A .NET Wizard control

using System;
using System.IO;
using System.Net.Sockets;
using System.Text;
using System.Diagnostics;

namespace UtilityLibrary.Smtp
{ 
  /// <summary>
  /// Class for handling an SMTP connection.
  /// </summary>
  internal class SmtpConnection
  {
    #region Class members
    private TcpClient socket;
    private StreamReader reader;
    private StreamWriter writer;
    private bool connected;
    #endregion

    #region Class Constructor
    /// <summary>
    /// Create a new connection.
    /// </summary>
    internal SmtpConnection()
    {
      socket = new TcpClient();     
    }
    #endregion 

    #region Class methods
    /// <summary>
    /// Connection status.
    /// </summary>
    public bool Connected
    {
      get{return connected;}
    }

    /// <summary>
    /// Open connection with specified host and default port.
    /// </summary>
    /// <param name="host">Host name to connect to.</param>
    internal void Open(string host)
    {
      Open(host, 25);
    }
    
    /// <summary>
    /// Open connection to host on port.
    /// </summary>
    /// <param name="host">Host name to connect to.</param>
    /// <param name="port">Port to connect to.</param>
    internal void Open(string host, int port)
    {
      if(host == null || host.Trim().Length == 0 || port <= 0)
      {
        throw new System.ArgumentException("Invalid Argument found.");
      }
      socket.Connect(host, port);
      reader = new StreamReader(socket.GetStream(), System.Text.Encoding.ASCII);
      writer = new StreamWriter(socket.GetStream(), System.Text.Encoding.ASCII);
      connected = true;
    }
    
    /// <summary>
    /// Close connection.
    /// </summary>
    internal void Close()
    {
      reader.Close();
      writer.Flush();
      writer.Close();
      reader = null;
      writer = null;
      socket.Close();
      connected = false;
    }

    /// <summary>
    /// Send a command to the server.
    /// </summary>
    /// <param name="cmd">Command to send.</param>
    internal void SendCommand(string cmd)
    {
#if DEBUG
      Trace.WriteLine( cmd, "TO SMTP" );
#endif

      writer.WriteLine( cmd );
      writer.Flush();
    }

    /// <summary>
    /// Send data to the server. Used for sending attachments.
    /// </summary>
    /// <param name="buf">Data buffer.</param>
    /// <param name="start">Starting position in buffer.</param>
    /// <param name="length">Length to send.</param>
    internal void SendData(char[] buf, int start, int length)
    {
      writer.Write(buf, start, length);
    }

    /// <summary>
    /// Get the reply message from the server.
    /// </summary>
    /// <param name="reply">Text reply from server.</param>
    /// <param name="code">Status code from server.</param>
    internal void GetReply(out string reply, out int code)
    {
      reply = reader.ReadLine();

#if DEBUG
      Trace.WriteLine( reply, "FROM SMTP" );
#endif

      code = ( reply == null ) ? -1 : Int32.Parse(reply.Substring(0, 3));     
    }
    #endregion
  }
}