gistfile1.rb

require 'thread'
begin
	require 'soap/wsdlDriver'
rescue LoadError
	require 'savon'
end

class VatUtils
	SERVICE_URL = 'http://ec.europa.eu/taxation_customs/vies/checkVatService.wsdl'.freeze
	VAT_FORMAT  = /\A([A-Z]{2})([0-9A-Za-z\+\*\.]{2,12})\Z/.freeze
	
	# Names must be consistent with the country_select plugin.
	EU_MEMBER_STATES = [
		'Austria',
		'Belgium',
		'Bulgaria',
		'Cyprus',
		'Czech Republic',
		'Denmark',
		'Estonia',
		'Finland',
		'France',
		'Germany',
		'Greece',
		'Hungary',
		'Ireland',
		'Italy',
		'Latvia',
		'Lithuania',
		'Luxembourg',
		'Malta',
		'Netherlands',
		'Poland',
		'Portugal',
		'Romania',
		'Slovakia',
		'Slovenia',
		'Spain',
		'Sweden',
		'United Kingdom'
	].freeze
	
	@@mutex     = Mutex.new
	@@vat_check_driver = nil
	
	class InvalidFormatError < StandardError
	end
	
	# Any exception other than InvalidFormatError indicates that the service is down.
	def self.check_vat_number(vat_number)
		if vat_number =~ VAT_FORMAT
			country_code = $1
			number = $2
			@@mutex.synchronize do
				@@vat_check_driver ||= create_vat_check_driver
			end
			if @@vat_check_driver.respond_to?(:checkVat)
				# TODO: is this thread-safe?
				result = @@vat_check_driver.checkVat(
					:countryCode => country_code,
					:vatNumber => number)
				return result.valid == "true"
			else
				result = @@vat_check_driver.request(:checkVat) do
					soap.body = {
						:countryCode => country_code,
						:vatNumber => number
					}
				end
				return result[:check_vat_response][:valid]
			end
		else
			raise InvalidFormatError
		end
	end
	
	def self.must_charge_vat?(country, vat_number)
		# http://www.belastingdienst.nl/reken/diensten_in_en_uit_het_buitenland/
		if country == 'Netherlands'
			return true
		else
			if vat_number.present?
				return false
			else
				return EU_MEMBER_STATES.include?(country)
			end
		end
	end

private
	def self.create_vat_check_driver
		if defined?(SOAP)
			return SOAP::WSDLDriverFactory.new(SERVICE_URL).create_rpc_driver
		else
			return Savon::Client.new(SERVICE_URL)
		end
	end
end