using System;
using System.Threading;
using System.Net;
using System.Text;
using System.Net.Sockets;

using Microsoft.SPOT;
using Microsoft.SPOT.Hardware; //need for Utility class
using Microsoft.SPOT.Net;
using GHI.Premium.Net;

namespace WIFI
{
    public class NTP
    {
        public static bool Time(string TimeServer, int GmtOffset = 0)
        {
            Socket s = null;
            try
            {
                EndPoint rep = new IPEndPoint(Dns.GetHostEntry(TimeServer).AddressList[0], 123);
                s = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
                byte[] ntpData = new byte[48];
                Array.Clear(ntpData, 0, 48);
                ntpData[0] = 0x1B; // Set protocol version
                s.SendTo(ntpData, rep); // Send Request   
                if (s.Poll(30 * 1000 * 1000, SelectMode.SelectRead)) // Waiting an answer for 30s, if nothing: timeout
                {
                    s.ReceiveFrom(ntpData, ref rep); // Receive Time
                    byte offsetTransmitTime = 40;
                    ulong intpart = 0;
                    ulong fractpart = 0;
                    for (int i = 0; i <= 3; i++) intpart = (intpart << 8) | ntpData[offsetTransmitTime + i];
                    for (int i = 4; i <= 7; i++) fractpart = (fractpart << 8) | ntpData[offsetTransmitTime + i];
                    ulong milliseconds = (intpart * 1000 + (fractpart * 1000) / 0x100000000L);
                    s.Close();

                    TimeSpan TimeSpan = TimeSpan.FromTicks((long)milliseconds * TimeSpan.TicksPerMillisecond);
                    DateTime dateTime = new DateTime(1900, 1, 1);
                    dateTime += TimeSpan;

                    TimeSpan offsetAmount = TimeZone.CurrentTimeZone.GetUtcOffset(dateTime);
                    DateTime networkDateTime = (dateTime + offsetAmount);
                    Utility.SetLocalTime(networkDateTime);
                    return true;
                }
                s.Close();
            }
            catch
            {
                try
                {
                    s.Close();
                }
                catch
                {
                }
            }
            return false;
        }
    }
}