Booking System Integration with Paymob and Brevo

Hi, I need a developer to complete my booking system integrations:

1) Paymob Oman payments (Next.js + Firebase/Firestore)

Implement full Paymob Oman payment flow server-side:

auth token → order → payment key → checkout (redirect/iframe)

Implement Paymob webhook/callback verification (must verify paid securely)

Update Firestore booking record: pending_payment → paid

Add error logging (no hidden 500s)

2) WhatsApp notifications using Brevo

I already have a Brevo account and WhatsApp access.
I need WhatsApp messages triggered by backend events:

A) After payment confirmed

Send WhatsApp message to SHOP/admin number with booking details

Send WhatsApp message to CUSTOMER confirming booking

B) Reminder

Send customer WhatsApp reminder 1 hour before reservation

Must avoid duplicates (store reminderSent=true)

Tech

Next.js API routes or Firebase Functions

Firestore database

Use env/secrets properly (Paymob keys + Brevo API key)

Provide documentation: how to set env vars, templates, phone formatting (E.164), deploy steps

Acceptance criteria

A customer books, pays successfully, booking becomes paid in Firestore

Immediately: shop receives WhatsApp + customer receives confirmation WhatsApp

Automatically: customer receives reminder 1 hour before reservation

Production-ready and secure

Please share similar Paymob/Brevo WhatsApp work and what access you need.
Live Project link : https://studio--studio-8973841198-9b276.us-central1.hosted.app/