class Faker::Travel::TrainStation

def fill_missing_inputs_with_samples(region, type)
  regions = %w[germany spain united_kingdom united_states]
  types = %w[metro railway]
  if region.nil? && type.nil?
    region = sample(regions)
    type = sample(types)
  elsif region.nil?
    validate_arguments(type, types, 'type')
    region = sample(regions)
  elsif type.nil?
    validate_arguments(region, regions, 'region')
    type = sample(types)
  end
  [region, type]
end

def name(region: nil, type: nil)
  region, type = fill_missing_inputs_with_samples(region, type)
  fetch("train_station.#{region}.#{type}")
end

def validate_arguments(argument, correct_values, argument_name)
  return if correct_values.include?(argument)
  raise ArgumentError, "'#{argument}' not found, #{argument_name} can be blank, or one of the following, as strings: #{correct_values.join(', ')}"
end