package deque;

import deque.utility.DLNode;
import exceptions.EmptyDequeException;

/**
 * Created with xgiovio.macbookair.
 * User: xgiovio
 * Date: 17/03/14
 * Time: 16:26
 */
//Copyright (c) 2003 Brown University, Providence, RI
//Additional modifications and methods by xgiovio
public class NodeDeque<E> implements Deque <E>  {

    public NodeDeque(){
        header.setNext(trailer);
        trailer.setPrev(header);
    }

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

    @Override
    public boolean isEmpty() {
        if (nelements == 0){
            return true;
        } else{
            return  false;
        }
    }

    @Override
    public E getFirst() throws EmptyDequeException {
        if (isEmpty()){
            throw new EmptyDequeException();
        } else {
            return header.getNext().getElement();
        }
    }

    @Override
    public E getLast() throws EmptyDequeException {
        if (isEmpty()){
            throw new EmptyDequeException();
        } else {
            return trailer.getPrev().getElement();
        }
    }

    @Override
    public void addFirst(E element) {
        DLNode<E> temp = new DLNode<E>(element);
        temp.setNext(header.getNext());
        temp.getNext().setPrev(temp);
        header.setNext(temp);
        temp.setPrev(header);
        nelements++;

    }

    @Override
    public void addLast(E element) {
        DLNode<E> temp = new DLNode<E>(element);
        temp.setPrev(trailer.getPrev());
        temp.getPrev().setNext(temp);
        temp.setNext(trailer);
        trailer.setPrev(temp);
        nelements++;

    }

    @Override
    public E removeFirst() throws EmptyDequeException {
        if (isEmpty()){
            throw new EmptyDequeException();
        } else {
            DLNode<E> temp = header.getNext();
            header.setNext( header.getNext().getNext());
            header.getNext().setPrev(header);
            nelements--;
            return temp.getElement();
        }
    }

    @Override
    public E removeLast() throws EmptyDequeException {
        if (isEmpty()){
            throw new EmptyDequeException();
        } else {
            DLNode<E> temp = trailer.getPrev();
            trailer.setPrev(trailer.getPrev().getPrev());
            trailer.getPrev().setNext(trailer);
            nelements--;
            return temp.getElement();
        }
    }


    @Override
    public String toString() {

        String to_return = "";
        to_return = to_return + "[";

        for (  DLNode<E> temp = header.getNext(); temp != trailer ; temp = temp.getNext()){

            if ( temp.getNext() == trailer){
                to_return+=(temp.getElement().toString());
            }else{
                to_return+=( temp.getElement().toString() + ",");
            }
        }
        to_return = to_return + "]";

        return to_return;
    }

    private DLNode<E> header = new DLNode<E>();
    private DLNode<E> trailer = new DLNode<E>();
    private int nelements = 0;

}