User Library API

Overview

This is a Node.js REST API application that manages a collection of users and tracks whether they have borrowed a book, along with the borrowing date and time. The API provides endpoints for lending a book to a user, returning a book, and checking if a user has overdue items.

Features

Lend a Book: Allows a user to borrow a book if they don't have one already borrowed. Return a Book: Allows a user to return a borrowed book. Check Overdue Items: Checks if a user has borrowed an item for more than 14 days and flags it as overdue. Requirements Node.js (version 12 or higher) npm (Node Package Manager) Installation Clone the repository:

git clone https://github.com/your-username/user-library-api.git
cd user-library-api

Install the necessary packages:

npm install

Running the Application

To start the server, use the following command:

node server.js

Alternatively, if you have nodemon installed, you can use:

npx nodemon server.js

The server will start on port 3000. You can change the port by setting the PORT environment variable.

API Endpoints

1. Lend a Book

Endpoint: /lend

Method: POST

Request Body:

{
  "username": "string"
// Response: Returns a success message with the user details.
}

Example:

curl -X POST http://localhost:3000/lend -H "Content-Type: application/json" -d '{"username": "Aryan"}'

2. Return a Book Endpoint: /return

Method: POST

Request Body:

{
  "username": "string"
}
// Response: Returns a success message with the user details.

Example:

curl -X POST http://localhost:3000/return -H "Content-Type: application/json" -d '{"username": "Aryan"}'

3. Check Overdue Items Endpoint: /overdue

Method: GET

Query Parameter:

username: The username to check for overdue items. Response: Returns a message indicating whether the user has overdue items.

Example:

curl http://localhost:3000/overdue?username=Aryan

Assumptions and Decisions

In-Memory Storage: The application uses an in-memory array to store user data. This approach was chosen for simplicity and to avoid dependencies on a database. This means that the data will be reset every time the server restarts.

Validation: The API includes basic validation to ensure that a user cannot borrow a book if they already have one borrowed and cannot return a book if they haven't borrowed one.

Overdue Calculation: The overdue calculation assumes a fixed 14-day period for all borrowed items. The Luxon library is used for date manipulation and comparison.

No Authentication: The application does not include authentication or user management features. It assumes that usernames are unique and manages users based solely on their usernames.

Testing the Application

You can use tools like Postman or cURL to test the API endpoints. Examples of how to test each endpoint using cURL are provided above.

If you wish to write unit tests, consider using a testing framework like Jest or Mocha.