1. Functional Requirements 

1.1 Customer Order Flow

• A customer can place an order containing one or more pizzas.
• Each pizza can have a specific size (Small, Medium, Large), crust type (Thin, Cheese Burst, etc.), and multiple toppings.
• Orders can include beverages and sides.
• Each order must have a unique ID, timestamp, and total cost.
• Orders move through statuses: NEW → PREPARING → BAKED → PACKED → DELIVERED.

1.2 Menu Management

• Maintain a catalog of items (Pizza, Sides, Drinks).
• Menu items have price, category, and availability status.
• Enable dynamic updates to the menu (add, remove, update items).

1.3 Pizza Customization

• Enable customers to build custom pizzas.
• Each topping/crust/size has a configurable price.
• A Pizza is composed of base + crust + toppings + optional extras.

1.4 Kitchen Management

• Display orders in a queue to the kitchen staff.
• Track preparation time per order.
• Update order status as it moves through the kitchen.

1.5 Inventory Management

• Maintain quantity for ingredients (cheese, dough, sauce, toppings, etc.).
• Reduce inventory as pizzas are prepared.
• Trigger alerts for low-stock items.
• Restocking should update inventory records.

1.6 Delivery Management

• Assign delivery agents to orders once packed.
• Track delivery status and update order when completed.
• Calculate estimated delivery time and route optimization (basic simulation in LLD).

1.7 Billing & Payment

• Calculate subtotal, taxes, discounts, and total.
• Support multiple payment methods (Cash, Card, UPI).
• Generate printable/digital receipt.

1.8 User Management

• Roles: Customer, Chef, DeliveryAgent, Manager.
• Role-based access: e.g., only chefs can update preparation status, only managers can restock inventory.
• User registration and authentication system.

1.9 Notifications (Optional/Bonus)

• Notify kitchen when a new order arrives.
• Notify customer when order is out for delivery.

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2. Non-Functional Requirements 

• Modular design (SOLID principles)
• Use design patterns where appropriate (e.g., Factory for Pizza, Strategy for Payment)
• Maintainability: Clear separation of concerns between modules
• Scalability: Support for multiple kitchens or branches (extendible class structure)
• Testability: Mock interfaces for components like inventory or payment