Emotion Tracking Web Application

A full-stack web application for tracking, storing, and managing user emotions securely over time.

Built using Svelte, Node.js (Express), and PostgreSQL, deployed on Azure with Nginx as a reverse proxy and PM2 for process management.

Features

• User authentication
• Session-based authentication
• Emotion logging with color tagging
• Retrieve emotion history per user
• Manage active sessions (view, revoke single session, revoke all)
• Cross-origin support with secure CORS configuration
• Scalable backend with database abstraction

Architecture Overview

Software Design

• Polymorphic Abstraction: A class-based database layer allows the app to switch between PostgreSQL and MongoDB via .env configuration without changing the API logic.
• Layered N-Tier Architecture: Clean separation between the Presentation (Svelte), Logic (Express Middleware), and Data Abstraction layers.
• Low Coupling: The frontend and backend communicate strictly via a JSON API contract.
• Stateful Security: Unlike stateless JWTs, database-backed sessions allow for Remote Session Revocation.

Tech Stack

• Frontend: Svelte + JavaScript
• Backend: NodeJS + ExpressJS
• Database: PostgreSQL
• Deployment & Infrastructure: Azure VM - Nginx & PM2

Project Structure

├── backend/
│   ├── app.js
│   ├── classes/ 
│   ├── Dockerfile
│   ├── package.json
│   └── package-lock.json
├── design/
│   ├── architecture2.png
│   └── architecture.png
├── frontend/
│   ├── Dockerfile
│   ├── index.html
│   ├── jsconfig.json
│   ├── nginx/
│   ├── package.json
│   ├── package-lock.json
│   ├── public/                 
│   ├── src/
│   ├── svelte.config.js
│   └── vite.config.js
├── package.json
├── docker-compose.yml
└── README.md

Environment Variables

Create a .env file in the backend root:

FRONTEND_URL=http://localhost:5173
DATABASE_URL=postgresql://user:password@host:port/dbname
MONGO_URL=mongodb://localhost:27017/dbname

Running Locally

Backend

npm install
node index.js

Backend runs on:

http://localhost:3000

Frontend

npm install
npm run dev

Authentication Flow

1. User signs up → password hashed using bcrypt
2. User logs in → credentials verified
3. Server creates session token
4. Token stored as HTTP-only cookie
5. Protected routes validate session

API Endpoints

Security

• Password hashing with bcrypt
• HTTP-only cookies for sessions
• CORS configured with credentials
• Designed to support HTTPS with SSL/TLS via Nginx

Future Improvements

• Emotion analytics & visualization
• Neo4j for social emotion sharing graph