class Poll::Answer < ApplicationRecord
  belongs_to :question, -> { with_hidden }, inverse_of: :answers
  belongs_to :option, class_name: "Poll::Question::Option"
  belongs_to :author, -> { with_hidden }, class_name: "User", inverse_of: :poll_answers

  delegate :poll, :poll_id, to: :question

  validates :question, presence: true
  validates :author, presence: true
  validates :answer, presence: true
  validates :option, uniqueness: { scope: :author_id }, allow_nil: true
  validate :max_votes

  validates :answer, inclusion: { in: ->(a) { a.question.possible_answers }},
                     unless: ->(a) { a.question.blank? }

  scope :by_author, ->(author_id) { where(author_id: author_id) }
  scope :by_question, ->(question_id) { where(question_id: question_id) }

  private

    def max_votes
      return if !question || !author || persisted?

      if question.answers.by_author(author).count >= question.max_votes
        errors.add(:answer, "Maximum number of votes per user exceeded")
      end
    end
end