import java.util.ArrayList;
import java.util.List;
 
/**
 * <code>ShoppingCart</code> holds a collection of <code>ItemOrder</code> objects 
 * in an array list. The list is used to calculate total cost and to add new 
 * purchases requests.  
 * 
 * @author Christopher Martin
 * @version 1.0
 *
 */
 
public class ShoppingCart
{
  /**
   * Constant used to compute the 10% discount.
   */
  private static final double DISCOUNT = 0.9;
 
  /**
   * Array list for holding ItemOrder objects that contain order name and 
   * quantity.
   */
  private List <ItemOrder> my_order_list;
 
  /**
   * A flag for determining if an overall discount should be applied to the 
   * final total.
   */
  private boolean my_discount;
 
  /**
   * Create an empty array list to hold purchases requests in the form of 
   * ItmeOrder objects. There are no parameters on purpose.
   */
  public ShoppingCart()
  {
    my_order_list = new ArrayList<ItemOrder>();
  }
 
  /**
   * Goes through the array list and replaced old ItemOrders with the new one.
   * If there is no previous entry an new one is added with out replacement.
   * 
   * @param the_order A new request of purchase for an item.
   */
  public void add(final ItemOrder the_order)
  {    
    for (int i = 0; i < my_order_list.size(); i++)
    {
      //compare the string representation of Items in the list to the param Item.
      if (the_order.getItem().equals(my_order_list.get(i).getItem()))
      {
        //replace and exit method
        my_order_list.set(i, the_order);
        return;
      }
    }
    //add if not in the list already
    my_order_list.add(the_order);
  }
 
  /**
   * Turn on or off the discount to be applied to all items.
   * @param the_discount Indicator to determine if discount should be applied.
   */
  public void setDiscount(final boolean the_discount)
  {
    my_discount = the_discount;
  }
 
  /**
   * Goes through the array list of ItemOrders calculating the total including 
   * a discount when applicable.
   * 
   * @return total cost of all items based on their quantity selected
   */
  public double getTotal()
  {
    double sum = 0.0;
 
    for (ItemOrder temp_list : my_order_list)
    {
      sum += temp_list.getPrice();      
    }
 
    if (my_discount)
    {
      sum *= DISCOUNT;
    }
 
    return sum;
  }
}

/**
 * When a valid number is entered to purchase an item a new ItemOrder object is 
 * created to hold the item being selected and the quantity being purchased.
 * 
 * @author christopher martin
 * @version 1.0
 */
public class ItemOrder
{
  /**
   * The reference to an <code>Item</code> object.
   */
  private Item my_item;
 
  /**
   * The number of items being purchased.
   */
  private int my_quanity;
 
  /**
   * Constructs <code>ItemOrder</code> object with <code>Item</code> reference 
   * and the amount of items being purchased.
   * 
   * @param the_item Reference to an <code>Item</code> object.
   * @param the_quantity The amount of items being purchased.
   */
  public ItemOrder(final Item the_item, final int the_quantity)
  {
    my_item = the_item;
    my_quanity = the_quantity;
  }
 
  /**
   * Returns the total cost of the items being purchased including 
   * bulk discount.
   * 
   * @return price for item including bulk discount if it applies.
   */
 
  public double getPrice()
  {
    return my_item.priceFor(my_quanity);
  }
 
  /**
   * 
   * @return Reference to current <code>Item</code>.
   */
  public Item getItem()
  {
    return my_item;
  }
}