package esercizi;

import exceptions.EmptyQueueException;
import queue.Queue;
import sequence.ArraySequence;
import stack.ArrayStack;

/**
 * Created with MONSTER.
 * User: xgiovio
 * Date: 13/04/2014
 * Time: 23:01
 */

// queue emulated via 2 stacks

public class SQueue<E> implements Queue<E> {


    private ArrayStack<E> accoda = new ArrayStack<E>();
    private ArrayStack<E> decoda = new ArrayStack<E>();

    @Override
    public void enqueue(E element) {

        accoda.push(element);

    }

    @Override
    public E dequeue() throws EmptyQueueException {

        if (accoda.isEmpty()){
            throw new EmptyQueueException();
        } else {

            E temp;
            int size = accoda.size();
            for (int i = 0; i <size; i++) {
                decoda.push(accoda.pop());
            }
            temp = decoda.pop();
            size = decoda.size();
            for (int i = 0; i < size; i++) {
                accoda.push(decoda.pop());
            }
            return temp;
        }
    }

    @Override
    public E front() throws EmptyQueueException {
        if (accoda.isEmpty()){
            throw new EmptyQueueException();
        } else {

            E temp;
            int size = accoda.size();
            for (int i = 0; i <size; i++) {
                decoda.push(accoda.pop());
            }
            temp = decoda.top();
            size = decoda.size();
            for (int i = 0; i < size; i++) {
                accoda.push(decoda.pop());
            }
            return temp;
        }
    }

    @Override
    public boolean isEmpty() {
        return accoda.isEmpty();
    }

    @Override
    public int size() {
        return accoda.size();
    }

    @Override
    public String toString() {
        return accoda.toString();
    }
}