class Restaurant {
  int id;
  String name;
  Address address;
  FoodMenu foodMenu;
}

class Address {
  String street;
  String city;
  String state;
  String country;
  int zipCode;
}

class FoodMenu {
  int id;
  List<FoodItem> foodItems;
  String restaurantId;
}

class FoodItem {
  int id;
  String name;
  String description;
  double cost;
  CuisineType cuisinType;
  MealType mealType;
}

enum CuisinType {
  INDIAN, SOUTH_INDIAN, CHINESE, HYDERABADI
}

enum MealType {
  LUNCH, BREAKFAST, DINNER 
}

class Order {
  int orderId;
  Date orderDate;
  Map<Integer, FoodItem> foodItems;
  OrderStatus orderStatus;
  Address address;
  String userId;
  String restaurantId;
}  

class Bill {
  int billId;
  int orderId;
  double totalAmount;
  double tax;
  double discount;
  double totalAmountToBePaid;
  Date currDate;
}

class Payment {
  int id;
  int billId;
  double amount;
  Date date;
  PaymentStatus status;
  PaymentMode mode;
  CouponCode code;
}

enum CouponCode {
  SIXTY_PERCENT_OFF, TWENTY_PERCENT_OFF
}

enum PaymentStatus {
  SUCCESS, FAILED, DECLINED
}

enum PaymentMode {
  CASH, CARD, UPI
}

class Delivery {
  int id;
  String orderId;
  Date startDateTime;
  Date endDateTime;
  String deliveryBoyId;
  String customerNumber;
  Address customerAddress;
  DeliveryStatus status;
}


Some Major Services
1) RestaurantService
2) OrderService
3) FoodMenuDisplayService
4) PricingService
5) CartService
6) PaymentService
7) NotificationService
8) DeliveryService