book.rb

require 'json'

class Book
  attr_accessor :title, :author, :rentals

  def initialize(title, author)
    @title = title
    @author = author
    @rentals = []
  end

  def self.all
    ObjectSpace.each_object(self).to_a
  end

  def to_s
    index = Book.all.index(self)
    "#{index}) Title: \"#{title}\", Author: #{author}"
  end

  def self.list_books
    puts 'List of books:'
    all_books = all.empty? ? 'No books available yet' : all
    puts all_books
    all_books
  end

  def self.create_book
    puts
    puts 'Title:'
    title = gets.chomp

    puts 'Author:'
    author = gets.chomp

    book = new(title, author)

    puts
    puts 'Book created successfully'
    puts book

    book.save
  end

  def self.select_book_for_renting
    puts 'Select a book from the following list by number'
    if all.empty?
      puts
      puts 'No books available'
      return
    end
    puts all
    book_idx = gets.chomp.to_i

    if book_idx > all.length || book_idx.negative?
      puts 'Invalid book number'
      return
    end
    book_idx
  end

  def save
    if File.exist?('books.json')
      books_file = File.read('books.json')
      books = JSON.parse(books_file)
      books << { title: title, author: author }

      File.write('books.json', JSON.pretty_generate(books))
    else
      File.write('books.json', JSON.pretty_generate([{ title: title, author: author }]))
    end
  end

  def self.load_books
    return unless File.exist?('books.json')

    books_file = File.read('books.json')
    books = JSON.parse(books_file)
    books.each do |book|
      new(book['title'], book['author'])
    end
  end
end