Android-Based Teacher Booking System

This is primarily an Android + backend booking system project, not just an Android UI app. The important parts are the booking logic, conflict prevention, email workflow, teacher admin panel, and booking history.

Recommended architecture
Android app: Kotlin + Jetpack Compose
Backend: Node.js/NestJS or Node.js/Express
Database: PostgreSQL
Authentication: Firebase Authentication or email-based authentication
Email: Gmail/Google Workspace API or transactional email service such as SendGrid
Teacher admin panel: React/Next.js web dashboard
Notifications: Email, with optional Firebase push notifications
Booking engine: Server-side availability checking + database transactions to prevent double bookings
Main workflow
Student opens the Android app.
Selects teacher and available date/time.
Enters the teacher's Gmail address.
App sends booking request to backend.
Backend validates availability and creates the booking.
Teacher receives an email containing:
Student information
Lesson date/time
Accept button
Reject button
Teacher accepts/rejects directly from the email or admin panel.
Student receives the result automatically.
Teacher can modify/delete bookings from the admin panel.
Any modification/deletion requires a reason.
The reason is stored permanently in the booking history and emailed to the student.
Backend prevents overlapping/duplicate bookings using server-side validation and database constraints.
Important implementation detail

I would not rely on Gmail itself as the booking database or source of truth. Gmail should only be used for notifications and teacher responses. The backend/database should control booking status, availability, conflicts, history, and audit records.

For example:

PENDING → ACCEPTED

or

PENDING → REJECTED

and for modifications:

ACCEPTED → MODIFIED

with something like:

Reason: Teacher unavailable at the originally selected time.

This makes the system much more reliable and auditable.

Freelancer project classification

I would categorize it as:

Android App Development + Full-Stack Development + Booking System + Admin Panel + Email Automation

It is a medium-complexity full-stack project, even though the Android app itself can be relatively simple. The backend booking logic is the part that needs the most careful implementation.