import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.util.Collections;
import java.util.Comparator;

public class Server implements Runnable {

    public static String leader = "";
    public static boolean isLeader = false;
    public static ServerSocket serverSocket = null; // Sempre que for o leader vai ter valor definido
    public static ArrayList<String> IP_LIST = new ArrayList<>();
    public static int PORT = 4000;
    public static boolean IN_SELECTION = false;
    public static int tries = 3;

    public Server() {
        System.out.println("Initializing....");
        Thread t = new Thread(this);
        t.start();
    }

    @Override
    public void run() {
        Server.IP_LIST.add("10.3.15.17");
        //Server.IP_LIST.add("10.3.15.18");
        Server.IP_LIST.add("10.3.15.19");

        String candidateLeader = "";
        while (true) {
            try {
                if (Server.isLeader()) {
                    System.out.println("----------------------------------");

                    if (!amIRealyTheLeader()) {
                        candidateLeader = Server.electLeader();

                        if (candidateLeader.isEmpty()) {
                            System.out.println("Assuming leadership...");
                            Server.takeLeadership();
                        } else {
                            System.out.println("Defining candidate leader...");
                            Server.defineLider(candidateLeader);
                        }
                    }

                    try (final DatagramSocket socket = new DatagramSocket()) {
                        socket.connect(InetAddress.getByName("8.8.8.8"), 10002);
                        String ip = socket.getLocalAddress().getHostAddress();

                        System.out.println("I am the leader - " + ip);
                    }

                    Thread.sleep(5 * 1000);

                } else if (!Server.ping(Server.leader).isEmpty()) {
                    System.out.println("----------------------------------");
                    System.out.println("I am not the leader, but ping to leader responded");
                    System.out.println("The leader is: " + Server.leader);

                    System.out.println("Wait 10 seconds");
                    Thread.sleep(10 * 1000);
                } else {
                    System.out.println("----------------------------------");
                    System.out.println("There is no leader. Initializing election.");

                    if (!Server.IN_SELECTION) {
                        candidateLeader = Server.electLeader();

                        if (candidateLeader.isEmpty()) {
                            System.out.println("Assuming leadership...");
                            Server.takeLeadership();
                        } else {
                            System.out.println("Defining candidate leader...");
                            Server.defineLider(candidateLeader);
                        }
                    }
                }

                printActiveIps();
            } catch (Exception e) {
                try {
                    Server.resetLeader();
                } catch (IOException ex) {
                    Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
                }
                e.printStackTrace();
            }
        }
    }

    public static boolean hasLeader() {
        return Server.leader != null;
    }

    public static boolean isLeader() {
        return Server.isLeader;
    }

    public static void resetLeader() throws IOException {
        Server.isLeader = false;

        Server.leader = null;
    }

    public static boolean amIRealyTheLeader() {
        boolean answer = true;

        ArrayList<String> tempArray = Server.clone(Server.IP_LIST);

        Collections.sort(tempArray, new Comparator<String>() {
            public int compare(String s1, String s2) {
                return s2.compareToIgnoreCase(s1);
            }
        });

        for (int i = 0; i < tempArray.size(); i++) {
            String highestIp = tempArray.get(i);

            String response = ping(highestIp);

            if (response.isEmpty()) {
                continue;
            }

            if (response.equals("I am the leader!")) {
                answer = false;
                break;
            }
        }

        return answer;
    }

    public static String electLeader() throws IOException {
        String leader = "";
        Server.IN_SELECTION = true;
        ArrayList<String> tempArray = Server.clone(Server.IP_LIST);

        Collections.sort(tempArray, new Comparator<String>() {
            public int compare(String s1, String s2) {
                return s2.compareToIgnoreCase(s1);
            }
        });

        for (int j = 0; j < tries; j++) {
            for (int i = 0; i < tempArray.size(); i++) {
                String highestIp = tempArray.get(i);
                System.out.println("Tryng pinging - " + highestIp);

                String response = ping(highestIp);

                if (response.isEmpty()) {
                    System.out.println("Did not respond...");
                    continue;
                }

                if (response.equals("I am the leader!")) {
                    leader = highestIp;
                    break;
                }
            }
        }

        Server.IN_SELECTION = false;
        return leader;
    }

    public static ArrayList<String> clone(ArrayList<String> list) {
        ArrayList<String> clone = new ArrayList<String>(list.size());
        for (int i = 0; i < list.size(); i++) {
            clone.add(list.get(i));
        }
        return clone;
    }

    public static boolean defineLider(String s) throws IOException {
        Server.resetLeader();
        Server.leader = s;
        return true;
    }

    public static boolean takeLeadership() throws IOException {

        Server.isLeader = true;

        return true;
    }

    public static String ping(String ip) {
        String response = "";

        try {
            Socket socket = new Socket();
            socket.connect(new InetSocketAddress(ip, Server.PORT), 5 * 1000);

            ObjectOutputStream saida = new ObjectOutputStream(socket.getOutputStream());
            ObjectInputStream entrada = new ObjectInputStream(socket.getInputStream());

            saida.flush();
            saida.writeObject("pinging...");

            response = (String) entrada.readObject();
        } catch (Exception e) {
            return response;
        }

        return response;
    }

    public static synchronized void printActiveIps() {
        String ips = "";
        for (String ip : IP_LIST) {
            String response = ping(ip);

            if (!response.isEmpty()) {
                ips += ips.isEmpty() ? ip : "\n" + ip;
            }
        }

        System.out.println("----------------------------------");
        System.out.println("Active ips:");
        System.out.println(ips);
    }

    public static void main(String[] args) {
        new Server();
        ThreadLeader l = new ThreadLeader();
        l.run();
    }
}