforeAssemblyReload -= OnBeforeAssemblyReload; } catch { }
                    try { AssemblyReloadEvents.beforeAssemblyReload += OnBeforeAssemblyReload; } catch { }
                    try { AssemblyReloadEvents.afterAssemblyReload -= OnAfterAssemblyReload; } catch { }
                    try { AssemblyReloadEvents.afterAssemblyReload += OnAfterAssemblyReload; } catch { }
                    try { EditorApplication.quitting -= Stop; } catch { }
                    try { EditorApplication.quitting += Stop; } catch { }
                    // Write initial heartbeat immediately
                    heartbeatSeq++;
                    StatusHelper.WriteHeartbeat(currentUnityPort, false, heartbeatSeq, "ready");
                    nextHeartbeatAt = EditorApplication.timeSinceStartup + 0.5f;
                }
                catch (SocketException ex)
                {
                    Debug.LogError($"Failed to start TCP listener: {ex.Message}"); 
                }
            }
        }

        public static void Stop()
        {
            Stop(false); 
        }

        /// <summary>
        /// Stop the TCP bridge server
        /// </summary>
        /// <param name="isManualStop">If true, prevents auto-start after compilation until Unity quits</param>
        public static void Stop(bool isManualStop)
        {
            if (isManualStop)
            {
                // Set flag in SessionState to survive domain reloads
                SessionState.SetBool(ManualStopSessionKey, true);
            }

            Task toWait = null;
            lock (startStopLock)
            {
                if (!isRunning)
                {
                    return;
                }

                try
                {
                    // Mark as stopping early to avoid accept logging during disposal
                    isRunning = false;

                    // Quiesce background listener quickly
                    var cancel = cts;
                    cts = null;
                    try { cancel?.Cancel(); } catch { }

                    try { listener?.Stop(); } catch { }
                    listener = null;

                    // Capture background task to wait briefly outside the lock
                    toWait = listenerTask;
                    listenerTask = null;
                }
                catch (Exception ex)
                {
                    Debug.LogError($"Error stopping UnityTcpBridge: {ex.Message}");
                }
            }

            // Proactively close all active client sockets to unblock any pending reads
            TcpClient[] toClose;
            lock (clientsLock)
            {
                toClose = activeClients.ToArray();
                activeClients.Clear();
            }
            foreach (var c in toClose)
            {
                try { c.Close(); } catch { }
            }
            
            // Clear all client platform mappings (thread-safe)
            clientPlatforms.Clear();

            // Give the background loop a short window to exit without blocking the editor
            // Wait longer on Windows to allow TCP port to fully release (typical TIME_WAIT is 200-500ms)
            if (toWait != null)
            {
                try
                {
                try { toWait.Wait(500); } catch { }

                } catch { }
            }

            // Now unhook editor events safely
            try { EditorApplication.update -= ProcessCommands; } catch { }
            try { AssemblyReloadEvents.beforeAssemblyReload -= OnBeforeAssemblyReload; } catch { }
            try { AssemblyReloadEvents.afterAssemblyReload -= OnAfterAssemblyReload; } catch { }
            try { EditorApplication.quitting -= Stop; } catch { }

            if (IsDebugEnabled()) Debug.Log("<b><color=#2EA3FF>Codely-Bridge</color></b>: UnityTcpBridge stopped.");
        }

        private static async Task ListenerLoopAsync(CancellationToken token)
        {
            while (isRunning && !token.IsCancellationRequested)
            {
                try
                {
                    TcpClient client = await listener.AcceptTcpClientAsync();
                    // Enable basic socket keepalive
                    client.Client.SetSocketOption(
                        SocketOptionLevel.Socket,
                        SocketOptionName.KeepAlive,
                        true
                    );

                    // Set longer receive timeout to prevent quick disconnections
                    client.ReceiveTimeout = 60000; // 60 seconds

