Sprint 6 Challenge

# Sprint Challenge

**The code you write for this challenge is mandatory homework and should be completed and sent in a PR for review before class.**

## Requirements

### Overview

Create a library system for managing book borrowing and returns.

### Acceptance Criteria

Ability to:
- Save new books
- Validate against duplicates
- New book saved to database (in memory or text file)
- Borrow a book
- Validate if it's available to borrow
- Start with a fixed borrow period (maybe 1 month) and optionally refactor later to be variable
- Update database record to set that the book is now borrowed and hence not available for someone else to borrow
- Should include a borrow / return date
- List the books currently borrowed by a user
- Actively borrowed books only, not ones that have been returned
- Return a book
- If it's being returned late report that the borrower should be fined £1 per day late
- Update database record to set that the book has been returned and hence can now be borrowed again
- Search for a book by title or author to see if it's available to borrow or not
- Present sensible responses for the cases:
- Book exists and can be borrowed
- Book exists but is already borrowed by someone else
- Book does not exist

### Code Quality

- Tiered architecture used with an in memory database (or you can write to a text file, your choice!) and console used as the presentation layer
- Interfaces used in service layer and DI used throughout
- Code clearly documented and unit tested!

### Developer Guidance (deliberately limited!)

- Think about the models you'll want first, and what data you'll need to store in order to meet the above criteria
- Think about how to save the data in a format (using appropriate data structures) that you'll be able to read and write to → the internet can help here!
- Create an access class responsible for reading and writing to the 'database'
- Create a suitable service layer using interfaces that you call from a main method to perform the library operations detailed in the acceptance criteria
- Make sure the service layer is unit tested

### Submission & Review

Fork the coursework repo to your own GitHub account.
Make regular small commits with clear messages.
When you are ready, open a Pull Request to the CYF repo. Make sure you fill in the PR template provided.
A volunteer will review your submission and send you feedback.