using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Configuration;
using System.Net;
using System.IO;
using System.Diagnostics;
using System.Threading;

namespace IPMonitor
{
  class Program
  {
    public static String GetPublicIPAddress()
    {
      String address = "";  
      WebRequest request = WebRequest.Create("http://checkip.dyndns.org/");  
      using (WebResponse response = request.GetResponse())  
       using (StreamReader stream = new StreamReader(response.GetResponseStream()))  
       {  
          address = stream.ReadToEnd();  
       }  
  
       int first = address.IndexOf("Address: ") + 9;  
       int last = address.LastIndexOf("</body>");  
       address = address.Substring(first, last - first);  
  
       return address;  
    }

    public static void UpdateIPAddress(String ipAddress)
    {


      String strPathFileName="ipaddress.txt";
      if(!File.Exists(strPathFileName))
      {
        WriteFile(strPathFileName, ipAddress);
        SendSMSEmail(String.Format("IPMonitor IPAddress {0}",ipAddress));
      }
      else
      {
        String currentIPAddress=ReadFile(strPathFileName);
        if(null!=currentIPAddress && !currentIPAddress.Equals(ipAddress))
        {
          WriteFile(strPathFileName,ipAddress);
          SendSMSEmail(String.Format("IPMonitor IPAddress {0}",ipAddress));
        }
      }
    }

    public static void WriteFile(String strPathFileName,String ipAddress)
    {
      if(File.Exists(strPathFileName))File.Delete(strPathFileName);
      FileStream fileStream=new FileStream(strPathFileName,FileMode.Create,FileAccess.Write,FileShare.Read);
      StreamWriter streamWriter=new StreamWriter(fileStream);
      MDTrace.WriteLine(LogLevel.DEBUG,String.Format("Creating address file:{0}",strPathFileName));
      streamWriter.WriteLine(ipAddress);
      streamWriter.Flush();
      streamWriter.Close();
      streamWriter.Dispose();
    }

    public static String ReadFile(String strPathFileName)
    {
      try
      {
        FileStream fileStream=new FileStream(strPathFileName,FileMode.Open,FileAccess.ReadWrite,FileShare.Read);
        StreamReader streamReader=new StreamReader(fileStream);
        String item=null;
        item=streamReader.ReadLine();
        streamReader.Close();
        streamReader.Dispose();
        return item;
      }
      catch(Exception exception)
      {
        MDTrace.WriteLine(LogLevel.DEBUG,String.Format("[IPMonitor::ReadFile] Exception:{0}",exception.ToString()));
        return null;
      }
    }

    public static void SendSMSEmail(string message)
    {
      String smsSMTPAddress = ConfigurationManager.AppSettings["sms_smtpaddress"];
      String smsUserName = ConfigurationManager.AppSettings["sms_smsusername"];
      String smsPassword = ConfigurationManager.AppSettings["sms_smspassword"];
      String[] smsRecipients = ConfigurationManager.AppSettings["sms_smsrecipients"].Split(',');
      SMSClient.SendSMSEmail(message, smsUserName, smsRecipients, smsSMTPAddress, smsUserName, smsPassword);
    }

    static void Main(string[] args)
    {
      int interval_ms = int.Parse(ConfigurationManager.AppSettings["poll_time_ms"]);
      int notify_ms = int.Parse(ConfigurationManager.AppSettings["notify_time_ms"]);

      try
      {
        MDTrace.LogLevel = LogLevel.DEBUG;
        String strLogFile = "ipmonitor.log";
        Utility.CopyFile(strLogFile,Utility.DateTimeToStringYYYYMMDDMMSSTT(DateTime.Now)+strLogFile);
        Utility.DeleteFile(strLogFile);
        Trace.Listeners.Add(new TextWriterTraceListener(strLogFile));

        Profiler profiler=new Profiler();
        profiler.Start();
        while(true)
        {
          String ipAddress=GetPublicIPAddress();
          UpdateIPAddress(ipAddress);
          try{Thread.Sleep(interval_ms);}catch{;}
          if(profiler.Split()>=notify_ms)
          {
            SendSMSEmail(String.Format("IPMonitor IPAddress {0}",ipAddress));
            profiler.Start();
          }
        }
      }
      catch(Exception exception)
      {
        MDTrace.WriteLine(LogLevel.DEBUG,String.Format("[IPMonitor] Exception:{0}",exception.ToString()));
      }
    }
  }
}