module TrackingNumber::Loader

def create_class(courier_info, tracking_info)
  klass = Class.new(TrackingNumber::Base)
  klass.const_set('COURIER_CODE', courier_info[:courier_code])
  info = courier_info.dup
  info.delete(:tracking_numbers)
  klass.const_set('COURIER_INFO', info)
  pattern = tracking_info[:regex]
  pattern = tracking_info[:regex].join if tracking_info[:regex].is_a?(Array)
  verify_pattern = "^#{pattern}$"
  search_pattern = "\\b#{pattern}\\b"
  klass.const_set('SEARCH_PATTERN', Regexp.new(search_pattern))
  klass.const_set('VERIFY_PATTERN', Regexp.new(verify_pattern))
  klass.const_set('VALIDATION', tracking_info[:validation])
  klass.const_set('ADDITIONAL', tracking_info[:additional])
  klass.const_set('TRACKING_URL', tracking_info[:tracking_url])
  klass.const_set('PARTNERS', tracking_info[:partners])
  klass.const_set('ID', tracking_info[:id])
  klass
end

def has_test_numbers?(tracking)
  tracking[:test_numbers] && tracking[:test_numbers][:valid]
end

def load_tracking_number_data(couriers_path = File.join(File.dirname(__FILE__), '../data/couriers/'))
  mapping_data = []
  tracking_number_types = []
  Dir.glob(File.join(couriers_path, '/*.json')).each do |file|
    courier_info = read_courier_info(file)
    courier_info[:tracking_numbers].each do |tracking_info|
      klass = create_class(courier_info, tracking_info)
      # Do some basic checks on the data file
      throw 'missing test numbers' unless has_test_numbers?(tracking_info)
      throw 'missing regex match groups' unless test_numbers_return_required_groups?(tracking_info,
                                                                                     Regexp.new(klass::VERIFY_PATTERN))
      const = register_class(klass, tracking_info[:name])
      tracking_number_types.push(const)
      mapping_data << {
        class: const,
        name: courier_info[:name],
        courier_code: courier_info[:courier_code],
        info: tracking_info
      }
    end
  end
  TrackingNumber.const_set('TYPES', tracking_number_types)
  mapping_data
end

def read_courier_info(file)
  JSON.parse(File.read(file)).deep_symbolize_keys!
end

def register_class(klass, tracking_name)
  klass_name = tracking_name.gsub(/[^0-9A-Za-z]/, '')
  TrackingNumber.const_set(klass_name, klass)
end

def test_numbers_return_required_groups?(tracking, regex)
  test_number = tracking[:test_numbers][:valid][0]
  matches = test_number.match(regex)
  matches['SerialNumber']
end