Nexstar Graphs

Real-time sales and stock dashboard for Nexstar. The app receives Tiny ERP data through n8n webhooks, stores it in PostgreSQL, and renders sales, products, clients, stock, and WhatsApp campaign data in a React dashboard.

Stack

• Frontend: React, TypeScript, Vite, Tailwind CSS, Recharts
• Backend: Node.js, Express, PostgreSQL, JWT, API-key webhook auth
• Runtime: Docker Compose, Nginx, n8n

Main Flows

Sales Ingestion

n8n -> POST /api/data -> PostgreSQL orders -> dashboard

The endpoint accepts a single order item or an array. Requests must include:

x-api-key: <API_KEY>
Content-Type: application/json

Stock Ingestion

n8n -> POST /api/stock -> PostgreSQL stock + campaign queue

Positive stock deltas are queued for WhatsApp campaigns. The scheduled processor groups pending queue rows by base product name and sends a campaign only when the accumulated pending delta reaches at least 100.

Scheduled WhatsApp Campaigns

n8n schedule at 12:00/18:00 BRT
-> POST /api/internal/process-stock-campaigns
-> backend calls N8N_WHATSAPP_TRIGGER_URL
-> n8n WhatsApp workflow sends templates

The scheduled endpoint is API-key protected and returns a summary:

{
  "claimed": 0,
  "sentGroups": 0,
  "skippedGroups": 0,
  "failedGroups": 0,
  "pendingBelowThresholdGroups": 0
}

Local Development

Start PostgreSQL:

docker compose up -d db

Start the backend:

cd backend
npm install
npm start

Start the frontend:

npm install
npm run dev

Default local URLs:

Frontend: http://127.0.0.1:3001
Backend:  http://127.0.0.1:3004

Vite may choose a different frontend port if 3001 is already in use.

Environment

Copy .env.example and configure production secrets in the runtime environment:

POSTGRES_USER
POSTGRES_PASSWORD
POSTGRES_DB
API_KEY
N8N_WHATSAPP_TRIGGER_URL
ADMIN_EMAIL
ADMIN_PASSWORD
JWT_SECRET

Validation

npm run lint
npm run build

For backend syntax checks:

cd backend
node --check index.js
node --check services/campaignService.js
node --check services/stockService.js