import java.util.ArrayList;
import java.util.List;

/**
 * {@link <a href=
 * "https://[Log in to view URL]"
 * target= "_blank"></a>}
 * 
 * @author itammb ( Italia Massimiliano Buscati )
 * @version JDK 1.15
 *
 */
class Main {
    
	interface ShoppingCartVisitor {
		double visit(Book book);

		double visit(Electronic electronic);
	}

	public static class DiscountCalculator implements ShoppingCartVisitor {
		@Override
		public double visit(Book book) {
			double discount = book.getPrice() > 50 ? 10 : 5;
			double finalPrice = book.getPrice() - discount;
			System.out.println("Book: " + book.getTitle() + " final price: " + finalPrice);
			return finalPrice;
		}

		@Override
		public double visit(Electronic electronic) {
			double discount = electronic.getPrice() * 0.1;
			double finalPrice = electronic.getPrice() - discount;
			System.out.println("Electronic Item: " + electronic.getName() + " final price: " + finalPrice);
			return finalPrice;
		}
	}

	interface Product {
		double accept(ShoppingCartVisitor visitor);
	}

	public static class Electronic implements Product {
		private String name;
		private double price;

		public Electronic(String name, double price) {
			this.name = name;
			this.price = price;
		}

		public String getName() {
			return name;
		}

		public double getPrice() {
			return price;
		}

		@Override
		public double accept(ShoppingCartVisitor visitor) {
			return visitor.visit(this);
		}
	}

	public static class Book implements Product {
		private String title;
		private double price;

		public Book(String title, double price) {
			this.title = title;
			this.price = price;
		}

		public String getTitle() {
			return title;
		}

		public double getPrice() {
			return price;
		}

		@Override
		public double accept(ShoppingCartVisitor visitor) {
			return visitor.visit(this);
		}
	}
	
	public static class ShoppingCart {
	    private List<Product> products = new ArrayList<>();
	    public void addProduct(Product product) {
	        products.add(product);
	    }
	    public double calculateTotal(ShoppingCartVisitor visitor) {
	        double sum = 0;
	        for (Product product : products) {
	            sum += product.accept(visitor);
	        }
	        return sum;
	    }
	}

	public static void main(String args[]) {
		// Unit test - uso del design pattern: visitor
		
		ShoppingCart cart = new ShoppingCart();
        cart.addProduct(new Book("Design Patterns", 60));
        cart.addProduct(new Electronic("Laptop", 800));
        cart.addProduct(new Book("Clean Code", 40));
        
        ShoppingCartVisitor discountCalculator = new DiscountCalculator();
        double totalPrice = cart.calculateTotal(discountCalculator);
        
        System.out.println("Total Cart Price after Discount: " + totalPrice);
	}

}