added Markdown to answers

app/helpers/markdown_helper.rb

@@ -0,0 +1,21 @@
+module MarkdownHelper
+
+  def markdown(content)
+    md = Redcarpet::Markdown.new(FlavoredMarkdown,
+                                 filter_html: true,
+                                 escape_html: true,
+                                 no_images: true,
+                                 no_styles: true,
+                                 safe_links_only: true,
+                                 xhtml: false,
+                                 hard_wrap: true,
+                                 no_intra_emphasis: true,
+                                 tables: true,
+                                 fenced_code_blocks: true,
+                                 autolink: true,
+                                 disable_indented_code_blocks: true,
+                                 strikethrough: true,
+                                 superscript: true)
+    Sanitize.fragment(md.render(content), EVIL_TAGS).html_safe
+  end
+end

app/services/flavored_markdown.rb

@@ -0,0 +1,26 @@
+class FlavoredMarkdown < Redcarpet::Render::HTML
+  include Rails.application.routes.url_helpers
+
+  def preprocess(text)
+    wrap_mentions(text)
+  end
+
+  def wrap_mentions(text)
+    text.gsub! /(^|\s)(@\w+)/ do
+      "#{$1}[#{$2}](#{show_user_profile_path $2.tr('@', '')})"
+    end
+    text
+  end
+
+  def header(text, _header_level)
+    paragraph text
+  end
+
+  def paragraph(text)
+    "<p>#{text}</p>"
+  end
+
+  def raw_html(raw_html)
+    Rack::Utils.escape_html raw_html
+  end
+end

app/views/shared/_answerbox.html.haml

@@ -25,14 +25,14 @@
   .panel-body
     %p
       - if @display_all.nil?
-        = a.content[0..255]
+        = markdown a.content[0..255]
         - if a.content.length > 255
           [...]
           %p
             %a.btn.btn-primary{href: show_user_answer_path(a.user.screen_name, a.id)}
               Read the entire answer
       - else
-        = a.content
+        = markdown a.content
     - if @user.nil?
       .row
         .col-md-6.col-sm-4.col-xs-7.text-left.text-muted