Module: Ibandit::CheckDigit

Defined in:
lib/ibandit/check_digit.rb

Class Method Summary collapse

Class Method Details

.iban(country_code, bban) ⇒ Object 



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# File 'lib/ibandit/check_digit.rb', line 3

def self.iban(country_code, bban)
  chars = bban + country_code + '00'
  digits = chars.bytes.map do |byte|
    case byte
    when 48..57 then byte.chr           # 0..9
    when 65..90 then (byte - 55).to_s   # A..Z
    else
      raise InvalidCharacterError,
            "Unexpected non-alphanumeric character '#{byte.chr}'"
    end
  end
  remainder = digits.join.to_i % 97
  format('%02d', 98 - remainder)
end

.italian(string) ⇒ Object 



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# File 'lib/ibandit/check_digit.rb', line 18

def self.italian(string)
  odd_mapping = {
    'A' => 1,  'B' => 0,  'C' => 5,  'D' => 7,  'E' => 9,  'F' => 13,
    'G' => 15, 'H' => 17, 'I' => 19, 'J' => 21, 'K' => 2,  'L' => 4,
    'M' => 18, 'N' => 20, 'O' => 11, 'P' => 3,  'Q' => 6,  'R' => 8,
    'S' => 12, 'T' => 14, 'U' => 16, 'V' => 10, 'W' => 22, 'X' => 25,
    'Y' => 24, 'Z' => 23, '0' => 1,  '1' => 0,  '2' => 5,  '3' => 7,
    '4' => 9,  '5' => 13, '6' => 15, '7' => 17, '8' => 19, '9' => 21
  }

  scaled_values = string.chars.map.with_index do |char, index|
    if index.even?
      odd_mapping[char]
    else
      case char.ord
      when 48..57 then char.to_i         # 0..9
      when 65..90 then char.ord - 65     # A..Z
      else
        raise InvalidCharacterError,
              "Unexpected character '#{char}'"
      end
    end
  end

  (scaled_values.inject(:+) % 26 + 65).chr
end