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

namespace IPMonitor
{
  class Program
  {


// Main 
    public static void UpdateIPAddress(String ipAddress)
    {
      try
      {
        String strPathFileName="ipaddress.txt";
        if(!File.Exists(strPathFileName))
        {
          WriteFile(strPathFileName, ipAddress);
          ZoneEditResponses zoneEditResponses=UpdateZoneEditRecord(ipAddress);
          SendSMSEmail(String.Format("IPMonitor IPAddress {0}.  ZoneEditUpdated={1}",ipAddress,zoneEditResponses.IsSuccess()));
        }
        else
        {
          String currentIPAddress=ReadFile(strPathFileName);
          if(null!=currentIPAddress && !currentIPAddress.Equals(ipAddress))
          {
            WriteFile(strPathFileName,ipAddress);
            ZoneEditResponses zoneEditResponses=UpdateZoneEditRecord(ipAddress);
            SendSMSEmail(String.Format("IPMonitor IPAddress {0}.  ZoneEditUpdated={1}",ipAddress,zoneEditResponses.IsSuccess()));
          }
          else if(null==currentIPAddress)
          {
           SendSMSEmail("IPMonitor "+ipAddress+ ".  IPMonitor encountered an issue reading the IPAddress file.");
          }
        }
      }
      catch(Exception exception)
      {
        MDTrace.WriteLine(LogLevel.DEBUG,String.Format("[IPMonitor::UpdateIPAddress] Exception:{0}",exception.ToString()));
      }
    }

    public static String GetPublicIPAddress()
    {
      int MAX_RETRIES=5;
      int TIMEOUT_BETWEEN_ATTEMPTS=30000;
      String request="http://checkip.dyndns.org/";

      try
      {
         String address = null; 
         
         for(int index=0;index<MAX_RETRIES && null==address;index++)
         {
           if(!NetworkStatus.IsNetworkAvailable(0))
           {
             MDTrace.WriteLine(LogLevel.DEBUG,String.Format("[IPMonitor::GetPublicIPAddress] The Network seems to be disconnected.  Will retry after {0} (ms) ",request,TIMEOUT_BETWEEN_ATTEMPTS));
             try{Thread.Sleep(TIMEOUT_BETWEEN_ATTEMPTS);}catch{;}
             continue;
           }
           address = GetHttpRequest(request);
           if(null==address)
           {
             MDTrace.WriteLine(LogLevel.DEBUG,String.Format("[IPMonitor::GetPublicIPAddress] Request failed {0}.  Will retry after {1} (ms) ",request,TIMEOUT_BETWEEN_ATTEMPTS));
             try{Thread.Sleep(TIMEOUT_BETWEEN_ATTEMPTS);}catch{;}
             continue;
           }
         } 

         try
         {
           int first = address.IndexOf("Address: ") + 9;  
           int last = address.LastIndexOf("</body>");  
           address = address.Substring(first, last - first);  
           MDTrace.WriteLine(LogLevel.DEBUG,String.Format("Request succeeded: {0} -> {1}",request,address));
           return address;  
         }
         catch(Exception exception)
         {
           MDTrace.WriteLine(LogLevel.DEBUG,String.Format("Exception parsing address: {0}",exception.ToString()));
           return null;
         }
       }
       catch(Exception exception)
       {
         String message = String.Format("[IPMonitor::GetPublicIPAddress] Exception:{0}",exception.ToString());
         MDTrace.WriteLine(LogLevel.DEBUG,message);
         SendSMSEmail("IPMonitor encountered an issue retrieving.");
         return null;
       }
    }

    public static String GetHttpRequest(String strRequest)
    {
      try
      {
        WebRequest request = WebRequest.Create(strRequest);  
        using (WebResponse response = request.GetResponse())  
        using (StreamReader stream = new StreamReader(response.GetResponseStream()))  
        {  
          return stream.ReadToEnd();  
        }
      }
      catch(Exception exception)
      {
        MDTrace.WriteLine(LogLevel.DEBUG,String.Format("[IPMonitor:GetHttpRequest] failed with {0}",exception.ToString()));
        return null;
      }        
    } 

    public static ZoneEditResponses UpdateZoneEditRecord(String ipAddress)
    {
      HttpClient client = new HttpClient();

      String user=ConfigurationManager.AppSettings["zoneedit_user"];
      String password=ConfigurationManager.AppSettings["zoneedit_password"];
      String host=ConfigurationManager.AppSettings["zoneedit_host"];

      String strRequest=null; 
      StringBuilder sb=new StringBuilder();
      HttpNetResponse httpNetResponse=null;

      sb = new StringBuilder();
      sb.Append("https://");
      sb.Append("dynamic.zoneedit.com/auth/dynamic.html");
      sb.Append("?host=").Append(HttpUtility.UrlEncode(host));
      sb.Append("&dnsto=").Append(HttpUtility.UrlEncode(ipAddress));
      strRequest=sb.ToString();
      httpNetResponse = HttpNetRequest.GetRequestNoEncodingV5C(strRequest,user,password);

      if(!httpNetResponse.Success)
      {
        return new ZoneEditResponses();
      }

      MDTrace.WriteLine(LogLevel.DEBUG,String.Format("{0}",httpNetResponse.ResponseString));
      return new ZoneEditResponses(httpNetResponse.ResponseString);
    }

    public static void WriteFile(String strPathFileName,String ipAddress)
    {
      try
      {
        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();
      }
      catch(Exception exception)
      {
        MDTrace.WriteLine(LogLevel.DEBUG,String.Format("[IPMonitor::WriteFile] Exception:{0}",exception.ToString()));
        return;
      }
    }

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