# 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