package perf;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

class UDPPerfServer {
	public static void main(String argv[]) throws Exception {
		int udpPort = 36039;
		Long clientNumberOfMegabytes;

		DatagramSocket datagramSocket = new DatagramSocket(udpPort);

		byte[] receiveData = new byte[1024];
		byte[] sendData = new byte[1024];		

		System.out.println("UDPPerfServer gestartet. Warte auf eingehende Requests...");
		
		while (true) {
			DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
			datagramSocket.receive(receivePacket);

			InetAddress clientAddress = receivePacket.getAddress();
			int clientSrcPort = receivePacket.getPort();

			BufferedReader inFromClient = new BufferedReader(new InputStreamReader(new ByteArrayInputStream(receivePacket.getData())));

			clientNumberOfMegabytes = new Long(inFromClient.readLine());

			if (clientNumberOfMegabytes == 0) {
				break;
			}
			
			for (long mb = 0; mb < clientNumberOfMegabytes; mb++) {
				long megabyteStartTimeMilli = System.currentTimeMillis();
				for (long segment = 1; segment < 1024; segment++) {
					//long segmentStartTimeNano = System.nanoTime();
					DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, clientAddress, clientSrcPort);
					datagramSocket.send(sendPacket);
					//double transferDurationSegment = System.nanoTime() - segmentStartTimeNano;
					//System.out.printf("Dauer pro Segment: %.0f ns, Rate: %.0f KByte/s (MB: %d, Segment: %d)\n", transferDurationSegment, (1024 / (transferDurationSegment / 1000000000)), mb, segment);
					// CSV Output Excel
					//System.out.println(mb + "," + segment + "," + transferDurationSegment);
				}
				double transferDurationMB = System.currentTimeMillis() - megabyteStartTimeMilli;
				System.out.printf("1 MB (genauer MiB) gesendet in: %.0f ms, Rate: %.0f Bytes/s (MB: %d)\n", transferDurationMB, ((1024 * 1024) / (transferDurationMB / 1000)), mb);
			}
			System.out.print("\n");
			byte[] finishLabel = (new String("done")).getBytes(); 
			DatagramPacket sendPacket = new DatagramPacket(finishLabel, finishLabel.length, clientAddress, clientSrcPort);
			datagramSocket.send(sendPacket);
		}
		datagramSocket.close();
	}
}