FreshCart: Integrated Grocery Mobile Solution

FreshCart is a professional-grade full-stack mobile application developed for a grocery chain to optimize the customer purchasing process. The solution integrates real-time barcode scanning, secure JWT authentication, and mandatory PayPal payment processing, all served over a secure HTTPS infrastructure.

---

Production Team

• Elie Zaylaa (@eliezaylaa)
• Xinxin Miao (@Cello-miao)
• Boyu Fu (@boyufu)

---

Branching model & documents

• main: production branch — contains client-ready, release-tested code. The documents/ directory lives in main and holds high-level project artifacts (architecture and design documents, diagrams, and exported PDFs) used for production handoff and audits.
• dev: development branch — active feature work, experiments, and integration testing. Developers should base daily work on dev and open pull requests into main when a feature is release-ready.

documents/ contains:

• Architecture and system diagrams (UML, class diagrams)
• Activity and data-flow diagrams
• Technology choices and design rationale
• Exported design artifacts (PDF/ODT) for stakeholder review

Production Deployment (Physical Device)

In accordance with project specifications, this application is designed for demonstration on physical Android devices. Emulators are not supported for the final production release.

Production Endpoints

• Production APK: https://13.37.46.130/downloads/app-release.apk
• Root CA Certificate: https://13.37.46.130/downloads/rootCA.crt
• Backend API: https://13.37.46.130/api

Installation Guide

1. Security: Download and install the rootCA.crt. This is required for the device to trust the project's private CA for secure HTTPS communication.
2. Installation: Download and install app-release.apk.
3. Execution: Launch "FreshCart" directly from the Android launcher. This standalone build does not require Expo Go or a Metro server.

---

🛠 Tech Stack

• Frontend: React Native + Expo (Standalone Release), TypeScript, Expo Camera, Expo Web Browser.
• Backend: Node.js + Express, Nginx (Reverse Proxy & HTTPS Termination).
• Database: PostgreSQL (Transactional storage for users, products, and orders).
• External APIs: OpenFoodFacts (Product metadata), PayPal Sandbox (Financial transactions).
• DevOps: Docker & Docker Compose, GitHub Actions CI/CD, Jest (Testing).

---

Key Feature Specifications

1. Secure Authentication & Identity

• JWT Auth: Implements 15-minute access tokens with 7-day rotating refresh tokens.
• Encryption: Password hashing via bcrypt.
• RBAC: Role-based access control for Admin and Customer privileges.

2. Intelligent Barcode Scanner

• Hardware Access: Real-time decoding via the smartphone camera.
• Data Fetching: Automatic product lookup via OpenFoodFacts with 24-hour in-memory caching.
• Error Handling: Immediate feedback for unreadable codes or "Product Not Found" scenarios.

3. Product & Cart Management

• Detailed View: Displays name, brand, category, price, nutritional information, and live stock quantity.
• Dynamic Cart: Real-time total calculation, quantity modification, and item removal.

4. Checkout & Secure Payment

• Billing Info: Mandatory collection of First Name, Last Name, Address, Zip Code, and City.
• PayPal Integration: Secure financial transactions via PayPal Sandbox API.
• Purchase History: Persistent logs of all previous transactions and digital receipts.

---

Production API Endpoints

Scanner & Products

Method	Endpoint	Description
POST	/api/scanner/lookup	Find product by barcode (returns full metadata)
POST	/api/scanner/add-to-cart	Scan and directly add item to user's cart
GET	/api/products/recommendations	Personalized suggestions based on history

Orders & Payment

Method	Endpoint	Description
POST	/api/paypal/create-order	Initialize PayPal transaction
POST	/api/paypal/capture-order	Confirm and finalize payment
POST	/api/orders	Create internal order and clear cart
GET	/api/orders/me	Retrieve user purchase history

---

System Architecture

The project follows a Layered Architecture designed for high availability and security:

1. Client Layer: React Native App handling UI/UX and hardware (Camera).
2. Security Layer: Nginx Gateway managing HTTPS termination and reverse proxying.
3. Application Layer: Express API handling business logic and external service orchestration.
4. Data Layer: PostgreSQL for transactional persistence.

---

Quality Assurance

• Unit Testing: Minimum 20% code coverage (actually over 60%) across all core modules (Jest).
• CI/CD Pipeline: Automated testing and deployment via GitHub Actions on every push to prod.
• Security Audit: Verification of HTTPS encryption for all external communication.

---

Demo Credentials (Admin)

• Email: admin@trinity.com
• Password: admin123

---

Developed as part of the Epitech MSc program (2025–2027).