module LtiXml
  class BasePlatform
    attr_accessor :parsed_request_url, :platform, :main_app

    def initialize(platform, full_request_url, main_app)
      @platform = platform
      @parsed_request_url = URI.parse(full_request_url)
      @main_app = main_app
    end

    # Override one of the following formatter methods in your individual platform class, or if you must, you can override
    # the whole xml method and do it all custom.
    def xml
      ims_tool_config
      add_domain
      add_privacy_level
      add_lti_properties
      add_lti_custom_params
      add_lti_options
      add_lti_nav
      add_environments

      #strip the launch url
      xml = @tc.to_xml
      xml = xml.sub(/<blti:launch_url>.*<\/blti:launch_url>/, '') if PandaPal.lti_options[:launch_url] === false

      return xml
    end

    private

    def ims_tool_config
      ims_lti_config = {title: PandaPal.lti_options[:title]}
      if PandaPal.lti_options[:secure_launch_url].present? # Assumes full URL is provided
        ims_lti_config[:secure_launch_url] = PandaPal.lti_options[:secure_launch_url]
      elsif PandaPal.lti_options[:secure_launch_path].present? # Assumes path is provided
        ims_lti_config[:secure_launch_url] = "#{parsed_request_url.host}#{PandaPal.lti_options[:secure_launch_path]}"
      elsif PandaPal.lti_options[:launch_url].present? # Assumes full URL is provided
        ims_lti_config[:launch_url] = PandaPal.lti_options[:launch_url]
      elsif PandaPal.lti_options[:launch_path].present? # Assumes path is provided
        ims_lti_config[:launch_url] = "#{parsed_request_url.host}#{PandaPal.lti_options[:launch_path]}"
      else
        ims_lti_config[:launch_url] = parsed_request_url.host
      end
      @tc = IMS::LTI::Services::ToolConfig.new(ims_lti_config)
    end

    def add_domain
      @tc.set_ext_param(platform, :domain, parsed_request_url.host) unless PandaPal.lti_properties.has_key?(:domain)
    end

    def add_privacy_level
      @tc.set_ext_param(platform, :privacy_level, 'public') unless PandaPal.lti_properties.has_key?(:public)
    end

    def add_lti_properties
      PandaPal.lti_properties.each do |k, v|
        @tc.set_ext_param(platform, k, v)
      end
    end

    def add_lti_custom_params
      PandaPal.lti_custom_params.each do |k, v|
        @tc.set_custom_param k, v
      end
    end

    def add_lti_options
      if PandaPal.lti_options.has_key?(:custom_fields)
        @tc.set_ext_param(platform, :custom_fields, PandaPal.lti_options[:custom_fields])
        PandaPal.lti_options[:custom_fields].each do |k, v|
          @tc.set_ext_param(platform, k, v)
        end
      end
    end

    def add_lti_nav
      PandaPal.lti_paths.each do |k, v|
        @tc.set_ext_param(platform, k.to_sym, ext_params(v, k))
      end
    end

    def add_environments
      @tc.set_ext_param(platform, :environments, PandaPal.lti_environments)
    end

    def ext_params(options, k)
      options = LaunchUrlHelpers.normalize_lti_launch_desc(options)
      options[:url] = PandaPal::LaunchUrlHelpers.absolute_launch_url(k.to_sym, host: parsed_request_url, launch_handler: nil)
      options
    end
  end
end