Requirements

Functional Requirements:

• Allow users to search the library catalog by title, author, ISBN, or subject and see matching books with availability status.
• Enable members to check out available physical copies with a due date and return them, while tracking lending records and updating copy status.
• Allow members to reserve a book when all copies are checked out, and notify the first member in the reservation queue when a copy is returned.
• Support automatic calculation of overdue fines for late returns based on overdue days, allowing members to view and pay outstanding fines.
• Distinguish between Member and Librarian roles, enabling Members to search, checkout, return, and reserve books, while allowing Librarians to add or remove books and block members.

Non-Functional Requirements:

• List the key non-functional requirements (eg thread safety, extensibility, maintainability, etc.)...

Core Objects & Relationships

## core entities

- Book

- User

- BookItem

- Member

- Librarian

- Fine

- Catalog

- Library

- Reservation

- BookReport

- DailyRateFineStrategy

## enums

- BookStatus: AVAILABLE, BORROWED, RESERVED, LOST

- AccountStatus: ACTIVE, INACTIVE, BLOCKED

## Interfaces

- CalculateFineStrategy

APIs & Class Members

For each class, define the attributes (data) it will hold and the methods (functions) that operate on the attributes. Ensure they align with the object's responsibilities and adhere to the principle of encapsulation. Write your code in the code editor below.

Deep Dive

When considering the design trade-offs for your Library Management System, it's essential to balance complexity with functionality. For instance, while implementing a synchronized method for checkout ensures thread safety, it may introduce performance bottlenecks under high load, especially if many users are trying to access the same resource simultaneously. In contrast, using optimistic locking could improve performance but might require more complex error handling for failed transactions.

Regarding adherence to SOLID principles, your design appears to align well with the Single Responsibility Principle, as each class has a focused purpose, such as the Catalog for searching and the BookLending class for managing loans. The Open/Closed Principle is also respected, as you can extend user roles or functionalities without modifying existing code, allowing for easy addition of features like digital lending or new user types. The Liskov Substitution Principle is upheld since Member and Librarian can be treated interchangeably as Users without altering expected behaviors.

In terms of scalability, your design can handle increased load by employing efficient data structures like hash maps for quick lookups, which support O(1) search times. This efficiency is crucial as the number of books and users grows. Additionally, using a queue for reservations ensures fair handling of requests, which is vital as demand increases.

For future improvements, consider integrating a recommendation engine based on user borrowing history to enhance user engagement. You might also explore adding a digital lending feature, allowing users to borrow e-books with license management. Furthermore, implementing analytics could provide insights into user behavior and system performance, guiding future enhancements. Overall, your design is well-structured for current needs while allowing for future growth and adaptability.