import java.util.Iterator;
import java.util.NoSuchElementException;

public class FIFOListe<T> implements Iterable<T>{

	private Node hode;
	private Node hale;

	private class Node {
        private Node neste;
        private T verdi;

        public Node(T v) {
            verdi = v;
        }
    }

	public int storrelse() {
        int teller = 0;
        for (Node tmp = hode; tmp != null; tmp = tmp.neste) {
            teller++;
        }
        return teller;
    }

	public boolean erTom() {
        return hode == null;
    }

	public void leggTil(T t) {
        Node ny = new Node(t);
        if (erTom()) {
            hode = ny;
        }
        else {
            hale.neste = ny;
        }
        hale = ny;
    }

	public void fjernAlt() {
        hale = hode = null;
    }

	public T pop() {
        if (erTom()) {
            return null;
        }
        Node returneres = hode;
        if (hode == hale) {
            fjernAlt();
        }
        else {
            hode = hode.neste;
        }
        return returneres.verdi;
    }

	public void skrivUtListe() {
        Node tmp = hode;
        System.out.print("[");
        while (tmp != null) {
            if (tmp.neste == null)
                System.out.print(tmp.verdi);
            else
                System.out.print(tmp.verdi + ", ");
            tmp = tmp.neste;
        }
        System.out.println("]");
    }

    @Override       
    public Iterator<T> iterator() {
        return new FIFOIterator();
    } 

    private class FIFOIterator implements Iterator<T> {
        private Node denne = hode;

        @Override
        public boolean hasNext() {
            return denne != null;
        }

        @Override
        public T next() {
            if (!hasNext()) throw new NoSuchElementException("next");
            Node tmp = denne;
            denne = tmp.neste;
            return tmp.verdi;
        }
    }
    public static void main(String[] args) {
        FIFOListe<String> liste = new FIFOListe<>();
        liste.leggTil("Hei");
        liste.leggTil(" paa");
        liste.leggTil(" deg");
        liste.leggTil("!");

        liste.skrivUtListe();
        
        for (String s : liste) {
            System.out.println(s);
        }
        System.out.println("\nTest pop");
        System.out.println(liste.pop());
        System.out.println(liste.pop());
        System.out.println(liste.pop());
        System.out.println(liste.pop());

    }
}