using System;
using System.Collections.Concurrent;
using System.Diagnostics;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace CtrEditor.Services
{
    /// <summary>
    /// Servidor TCP que captura y retransmite mensajes de debug console
    /// Permite al MCP Proxy escuchar los logs de debug de CtrEditor
    /// </summary>
    public class DebugConsoleServer : IDisposable
    {
        private readonly int _port;
        private TcpListener _tcpListener;
        private bool _isRunning;
        private CancellationTokenSource _cancellationTokenSource;
        private readonly object _lockObject = new object();
        private readonly ConcurrentQueue<string> _messageQueue = new ConcurrentQueue<string>();
        private readonly ConcurrentBag<TcpClient> _connectedClients = new ConcurrentBag<TcpClient>();
        
        // Custom TraceListener para capturar Debug.WriteLine
        private DebugTraceListener _traceListener;

        public DebugConsoleServer(int port = 5007)
        {
            _port = port;
            _cancellationTokenSource = new CancellationTokenSource();
        }

        /// <summary>
        /// Inicia el servidor de debug console
        /// </summary>
        public void Start()
        {
            if (_isRunning) return;

            try
            {
                _tcpListener = new TcpListener(IPAddress.Loopback, _port);
                _tcpListener.Start();
                _isRunning = true;

                // Instalar el trace listener personalizado solo para Trace
                _traceListener = new DebugTraceListener(this);
                Trace.Listeners.Add(_traceListener);

                Trace.WriteLine($"[Debug Console Server] Servidor de debug iniciado en puerto {_port}");

                // Procesar conexiones en background
                _ = Task.Run(async () => await AcceptConnectionsAsync(_cancellationTokenSource.Token));
                
                // Procesar cola de mensajes
                _ = Task.Run(async () => await ProcessMessageQueueAsync(_cancellationTokenSource.Token));
            }
            catch (Exception ex)
            {
                Debug.WriteLine($"[Debug Console Server] Error al iniciar servidor: {ex.Message}");
                throw;
            }
        }

        /// <summary>
        /// Detiene el servidor de debug console
        /// </summary>
        public void Stop()
        {
            if (!_isRunning) return;

            lock (_lockObject)
            {
                if (!_isRunning) return;

                _isRunning = false;
                _cancellationTokenSource?.Cancel();
                
                // Remover el trace listener
                if (_traceListener != null)
                {
                    Trace.Listeners.Remove(_traceListener);
                    _traceListener = null;
                }

                _tcpListener?.Stop();
                
                // Cerrar todas las conexiones de clientes
                foreach (var client in _connectedClients)
                {
                    try
                    {
                        client?.Close();
                    }
                    catch { }
                }

                Debug.WriteLine("[Debug Console Server] Servidor de debug detenido");
            }
        }

        /// <summary>
        /// Acepta conexiones de clientes
        /// </summary>
        private async Task AcceptConnectionsAsync(CancellationToken cancellationToken)
        {
            try
            {
                while (_isRunning && !cancellationToken.IsCancellationRequested)
                {
                    Debug.WriteLine("[Debug Console Server] Esperando conexión de cliente...");
                    var tcpClient = await _tcpListener.AcceptTcpClientAsync();
                    _connectedClients.Add(tcpClient);

                    Debug.WriteLine("[Debug Console Server] Cliente debug conectado");

                    // Manejar cliente en background
                    _ = Task.Run(async () => await HandleClientAsync(tcpClient, cancellationToken));
                }
            }
            catch (Exception ex)
            {
                if (_isRunning)
                {
                    Debug.WriteLine($"[Debug Console Server] Error aceptando conexión: {ex.Message}");
                }
            }
        }

        /// <summary>
        /// Maneja un cliente conectado
        /// </summary>
        private async Task HandleClientAsync(TcpClient client, CancellationToken cancellationToken)
        {
            try
            {
                var stream = client.GetStream();
                
                // Enviar mensaje de bienvenida
                var welcomeMessage = $"[Debug Console Server] Conectado al servidor de debug de CtrEditor en puerto {_port}\n";
                await SendMessageToClientAsync(stream, welcomeMessage);

                // Mantener conexión viva hasta cancelación
                while (_isRunning && client.Connected && !cancellationToken.IsCancellationRequested)
                {
                    await Task.Delay(1000, cancellationToken);
                }
            }
            catch (Exception ex)
            {
                Debug.WriteLine($"[Debug Console Server] Error en cliente debug: {ex.Message}");
            }
            finally
            {
                try
                {
                    client?.Close();
                }
                catch { }
                Debug.WriteLine("[Debug Console Server] Cliente debug desconectado");
            }
        }

        /// <summary>
        /// Procesa la cola de mensajes y los envía a todos los clientes conectados
        /// </summary>
        private async Task ProcessMessageQueueAsync(CancellationToken cancellationToken)
        {
            try
            {
                while (_isRunning && !cancellationToken.IsCancellationRequested)
                {
                    if (_messageQueue.TryDequeue(out string message))
                    {
                        await BroadcastMessageAsync(message);
                    }
                    else
                    {
                        await Task.Delay(50, cancellationToken); // Pequeña pausa si no hay mensajes
                    }
                }
            }
            catch (Exception ex)
            {
                if (_isRunning)
                {
                    Debug.WriteLine($"[Debug Console Server] Error procesando cola de mensajes: {ex.Message}");
                }
            }
        }

        /// <summary>
        /// Envía un mensaje a todos los clientes conectados
        /// </summary>
        private async Task BroadcastMessageAsync(string message)
        {
            var timestamp = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff");
            var formattedMessage = $"[{timestamp}] {message}\n";
            
            var clientsToRemove = new List<TcpClient>();

            foreach (var client in _connectedClients)
            {
                try
                {
                    if (client.Connected)
                    {
                        var stream = client.GetStream();
                        await SendMessageToClientAsync(stream, formattedMessage);
                    }
                    else
                    {
                        clientsToRemove.Add(client);
                    }
                }
                catch
                {
                    clientsToRemove.Add(client);
                }
            }

            // Remover clientes desconectados
            // Nota: ConcurrentBag no permite eliminación directa, pero no es crítico
            // Los clientes desconectados se manejan en HandleClientAsync
        }

        /// <summary>
        /// Envía un mensaje a un cliente específico
        /// </summary>
        private async Task SendMessageToClientAsync(NetworkStream stream, string message)
        {
            var data = Encoding.UTF8.GetBytes(message);
            await stream.WriteAsync(data, 0, data.Length);
            await stream.FlushAsync();
        }

        /// <summary>
        /// Agrega un mensaje a la cola para transmisión
        /// </summary>
        public void QueueMessage(string message)
        {
            if (_isRunning)
            {
                _messageQueue.Enqueue(message);
            }
        }

        public void Dispose()
        {
            Stop();
            _cancellationTokenSource?.Dispose();
        }
    }

    /// <summary>
    /// TraceListener personalizado que captura mensajes de Debug.WriteLine
    /// y los envía al servidor de debug console
    /// </summary>
    internal class DebugTraceListener : TraceListener
    {
        private readonly DebugConsoleServer _server;

        public DebugTraceListener(DebugConsoleServer server)
        {
            _server = server;
        }

        public override void Write(string message)
        {
            _server?.QueueMessage(message);
        }

        public override void WriteLine(string message)
        {
            _server?.QueueMessage(message);
        }
    }
}