                    // Fire and forget each client connection
                    _ = Task.Run(() => HandleClientAsync(client, token), token);
                }
                catch (ObjectDisposedException)
                {
                    // Listener was disposed during stop/reload; exit quietly
                    if (!isRunning || token.IsCancellationRequested)
                    {
                        break;
                    }
                }
                catch (OperationCanceledException)
                {
                    break;
                }
                catch (Exception ex)
                {
                    if (isRunning && !token.IsCancellationRequested)
                    {
                        if (IsDebugEnabled()) Debug.LogError($"Listener error: {ex.Message}");
                    }
                }
            }
        }

        private static async Task HandleClientAsync(TcpClient client, CancellationToken token)
        {
            using (client)
            using (NetworkStream stream = client.GetStream())
            {
                lock (clientsLock) { activeClients.Add(client); }
                try
                {
                    // Framed I/O only; legacy mode removed
                    try
                    {
                        if (IsDebugEnabled())
                        {
                            var ep = client.Client?.RemoteEndPoint?.ToString() ?? "unknown";
                            Debug.Log($"<b><color=#2EA3FF>Codely-Bridge</color></b>: Client connected {ep}");
                        }
                    }
                    catch { }
                    // Strict framing: always require FRAMING=1 and frame all I/O
                    try
                    {
                        client.NoDelay = true;
                    }
                    catch { }
                    try
                    {
                        string handshake = "WELCOME UNITY-TCP 1 FRAMING=1\n";
                        byte[] handshakeBytes = System.Text.Encoding.ASCII.GetBytes(handshake);
                        using var cts = new CancellationTokenSource(FrameIOTimeoutMs);
#if NETSTANDARD2_1 || NET6_0_OR_GREATER
                        await stream.WriteAsync(handshakeBytes.AsMemory(0, handshakeBytes.Length), cts.Token).ConfigureAwait(false);
#else
                        await stream.WriteAsync(handshakeBytes, 0, handshakeBytes.Length, cts.Token).ConfigureAwait(false);
#endif
                        if (IsDebugEnabled()) TcpLog.Info("Sent handshake FRAMING=1 (strict)", always: false);
                    }
                    catch (Exception ex)
                    {
                        if (IsDebugEnabled()) TcpLog.Warn($"Handshake failed: {ex.Message}");
                        return; // abort this client
                    }

                    while (isRunning && !token.IsCancellationRequested)
                    {
                        try
                        {
                            // Strict framed mode only: enforced framed I/O for this connection
                            string commandText = await BinaryFrameHelper.ReadFrameAsUtf8Async(stream, FrameIOTimeoutMs, token).ConfigureAwait(false);

                            try
                            {
                                if (IsDebugEnabled())
                                {
                                    var preview = commandText.Length > 120 ? commandText.Substring(0, 120) + "…" : commandText;
                                    TcpLog.Info($"recv framed: {preview}", always: false);
                                }
                            }
                            catch { }
                            string commandId = Guid.NewGuid().ToString();
                            var tcs = new TaskCompletionSource<string>(TaskCreationOptions.RunContinuationsAsynchronously);

                            // Special handling for ping command to avoid JSON parsing
                            if (commandText.Trim() == "ping")
                            {
                                // Direct response to ping without going through JSON parsing
                                byte[] pingResponseBytes = System.Text.Encoding.UTF8.GetBytes(
                                    /*lang=json,strict*/
                                    "{\"success\":true,\"message\":\"pong\"}"
                                );
                                await BinaryFrameHelper.WriteFrameAsync(stream, pingResponseBytes);
                                continue;
                            }
                            
                            // Handle platform identification message
                            if (commandText.StartsWith("PLATFORM="))
                            {
                                string clientPlatform = commandText.Substring(9).Trim(); // Extract platform after "PLATFORM="
                                
                                // Associate platform with this client (thread-safe)
                                clientPlatforms[client] = clientPlatform;
                                
                                if (IsDebugEnabled()) TcpLog.Info($"Client platform: {clientPlatform}", always: false);
                                
                                // Notify listeners about client platform changes
                                OnClientPlatformsChanged?.Invoke();
                                
