Extract markdown helper logic to a class

This way it'll be easier for other Consul installations to overwrite
parts of the code, like the default options.

app/helpers/application_helper.rb

@@ -11,26 +11,7 @@ def rtl?(locale = I18n.locale)
   end
 
   def markdown(text, **render_options)
-    return text if text.blank?
-
-    default_render_options = {
-      filter_html:     false,
-      hard_wrap:       true,
-      link_attributes: {  target: "_blank" }
-    }
-    renderer = Redcarpet::Render::HTML.new(default_render_options.merge(render_options))
-
-    extensions = {
-      autolink:           true,
-      fenced_code_blocks: true,
-      lax_spacing:        true,
-      no_intra_emphasis:  true,
-      strikethrough:      true,
-      superscript:        true,
-      tables:             true
-    }
-
-    AdminLegislationSanitizer.new.sanitize(Redcarpet::Markdown.new(renderer, extensions).render(text))
+    MarkdownConverter.new(text, **render_options).render
   end
 
   def wysiwyg(text)

app/models/legislation/draft_version.rb

@@ -22,13 +22,11 @@ class Legislation::DraftVersion < ApplicationRecord
   scope :published, -> { where(status: "published").order("id DESC") }
 
   def body_html
-    ApplicationController.helpers.markdown(body, with_toc_data: true)
+    MarkdownConverter.new(body, with_toc_data: true).render
   end
 
   def toc_html
-    renderer = Redcarpet::Render::HTML_TOC.new(with_toc_data: true)
-
-    Redcarpet::Markdown.new(renderer).render(body)
+    MarkdownConverter.new(body).render_toc
   end
 
   def display_title

lib/markdown_converter.rb

@@ -0,0 +1,48 @@
+class MarkdownConverter
+  attr_reader :text, :render_options
+
+  def initialize(text, **render_options)
+    @text = text
+    @render_options = render_options
+  end
+
+  def render
+    return text if text.blank?
+
+    AdminLegislationSanitizer.new.sanitize(Redcarpet::Markdown.new(renderer, extensions).render(text))
+  end
+
+  def render_toc
+    Redcarpet::Markdown.new(toc_renderer).render(text)
+  end
+
+  private
+
+    def renderer
+      Redcarpet::Render::HTML.new(default_render_options.merge(render_options))
+    end
+
+    def toc_renderer
+      Redcarpet::Render::HTML_TOC.new(with_toc_data: true)
+    end
+
+    def default_render_options
+      {
+        filter_html:     false,
+        hard_wrap:       true,
+        link_attributes: { target: "_blank" }
+      }
+    end
+
+    def extensions
+      {
+        autolink:           true,
+        fenced_code_blocks: true,
+        lax_spacing:        true,
+        no_intra_emphasis:  true,
+        strikethrough:      true,
+        superscript:        true,
+        tables:             true
+      }
+    end
+end