class Book < ApplicationRecord
  has_many :users_books
  has_many :users, through: :users_books

  enum genre: [ :tech, :science, :nonfiction, :fiction, :philosophy ]

  enum sub_genre: {
    signal_processing: 0,
    data_science: 1,
    mathematics: 2,
    economics: 3,
    history: 4,
    psychology: 5,
    classic: 6,
    computer_science: 7,
    novel: 8,
    science: 9,
    autobiography: 10,
    physics: 11,
    objectivism: 12,
    trivia: 13,
    misc: 14,
    poetry: 15,
    education: 16,
    philosophy: 17,
    anthology: 18,
    politics: 19,
    comic: 20,
    legal: 21
  }, _prefix: :sub
  
  def description
    str = ''
    str += genre if genre
    str += ' / ' if sub_genre
    str += sub_genre if sub_genre
    str += ', ' if author
    str += "by #{author}" if author
    str += ', ' if publisher
    str += "published by #{publisher}" if publisher
    str += ' - ' if available_copies > 0
    str += "<b>#{available_copies} copies left</b>" if available_copies > 0
    str.html_safe
  end

  def available_copies
    copies - users_books.where(status: :borrowed).count
  end
end