Library Management System

A comprehensive console-based Python application that provides complete book and user management with borrowing, returns, popularity tracking, and graph‑based recommendations.

🏫 Overview

This Library Management System showcases solid Python design with clear separation between domain models, services, and UI helpers. It supports CRUD operations, a borrow queue when copies are unavailable, top‑K popular books, and a recommendation engine that leverages a simple user–book graph and user interests.

✨ Features

📚 Books & Users

• CRUD Operations: Create, read, update, and delete books and users
• Search: Filter books by title, author, or genre
• Structured Models: Book, User, and base LibraryItem with validation

🔄 Borrowing Workflow

• Borrow/Return: Safe borrowing with availability checks and returns
• Request Queue: FIFO queue when copies are unavailable (auto-processed on return)
• Popularity Tracking: borrow_count increments to support rankings

📈 Analytics & Recommendations

• Top‑K Books: List the most borrowed books
• Recommendations: Graph traversal + interests + popularity scoring

🖥️ Console UI

• Consistent Output: Title, subtitles, tables, and status messages
• Simple Menu Flow: Numbered options and validated inputs

💾 Persistence

• JSON Storage: Automatically loads state on startup and saves on exit
• Location: data/library.json (ignored by Git)

🏗️ Architecture

Design Principles

• Separation of Concerns: Domain, services, UI, and utilities
• Data Structures: Custom LinkedListQueue and Graph to illustrate CS basics

Module/Class Structure

src/book.py
├── LibraryItem (base)
└── Book (domain model)

src/user.py
└── User (domain model)

src/data_structures.py
├── LinkedListQueue[T]
└── Graph (undirected)

src/library.py
└── Library (service: CRUD, borrow/return, queries)

src/recommendation.py
└── RecommendationEngine

src/ui.py
└── Console helpers (title, table, messages)

src/app.py
└── CLI entry point and menu loop

🚀 Getting Started

Prerequisites

• Python 3.9 or later

Installation

1. Create and activate a virtual environment

   python -m venv .venv
   # Windows
   .venv\Scripts\activate
   # macOS/Linux
   source .venv/bin/activate

2. Install dependencies

   pip install -r requirements.txt

First Run

The app seeds a few demo books and users at startup so you can explore features immediately.

🔧 Usage Guide

Start the Application

• Windows: python .\src\app.py
• macOS/Linux: python src/app.py

Main Menu Options

1. Add Book – Create a new book
2. Remove Book – Delete a book by ID
3. Update Book – Modify title/author/genre
4. Add User – Create a user with interests
5. Borrow Book – Borrow if available, else enqueue
6. Return Book – Return and auto-process queue
7. Show Available Books – List books with copies left
8. Show Top‑K Books – Most borrowed rankings
9. Recommend Books – Personalized suggestions
10. Exit – Quit the application

When you exit, the current state (books, users, borrow queue, popularity) is saved to data/library.json. Next launch will restore this state automatically.

🔒 Security Considerations

Current Implementation

• In‑Memory Storage: Data is kept in memory during runtime
• No Secrets: Application does not require authentication

Recommended Improvements

• Persistence Layer: Add database or file storage
• Input Hardening: Expand validation and error handling
• Note: Basic JSON persistence is included; switch to a database for multi‑user or concurrent scenarios

🛠️ Technical Details

Data Structures

• LinkedListQueue[T]: O(1) enqueue/dequeue; used for borrow requests
• Graph: Undirected adjacency list; used for recommendations (BFS)

Testing & Quality

• (Optional) Tests: pytest
• (Optional) Lint: ruff check .
• (Optional) Format: black .
• (Optional) Type Check: mypy .

📁 Project Structure

Library-Management-System/
├── src/
│   ├── app.py
│   ├── book.py
│   ├── data_structures.py
│   ├── library.py
│   ├── recommendation.py
│   ├── ui.py
│   └── user.py
├── data/                 # runtime state (JSON), ignored by Git
├── requirements.txt
├── .gitignore
├── LICENSE
└── README.md

🐛 Known Issues

1. JSON persistence is basic (single-user, no concurrency guarantees)
2. Minimal validation in CLI prompts
3. Simple recommendation heuristic (educational)

👥 Contributing

Contributions are welcome via pull requests.

📄 License

MIT © 2025 elseh — see LICENSE.

📞 Support

If you have questions or issues:

1. Review this README and docstrings in src/
2. Open an issue or PR if something can be improved