module NoteFrequencies

# File lib/note_frequencies.rb, line 53
def self.delta(name)
  @deltas ||= begin
    {
      :a => 0,
      :b => 2,
      :c => -9,
      :d => -7,
      :e => -5, 
      :f => -4,
      :g => -2
    }
  end
  @deltas[name.to_sym]
end

# File lib/note_frequencies.rb, line 20
def self.delta_from_name(name)
  note, alt, octave = name.scan(/([a-g])(eses|isis|bb|##|es|is|b|#|x)?(\d|(,+)|('+))?/).first
  # puts octave.inspect
  octave_delta = if octave
    if octave.start_with?("'")
      octave.length - 1
    elsif octave.start_with?(",")
      -octave.length - 1
    else
      octave.to_i - 4
    end
  else
    -1
  end
  # puts octave_delta.inspect
  alt_delta = if (alt == 'is' || alt == '#')
    1
  elsif (alt == 'isis' || alt == '##' || alt == 'x')
    2
  elsif (alt == 'es' || alt == 'b')
    -1
  else
    0
  end
  delta(note) + alt_delta + 12 * octave_delta
end

# File lib/note_frequencies.rb, line 9
def self.frequency(delta_from_a, conf = {})
  conf = {
    :tuning => DEFAULT_TUNING,
    :round => DEFAULT_ROUND
  }.update(conf)
  tuning = conf[:tuning]
  freq = tuning * (2**(delta_from_a.to_f/12))
  round(freq, conf[:round])
end

# File lib/note_frequencies.rb, line 68
def self.frequency_from_name(name, conf = {})
  conf = {
    :tuning => DEFAULT_TUNING,
    :round => DEFAULT_ROUND
  }.update(conf)
  frequency(delta_from_name(name), conf)
end

# File lib/note_frequencies.rb, line 47
def self.round(q, r)
  pow = 10**r
  (q*pow).round/pow.to_f
end