Scale Gizmo

KEY_COUNT = 12

KEYS = []
KEYS[0] = "C"
KEYS[1] = "C#"
KEYS[2] = "D"
KEYS[3] = "D#"
KEYS[4] = "E"
KEYS[5] = "F"
KEYS[6] = "F#"
KEYS[7] = "G"
KEYS[8] = "G#"
KEYS[9] = "A"
KEYS[10] = "A#"
KEYS[11] = "B"

KEYS_S = {}
for i in 0...KEYS.size ; KEYS_S[KEYS[i]] = i ; end
KEYS_S["BB"] = KEYS_S["A#"]

SCALES = {}
SCALES["MAJ"]  = [0, 4, 3]
SCALES["MIN"]  = [0, 3, 4]
SCALES["MAJ7"] = [0, 4, 3, 4]

def scale_to_keys( scale )
  result = []
  num = 0
  for key in scale
    num += key
    num %= KEY_COUNT
    result << num
  end
  return result
end

def scale_to_keys_s( scale )
  result = []
  num = 0
  for key in scale
    num += key
    num %= KEY_COUNT
    result << KEYS[num]
  end
  return result
end

def array_space_to_s( arra )
  result = ""
  arra.each { |e| result += "#{e} " }
  return result
end

def offset_scale( scale, amount )
  result = scale.clone ; result[0] += amount ; return result
end

loop do

  case gets
  # // scale maj D
  when /scale[ ](.*) (.*)/i
    sc    = $1 # // Scale
    key   = $2 # // Note
    scal  = SCALES[sc.upcase]
    scal2 = offset_scale( scal, KEYS_S[key.upcase] )

    notes = scale_to_keys_s( scal2 )
    keys1 = scal
    keys2 = scale_to_keys( scal2 )

    notes = array_space_to_s(notes)
    keys1 = array_space_to_s(keys1)
    keys2 = array_space_to_s(keys2)

    puts "#{notes} : #{keys1} : #{keys2}"
  when /break/i
    break
  end

end