package com.company;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
import java.net.SocketTimeoutException;
import java.nio.ByteBuffer;
import java.util.UUID;

public class CopyFinder {
    private String message = "pugs_do_drug_uuu_vatrushki";
    private byte[] sendPacket = new byte[32];
    byte[] rcvPacket = new byte[32];


    byte[] UUIDtoByte(UUID uuid) {
        ByteBuffer bb = ByteBuffer.wrap(new byte[16]);
        bb.putLong(uuid.getMostSignificantBits());
        bb.putLong(uuid.getLeastSignificantBits());
        return bb.array();
    }

    UUID BytetoUUID(byte[] bb) {
        ByteBuffer byteBuffer = ByteBuffer.wrap(bb);
        Long high = byteBuffer.getLong();
        Long low = byteBuffer.getLong();
        return new UUID(high, low);
    }

    void findCopy() throws IOException {
        UUID uuid = UUID.nameUUIDFromBytes(message.getBytes());
        UUID uuidUnique = UUID.randomUUID();

        byte[] sendFirstPart = UUIDtoByte(uuid);
        byte[] sendSecondPart = UUIDtoByte(uuidUnique);

        for (int i = 0; i < sendPacket.length; i++) {
            sendPacket[i] = i < sendFirstPart.length ? sendFirstPart[i] : sendSecondPart[i - sendFirstPart.length];
        }

        MulticastSocket multicastSocket = new MulticastSocket(8000);
        InetAddress inetGroupAddress = InetAddress.getByName("224.1.1.1");
        multicastSocket.joinGroup(inetGroupAddress);

        DatagramPacket datagramSendPacket = new DatagramPacket(sendPacket, sendPacket.length, inetGroupAddress, 8000);
        DatagramPacket datagramRcvPacket = new DatagramPacket(rcvPacket, rcvPacket.length);

        long timeout = 3000;
        while (true) {
            multicastSocket.send(datagramSendPacket);
            long sendTime = System.currentTimeMillis();

            while (timeout - (System.currentTimeMillis() - sendTime) > 0) {
                multicastSocket.setSoTimeout((Long.valueOf(timeout - (System.currentTimeMillis() - sendTime))).intValue() + 1);

                try {
                    multicastSocket.receive(datagramRcvPacket);
                } catch (SocketTimeoutException exception) {
                    continue;
                }

                rcvPacket = datagramRcvPacket.getData();
                byte[] firstPartRcv = new byte[16];
                byte[] secondPartRcv = new byte[16];
                for (int i = 0; i < rcvPacket.length / 2; i++) {
                    firstPartRcv[i] = rcvPacket[i];
                    secondPartRcv[i] = rcvPacket[i + rcvPacket.length / 2];
                }

                UUID uuidFirst = BytetoUUID(firstPartRcv);
                UUID uuidSecond = BytetoUUID(secondPartRcv);

                if (!uuidSecond.equals(uuidUnique) && uuidFirst.equals(uuid)) {
                    System.out.println("Clone appeared!!!");
                }
                else if (uuidSecond.equals(uuidUnique) && uuidFirst.equals(uuid)) {
                    System.out.println("It's me!!!");
                }
                else System.out.println("No clone appeared!!!");

            }
        }
    }

}