                                continue;
                            }

                            lock (lockObj)
                            {
                                commandQueue[commandId] = (commandText, tcs);
                            }

                            // Wait for the handler to produce a response, but do not block indefinitely
                            string response;
                            try
                            {
                                using var respCts = new CancellationTokenSource(FrameIOTimeoutMs);
                                var completed = await Task.WhenAny(tcs.Task, Task.Delay(FrameIOTimeoutMs, respCts.Token)).ConfigureAwait(false);
                                if (completed == tcs.Task)
                                {
                                    // Got a result from the handler
                                    respCts.Cancel();
                                    response = tcs.Task.Result;
                                }
                                else
                                {
                                    // Timeout: return a structured error so the client can recover
                                    var timeoutResponse = new
                                    {
                                        success = false,
                                        error = $"Command processing timed out after {FrameIOTimeoutMs} ms",
                                    };
                                    response = JsonConvert.SerializeObject(timeoutResponse);
                                }
                            }
                            catch (Exception ex)
                            {
                                var errorResponse = new
                                {
                                    success = false,
                                    error = ex.Message,
                                };
                                response = JsonConvert.SerializeObject(errorResponse);
                            }

                            if (IsDebugEnabled())
                            {
                                try { TcpLog.Info("[TCP] sending framed response", always: false); } catch { }
                            }
                            // Crash-proof and self-reporting writer logs (direct write to this client's stream)
                            long seq = System.Threading.Interlocked.Increment(ref _ioSeq);
                            byte[] responseBytes;
                            try
                            {
                                responseBytes = System.Text.Encoding.UTF8.GetBytes(response);
                                IoInfo($"[IO] ➜ write start seq={seq} tag=response len={responseBytes.Length} reqId=?");
                            }
                            catch (Exception ex)
                            {
                                IoInfo($"[IO] ✗ serialize FAIL tag=response reqId=? {ex.GetType().Name}: {ex.Message}");
                                throw;
                            }

                            var swDirect = System.Diagnostics.Stopwatch.StartNew();
                            try
                            {
                                await BinaryFrameHelper.WriteFrameAsync(stream, responseBytes);
                                swDirect.Stop();
                                IoInfo($"[IO] ✓ write end   tag=response len={responseBytes.Length} reqId=? durMs={swDirect.Elapsed.TotalMilliseconds:F1}");
                            }
                            catch (Exception ex)
                            {
                                IoInfo($"[IO] ✗ write FAIL  tag=response reqId=? {ex.GetType().Name}: {ex.Message}");
                                throw;
                            }
                        }
                        catch (Exception ex)
                        {
                            // Treat common disconnects/timeouts as benign; only surface hard errors
                            string msg = ex.Message ?? string.Empty;
                            bool isBenign =
                                msg.IndexOf("Connection closed before reading expected bytes", StringComparison.OrdinalIgnoreCase) >= 0
                                || msg.IndexOf("Read timed out", StringComparison.OrdinalIgnoreCase) >= 0
                                || ex is System.IO.IOException;
                            if (isBenign)
                            {
                                if (IsDebugEnabled()) TcpLog.Info($"Client handler: {msg}", always: false);
                            }
                            else
                            {
                                TcpLog.Error($"Client handler error: {msg}");
                            }
                            break;
                        }
                    }
                }
                finally
                {
                    lock (clientsLock) { activeClients.Remove(client); }
                    // Remove client platform mapping when client disconnects (thread-safe)
                    clientPlatforms.TryRemove(client, out _);
                    
                    // Notify listeners about client platform changes
                    OnClientPlatformsChanged?.Invoke();
                }
            }
        }


        private static void ProcessCommands()
        {
            if (!isRunning) return;
            if (Interlocked.Exchange(ref processingCommands, 1) == 1) return; // reentrancy guard
            try
            {
                // Heartbeat without holding the queue lock
                double now = EditorApplication.timeSinceStartup;
                if (now >= nextHeartbeatAt)
                {
                    StatusHelper.WriteHeartbeat(currentUnityPort, false, heartbeatSeq);
                    nextHeartbeatAt = now + 0.5f;
                }

