Extract markdown helper; use Nokogiri for link_most_content

Gemfile

@@ -55,6 +55,9 @@ gem 'bcrypt-ruby', '~> 3.1.2'
 # Paignator
 gem 'kaminari', '~> 0.15.1'
 
+# Nokogiri XML parser
+gem 'nokogiri', '~> 1.6.1'
+
 group :development do
   # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/jonleighton/spring
   gem 'spring'

Gemfile.lock

@@ -142,8 +142,11 @@ GEM
       treetop (~> 1.4.8)
     method_source (0.8.2)
     mime-types (1.25.1)
+    mini_portile (0.5.2)
     minitest (5.2.0)
     multi_json (1.8.2)
+    nokogiri (1.6.1)
+      mini_portile (~> 0.5.0)
     pg (0.17.1)
     polyglot (0.3.3)
     pry (0.9.12.4)
@@ -204,6 +207,7 @@ DEPENDENCIES
   jquery-rails
   jquery-turbolinks (~> 2.0.1)
   kaminari (~> 0.15.1)
+  nokogiri (~> 1.6.1)
   pg
   rack-livereload
   rails!

app/helpers/markdown_helper.rb

@@ -0,0 +1,22 @@
+require 'rouge/plugins/redcarpet'
+
+module MarkdownHelper
+  class HTMLRender < Redcarpet::Render::HTML
+    include Rouge::Plugins::Redcarpet
+  end
+
+  def markdown_post(content)
+    renderer = HTMLRender.new(hard_wrap: true,
+
+                              filter_html: true,
+                              link_attributes: { rel: 'nofollow' })
+
+    markdown = Redcarpet::Markdown.new(renderer,
+                                       autolink: true,
+                                       space_after_headers: true,
+                                       space_after_headers: true,
+                                       fenced_code_blocks: true)
+
+    markdown.render(content)
+  end
+end

app/helpers/posts_helper.rb

@@ -1,5 +1,3 @@
-require 'rouge/plugins/redcarpet'
-
 module PostsHelper
   def post_votes(posts, user)
     user.post_votes.where(post_id: posts.pluck(:id)).map { |post_vote|
@@ -7,45 +5,34 @@ module PostsHelper
     }
   end
 
-  def format_post(content)
-    sanitize(markdown_post(content),
+  def format_post(text)
+    sanitize(link_post_content(markdown_post(text)),
              tags: %w(p br img h1 h2 h3 h4 blockquote pre code strong em a ul ol li span),
              attributes: %w(href src class title alt target rel))
   end
 
-  class PostHTMLRender < Redcarpet::Render::HTML
-    include Rouge::Plugins::Redcarpet
+  def link_post_content(text)
+    doc = Nokogiri::HTML.fragment(text)
 
-    def normal_text(text)
-      # extract @username
-      text.gsub!(/@(\w+)/) { |match|
-        username = $1
-        %Q|<a href="/~#{username}">#{match}</a>|
-      }
+    doc.search('text()').each do |node|
+      unless node.ancestors('a, pre, code').any?
+        text = node.text
+        # link @username
+        text.gsub!(/@(\w+)/) { |match|
+          username = $1
+          %Q|<a href="/~#{username}">#{match}</a>|
+        }
 
-      # extract #floor
-      text.gsub!(/#(\d+)/) { |match|
-        floor = $1
-        page = (floor.to_i + 24) / 25
-        %Q|<a href="?page=#{page}##{floor}">#{match}</a>|
-      }
-
-      text
+        # link #floor
+        text.gsub!(/#(\d+)/) { |match|
+          floor = $1
+          page = (floor.to_i + 24) / 25
+          %Q|<a href="?page=#{page}##{floor}">#{match}</a>|
+        }
+        node.replace text
+      end
     end
-  end
 
-  def markdown_post(content)
-    renderer = PostHTMLRender.new(
-      hard_wrap: true,
-      filter_html: true,
-      link_attributes: { rel: 'nofollow' }
-    )
-
-    markdown = Redcarpet::Markdown.new(renderer,
-                                       autolink: true,
-                                       space_after_headers: true,
-                                       fenced_code_blocks: true)
-
-    markdown.render(content)
+    doc.to_html
   end
 end

test/helpers/markdown_helper_test.rb

@@ -0,0 +1,4 @@
+require 'test_helper'
+
+class MarkdownHelperTest < ActionView::TestCase
+end

test/helpers/posts_helper_test.rb

@@ -16,16 +16,17 @@ class PostsHelperTest < ActionView::TestCase
     )
   end
 
-  test "should convert @username" do
-    create :user, username: 'username'
-    assert_equal %Q|<p><a href="/~username">@username</a></p>\n|, markdown_post('@username')
+  test "should link mentions" do
+    assert_equal %q|<p><a href="/~username">@username</a></p>|, link_post_content('<p>@username</p>')
+    assert_equal %q|<a href="http://example.org/">@username</a>|, link_post_content(%q|<a href="http://example.org/">@username</a>|)
+    assert_equal %q|<pre>@username</pre>|, link_post_content(%q|<pre>@username</pre>|)
+    assert_equal %q|<code>@username</code>|, link_post_content(%q|<code>@username</code>|)
   end
 
-  test "should convert floor" do
-    assert_equal %Q|<p><a href="?page=1#1">#1</a></p>\n|, markdown_post('#1')
-
-    assert_equal %Q|<p><a href="?page=1#25">#25</a></p>\n|, markdown_post("#25")
-    assert_equal %Q|<p><a href="?page=2#26">#26</a></p>\n|, markdown_post("#26")
-    assert_equal %Q|<p><a href="?page=3#51">#51</a></p>\n|, markdown_post("#51")
+  test "should link floor" do
+    assert_equal %Q|<p><a href="?page=1#1">#1</a></p>|, link_post_content('<p>#1</p>')
+    assert_equal %Q|<p><a href="?page=1#25">#25</a></p>|, link_post_content("<p>#25</p>")
+    assert_equal %Q|<p><a href="?page=2#26">#26</a></p>|, link_post_content("<p>#26</p>")
+    assert_equal %Q|<p><a href="?page=3#51">#51</a></p>|, link_post_content("<p>#51</p>")
   end
 end