// CSE 143, Summer 2012
// A LinkedIntList object is a list of integers represented as linked nodes.
// LinkedIntList implements the same methods as ArrayIntList but with
// different runtime efficiencies.

import java.util.*;

public class LinkedIntList {
	private ListNode front;
	private int size;
	
	// Constructs an empty list
	public LinkedIntList () {
		front = null;
		size = 0;
	}
	
	// The value will be added at the end of the list, 
	// the size of the list will be one greater
	public void add (int value) {
		if (front == null) {
			front = new ListNode (value);
		} else {
			// list wasn't empty; find the back
			// (note: this is inefficient.  We could keep a reference to the last node)
			ListNode current = front;
			while (current.next != null) {
				current = current.next;
			}
			current.next = new ListNode (value);
		}
		size++;
	}
	
	// Returns the value at a given index.
	// pre: 0 <= index < size
	// Throws a NullPointerException if index > size or index < 0.
	public int get (int index) {
		if (index < 0 || index >= size) {
			throw new IllegalArgumentException("index was out of bounds");
		}	
		ListNode current = front;
		for (int i = 0; i < index; i++) {
			current = current.next;
		}
		return current.data;
	}
	
	// Adds a value at a given index.
	// Pre: 0 <= index <= size
	// Throws a NullPointerException if index > size or index < 0
	public void add (int index, int value) {
		if (index < 0 || index > size) {
			throw new IllegalArgumentException("index was out of bounds");
		}	else if (index == 0) {
			front = new ListNode (value, front);
		} else {
			ListNode current = front;
			for (int i = 0; i < index - 1; i++) {
				current = current.next;
			}
			current.next = new ListNode (value, current.next);
		}
		size++;
	}
	
	// Removes the value at the given index.
	public int remove() {
		if (front == null) {
			throw new NoSuchElementException();
		}
		size--;
		int temp = front.data;
		front = front.next;
		return temp;
	}
	
	
	// Removes the value at the given index.
	// Pre: 0 <= index < size
	public void remove (int index) {
		if (index < 0 || index >= size) {
			throw new NoSuchElementException();
		} else if (index == 0) {
			remove();
		} else {
	
			ListNode current = front;
			for  (int i = 0; i < index - 1; i++) {
				current = current.next; 
			}
			current.next = current.next.next;
			size--;
		}
	}
		
	// Adds the given element value to the list in sorted order.
	// Pre: the list is already sorted
	// Post: the new element is added and the list is still sorted	
	public void addSorted (int value) {
		if (front == null || value < front.data) {
			front = new ListNode (value, front);	
		} else {
			ListNode current = front;
			while (current.next != null && current.next.data < value) {
				current = current.next;
			}	
			current.next = new ListNode(value, current.next);
		}
		size++;
	}
	
	// returns the number of elements in the list
	public int size() {
		return size;
	}
	
	// returns a string representation of the data in the list
	// surrounded by square brackets and separated by commas 
	public String toString () {
		String str = "[";
		if (front != null) {
			str += front.data;
			ListNode current = front.next;
			while (current !=  null) {
				str += ", " + current.data;
				current = current.next;
			}
		}
		str += "]";
		return str;
	}
}