                // Snapshot under lock, then process outside to reduce contention
                List<(string id, string text, TaskCompletionSource<string> tcs)> work;
                lock (lockObj)
                {
                    work = commandQueue
                        .Select(kvp => (kvp.Key, kvp.Value.commandJson, kvp.Value.tcs))
                        .ToList();
                }

                foreach (var item in work)
                {
                    string id = item.id;
                    string commandText = item.text;
                    TaskCompletionSource<string> tcs = item.tcs;

                    try
                    {
                        // Special case handling
                        if (string.IsNullOrEmpty(commandText))
                        {
                            var emptyResponse = Response.Error("Empty command received");
                            tcs.SetResult(JsonConvert.SerializeObject(emptyResponse));
                            // Remove quickly under lock
                            lock (lockObj) { commandQueue.Remove(id); }
                            continue;
                        }

                        // Trim the command text to remove any whitespace
                        commandText = commandText.Trim();

                        // Non-JSON direct commands handling (like ping)
                        if (commandText == "ping")
                        {
                            var pingResponse = Response.Success("pong");
                            tcs.SetResult(JsonConvert.SerializeObject(pingResponse));
                            lock (lockObj) { commandQueue.Remove(id); }
                            continue;
                        }

                        // Check if the command is valid JSON before attempting to deserialize
                        if (!JsonCommandHelper.IsValidJson(commandText))
                        {
                            var invalidJsonResponse = Response.Error("Invalid JSON format", new
                            {
                                receivedText = commandText.Length > 50
                                    ? commandText[..50] + "..."
                                    : commandText
                            });
                            tcs.SetResult(JsonConvert.SerializeObject(invalidJsonResponse));
                            lock (lockObj) { commandQueue.Remove(id); }
                            continue;
                        }

                        // Normal JSON command processing
                        Command command = JsonConvert.DeserializeObject<Command>(commandText);

                        if (command == null)
                        {
                            var nullCommandResponse = Response.Error("Command deserialized to null",
                                "The command was valid JSON but could not be deserialized to a Command object");
                            tcs.SetResult(JsonConvert.SerializeObject(nullCommandResponse));
                        }
                        else
                        {
                            string responseJson = ExecuteCommand(command);
                            tcs.SetResult(responseJson);
                        }
                    }
                    catch (Exception ex)
                    {
                        Debug.LogError($"Error processing command: {ex.Message}\n{ex.StackTrace}");

                        var response = Response.Error(ex.Message, new
                        {
                            commandType = "Unknown (error during processing)",
                            receivedText = commandText?.Length > 50
                                ? commandText[..50] + "..."
                                : commandText,
                            stackTrace = ex.StackTrace
                        });
                        string responseJson = JsonConvert.SerializeObject(response);
                        tcs.SetResult(responseJson);
                    }

                    // Remove quickly under lock
                    lock (lockObj) { commandQueue.Remove(id); }
                }
            }
            finally
            {
                Interlocked.Exchange(ref processingCommands, 0);
            }
        }



        private static string ExecuteCommand(Command command)
        {
            try
            {
                if (string.IsNullOrEmpty(command.type))
                {
                    var errorResponse = Response.Error("Command type cannot be empty",
                        "A valid command type is required for processing");
                    return JsonConvert.SerializeObject(errorResponse);
                }

                // Handle ping command for connection verification
                if (command.type.Equals("ping", StringComparison.OrdinalIgnoreCase))
                {
                    var pingResponse = Response.Success("pong");
                    return JsonConvert.SerializeObject(pingResponse);
                }

                // Use JObject for parameters as the new handlers likely expect this
                JObject paramsObject = command.@params ?? new JObject();

