module RubyQuiz1
  class Solitaire

    attr_reader :deck

    def initialize(deck)
      @deck = deck
      jokers = deck.select { |c| c.is_a?(Joker) }
      raise ArgumentError, "#{jokers.size} jokers in the deck but 2 required" unless jokers.size == 2
      @joker_a, @joker_b = jokers
    end


    def next_key
      key = nil
      until key
        move_card(joker_a, 1)
        move_card(joker_b, 2)
        triple_cut
        count_cut
        key = current_letter
      end
      key
    end

  private

    def joker_a_index
      deck.cards.index(joker_a)
    end

    def joker_b_index
      deck.cards.index(joker_b)
    end

    def joker_a
      @joker_a
    end

    def joker_b
      @joker_b
    end

    def max_index
      deck.size - 1
    end

    def move_card(card, distance)
      start_index = deck.cards.index(card)
      end_index = start_index + distance
      if end_index > max_index
        end_index = end_index % max_index
      end
      deck.cards.insert(end_index, deck.cards.delete(card))
    end

    def triple_cut
      c1, c2 = [joker_a_index, joker_b_index].sort
      new_end = []
      if c1 > 0
        new_end = deck.cards[0..(c1 - 1)]
      end
      new_middle = deck.cards[c1..c2]
      new_beginning = []
      if c2 < max_index
        new_beginning = deck.cards[(c2 + 1)..max_index]
      end
      deck.cards.replace(new_beginning + new_middle + new_end)
    end

    def count_cut
      deck.cards.last.total_value.times do
        deck.cards.insert(-2, deck.cards.shift)
      end
    end

    def current_letter
      letter_card = deck.cards[deck.cards[0].total_value]
      return nil if letter_card.is_a? Joker
      ("A".."Z").to_a[(letter_card.total_value % 26) - 1]
    end

  end
end