🏥 MediLink — Enterprise Telehealth & Hospital SaaS Platform

MediLink is a modern, scalable, containerized SaaS platform engineered for clinical workflows, multi-role hospital management (Patients, Doctors, Administrators), electronic health records (EHR), scheduling, and billing.

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🌟 Key Architecture & SaaS Features

• Multi-Role Access Control (RBAC):
  • Patients: Book doctor appointments, view diagnosis history, access prescriptions, and process full/partial medical payments.
  • Doctors: Manage clinical appointments, record diagnoses, issue prescriptions, and view assigned patient charts.
  • Hospital Admins: Monitor platform revenue, oversee appointment metrics, approve insurance claims, and audit platform activity.
• Enterprise Performance & Query Optimization:
  • Zero N+1 Query Overhead: All DRF ViewSets utilize explicit select_related() and prefetch_related() joins.
  • Double-Booking Prevention: Transactional slot locking prevents overlapping doctor schedules.
  • Invoice & Partial Payment Tracking: Supports itemized billing, auto-calculated tax/discounts, instant PDF invoice generation, and status sync (pending, partially_paid, paid).
• Asynchronous Task Processing:
  • Celery + Redis: Background worker handles automated appointment reminders and hourly overdue invoice reconciliation.
• Production Containerization:
  • Docker Compose: Orchestrates 6 micro-services (Postgres, Redis, Django API, Celery Worker, Celery Beat, and React Nginx SPA).

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🏛 Architecture Diagram

┌────────────────────────────────────────────────────────┐
│                   Client Browser                       │
└──────────────┬─────────────────────────┬───────────────┘
               │ Port 3000               │ Port 8000
               ▼                         ▼
    ┌──────────────────────┐  Proxy   ┌──────────────────────┐
    │  React 18 + Nginx    │ ───────> │  Django REST API     │
    │  (Static SPA Server) │  /api/   │  (Gunicorn WSGI)     │
    └──────────────────────┘          └──────────┬───────────┘
                                                 │
                        ┌────────────────────────┼────────────────────────┐
                        ▼                        ▼                        ▼
               ┌────────────────┐       ┌────────────────┐       ┌────────────────┐
               │  PostgreSQL 15 │       │  Redis 7 Cache │ <──── │ Celery Worker  │
               │  (Primary DB)  │       │  & Message Bus │ <──── │ & Celery Beat  │
               └────────────────┘       └────────────────┘       └────────────────┘

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🚀 Quickstart (One-Command Docker Compose)

1. Clone & Start Containers

Ensure Docker Desktop is running, then run:

# Start all 6 services (Database, Redis, API, Worker, Beat, Frontend)
docker compose up --build -d

2. Seed Realistic SaaS Demo Data (For Interviews)

Populate the database with pre-configured Doctors, Patients, Appointments, Medical Records, and Billing:

docker compose exec backend python manage.py seed_demo_data

3. Access the Platform

• 🌐 Web Application: http://localhost:3000
• 🔌 REST API & Swagger Docs: http://localhost:8000/api/
• ⚙️ Django Admin Portal: http://localhost:8000/admin/

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🔑 Pre-Configured Demo Credentials

Use these credentials to seamlessly demonstrate different user perspectives in interviews:

Role	Username	Password	Key Responsibilities
Hospital Admin	admin	AdminPassword123!	System statistics, revenue metrics, insurance claim approvals
Cardiologist	doctor_sarah	DoctorPassword123!	Patient chart review, clinical record creation, appointments
Pediatrician	doctor_james	DoctorPassword123!	Availability schedules, prescription management
Patient 1	patient_john	PatientPassword123!	Active hypertension record, partial invoice payment
Patient 2	patient_emma	PatientPassword123!	Paid invoices, upcoming scheduled appointments

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🧪 Service Composition in docker-compose.yml

Service	Technology	Port	Description
db	PostgreSQL 15	5432	Relational storage with persistent volume & health check
redis	Redis 7 Alpine	6379	Fast in-memory cache & Celery task queue broker
backend	Django 4.2 + Gunicorn	8000	REST API with automated migrations on boot
celery-worker	Celery 5.3	Internal	Background task execution (emails, async processing)
celery-beat	Celery Beat	Internal	Scheduled cron tasks (hourly invoice reconciler)
frontend	React 18 + Nginx	3000	High-performance SPA with client-side routing & /api/ reverse proxy

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🛠 Manual Local Development (Without Docker)

Backend

cd backend
python -m venv venv
venv\Scripts\activate  # Windows (or source venv/bin/activate on Linux/Mac)
pip install -r requirements.txt
python manage.py migrate
python manage.py seed_demo_data
python manage.py runserver

Frontend

cd frontend
npm install --legacy-peer-deps
npm start

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🔒 Security Implementations

1. Privilege Escalation Prevention: Public registration strictly denies unauthorized admin role elevation.
2. Password Validation: Enforces complexity checks and confirmation checks across frontend and backend.
3. Robust DRF Permissions: Custom permission classes verify authentication state before inspecting user attributes, preventing AnonymousUser crashes.
4. CORS Hardening: Configurable origin whitelists preventing cross-origin resource exploitation.