/**
 * Implements a queue using two stacks.
 * For CS 10 Short Assigment 6
 * 
 * @author YOU
 */
public class StacksQueue<T> implements CS10Queue<T> {
  CS10Stack<T> inStack;   // place where enqueued
  CS10Stack<T> outStack;  // place where dequeued
  
  /**
   * Constructor, makes an empty queue.
   */
  public StacksQueue() {
    inStack = new ArrayListStack<T>();
    outStack  = new ArrayListStack<T>();
  }
    
  /**
   * Add an element to the rear of the queue.
   * @param obj element to be enqueued
   */
  public void enqueue(T obj) {
    // YOU FILL THIS IN.
  }
  
  /**
   * Remove an element from the front of the queue.
   * @return the element removed from the front of the queue
   *   or null if the queue is empty.
   */
  public T dequeue() {
    // YOU FILL THIS IN.
  }
  
  /**
   * Return the element at the front of queue, but do not remove it
   * @return the element at the front of the queue,
   *   or null if the queue is empty.
   */
  public T front() {
    // YOU FILL THIS IN.
  }
  
  /**
   * Is the queue empty?
   * @return true if queue is empty, false otherwise
   */
  public boolean isEmpty() {
    return inStack.isEmpty() && outStack.isEmpty();
  }
  
   /**
    * A testing program
    */
	 /**
	  * A testing program
	  */
  public static void main (String [] args)  {
  	CS10Queue<String> q = new StacksQueue<String>();
  	q.enqueue("cat");
  	q.enqueue("dog");
  	q.enqueue("bee");
  	System.out.println("First thing dequeued is: " + q.dequeue());
  	System.out.println("Next thing dequeued is: " + q.dequeue());
  	System.out.println("Is it empty? : " + q.isEmpty());
  	q.enqueue("eagle");
  	System.out.println("Next thing dequeued is: " + q.dequeue());
  	System.out.println("Next thing dequeued is: " + q.dequeue());
  	System.out.println("Is it empty? : " + q.isEmpty());
  	System.out.println("dequeue of empty stack: " + q.dequeue());
  	q.enqueue("bear");
  	System.out.println("front is: " + q.front());
  	System.out.println("Next thing dequeued is: " + q.dequeue());
  	q.enqueue("cat");
  	q.enqueue("dog");
  	q.enqueue("sheep");
  	q.enqueue("cow");
  	q.enqueue("eagle");
  	q.enqueue("bee");
  	q.enqueue("lion");
  	q.enqueue("tiger");
  	q.enqueue("zebra");
  	q.enqueue("ant");
  	System.out.println("Bigger example:");
  	System.out.println("front is: " + q.front());
  	System.out.println("Next thing dequeued is: " + q.dequeue());
  	System.out.println("front is: " + q.front());
  	System.out.println("Next thing dequeued is: " + q.dequeue());
  	System.out.println("Next thing dequeued is: " + q.dequeue());
  	System.out.println("Next thing dequeued is: " + q.dequeue());
  	System.out.println("Next thing dequeued is: " + q.dequeue());
  	System.out.println("Next thing dequeued is: " + q.dequeue());
  	System.out.println("Next thing dequeued is: " + q.dequeue());
  	System.out.println("Next thing dequeued is: " + q.dequeue());
  	System.out.println("Next thing dequeued is: " + q.dequeue());
  	System.out.println("Next thing dequeued is: " + q.dequeue());  	
  	System.out.println("Next thing dequeued is: " + q.dequeue());
  }
}