package cz.cvut.fel.pjv;

/**
 * Implementation of the {@link Queue} backed by fixed size array.
 */
public class CircularArrayQueue implements Queue {
    String [] pole;
    int head =0;
    int end =0;

    public CircularArrayQueue() {
        pole = new String [5];
    }

    public CircularArrayQueue(int capacity) {
        pole = new String [capacity];
    }

    @Override
    public int size() {
        int size=0;
        for (String x : pole ){
            if (x!=null){
                size++;
            }
        }
        return size;
    }

    @Override
    public boolean isEmpty() {
        if (pole[head]==null){
            return true;
        }
        return false;
    }

    @Override
    public boolean isFull() {
        if(head-end==0 && pole[head]!=null ){
            return true;
        }
        return false;
    }

    @Override
    public boolean enqueue(String obj) {
        if(this.isFull() || obj==null){
            return false;
        }
        if (this.isEmpty()){
            pole[head]=obj;
        }
        pole[end]=obj;
        if(end==pole.length-1){
            end=0;
        } else{
            end++;
        }
        return true;
    }

    @Override
    public String dequeue() {
        if (!this.isEmpty()){
            String deq=pole[head];
            pole[head]=null;
            if(head==pole.length-1){
                head=0;
            }else {
                head++;
            }
            return deq;
        }
        return null;
    }

    @Override
    public void printAllElements() {
        for(String x : pole ){
            if(x!=null){
                System.out.println(x);
            }
        }
    }
}