module Saml
  class Util
    class << self
      def parse_params(url)
        query = URI.parse(url).query
        return {} unless query

        params = {}
        query.split(/[&;]/).each do |pairs|
          key, value  = pairs.split('=', 2)
          params[key] = value
        end

        params
      end

      def post(location, message)
        request = HTTPI::Request.new

        request.url                     = location
        request.headers['Content-Type'] = 'text/xml'
        request.body                    = message
        request.auth.ssl.cert_file      = Saml::Config.ssl_certificate_file
        request.auth.ssl.cert_key_file  = Saml::Config.ssl_private_key_file

        HTTPI.post request
      end

      def sign_xml(message, format = :xml, &block)
        message.add_signature

        document = Xmldsig::SignedDocument.new(message.send("to_#{format}"))
        if block_given?
          document.sign(&block)
        else
          document.sign do |data, signature_algorithm|
            message.provider.sign(signature_algorithm, data)
          end
        end
      end

      def encrypt_assertion(assertion, certificate)
        encrypted_data = Xmlenc::Builder::EncryptedData.new
        encrypted_data.set_encryption_method(algorithm: 'http://www.w3.org/2001/04/xmlenc#aes128-cbc')

        encrypted_key = encrypted_data.encrypt(assertion)
        encrypted_key.set_encryption_method(algorithm:               'http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p',
                                            digest_method_algorithm: 'http://www.w3.org/2000/09/xmldsig#sha1')
        encrypted_key.encrypt(certificate.public_key)

        Saml::Elements::EncryptedAssertion.new(encrypted_data: encrypted_data, encrypted_keys: encrypted_key)
      end

      def verify_xml(message, raw_body)
        document = Xmldsig::SignedDocument.new(raw_body)

        signature_valid = document.validate do |signature, data, signature_algorithm|
          message.provider.verify(signature_algorithm, signature, data, message.signature.key_name)
        end

        raise Saml::Errors::SignatureInvalid.new unless signature_valid

        signed_node = document.signed_nodes.find { |node| node['ID'] == message._id }

        message.class.parse(signed_node.to_xml, single: true)
      end
    end
  end
end