/* File : List.java
 * Program : Handle Reduction Aimation - Applet 
 * By Jean Fromentin <jfroment@info.unicaen.fr>
 * Copyright 2008 Jean Fromentin
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

class List {
    private Node first;
    private Node last;
    public Node current;  
    public int length;
    
    public List(){
	length=0;
    }
    
    public Node getFirst(){
	return first;
    }	
    
    public Node getLast(){
	return last;
    }
	
    public void initCurrent(){
	current=first;
    }
    
    public void setCurrent(Node _current){
	current=_current;
    }
    
    public Node getCurrent(){
	return current;
    }
    
    public boolean isEnd(){
	return current==last;
    }
	
    public void shift(){
	current=current.getNext();
    }
	
    public void addFirst(int value){
	Node node=new Node(value);
	if(length==0){
	    first=node;
	    last=node;
	}
	else{
	    first.setPrevious(node);
	    node.setNext(first);
	    first=node;
	}
	length++;
    }
	
    public void addLast(int value){
	Node node=new Node(value);
	if(length==0){
	    first=node;
	    last=node;
	}
	else{
	    last.setNext(node);
	    node.setPrevious(last);
	    last=node;
	}
	length++;
    }
    
    public Node addBefore(int value){
	Node node=new Node(value);
	if(current==first){
	    first=node;
	    node.setNext(current);
	    current.setPrevious(node);
	}
	else {
	    Node temp=current.getPrevious();
	    temp.setNext(node);
	    node.setPrevious(temp);
	    current.setPrevious(node);
	    node.setNext(current);
	}
	length++;
	return node;
    }
    
    public Node addAfter(int value){
	Node node=new Node(value);
	if(current==last){
	    last=node;
	    node.setPrevious(current);
	    current.setNext(node);
	}
	else{
	    Node temp=current.getNext();
	    temp.setPrevious(node);
	    node.setNext(temp);
	    current.setNext(node);
	    node.setPrevious(current);
	}
	length++;
	return node;
    }
	
    public void remove(Node node){
	if(length!=0){
	    if(length==1){
		length=0;
	    }
	    else{
		if(node==first){
		    first=node.getNext();
		    node=first;
		}
		else if(node==last){
		    last=node.getPrevious();
		    current=last;
		}
		else{
		    (node.getPrevious()).setNext(node.getNext());
		    (node.getNext()).setPrevious(node.getPrevious());
		}
		length--;
	    }
	}
    }
    
    public int value(){
	return current.getValue();
    }
	
    public int length(){
	return length;
    }
}