onLift is a web application built as a learning exercise to simulate the operation of an elevator system, inspired by observations of a hostel lift. It goes beyond a simple visual representation, incorporating distinct user roles (Admin and User), complex state management, and manual operational logic. The project served as a deep dive into backend development concepts, full-stack integration, and simulating real-world, state-dependent interactions.

The application is built using the MEEN stack (MongoDB, Express.js, EJS, Node.js), with initial UI concepts designed in Figma.

• Manual Lift Operation:
  • GO: Manually dispatches the lift to the next floor in the user request queue.
• Monitoring & Control:
  • CAMERA: Allows the admin to view the profile pictures of users currently inside the elevator cabin.
  • ORDER: Toggles the lift's operational status between "In Service" (Green Light) and "Out of Order" (Red Light).
• Emergency Protocol:
  • RESCUE: This button only appears if the lift is marked "Out of Order" while users are still inside. Clicking it simulates an emergency evacuation, clearing the lift occupants.

• Authentication:
  • Signup: Users can register with a Username, Weight (in KGs), Password, and upload a Profile Picture.
  • Login: Secure login for registered users.
  • Personalized welcome message and profile picture display upon login.
• Elevator Interaction:
  • ENTER: Button appears when the lift is not on the user's current floor. Clicking it adds the user to the destination queue.
  • WAITING: Status indication after clicking ENTER while the lift is en route.
  • ENTER NOW: Button appears only when the lift arrives at the user's floor, is operational (Green Light), and has sufficient weight capacity remaining.
  • Weight Limit: The system prevents users from entering if their weight exceeds the lift's remaining capacity (based on signup data and current occupants).
  • Floor Selection: Once inside the lift (after clicking ENTER NOW), users are presented with floor buttons to choose their destination.

• State Management: Tracks lift's current floor, direction, operational status, user queue, current occupants (and their total weight).
• Dynamic UI: Interface elements (buttons, status lights, occupant view) change based on the lift's state and the user's role/location.
• Alerts: Uses browser alerts for system messages (e.g., "Lift out of order", "No users inside", potentially "Lift is full").
• Data Persistence: User credentials, profile pictures, and potentially lift state are stored in MongoDB.

• Backend: Node.js, Express.js
• Frontend Templating: EJS (Embedded JavaScript templates)
• Database: MongoDB (potentially with Mongoose ODM)
• Design: Figma (for initial UI/UX concepts)
• Environment Variables: dotenv

1. Clone the repository:

   git clone https://github.com/your-username/onlift.git
   cd onlift

2. Install dependencies:

   npm install

3. Create Environment Variables: Create a .env file in the root directory and add the following variables. Replace the placeholder values with your actual configuration.

   # .env file
   MONGODB_URI=your_mongodb_connection_string # e.g., mongodb://localhost:27017/onlift or MongoDB Atlas URI

   Note: Ensure you have a running MongoDB instance accessible via the MONGODB_URI.

4. Run the application:

   • For development (if you have nodemon):

     npm run dev

   Or directly using node:

   node app.js # Or your main server file name

5. Access the application: Open your web browser and navigate to http://localhost:PORT (e.g., http://localhost:3000).

1. Navigate to the application URL.
2. Signup: Create a new user account, providing username, weight, password, and optionally a profile picture.
3. Login: Log in using your credentials.
   • If you log in with the username defined as ADMIN_USERNAME in your .env file, you will access the Admin dashboard.
   • Otherwise, you will access the standard User dashboard.
4. User Flow:
   • See the lift status and your current floor.
   • Click ENTER to request the lift to your floor. Wait for it to arrive (WAITING state).
   • If conditions are met (lift arrives, operational, capacity available), click ENTER NOW.
   • Once inside, select your destination floor.
5. Admin Flow:
   • View the overall lift status, current floor, and direction.
   • Use GO to move the lift to the next requested floor.
   • Use CAMERA to see who is inside.
   • Use ORDER to toggle the lift's operational status.
   • Use RESCUE if the lift is Out of Order with users inside.

This project is primarily a learning exercise and a functional prototype demonstrating complex backend logic and state management. It was completed to practice and solidify full-stack development skills.

• Implement real-time updates using WebSockets (e.g., Socket.IO) for smoother UI updates.
• Add support for multiple elevators.
• Develop a more sophisticated lift scheduling algorithm instead of a simple queue.
• Implement actual image storage/retrieval (e.g., Cloudinary, S3) instead of just storing paths/placeholders.
• Add more detailed error handling and user feedback.
• Unit and integration tests.