game.rb

require_relative "frame"

class Game
  TOTAL_FRAMES = 10
  attr_reader :score

  def initialize
    @frames = [Frame.new]
    @score = 0
  end

  def throw! knocked_pins:
    raise(GameError, "The game is over, no more throws allowed.") if game_over?
    @frames.last.throw! knocked_pins: knocked_pins
    update_old_frames_with knocked_pins
    start_new_frame if @frames.last.over? && reached_last_frame?.!
    update_score
  end

  def game_over?
    reached_last_frame? && @frames.last.over?
  end

private

  def update_old_frames_with added_points
    old_frames = @frames.slice(0, (@frames.length-1)).to_a
    old_frames.each do |old_frame|
      old_frame.update_extra_score added_points: added_points
    end
  end

  def update_score
    @score = @frames.map(&:score).inject(&:+)
  end

  def start_new_frame
    @frames << (Frame.new last: reached_before_last_frame?)
  end

  def reached_last_frame?
    @frames.count == TOTAL_FRAMES
  end

  def reached_before_last_frame?
    @frames.count == TOTAL_FRAMES-1
  end
end

class GameError < StandardError
end