Module: Viitelaskuri

Extended by:
Viitelaskuri
Included in:
Viitelaskuri
Defined in:
lib/viitelaskuri.rb,
lib/viitelaskuri/version.rb

Overview

A collection of methods for calculating bank references for finnish invoices.

Constant Summary collapse

Version = 
'0.1.0'

Instance Method Summary collapse

Instance Method Details

#calculate(seed) ⇒ Integer

Calculates the bank reference for a given number

Parameters:

  • seed (Number, String) —

    The number to calculate the check number for. For instance in invoice number.

Returns:

  • (Integer) —

    The bank reference calculated.

Raises:

  • (ArgumentError) —

    Raises an error if the seed is less than 3 or more than 19 digits.



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# File 'lib/viitelaskuri.rb', line 13

def calculate(seed)
  str = seed.to_s

  if str.length < 3
    raise ArgumentError.new('The seed must be at least 3 digits.')
  end

  if str.length > 19
    raise ArgumentError.new('The seed must not be more than 19 digits.')
  end

  reversed = str.reverse
  sum = 0
  coefficients = [7, 3, 1]
  i = 0
  reversed.each_char do |c|
    n = c.to_i
    sum += n * coefficients[i % 3]
    i += 1
  end
  # sum -> nearest full ten - sum
  check = sum % 10 == 0 ? 0 : ((sum / 10).to_i + 1) * 10 - sum
  str = str + check.to_s
  str.to_i
end

#format(ref) ⇒ String

Formats a given number into five digit groups starting from the right

Parameters:

  • ref (Number, String) —

    The number to format.

Returns:

  • (String) —

    The formatted string.

Raises:

  • (ArgumentError) —

    Raises an error if the ref is less than 4 or more than 20 digits.



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# File 'lib/viitelaskuri.rb', line 44

def format(ref)
  str = ref.to_s

  if str.length < 4
    raise ArgumentError.new('The seed must be at least 4 digits.')
  end

  if str.length > 20
    raise ArgumentError.new('The seed must not be more than 20 digits.')
  end

   # organize in five letter groups starting from the right
  in_groups_of(str.reverse.split(''), 5, false).map { |e| e.join('')  }.join(' ').reverse
end

#generate ⇒ Integer

Generates an almost certainly unique bank reference. Uses a timestamp (10 digits) and a random number (9 digits) and adds the check number.

Returns:

  • (Integer) —

    the generated bank reference.



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# File 'lib/viitelaskuri.rb', line 77

def generate
  time = Time.now.utc.to_i
  random = 9.times.map { rand(10) }
  calculate(time.to_s + random.to_s)
end

#valid?(ref) ⇒ Boolean

Checks if a given number is a valid bank reference

Parameters:

  • ref (Number, String) —

    The number to check.

Returns:

  • (Boolean) —

    True if the ref is valid, false if not.



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# File 'lib/viitelaskuri.rb', line 63

def valid?(ref)
  if ref.to_s.length < 4 || ref.to_s.length > 20
    return false
  end

  str = ref.to_s[0...-1]
  calculate(str) == ref.to_i
end