Wikipedia Path Finder ( First Link Rule BackEnd )

A Python Flask API that powers the “First Link Rule” project by fetching and following the first link of any Wikipedia article until it reaches the Philosophy page, detects a loop, or hits a dead end. Supports both parsing-based traversal (BeautifulSoup) and optional Selenium-based traversal.

Live Demo (Frontend)

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Table of Contents

1. About
2. Features
3. Tech Stack
4. Setup & Installation
5. Configuration
6. API Endpoints
7. Project Structure
8. License
9. Acknowledgments

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About

This service handles traversal logic for the First Link Project. It exposes endpoints to start a traversal from any Wikipedia URL, returning the full path, step count, and any errors encountered.

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Features

• Parsing-Based Traversal with requests + BeautifulSoup for lightweight environments
• Selenium-Based Traversal (optional) for full browser simulation
• Loop & Dead-End Detection to prevent infinite cycles
• Configurable Limits (max iterations, target URL)
• Docker Support for containerized deployment

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Tech Stack

• Language: Python 3.12+
• Framework: Flask
• HTTP: Requests
• HTML Parsing: BeautifulSoup4
• Browser Automation: Selenium (optional)
• Containerization: Docker

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Setup & Installation

Local Development

git clone https://github.com/190-785/First_Link_Backend.git
cd First_Link_Backend
python3 -m venv venv
source venv/bin/activate    # Windows: venv\Scripts\activate
pip install -r requirements.txt
flask run --port 10000

Docker

docker build -t first-link-backend .
docker run -p 10000:10000 first-link-backend

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Configuration

Create a .env file in the project root with:

FLASK_ENV=development
SECRET_KEY=your_secret_key
MAX_ITERATIONS=30
PHILOSOPHY_URL=https://en.wikipedia.org/wiki/Philosophy
ALLOWED_ORIGINS=http://localhost:5173
USE_SELENIUM=false

• USE_SELENIUM: set to true to enable Selenium mode.

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API Endpoints

POST /start-traversal

Request Body (JSON):

{
  "start_url": "https://en.wikipedia.org/wiki/Physics"
}

Response (JSON):

{
  "path": [
    "https://en.wikipedia.org/wiki/Physics",
    "...",
    "https://en.wikipedia.org/wiki/Philosophy"
  ],
  "steps": 7,
  "last_link": "https://en.wikipedia.org/wiki/Philosophy",
  "error": null
}

GET /

Response (JSON):

{
  "status": "Backend is running"
}

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Project Structure

First_Link_Backend/
├── app.py                   # Flask application
├── parsing_traversal.py     # BeautifulSoup-based traversal logic
├── traversal.py             # Core traversal engine
├── predefined_paths.json    # Example path sets (optional)
├── requirements.txt         # Python dependencies
├── Dockerfile               # Container build instructions
└── .env.example             # Sample environment variables

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License

This backend is licensed under the GNU General Public License v3.0. See the LICENSE file for full terms.

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Acknowledgments

• Not David – For the inspiring “First Link Rule” video: https://youtu.be/-llumS2rA8I?feature=shared
• Wikipedia – For the open REST API
• Open‑source community – For all the libraries and tools used in this project