/** LinkedIntList is a class that represents a LinkedList with
 *  int data.  Stores a reference to the front of the LinkedList.
 *  
 *  @author Adam Blank
 */
public class LinkedIntList {
	/** Stores the front of the LinkedIntList */
	private ListNode front;
	
	/** Stores the size of the LinkedIntList */
	private int size;

	/** Creates a new empty LinkedIntList */
	public LinkedIntList() {
		this.front = null;
	}
	
	/** Constructs a String representation of the LinkedIntList.
	 *  For example, "[1, 2, 3]".
	 */
	public String toString() {
		String result = "[";
		ListNode current = this.front;
		
		// Process all but the last element of the LinkedList
		while (current != null && current.next != null) {
			result += current.data + ", ";
			current = current.next;
		}
		
		// Process the last element (if one exists)
		if (current != null) {
			result += current.data;
		}
		
		return result + "]";
	}
	
	/** Appends value to the end of the LinkedIntList. */
	public void add(int value) {
		if (this.front == null) {
			this.front = new ListNode(value);
		}
		else {
			ListNode current = this.front;
			while (current.next != null) {
				current = current.next;
			}
			current.next = new ListNode(value);
		}
		this.size++;
	}
	
	/** Returns the size of the LinkedIntList */
	public int size() {
		return this.size;
	}
	
	/** Returns the data at index.
	 *  pre: 0 <= index < size, otherwise throws IllegalArgumentException
	 */
	  public int get(int index) {
		checkIndex(index);

		ListNode current = this.front;
		for (int i = 0; i < index; i++) {
			current = current.next;
		}
		return current.data;
	}
	
	/** Sets the data at index to value. 
	 *  pre: 0 <= index <= size, otherwise throws IllegalArgumentException
	 */
	public void set(int index, int value) {
		checkIndex(index);

		ListNode current = this.front;
		for (int i = 0; i < index; i++) {
			current = current.next;
		}
		
		current.data = value;		
	}
	
	/** Checks that index is within valid bounds
	 *  for the LinkedIntList.
	 *  pre: 0 <= index <= size, otherwise throws IllegalArgumentException
	 */
	private void checkIndex(int index) {
		if (index < 0 || index >= this.size) {
			throw new IllegalArgumentException();
		}
	}
}