                // Route command based on the tool structure from the existing project
                object result = command.type switch
                {
                    // Maps the command type (tool name) to the corresponding handler's static HandleCommand method
                    "manage_script" => ManageScript.HandleCommand(paramsObject),
                    // High-level workflows (init_session, compile_and_validate, checkpoint)
                    "manage_workflow" => ManageWorkflow.HandleCommand(paramsObject),
                    // Run scene operations on the main thread to avoid deadlocks/hangs (with diagnostics under debug flag)
                    "manage_scene" => HandleManageScene(paramsObject)
                        ?? throw new TimeoutException($"manage_scene timed out after {FrameIOTimeoutMs} ms on main thread"),
                    "manage_editor" => ManageEditor.HandleCommand(paramsObject),
                    "manage_gameobject" => ManageGameObject.HandleCommand(paramsObject),
                    "manage_asset" => ManageAsset.HandleCommand(paramsObject),
                    "manage_shader" => ManageShader.HandleCommand(paramsObject),
                    "read_console" => ReadConsole.HandleCommand(paramsObject),
                    "execute_menu_item" => ExecuteMenuItem.HandleCommand(paramsObject),
                    "manage_screenshot" => ManageScreenshot.HandleCommand(paramsObject),
                    "execute_csharp_script" => ExecuteCSharpScript.HandleCommand(paramsObject),
                    // [EXPERIMENTAL] Phase 3 tools
                    "manage_package" => ManagePackage.HandleCommand(paramsObject),
                    "manage_bake" => ManageBake.HandleCommand(paramsObject),
                    "manage_ui_toolkit" => ManageUIToolkit.HandleCommand(paramsObject),
                    // Custom tool execution
                    "execute_custom_tool" => ExecuteCustomTool.HandleCommand(paramsObject),
                    // Internal tools (NOT exposed to LLM)
                    "_internal_state_dirty" => _InternalStateDirtyNotifier.HandleCommand(paramsObject),
                    _ => throw new ArgumentException(
                        $"Unknown or unsupported command type: {command.type}"
                    ),
                };

                // Convert result to success response format compatible with Response helper
                return JsonConvert.SerializeObject(Response.Success("Command executed successfully", result));
            }
            catch (Exception ex)
            {
                // Log the detailed error in Unity for debugging
                Debug.LogError(
                    $"Error executing command '{command?.type ?? "Unknown"}': {ex.Message}\n{ex.StackTrace}"
                );

                // Use Response helper for consistent error format
                var response = Response.Error(ex.Message, new
                {
                    command = command?.type ?? "Unknown",
                    stackTrace = ex.StackTrace,
                    paramsSummary = command?.@params != null
                        ? JsonCommandHelper.GetParamsSummary(command.@params)
                        : "No parameters"
                });
                return JsonConvert.SerializeObject(response);
            }
        }

        private static object HandleManageScene(JObject paramsObject)
        {
            try
            {
                if (IsDebugEnabled()) Debug.Log("[TCP] manage_scene: dispatching to main thread");
                var sw = System.Diagnostics.Stopwatch.StartNew();
                var r = MainThreadHelper.InvokeOnMainThreadWithTimeout(() => ManageScene.HandleCommand(paramsObject), FrameIOTimeoutMs);
                sw.Stop();
                if (IsDebugEnabled()) Debug.Log($"[TCP] manage_scene: completed in {sw.ElapsedMilliseconds} ms");
                return r ?? Response.Error("manage_scene returned null (timeout or error)");
            }
            catch (Exception ex)
            {
                return Response.Error($"manage_scene dispatch error: {ex.Message}");
            }
        }


        // Heartbeat/status helpers
        private static void OnBeforeAssemblyReload()
        {
            // Stop cleanly before reload so sockets close and clients see 'reloading'
            try { Stop(); } catch { }
            // Avoid file I/O or heavy work here
        }

        private static void OnAfterAssemblyReload()
        {
            // Will be overwritten by Start(), but mark as alive quickly
            StatusHelper.WriteHeartbeat(currentUnityPort, false, heartbeatSeq, "idle");
            LogBreadcrumb("Idle");
            // Schedule a safe restart after reload to avoid races during compilation
            ScheduleInitRetry();
        }



    }
}