import java.util.*;
public class XMLSalesFormatter implements SalesFormatter{
	 private final static String NEW_LINE =

	        System.getProperty("line.separator");
		static XMLSalesFormatter singletonInstance;
	static public XMLSalesFormatter getSingletonInstance()
	// Static method that obtains the single instance of class XMLSalesFormatter. 
	{
		 if (singletonInstance == null) {

	            singletonInstance = new XMLSalesFormatter();

	        }
	        return singletonInstance;
	}
	private XMLSalesFormatter()
	//Constructor that is declared private so it is inaccessible to other classes. A private constructor makes it impossible for any other class to create an instance of class XMLSalesFormatter. 
	{
		
	}
	public String formatSales(Sales sales)
	//Produces a string that contains the specified sales information in an XML format. 
	{
		int numOrders = sales.getNumberOfOrders();
		String out = "" ;
		if (numOrders != 0) {
			int orderNumber = 1;
			out+="<Sales>\n";
			for (Iterator i = sales.getOrdersIterator(); i.hasNext(); ) {
				Order order = (Order) i.next();
				orderNumber++;
				out+="<Order total=\""+order.getTotalCost()+" \">"+"\n";
				for (Iterator j = order.getItemsIterator(); j.hasNext();) {
					OrderItem item=(OrderItem)j.next();
					out+="<OrderItem quantity=\" "+item.getQuantity()+
					"\" price=\" "+item.getProduct().getPrice()+
					"\">"+item.getProduct().getCode()+"</OrderItem>\n";
				}
				out+="</Order>\n";
			}
			out+="</Sales>";
		} else {
			System.out.println("Sorry~There is no sales");
		}
		return out;
	}


}