import java.util.concurrent.Semaphore;

public class BlockingQueue<T> extends Thread{

    T[] contents;
    int capacity;
    int front;
    int back;

    public BlockingQueue(int capacity) {
        contents = (T[]) new Object[capacity];
        this.capacity = capacity;
        front = back = 0;
    }

    public void enqueue(T item) throws InterruptedException {
        if (this.back == this.capacity){
            System.out.println("The Queue is full. Item will not be added.\n"); //polna redica
        } else{
            contents[back] = item; // dodava item i go zgolemuva back za 1;
            back++;
            dequeueSemamphore.release();
        }
    }
    public T dequeue() throws InterruptedException {
        if (this.back == 0){
            System.out.println("Queue is empty\n");
            return null;
        } else{
            dequeueSemamphore.acquire();
            T item = contents[0];
            for (int i = 0; i < this.back-1; i++) {
                contents[i] = contents[i+1];
            }
            contents[back] = null; // brisam element sto e ostanat na krajot;
            this.back--;
            return item;
        }
    }
    public void print(){
        if (front==back){
            System.out.println("Queue is empty...");
            return;
        }
        for (int i = front; i < back; i++) {
            System.out.print(contents[i] + " ");
        }
        System.out.println();
    }

    public static Semaphore dequeueSemamphore = new Semaphore(0);
    public static void main(String[] args) {
        BlockingQueue<Integer> blockingQueue = new BlockingQueue<>(100);
        //treba da se testira
    }
}