package verteiltesysteme.socket.timecounter;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

class UDPTimeCounterClient {
	public static void main(String args[]) throws Exception {
		String hostname = "";
		int udpPort = 36038;
		BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
		DatagramSocket clientSocket = new DatagramSocket();
		byte[] sendData = new byte[1024];
		byte[] receiveData = new byte[1024];
		DateFormat df = new SimpleDateFormat("dd.MM.yyyy HH:mm:ss");
				
		System.out.println("Bitte geben Sie die Server-Adresse ein: ");
		hostname = inFromUser.readLine();
		InetAddress IPAddress = InetAddress.getByName(hostname);
		System.out.println("Bitte geben Sie eine Zahl ein: ");
		Long number = new Long(inFromUser.readLine());
		sendData = number.toString().getBytes();

		System.out.println(System.lineSeparator());
		long timestampStart = System.currentTimeMillis();
		System.out.println("Zeit vor Versand = " + timestampStart + " ms, " + df.format(new Date(timestampStart)));
		DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, udpPort);
		clientSocket.send(sendPacket);
		long timestampSent = System.currentTimeMillis();
		System.out.println("Zeit nach Versand = " + timestampSent + " ms, " + df.format(new Date(timestampSent)));
		DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);

		clientSocket.receive(receivePacket);

		long timestampEnd = System.currentTimeMillis();
		System.out.println("Zeit nach Empfang = " + timestampEnd + " ms, " + df.format(new Date(timestampEnd)));
		long delay = timestampEnd - timestampStart;
		System.out.println("Delay = " + delay + " ms");
		System.out.println(System.lineSeparator());
		
		String result = new String(receivePacket.getData());
		System.out.println("Ausgabe vom Server:" + System.lineSeparator() + result);
		long timestampServer = new Long(result.split(" ")[2]).longValue();
		float oneWayDelayEstimate = (timestampEnd - timestampSent) / 2;
		float timestampSkew = timestampServer - timestampSent - oneWayDelayEstimate;
		System.out.println("Zeitversatz zwischen Server und Client ca. = " + timestampSkew + " ms");
		System.out.println(System.lineSeparator());
		clientSocket.close();
	}
}