From 23d593c0f4ce6b3078dd3984ff85189a765f8501 Mon Sep 17 00:00:00 2001
From: Franck Nijhof <frenck@frenck.nl>
Date: Thu, 15 Mar 2018 22:21:57 +0100
Subject: [PATCH] Adds rel nofollow to external links (#4918)

* :sparkles: Adds rel nofollow to external links

Fixes #4583

Signed-off-by: Franck Nijhof <frenck@geekchimp.com>

* :ribbon: Adds support for appending nofollow to existing external links
---
 Gemfile                      |  1 +
 Gemfile.lock                 |  6 +++++-
 plugins/no_follow.rb         | 33 +++++++++++++++++++++++++++++++++
 source/_layouts/default.html |  2 +-
 4 files changed, 40 insertions(+), 2 deletions(-)
 create mode 100644 plugins/no_follow.rb

diff --git a/Gemfile b/Gemfile
index d7b8fe661d0..1b5ab49ea5a 100644
--- a/Gemfile
+++ b/Gemfile
@@ -24,3 +24,4 @@ group :jekyll_plugins do
 end
 
 gem 'sinatra', '~> 1.4.2'
+gem 'nokogiri'
diff --git a/Gemfile.lock b/Gemfile.lock
index 9b9a87a02c0..051fb09fdb5 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -42,6 +42,9 @@ GEM
       rb-inotify (~> 0.9, >= 0.9.7)
     mercenary (0.3.6)
     method_source (0.8.2)
+    mini_portile2 (2.3.0)
+    nokogiri (1.8.2)
+      mini_portile2 (~> 2.3.0)
     octopress (3.0.11)
       jekyll (>= 2.0)
       mercenary (~> 0.3.2)
@@ -100,6 +103,7 @@ DEPENDENCIES
   jekyll-redirect-from
   jekyll-sitemap
   jekyll-time-to-read
+  nokogiri
   octopress (~> 3.0)
   octopress-include-tag
   pry
@@ -113,4 +117,4 @@ RUBY VERSION
    ruby 2.4.1p111
 
 BUNDLED WITH
-   1.15.4
+   1.16.1
diff --git a/plugins/no_follow.rb b/plugins/no_follow.rb
new file mode 100644
index 00000000000..27da6c90f25
--- /dev/null
+++ b/plugins/no_follow.rb
@@ -0,0 +1,33 @@
+# Jekyll Auto Nofollow Plugin
+# Automatically adds rel='external nofollow' to outgoing links.
+
+require 'jekyll'
+require 'nokogiri'
+
+module Jekyll
+    module NoFollow
+        def nofollow(content)
+            dom = Nokogiri::HTML.fragment(content)
+
+            # Find all links
+            dom.css('a').each do |link|
+                rel = ['external', 'nofollow']
+
+                # All external links start with 'http', skip when this one does not
+                next unless link.get_attribute('href') =~ /\Ahttp/i
+
+                # Play nice with our own links
+                next if link.get_attribute('href') =~ /\Ahttps?:\/\/\w*.?home-assistant.io/i
+
+                # Play nice with links that already have a rel attribute set
+                rel.unshift(link.get_attribute('rel'))
+
+                # Add rel attribute to link
+                link.set_attribute('rel', rel.join(' ').strip)
+            end
+            dom.to_s
+        end
+    end
+end
+
+Liquid::Template.register_filter(Jekyll::NoFollow)
diff --git a/source/_layouts/default.html b/source/_layouts/default.html
index 5c8e47d068f..ca7e0199c2b 100644
--- a/source/_layouts/default.html
+++ b/source/_layouts/default.html
@@ -24,7 +24,7 @@ layout: compress
         <div class="grid__item two-thirds lap-one-whole palm-one-whole">
         {% endif %}
 
-          {{ content }}
+          {{ content | nofollow }}
 
         </div>