# frozen_string_literal: true

# Module for style guidelines.
module HeadMusic::Style::Guidelines; end

# marks the voice if the first note is not the first or fifth scale degree of the key.
class HeadMusic::Style::Guidelines::StartOnPerfectConsonance < HeadMusic::Style::Annotation
  MESSAGE = "Start on the tonic or a perfect consonance above the tonic (unless bass voice)."

  def marks
    return unless first_note && ((bass_voice? && !starts_on_tonic?) || !starts_on_perfect_consonance?)

    HeadMusic::Style::Mark.for(first_note)
  end

  private

  def starts_on_perfect_consonance?
    diatonic_interval_from_tonic(first_note).perfect_consonance?(:two_part_harmony)
  end
end