class Faker::Invoice

def amount_between(from: 0, to: 0)
  Faker::Base.rand_in_range(from, to).round(2)
end

def calculate_weighted_sum(base, weight_factors)
  base.to_s.reverse.each_char.with_index.map do |digit, index|
    digit.to_i * weight_factors.at(index % weight_factors.length)
  end.reduce(:+) # reduce(:+) = sum() but with better ruby version support
end

def creditor_reference(ref: '')
  ref = reference if ref.empty?
  "RF#{iban_checksum('RF', ref)}#{ref}"
end

def iban_checksum(country_code, account)
  # Converts letters to numbers according the iban rules, A=10..Z=35
  account_to_number = "#{account}#{country_code}00".upcase.chars.map do |d|
    d =~ /[A-Z]/ ? (d.ord - 55).to_s : d
  end.join.to_i
  # This is answer to (iban_to_num + checksum) % 97 == 1
  checksum = (1 - account_to_number) % 97
  # Use leftpad to make the size always to 2
  checksum.to_s.rjust(2, '0')
end

def kidmod10(base)
  weighted_sum = calculate_weighted_sum(base, [1, 2])
  mod10_remainder(weighted_sum)
end

def method_731(base)
  weighted_sum = calculate_weighted_sum(base, [7, 3, 1])
  mod10_remainder(weighted_sum)
end

def mod10_remainder(number)
  -number % 10
end

def reference(ref: '')
  pattern = fetch('invoice.reference.pattern')
  ref = Base.regexify(/#{pattern}/) if ref.empty?
  # If reference contains reserved '#' characters we need to calculate check_digits as well
  check_digit_match = ref.match(/#+/)
  if check_digit_match
    # Get the method for selected language
    check_digit_method = fetch('invoice.reference.check_digit_method')
    # Calculate the check digit with matching method name
    # Trim all '#' from the reference before calculating that
    check_digit = send(check_digit_method, ref.tr('#', ''))
    # Make sure that our check digit is as long as all of the '###' we found
    check_digit = check_digit.to_s.rjust(check_digit_match[0].length, '0')
    # Replace all of the
    ref = ref.sub(check_digit_match[0], check_digit)
  end
  ref
end