Update RssReader's liquid & youtube parsing logic (#3229)

* Loosen up Liquid::Variable

* Improve RssReader's youtube id detection

* Revert "Loosen up Liquid::Variable"

This reverts commit fd385c6649a9e0ca3786588a29a3ff2b8fe98218.

* RSS: Wrap liquid variable in backtick

* User inner_html intead of text

app/services/rss_reader/assembler.rb

@@ -37,9 +37,17 @@ class RssReader
     def assemble_body_markdown
       cleaned_content = HtmlCleaner.new.clean_html(get_content)
       cleaned_content = thorough_parsing(cleaned_content, @feed.url)
-      ReverseMarkdown.
+
+      content = ReverseMarkdown.
         convert(cleaned_content, github_flavored: true).
-        gsub("```\n\n```", "").gsub(/ |\u00A0/, " ")
+        gsub("```\n\n```", "").
+        gsub(/ |\u00A0/, " ")
+
+      content.gsub!(/{%\syoutube\s(.{11,18})\s%}/) do |tag|
+        tag.gsub("\\_", "_")
+      end
+
+      content
     end
 
     def get_content
@@ -53,6 +61,7 @@ class RssReader
         parse_and_translate_gist_iframe!(html_doc)
         parse_and_translate_youtube_iframe!(html_doc)
         parse_and_translate_tweet!(html_doc)
+        parse_liquid_variable!(html_doc)
       else
         clean_relative_path!(html_doc, feed_url)
       end
@@ -93,11 +102,19 @@ class RssReader
       end
     end
 
+    def parse_liquid_variable!(html_doc)
+      # Medium articles does not wrap {{ }} content in liquid tag.
+      # This will wrap do so for content that isn't in pre and code tag
+      html_doc.css("//body :not(pre):not(code)").each do |node|
+        node.inner_html = node.inner_html.gsub(/{{.*?}}/) { |liquid| "`#{liquid}`" }
+      end
+    end
+
     def parse_and_translate_youtube_iframe!(html_doc)
       html_doc.css("iframe").each do |iframe|
         if /youtube\.com/.match?(iframe.attributes["src"].value)
           iframe.name = "p"
-          youtube_id = iframe.attributes["src"].value.scan(/embed%2F(.{4,12})%3F/).flatten.first
+          youtube_id = iframe.attributes["src"].value.scan(/embed%2F(.{4,11})/).flatten.first
           iframe.keys.each { |attr| iframe.remove_attribute(attr) }
           iframe.inner_html = "{% youtube #{youtube_id} %}"
         end