package Lab3;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Semaphore;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class BarberShop {
    static Semaphore customer=new Semaphore(5);
    static Semaphore barber=new Semaphore(1);
    static int totalCustomers=0;
    static int waitingCustomers = 0;
    static Lock lock=new ReentrantLock();

    void customerComesIn() throws InterruptedException {
        // TODO: 3/29/20 Synchronize this method, invoked by a Customer thread
        customer.acquire();
        waitingCustomers++;


    }

    void barber() throws InterruptedException {
        // TODO: 3/29/20 Synchronize this method, invoked by Barber thread
        while(totalCustomers>0){
            while(waitingCustomers==0){
                Thread.sleep(50);
            }
            // Cutting hair....
            System.out.println("Next one please! "+(waitingCustomers--)+" customers left!");
            customer.release();
            lock.lock();
            totalCustomers--;
            lock.unlock();
        }
    }

    public static void main(String[] args) throws InterruptedException {
        List<Thread>list=new ArrayList<>();
        Thread barber=new Barber();
        for(int i=0;i<100;i++){
            list.add(new Customer());
        }
        totalCustomers=list.size();
        barber.start();
        for(Thread t:list){
            t.start();
        }
        for(Thread t:list){
            t.join();
        }
        barber.join();
        System.out.println("Finished for today!");
    }
    static class Barber extends Thread{
        BarberShop barber=new BarberShop();

        @Override
        public void run() {
            try {
                barber.barber();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    static class Customer extends Thread{
        BarberShop customer=new BarberShop();

        @Override
        public void run() {
            try {
                customer.customerComesIn();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}