require "rexml/document"

require "onelogin/ruby-saml/logging"
require "onelogin/ruby-saml/saml_message"
require "onelogin/ruby-saml/utils"
require "onelogin/ruby-saml/setting_error"

# Only supports SAML 2.0
module OneLogin
  module RubySaml
  include REXML

    # SAML2 Authentication. AuthNRequest (SSO SP initiated, Builder)
    #
    class Authrequest < SamlMessage

      # AuthNRequest ID
      attr_reader :uuid

      # Initializes the AuthNRequest. An Authrequest Object that is an extension of the SamlMessage class.
      # Asigns an ID, a random uuid.
      #
      def initialize
        @uuid = OneLogin::RubySaml::Utils.uuid
      end

      def request_id
        @uuid
      end

      # Creates the AuthNRequest string.
      # @param settings [OneLogin::RubySaml::Settings|nil] Toolkit settings
      # @param params [Hash] Some extra parameters to be added in the GET for example the RelayState
      # @return [String] AuthNRequest string that includes the SAMLRequest
      #
      def create(settings, params = {})
        params = create_params(settings, params)
        params_prefix = (settings.idp_sso_service_url =~ /\?/) ? '&' : '?'
        saml_request = CGI.escape(params.delete("SAMLRequest"))
        request_params = "#{params_prefix}SAMLRequest=#{saml_request}"
        params.each_pair do |key, value|
          request_params << "&#{key.to_s}=#{CGI.escape(value.to_s)}"
        end
        raise SettingError.new "Invalid settings, idp_sso_service_url is not set!" if settings.idp_sso_service_url.nil? or settings.idp_sso_service_url.empty?
        @login_url = settings.idp_sso_service_url + request_params
      end

      # Creates the Get parameters for the request.
      # @param settings [OneLogin::RubySaml::Settings|nil] Toolkit settings
      # @param params [Hash] Some extra parameters to be added in the GET for example the RelayState
      # @return [Hash] Parameters
      #
      def create_params(settings, params={})
        # The method expects :RelayState but sometimes we get 'RelayState' instead.
        # Based on the HashWithIndifferentAccess value in Rails we could experience
        # conflicts so this line will solve them.
        relay_state = params[:RelayState] || params['RelayState']

        if relay_state.nil?
          params.delete(:RelayState)
          params.delete('RelayState')
        end

        request_doc = create_authentication_xml_doc(settings)
        request_doc.context[:attribute_quote] = :quote if settings.double_quote_xml_attribute_values

        request = ""
        request_doc.write(request)

        Logging.debug "Created AuthnRequest: #{request}"

        request = deflate(request) if settings.compress_request
        base64_request = encode(request)
        request_params = {"SAMLRequest" => base64_request}

        if settings.idp_sso_service_binding == Utils::BINDINGS[:redirect] && settings.security[:authn_requests_signed] && settings.private_key
          params['SigAlg']    = settings.security[:signature_method]
          url_string = OneLogin::RubySaml::Utils.build_query(
            :type => 'SAMLRequest',
            :data => base64_request,
            :relay_state => relay_state,
            :sig_alg => params['SigAlg']
          )
          sign_algorithm = XMLSecurity::BaseDocument.new.algorithm(settings.security[:signature_method])
          signature = settings.get_sp_key.sign(sign_algorithm.new, url_string)
          params['Signature'] = encode(signature)
        end

        params.each_pair do |key, value|
          request_params[key] = value.to_s
        end

        request_params
      end

      # Creates the SAMLRequest String.
      # @param settings [OneLogin::RubySaml::Settings|nil] Toolkit settings
      # @return [String] The SAMLRequest String.
      #
      def create_authentication_xml_doc(settings)
        document = create_xml_document(settings)
        sign_document(document, settings)
      end

      def create_xml_document(settings)
        time = Time.now.utc.strftime("%Y-%m-%dT%H:%M:%SZ")

        request_doc = XMLSecurity::Document.new
        request_doc.uuid = uuid

        root = request_doc.add_element "samlp:AuthnRequest", { "xmlns:samlp" => "urn:oasis:names:tc:SAML:2.0:protocol", "xmlns:saml" => "urn:oasis:names:tc:SAML:2.0:assertion" }
        root.attributes['ID'] = uuid
        root.attributes['IssueInstant'] = time
        root.attributes['Version'] = "2.0"
        root.attributes['Destination'] = settings.idp_sso_service_url unless settings.idp_sso_service_url.nil? or settings.idp_sso_service_url.empty?
        root.attributes['IsPassive'] = settings.passive unless settings.passive.nil?
        root.attributes['ProtocolBinding'] = settings.protocol_binding unless settings.protocol_binding.nil?
        root.attributes["AttributeConsumingServiceIndex"] = settings.attributes_index unless settings.attributes_index.nil?
        root.attributes['ForceAuthn'] = settings.force_authn unless settings.force_authn.nil?

        # Conditionally defined elements based on settings
        if settings.assertion_consumer_service_url != nil
          root.attributes["AssertionConsumerServiceURL"] = settings.assertion_consumer_service_url
        end
        if settings.sp_entity_id != nil
          issuer = root.add_element "saml:Issuer"
          issuer.text = settings.sp_entity_id
        end

        if settings.name_identifier_value_requested != nil
          subject = root.add_element "saml:Subject"

          nameid = subject.add_element "saml:NameID"
          nameid.attributes['Format'] = settings.name_identifier_format if settings.name_identifier_format
          nameid.text = settings.name_identifier_value_requested

          subject_confirmation = subject.add_element "saml:SubjectConfirmation"
          subject_confirmation.attributes['Method'] = "urn:oasis:names:tc:SAML:2.0:cm:bearer"
        end

        if settings.name_identifier_format != nil
          root.add_element "samlp:NameIDPolicy", {
              # Might want to make AllowCreate a setting?
              "AllowCreate" => "true",
              "Format" => settings.name_identifier_format
          }
        end

        if settings.authn_context || settings.authn_context_decl_ref

          if settings.authn_context_comparison != nil
            comparison = settings.authn_context_comparison
          else
            comparison = 'exact'
          end

          requested_context = root.add_element "samlp:RequestedAuthnContext", {
            "Comparison" => comparison,
          }

          if settings.authn_context != nil
            authn_contexts_class_ref = settings.authn_context.is_a?(Array) ? settings.authn_context : [settings.authn_context]
            authn_contexts_class_ref.each do |authn_context_class_ref|
              class_ref = requested_context.add_element "saml:AuthnContextClassRef"
              class_ref.text = authn_context_class_ref
            end
          end

          if settings.authn_context_decl_ref != nil
            authn_contexts_decl_refs = settings.authn_context_decl_ref.is_a?(Array) ? settings.authn_context_decl_ref : [settings.authn_context_decl_ref]
            authn_contexts_decl_refs.each do |authn_context_decl_ref|
              decl_ref = requested_context.add_element "saml:AuthnContextDeclRef"
              decl_ref.text = authn_context_decl_ref
            end
          end
        end

        request_doc
      end

      def sign_document(document, settings)
        if settings.idp_sso_service_binding == Utils::BINDINGS[:post] && settings.security[:authn_requests_signed] && settings.private_key && settings.certificate
          private_key = settings.get_sp_key
          cert = settings.get_sp_cert
          document.sign_document(private_key, cert, settings.security[:signature_method], settings.security[:digest_method])
        end

        document
      end

    end
  end
end
