Fix up user links

extras/markdowner.rb

@@ -9,6 +9,11 @@ class Markdowner
 
     exts = [:tagfilter, :autolink]
     root = CommonMarker.render_doc(text.to_s, [:SMART], exts)
+
+    unless opts[:disable_profile_links]
+      walk_text_nodes(root) {|n| postprocess_text_node(n)}
+    end
+
     ng = Nokogiri::HTML(root.to_html([:SAFE], exts))
 
     # change <h1>, <h2>, etc. headings to just bold tags
@@ -22,34 +27,51 @@ class Markdowner
 
     # make links have rel=nofollow
     ng.css("a").each do |h|
-      h[:rel] = "nofollow"
+      h[:rel] = "nofollow" unless h[:href].starts_with?("/")
     end
 
-    # XXX: t.replace(tx) unescapes HTML, so disable for now.  this probably
-    # needs to split text into separate nodes and then replace the @username
-    # with a proper 'a' node
-if false
-    unless opts[:disable_profile_links]
-      # make @username link to that user's profile
-      ng.search("//text()").each do |t|
-        if t.parent && t.parent.name.downcase == "a"
-          # don't replace inside <a>s
-          next
-        end
-
-        tx = t.text.gsub(/\B\@([\w\-]+)/) do |u|
-          if User.exists?(:username => u[1 .. -1])
-            "<a href=\"/u/#{u[1 .. -1]}\">#{u}</a>"
-          else
-            u
-          end
-        end
-
-        t.replace(tx)
-      end
-    end
-end
-
     ng.at_css("body").inner_html
   end
+
+  def self.walk_text_nodes(node, &block)
+    return if node.type == :link
+    return block.call(node) if node.type == :text
+
+    node.each do |child|
+      walk_text_nodes(child, &block)
+    end
+  end
+
+  def self.postprocess_text_node(node)
+    while node
+      return unless node.string_content =~ /\B(@[\w\-]+)/
+      before, user, after = $`, $1, $'
+
+      node.string_content = before
+
+      if User.exists?(:username => user[1..-1])
+        link = CommonMarker::Node.new(:link)
+        link.url = "/u/#{user[1..-1]}"
+        node.insert_after(link)
+
+        link_text = CommonMarker::Node.new(:text)
+        link_text.string_content = user
+        link.append_child(link_text)
+
+        node = link
+      else
+        node.string_content += user
+      end
+
+      if after.length > 0
+        remainder = CommonMarker::Node.new(:text)
+        remainder.string_content = after
+        node.insert_after(remainder)
+
+        node = remainder
+      else
+        node = nil
+      end
+    end
+  end
 end