/**
 * IteratedArrayList.java
 * Class demo for CS 10 to show how to implement an Iterator object.
 * This functionality is already built into ArrayList, but this duplicates
 * it to show how it can be accomplished
 * 
 * @author Scot Drysdale - 10/7/2014
 */

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class IteratedArrayList<T>  extends ArrayList<T> {

	private static final long serialVersionUID = 1L;

	private class CS10Iterator<T> implements Iterator<T> {
		private int position;   // Position before the next thing to be returned
		private boolean nextWasCalled;  // True if next was called since the most recent remove
		private List<T> myList;
		/**
		 * Constructs an iterator for this ArrayList.
		 */
		private CS10Iterator(List<T> aList) {
			position = -1;
			nextWasCalled = false;
			myList = aList;
		}
		
		/**
		 * Implements the Iterator hasNext
		 */
		public boolean hasNext() {
			return position < myList.size()-1;
		}

		/**
		 * Implements the Iterator next
		 */
		public T next() {
			if(hasNext()) {
				nextWasCalled = true;
				position++;
				return myList.get(position);
			}
			else {
				System.err.println("No next item");
				return null;
			}
		}

		/**
		 * Implements the Iterator remove
		 */
		public void remove() {
			if(nextWasCalled) {
				nextWasCalled = false;
				myList.remove(position);
				position--;   // Removed the item at position, so must move one earlier
			}
			else
				System.err.println("No item to remove");
		}	
	}
	
	/**
	 * Override the built-in linked list iterator
	 */
	public Iterator<T> iterator() {
		return new CS10Iterator<T>(this);
	}
	
	/**
	 * A testing program
	 */
	public static void main(String [] args) {
		List<String> aList = new IteratedArrayList<String>();
		
		aList.add("cat");
		aList.add("dog");
		aList.add("eagle");
		
		Iterator<String> iter = aList.iterator();
		
		System.out.println(aList);
		System.out.println("hasNext on list: " + iter.hasNext());
		System.out.println("result of next: " + iter.next());
		iter.remove();
		System.out.println("list after remove: ");
		System.out.println(aList);
		iter.remove();
		
		System.out.println("result of next: " + iter.next());
		System.out.println("result of next: " + iter.next());
		System.out.println("hasNext on list: " + iter.hasNext());
		iter.remove();
		System.out.println("list after remove: ");
		System.out.println(aList);
		
		System.out.println("result of next: " + iter.next());
	}
}