mMDT5_GreenWatch/app/src/main/java/com/example/greenwatch/communication/WiFiCommunication.java

package com.example.greenwatch.communication;

import com.example.greenwatch.repositories.DeviceRepository;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.Inet4Address;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.Enumeration;

public class WiFiCommunication {

    private final InetAddress address;
    private final DatagramSocket socket;
    private final int port;
    private volatile String rxString;
    private String sendMessage;
    //private String sendMsg = "default";
    private boolean isNewMessage;
    volatile private boolean running;
    private static WiFiCommunication wifiCommunicationInstance;
    private DeviceRepository mDeviceRepository;

    private WiFiCommunication() {
        port = 1234;
        try {
            socket = new DatagramSocket(port);
            socket.setBroadcast(true);
            address = InetAddress.getByName("255.255.255.255");
            running = true;
            isNewMessage = false;
            new ReceiveThread().start();
            new SendThread().start();
        } catch (SocketException | UnknownHostException e) {
            throw new RuntimeException(e);
        }
    }

    public static synchronized WiFiCommunication getInstance() {
        if (wifiCommunicationInstance == null){
            wifiCommunicationInstance = new WiFiCommunication();
        }
        return wifiCommunicationInstance;
    }

    public void setDeviceRepository(DeviceRepository deviceRepository) {
        if (mDeviceRepository == null) {
            this.mDeviceRepository = deviceRepository;
        }
    }

    public void setNewMessage(String newMessage, boolean isNewMessage){
        this.sendMessage = newMessage;
        this.isNewMessage = isNewMessage;
    }

    public static String getLocalIpAddress() {
        try {
            for (Enumeration<NetworkInterface> en = NetworkInterface.getNetworkInterfaces(); en.hasMoreElements();) {
                NetworkInterface networkInterface = (NetworkInterface) ((Enumeration<?>) en).nextElement();
                for (Enumeration<InetAddress> addresses = networkInterface.getInetAddresses(); addresses.hasMoreElements();) {
                    InetAddress inetAddress = addresses.nextElement();
                    if (!inetAddress.isLoopbackAddress() && inetAddress instanceof Inet4Address) {
                        return inetAddress.getHostAddress();
                    }
                }
            }
        } catch (SocketException ex) {
            ex.printStackTrace();
        }
        return null;
    }

    public void stopCommunication() {
        running = false;
        socket.close();
    }

    private class SendThread extends Thread {
        private int tmpCnt = 0;
        @Override
        public void run() {
            try {
                do {

                    if(isNewMessage)
                    {
                        isNewMessage = false;
                        String txString = sendMessage;
                        byte[] txBuffer = txString.getBytes();

                        DatagramPacket txPacket = new DatagramPacket(txBuffer, txBuffer.length, address, port);

                        for(int i = 0; i < 20; i++) {
                            socket.send(txPacket);
                        }
                    }
                } while (running);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private class ReceiveThread extends Thread {
        private String rxString = "";
        private String previousRxString = "";
        @Override
        public void run() {
            try {
                do {
                    byte[] rxBuffer = new byte[1024];
                    DatagramPacket packet = new DatagramPacket(rxBuffer, rxBuffer.length);
                    socket.receive(packet);
                    rxString = new String(packet.getData(), 0, packet.getLength());

                    if(!previousRxString.equals(rxString)){
                        mDeviceRepository.getNewReceivedMessage(rxString);

                    }
                    previousRxString = rxString;

                } while (running);
            }
            catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}