Library API

Your task is to build a simple API to manage a library's book inventory. There are two main components of this API: management endpoints (to be used by the Librarians) and user facing endpoints for end-user actions.

Books are referenced by their ISBN. The library can have more than 1 copy of any given book (multiple copies of the same ISBN).

API Endpoints to be built:

Librarian Endpoints:

• An endpoint to add a book (by ISBN) to the library.
• An endpoint to remove a book (by its internal Id) from the library
• An endpoint that generates a list of all overdue books.

User Endpoints:

• An endpoint to check out a book (assume a 2 week checkout period from time of call). A User can check out any book except when:

• They currently have 3 checked out books.
• They are overdue on returning any book.

• An endpoint to return a checked out book.
• An endpoint that returns all currently checked out books for that user.

For the purposes of this exercise, we can assume there is a Librarian user (userId 1) and three regular users (userids, 2, 3, 4). You can hardcode this table. Also, no need to worry about authentication, etc.