Online Shopping System Class Diagram

classDiagram
  class User {
    <<abstract>>
    +int id
    +String name
    +String email
  }
  class Customer {
    +placeOrder(ShoppingCart) Order
  }
  class Seller {
    +listProduct(Product) void
  }
  class Category {
    +String name
  }
  class Product {
    +String name
    +decimal price
    +int stock
  }
  class ShoppingCart {
    +addItem(Product, int qty) void
    +total() decimal
  }
  class CartItem {
    +int quantity
  }
  class Order {
    +Date orderedOn
    +OrderStatus status
    +total() decimal
    +cancel() void
  }
  class OrderItem {
    +int quantity
    +decimal unitPrice
  }
  class OrderStatus {
    <<enumeration>>
    PLACED
    PAID
    SHIPPED
    DELIVERED
    CANCELLED
  }
  class PaymentMethod {
    <<interface>>
    +pay(decimal amount) bool
  }
  class CardPayment {
    +pay(decimal amount) bool
  }
  class UpiPayment {
    +pay(decimal amount) bool
  }
  class CashOnDelivery {
    +pay(decimal amount) bool
  }
  User <|-- Customer
  User <|-- Seller
  Category "1" o-- "many" Product
  Customer "1" *-- "1" ShoppingCart
  ShoppingCart "1" *-- "many" CartItem
  CartItem --> Product
  Customer "1" --> "many" Order
  Order "1" *-- "many" OrderItem
  OrderItem --> Product
  Order --> OrderStatus
  Order --> PaymentMethod
  PaymentMethod <|.. CardPayment
  PaymentMethod <|.. UpiPayment
  PaymentMethod <|.. CashOnDelivery