add fixed and variable parameters for lti2

fixes: PLAT-593 PLAT-594

test-plan:

specs should pass

Change-Id: I05e9b408655779f1c53ef17d5c98aeaf2a8e3a87
Reviewed-on: https://gerrit.instructure.com/39409
Reviewed-by: Brad Humphrey <brad@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Nathan Mills <nathanm@instructure.com>
QA-Review: Nathan Mills <nathanm@instructure.com>

Gemfile.d/other_stuff.rb

@@ -35,7 +35,7 @@ gem 'hoe', '3.8.1'
 gem 'i18n', '0.6.8'
 gem 'i18nema', RUBY_VERSION >= '2.2' ? '0.0.8' : '0.0.7'
 gem 'icalendar', '1.5.4'
-gem 'ims-lti', '2.0.0.beta.4'
+gem 'ims-lti', '2.0.0.beta.6'
 gem 'jammit', '0.6.6'
   gem 'cssmin', '1.0.3'
   gem 'jsmin', '1.0.1'

app/controllers/lti/message_controller.rb

@@ -28,7 +28,6 @@ module Lti
       @lti_launch.link_text = I18n.t('lti2.register_tool', 'Register Tool')
       @lti_launch.launch_type = message.launch_presentation_document_target
       @lti_launch.message_type = message.lti_message_type
-
       render template: 'lti/framed_launch'
     end
 
@@ -39,17 +38,19 @@ module Lti
         tool_proxy = resource_handler.tool_proxy
         #TODO create scoped method for query
         if ToolProxyBinding.where(tool_proxy_id: tool_proxy.id, context_id: @context.id, context_type: @context.class).count(:all) > 0
-          message_service = IMS::LTI::Services::MessageService.new(tool_proxy.guid, tool_proxy.shared_secret)
           message = IMS::LTI::Models::Messages::BasicLTILaunchRequest.new(
+            launch_url: message_handler.launch_path,
+            oauth_consumer_key: tool_proxy.guid,
             lti_version: IMS::LTI::Models::LTIModel::LTI_VERSION_2P0,
             resource_link_id: Lti::Asset.opaque_identifier_for(@context),
             context_id: Lti::Asset.opaque_identifier_for(@context),
             tool_consumer_instance_guid: @context.root_account.lti_guid,
             launch_presentation_document_target: IMS::LTI::Models::Messages::Message::LAUNCH_TARGET_IFRAME
           )
+          message.add_custom_params(custom_params(message_handler.parameters))
           @lti_launch = Launch.new
-          @lti_launch.resource_url = message_handler.launch_path
-          @lti_launch.params = message_service.signed_params(@lti_launch.resource_url, message)
+          @lti_launch.resource_url = message.launch_url
+          @lti_launch.params = message.signed_post_params(tool_proxy.shared_secret)
           @lti_launch.link_text = message_handler.resource.name
           @lti_launch.launch_type = message.launch_presentation_document_target
           @lti_launch.message_type = message.lti_message_type
@@ -63,6 +64,12 @@ module Lti
 
     private
 
+    def custom_params(parameters)
+      lookup_hash = common_variable_substitutions.inject({}) { |hash, (k,v)| hash[k.gsub(/\A\$/, '')] = v ; hash}
+      params = IMS::LTI::Models::Parameter.from_json(parameters || [])
+      IMS::LTI::Models::Parameter.process_params(params, lookup_hash)
+    end
+
     def tool_consumer_profile_url
       tp_id = SecureRandom.uuid
       case context

app/models/lti/tool_consumer_profile_creator.rb

@@ -61,7 +61,8 @@ module Lti
     end
 
     def capabilities
-      ['basic-lti-launch-request']
+
+      %w( basic-lti-launch-request Canvas.api.domain)
     end
 
   end

lib/lti/message_helper.rb

@@ -21,11 +21,13 @@
 
 module Lti
   module MessageHelper
+
     def common_variable_substitutions
       {
           '$Canvas.api.domain' => -> {HostUrl.context_host(@domain_root_account, request.host)},
           '$Canvas.xapi.url' => -> {lti_xapi_url(@tool)}
       }
     end
+
   end
 end