package grocerystore;

import java.util.Comparator;

public class CompareName implements Comparator<Product>{
    public int compare(Product a,Product b){
        return a.getName().compareTo(b.getName());
    }
}package grocerystore;

public interface Counter {

    // following attributes are public, static, and final, implicitly

    double VAT = 0.2;


    // following methods are public and abstract, implicitly

    void read(String code, int pieces) throws NoSuchProduct;
    void print();
    void close();
    double total();
    double gross();
    double taxes();
}
package grocerystore;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.Set;
import java.util.TreeMap;
import java.util.Map;

public class GroceryCounter implements Counter {
    Map<String,Product> inventory = new HashMap<String,Product>();
    Map<Product,Integer> shopping = new TreeMap<Product,Integer>(new CompareName());
    double total = 0.0;
    Product discProd;
    double discPrice;

    public void addProduct(String code, String desc, double price) {
        Product p = new Product(code, desc, price);
        inventory.put(code, p);
    }

    public void promo(String code, int discount) {
        Product p = inventory.get(code);
        if(p==null)
            discProd = null;
        else {
            discProd = p;
            discPrice = p.getPrice()*(1-discount/100.);
        }
    }

    public void read(String code, int pieces) throws NoSuchProduct{
        Product p = inventory.get(code);
        if(p==null)
            throw(new NoSuchProduct(code));
        Integer previous = shopping.get(p);
        previous = previous==null ? 0 : previous;
        shopping.put(p, pieces+previous);
        double price = p==discProd ? discPrice : p.getPrice();
        total += pieces * price;
    }

    public double total() {
        return total;
    }

    public double gross() {
        return total + taxes();
    }

    public double taxes() {
        return total * VAT;
    }

    public String invoice() {
        Set<Map.Entry<Product,Integer>> s =  shopping.entrySet();
        Iterator<Map.Entry<Product,Integer>> it = s.iterator();
        String inv = "";
        while(it.hasNext()){
            Map.Entry<Product,Integer> entry = it.next();
            Product p = entry.getKey();
            int n = entry.getValue();
            double price = p==discProd ? discPrice : p.getPrice();
            inv += n+" x "+p.getName()+" \t> "+n*price+"\n";

        }
        inv += "\nTotal: \t> "+total+"\n";
        inv += "VAT: \t> "+taxes()+"\n";
        inv += "Gross: \t> "+gross()+"\n";
        return inv;
    }

    public void print() {

        System.out.println(invoice());
    }

    public void close() {
        shopping.clear();
        total=0.0;
    }
}
package grocerystore;

public class NoSuchProduct extends Exception {
    String code;
    public NoSuchProduct(String c){
        code=c;
    }
    public String getMessage(){
        return "Unexisting code "+code;
    }

}package grocerystore;

public class Product {
    String code;
    String name;
    double price;

    public Product(String c, String n, double p){
        code=c;
        name=n;
        price=p;
    }

    public String getName(){
        return name;
    }

    public double getPrice(){
        return price;
    }
}