DceLti::Engine.setup do |lti|
  # "provider_*" attributes are used to describe this tool to the consumer,
  # where "consumer" is an LMS like canvas. The defaults are below, uncomment
  # and modify as necessary or (ideally) configure via environment variables.
  #
  # lti.provider_title = (ENV['LTI_PROVIDER_TITLE'] || 'DCE LTI Provider')
  # lti.provider_description = (ENV['LTI_PROVIDER_DESCRIPTION'] || 'A description of this')
  #
  # Set this to `true` to enable the form and URL-rewriting behavior that
  # allows for the creation of cookieless sessions. The default is `false`,
  # meaning we don't attempt to use cookieless sessions when a cookie cannot be
  # set - the session just fails.
  #
  # lti.enable_cookieless_sessions = false
  #
  # The default post-auth redirect includes the session key and session id so
  # that we can instantiate a successful cookieless session if needed.
  #
  # lti.redirect_after_successful_auth = ->(controller) {
  #   session_key_name = Rails.application.config.session_options[:key]
  #   Rails.application.routes.url_helpers.root_path(session_key_name => controller.session.id)
  # }

  lti.consumer_secret = (ENV['LTI_CONSUMER_SECRET'] || 'consumer_secret')
  lti.consumer_key = (ENV['LTI_CONSUMER_KEY'] || 'consumer_key')

  # `lti.copy_launch_attributes_to_session` is an array of attributes to copy
  # to the default rails session from the IMS::LTI::ToolProvider instance after
  # a successful launch. The default attributes are defined in
  # `DceLti::Engine.setup`, and the possible canvas-lms attributes are defined
  # in:
  #
  # https://github.com/instructure/ims-lti/blob/master/lib/ims/lti/launch_params.rb#L9
  # https://github.com/instructure/ims-lti/blob/master/lib/ims/lti/tool_provider.rb
  #
  # and in the spec as well:
  # http://www.imsglobal.org/LTI/v1p1p1/ltiIMGv1p1p1.html#_Toc330273026
  #
  # lti.copy_launch_attributes_to_session.push(:additional_attribute_to_capture)

  # The consumer_secret and consumer_key should be a lambda that will be
  # evaluated in the context of your application. You might use a service
  # object or model proper to find key and secret pairs. Example:
  #
  # lti.consumer_secret = ->(launch_params) {
  #   Consumer.find_by(context_id: launch_params[:context_id]).consumer_secret
  # }
  # lti.consumer_key = ->(launch_params) {
  #   Consumer.find_by(context_id: launch_params[:context_id]).consumer_key
  # }

  # The tool_config_extensions lambda runs before the XML Tool Provider config
  # is generated and gets two parameters:
  #
  # * controller - An instance of DceLti::ConfigsController
  # * tool_config - An instance of IMS::LTI::ToolConfig
  #
  # It allows you to config LMS-specific extensions. A common example for the
  # Canvas LMS is included below, see 
  # https://github.com/instructure/ims-lti/blob/master/lib/ims/lti/extensions/canvas.rb
  # for more canvas-specific configuration options.

  lti.tool_config_extensions = ->(controller, tool_config) do
    tool_config.extend ::IMS::LTI::Extensions::Canvas::ToolConfig
    tool_config.canvas_domain!(controller.request.host)
    tool_config.canvas_privacy_public!
  end
end