//  File: PurchaseListTester.java (requires Java 1.5 or newer)

//  The Purchase class: each object has the number of items purchased, 
//  a one-word description of the item, and the price of the item. Note:
//  Purchase class depends on Align class to format output.

//  The PurchaseList class: maintains a list of Purchases (using an ArrayList)

//  The test class creates a PurchaseList object and calls the readData() 
//  method which reads data for any number of purchases until eof. Each line 
//  read is scanned and a Purchase object is created from the tokens and added 
//  to the list. At end-of-file, the list is printed along with the total cost 
//  of all purchases.  Note: Test class depends on Align class to format output.

import java.util.* ;            		// for ArrayList and Scanner

/**
 * A class to represent a purchase - number of items, description, and price
 * per item
 */
class Purchase 
{
	// instance vars
	private int quantity ;				// number of each item purchased
    private String item ;				// description of the item
    private double price ;				// price of the item

	/**
	 * Creates a purchase object
	 * @param quantity number of items bought
	 * @param item one-word description of item
	 * @param price cost per item
	 */
	public Purchase(int quantity, String item, double price) 
	{
		this.quantity = quantity ;
		this.item = item ;
		this.price = price ;
	}
	
	/**
	 * Converts a Purchase object to a String.
	 * @return a String containing the quantity, description, price per item, 
	 * and total cost of a purchase.
	 * Example:	"   5 widgets @ 0.45 = $2.25"
	 */
    public String toString() 
	{
		return  "   " + quantity + " " + item + "(s) @ " + price + " = " 
		        + Align.currency(quantity * price,0) ;
	}
	
	/**
	 * Compute and return total cost of a purchase.
	 * @return the cost of a purchase (quantity * price)
	 */
    public double getCost()		// return cost of a purchase
	{
		return quantity * price ;
	}
	
} // end of Purchase class definition ========================================

/**
 * Maintains a list of purchases.
 */
class PurchaseList 
{
	private ArrayList<Purchase> list ;	// a list of Purchase objects
	private double totalCost ;			// total cost of all purchases listed
	private String purchases ;			// a multi-line String containing one
	                                    // purchase per line
   	
   	/**
   	 * Creates an empty list
   	 */
  	public PurchaseList() 
  	{
  	   	list = new ArrayList<Purchase>() ;
  	   	totalCost = 0.0 ;
  	   	purchases = "" ;				// the "null" (empty) String
    }
  	
  	/**
   	 * Reads lines of input from keyboard until eof.  Each line has number of 
   	 * items purchased, a one-word description of the item, and the price per 
   	 * item, separated by spaces
   	 */
	public void readData()
  	{
	  	Scanner input = new Scanner(System.in) ;
	  	
    	// "priming" read
    	System.out.println
    	      ("Enter quantity, description, and price of first item:") ;
                       	   
    	while ( input.hasNext() ) 		// while another line entered...
    	{
			// read number of items bought
	       	int quantity = input.nextInt() ;
        				
        	// read item description
        	String item  = input.next() ; 
        	
        	// read price per item
      		double price = input.nextDouble() ;	
      	    
      	    // create a Purchase object from data read
      	    Purchase current = new Purchase(quantity, item, price) ;
      	    
      	    // add Purchase object to list
      	    addToList(current) ;
      	    
      	    // "echo print" current purchase
      	    System.out.println( "\n\t" + current.toString() ) ;    	    	
      	    
     	    // prompt for next purchase
    		System.out.println
    	      ("\nEnter quantity, description, and price of next item " +
    	       "(or ^Z to quit):" ) ;
 		}
        // loop postcondition: at end-of-file
    }
        
    /**
  	 * Add a new purchase to the list, and concatenate it to the String 
  	 * containing all purchases.
  	 */
  	public void addToList(Purchase aPurchase) 
  	{	   
    	list.add(aPurchase) ;
    	purchases = purchases + aPurchase.toString() + "\n" ;
	}
    
	/**
	 * Returns the list of Purchases as a String. 
	 * @return a multi-line String containing each Purchase object on the list
	 */
	public String toString() 
  	{	   
    	return purchases ;
	}
    	
  	/**
  	 * Computes and returns the total cost of all purchases on the list.
  	 * @return the total cost of all purchases
  	 */
  	public double getTotalCost() 
  	{	   
    	// for each Purchase object on list...
    	for (int i = 0 ; i < list.size() ; i++)
    	{
    	   Purchase current = list.get(i) ;		// get next Purchase
    	   totalCost += current.getCost() ; 	// add cost to total		
    	}
		return totalCost ; 
	}
	
} // end of PurchaseList class definition =====================================

/**
 * Test class for Purchase and PurchaseList classes
 */
public class PurchaseListTester
{
  	public static void main(String[] args)  
  	{
		PurchaseList list = new PurchaseList() ;
		    	
    	list.readData() ;
    	
    	// print list of purchases and total cost
    	System.out.println("\nYour purchases:\n" + list.toString() ) ;
    	
    	System.out.println( "Your subtotal is: " 
    	                    + Align.currency( list.getTotalCost(),0 ) ) ;
	}
}

/*  sample output:

Enter quantity, description, and price of first item:
1 Hummer 53500

           1 Hummer(s) @ 53500.0 = $53,500.00

Enter quantity, description, and price of next item (or ^Z to quit):
2 Porsche 65500

           2 Porsche(s) @ 65500.0 = $131,000.00

Enter quantity, description, and price of next item (or ^Z to quit):
10 Yugo 6999.98

           10 Yugo(s) @ 6999.98 = $69,999.80

Enter quantity, description, and price of next item (or ^Z to quit):
^Z

Your purchases:
   1 Hummer(s) @ 53500.0 = $53,500.00
   2 Porsche(s) @ 65500.0 = $131,000.00
   10 Yugo(s) @ 6999.98 = $69,999.80

Your subtotal is: $254,499.80

*/