#working backwards, worked on another decorator class lined out in fluent, which refers to an earlier promotion class implemenation
#which is being refactored by the decorator class. Will have to come back to review, didn't make it in time for work

promos = []
def promotion(promo_func):
    promos.append(promo_func)
    return promo_func
@promotion
def fidelity(order):
    """5% discount for customers with 1000 or more fidelity points"""
    return order.total() * .05 if order.customer.fidelity >= 1000 else 0
@promotion
def bulk_item(order):
    """10% discount for each LineItem with 20 or more units"""
    discount = 0
    for item in order.cart:
        if item.quantity >= 20:
            discount += item.total() * .1
    return discount
@promotion
def large_order(order):
    """7% discount for orders with 10 or more distinct items"""
    distinct_items = {item.product for item in ordr.cart}
    if len(distinct_items) >= 10:
        return order.total() * .07
    return 0
def best_promo(order):
    """Select best discount available
    """
    return max(promo(order) for promo in promos)


class Order:
    def __init__(self, customer, cart, promotion=None):
        self.customer = customer
        self.cart = list(cart)
        self.promotion = promotion
    def total(self):
        if not hasattr(self, '__total'):
            self.__total = sum(item.total() for item in self.cart)
        return self.__total
    def due(self):
        if self.promotion is None:
            discount = 0
        else:
            discount = self.promotion.discount(self)
        return self.total() - discount
    def __repr__(self):
        fmt = '<Order total: {:.2f} due: {:.2f}>'
        return fmt.format(self.total(), self.due())