import java.util.AbstractQueue;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Queue;

public class FileChainee<E> extends AbstractQueue<E> implements Queue<E> {
    private static class Node<E> {
        E data;
        Node<E> next;

        Node(E data) {
            this.data = data;
        }
    }

    private Node<E> head; // Premier élément de la file
    private Node<E> tail; // Dernier élément de la file
    private int size = 0; // Taille de la file

    @Override
    public boolean offer(E element) {
        Node<E> newNode = new Node<>(element);
        if (head == null) {
            tail = newNode;
        } else {
            newNode.next = head;
        }
        head = newNode;
        size++;
        return true;
    }

    @Override
    public E poll() {
        if (isEmpty()) {
            return null;
        }
        E data = head.data;
        head = head.next;
        if (head == null) {
            tail = null;
        }
        size--;
        return data;
    }

    @Override
    public E peek() {
        return (head == null) ? null : head.data;
    }

    @Override
    public Iterator<E> iterator() {
        return new Iterator<>() {
            private Node<E> current = head;

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

            @Override
            public E next() {
                if (!hasNext()) {
                    throw new NoSuchElementException();
                }
                E data = current.data;
                current = current.next;
                return data;
            }
        };
    }

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