import java.util.ArrayList;
import java.util.concurrent.Semaphore;

class Customer extends Thread{
    private BarberShop shop;

    public Customer(BarberShop shop) {
        this.shop = shop;
    }

    @Override
    public void run() {
        for(int i=0;i<10;i++){
            try {
                execute();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public void execute() throws InterruptedException {

        shop.customerComesIn();

    }
}

class Barber extends Thread{
    private BarberShop shop;

    public Barber(BarberShop shop) {
        this.shop = shop;
    }

    @Override
    public void run() {
        for(int i=0;i<10;i++){
            try {
                execute();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public void execute() throws InterruptedException {
        shop.barber();

    }
}

class Semaphores{
    public static Semaphore whoCanWait;
    public static Semaphore barberWake;
    public static Semaphore protect;
}
public class BarberShop {

    public static void init(){
        Semaphores.whoCanWait = new Semaphore(5); //broj na slobodni mesta za cekanje
        Semaphores.barberWake = new Semaphore(0); //na pocetokot barberot spie
        Semaphores.protect=new Semaphore(1);
    }

    int waitingCustomers = 0;

    void customerComesIn() throws InterruptedException {
        // TODO: 3/29/20 Synchronize this method, invoked by a Customer thread
        Semaphores.protect.acquire();
        if(waitingCustomers==0){
            Semaphores.barberWake.release();
        }
        waitingCustomers++;
        Semaphores.whoCanWait.release();
        Semaphores.protect.release();

    }

    void barber() throws InterruptedException {
        // TODO: 3/29/20 Synchronize this method, invoked by Barber thread

        Semaphores.barberWake.acquire();
        Semaphores.protect.acquire();
        waitingCustomers--;

        if(waitingCustomers!=0) {
            Semaphores.barberWake.release();
        }
        Semaphores.whoCanWait.release();
        Semaphores.protect.release();



    }

    public static void main(String[] args) throws InterruptedException {
        // TODO: 3/29/20 Synchronize the scenario
        ArrayList<Thread> threads=new ArrayList<>();
        BarberShop shop=new BarberShop();
        Barber barber=new Barber(shop);

        init();
        for(int i=0;i<10;i++){
            Customer customer=new Customer(shop);
            threads.add(customer);
        }

        barber.start();
        for(Thread t: threads){
            t.start();
        }

        for(Thread t: threads){
            t.join();
        }

        for(Thread t:threads){
            if(t.isAlive())
                System.out.println("deadlock");
        }

        System.out.println("Uspeshna sinhronizacija");
    }
}