class Faker::Bank

def account_number(legacy_digits = NOT_GIVEN, digits: 10)
  warn_for_deprecated_arguments do |keywords|
    keywords << :digits if legacy_digits != NOT_GIVEN
  end
  output = ''
  output += rand.to_s[2..-1] while output.length < digits
  output[0...digits]
end

def checksum(num_string)
  num_array = num_string.split('').map(&:to_i)
  (
    7 * (num_array[0] + num_array[3] + num_array[6]) +
      3 * (num_array[1] + num_array[4] + num_array[7]) +
      9 * (num_array[2] + num_array[5])
  ) % 10
end

def compile_fraction(routing_num)
  prefix = (1..50).to_a.map(&:to_s).sample
  numerator = routing_num.split('')[5..8].join.to_i.to_s
  denominator = routing_num.split('')[0..4].join.to_i.to_s
  prefix + '-' + numerator + '/' + denominator
end

def compile_routing_number
  digit_one_two = %w[00 01 02 03 04 05 06 07 08 09 10 11 12]
  ((21..32).to_a + (61..72).to_a + [80]).each { |x| digit_one_two << x.to_s }
  routing_num = digit_one_two.sample + rand_numstring + rand_numstring + rand_numstring + rand_numstring + rand_numstring + rand_numstring + rand_numstring
  routing_num
end

def iban(legacy_country_code = NOT_GIVEN, country_code: 'GB')
  # Each country has it's own format for bank accounts
  # Many of them use letters in certain parts of the account
  # Using regex patterns we can create virtually any type of bank account
  warn_for_deprecated_arguments do |keywords|
    keywords << :country_code if legacy_country_code != NOT_GIVEN
  end
  begin
    pattern = fetch("bank.iban_details.#{country_code.downcase}.bban_pattern")
  rescue I18n::MissingTranslationData
    raise ArgumentError, "Could not find iban details for #{country_code}"
  end
  # Use Faker::Base.regexify for creating a sample from bank account format regex
  account = Base.regexify(/#{pattern}/)
  # Add country code and checksum to the generated account to form valid IBAN
  country_code.upcase + iban_checksum(country_code, account) + account
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 name
  fetch('bank.name')
end

def rand_numstring
  (0..9).to_a.map(&:to_s).sample
end

def routing_number
  valid_routing_number
end

def routing_number_with_format
  compile_fraction(valid_routing_number)
end

def swift_bic
  fetch('bank.swift_bic')
end

def valid_checksum?(routing_number, checksum)
  routing_number[8].to_i == checksum
end

def valid_routing_number
  routing_number = compile_routing_number
  checksum = checksum(routing_number)
  return routing_number if valid_checksum?(routing_number, checksum)
  routing_number[0..7] + checksum.to_s
end