E-commerce Domain (Mermaid Class)

classDiagram
  class Customer {
    +id: int
    +email: string
    +placeOrder() Order
  }
  class Order {
    +id: int
    +total: decimal
    +addItem(p, qty) void
  }
  class Product {
    +id: int
    +name: string
    +price: decimal
  }
  class OrderItem {
    +qty: int
    +subtotal() decimal
  }
  Customer "1" --> "*" Order
  Order "1" *-- "*" OrderItem
  OrderItem "*" --> "1" Product