From ba637e40b6ed4e3175a86a27d27e01f0bd08a3c1 Mon Sep 17 00:00:00 2001
From: Neil Lalonde <neillalonde@gmail.com>
Date: Thu, 14 Jul 2016 13:52:37 -0400
Subject: [PATCH] FEATURE: Google Tag Manager Universal Analytics support

---
 .../discourse/initializers/page-tracking.js.es6     | 13 +++++++++++++
 app/helpers/application_helper.rb                   | 12 ++++++++++--
 app/helpers/common_helper.rb                        |  6 ++++++
 app/views/common/_google_tag_manager.html.erb       | 11 +++++++++++
 app/views/layouts/application.html.erb              |  2 ++
 config/locales/server.en.yml                        |  2 ++
 config/site_settings.yml                            |  7 +++++++
 7 files changed, 51 insertions(+), 2 deletions(-)
 create mode 100644 app/views/common/_google_tag_manager.html.erb

diff --git a/app/assets/javascripts/discourse/initializers/page-tracking.js.es6 b/app/assets/javascripts/discourse/initializers/page-tracking.js.es6
index 7f680580ea3..860ddaf0f80 100644
--- a/app/assets/javascripts/discourse/initializers/page-tracking.js.es6
+++ b/app/assets/javascripts/discourse/initializers/page-tracking.js.es6
@@ -50,5 +50,18 @@ export default {
         window.ga('send', 'pageview', {page: url, title: title});
       });
     }
+
+    // And Google Tag Manager too
+    if (typeof window.dataLayer !== 'undefined') {
+      onPageChange((url, title) => {
+        window.dataLayer.push({
+          'event': 'virtualPageView',
+          'page': {
+            'title': title,
+            'url': url
+          }
+        });
+      });
+    }
   }
 };
diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index 06d782214fa..c8321c795cc 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -15,8 +15,8 @@ module ApplicationHelper
   include ConfigurableUrls
   include GlobalPath
 
-  def ga_universal_json
-    cookie_domain = SiteSetting.ga_universal_domain_name.gsub(/^http(s)?:\/\//, '')
+  def google_universal_analytics_json(ua_domain_name)
+    cookie_domain = ua_domain_name.gsub(/^http(s)?:\/\//, '')
     result = {cookieDomain: cookie_domain}
     if current_user.present?
       result[:userId] = current_user.id
@@ -24,6 +24,14 @@ module ApplicationHelper
     result.to_json.html_safe
   end
 
+  def ga_universal_json
+    google_universal_analytics_json(SiteSetting.ga_universal_domain_name)
+  end
+
+  def google_tag_manager_json
+    google_universal_analytics_json(SiteSetting.gtm_ua_domain_name)
+  end
+
   def shared_session_key
     if SiteSetting.long_polling_base_url != '/'.freeze && current_user
       sk = "shared_session_key"
diff --git a/app/helpers/common_helper.rb b/app/helpers/common_helper.rb
index 10992b1ae6b..e6107369038 100644
--- a/app/helpers/common_helper.rb
+++ b/app/helpers/common_helper.rb
@@ -10,4 +10,10 @@ module CommonHelper
       render partial: "common/google_analytics"
     end
   end
+
+  def render_google_tag_manager_code
+    if Rails.env.production? && SiteSetting.gtm_container_id.present?
+      render partial: "common/google_tag_manager"
+    end
+  end
 end
diff --git a/app/views/common/_google_tag_manager.html.erb b/app/views/common/_google_tag_manager.html.erb
new file mode 100644
index 00000000000..dca75352a06
--- /dev/null
+++ b/app/views/common/_google_tag_manager.html.erb
@@ -0,0 +1,11 @@
+<script>
+dataLayer = [<%= google_tag_manager_json %>];
+</script>
+
+<noscript><iframe src="//www.googletagmanager.com/ns.html?id=<%= SiteSetting.gtm_container_id %>"
+height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript>
+<script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
+new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
+j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
+'//www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
+})(window,document,'script','dataLayer','<%= SiteSetting.gtm_container_id %>');</script>
diff --git a/app/views/layouts/application.html.erb b/app/views/layouts/application.html.erb
index 3b8b4ccc61f..af5e7df438d 100644
--- a/app/views/layouts/application.html.erb
+++ b/app/views/layouts/application.html.erb
@@ -44,6 +44,8 @@
   </head>
 
   <body class="<%= body_classes %>">
+    <%= render_google_tag_manager_code %>
+
     <div class='debug-eyeline'></div>
 
     <noscript data-path="<%= request.env['PATH_INFO'] %>">
diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index 754ceccc5c6..28183ff667d 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -914,6 +914,8 @@ en:
     ga_domain_name: "Google analytics (ga.js) domain name, eg: mysite.com; see http://google.com/analytics"
     ga_universal_tracking_code: "Google Universal Analytics (analytics.js) tracking code code, eg: UA-12345678-9; see http://google.com/analytics"
     ga_universal_domain_name: "Google Universal Analytics (analytics.js) domain name, eg: mysite.com; see http://google.com/analytics"
+    gtm_container_id: "Google Tag Manager container id. eg: GTM-ABCDEF"
+    gtm_ua_domain_name: "Universal Analytics via Google Tag manager domain name. 'auto' is recommended."
     enable_escaped_fragments: "Fall back to Google's Ajax-Crawling API if no webcrawler is detected. See https://developers.google.com/webmasters/ajax-crawling/docs/learn-more"
     enable_noscript_support: "Enable standard webcrawler search engine support via the noscript tag"
     allow_moderators_to_create_categories: "Allow moderators to create new categories"
diff --git a/config/site_settings.yml b/config/site_settings.yml
index 9fe29a028cb..3fe8cf31da6 100644
--- a/config/site_settings.yml
+++ b/config/site_settings.yml
@@ -97,6 +97,13 @@ basic:
   ga_domain_name:
     client: true
     default: ''
+  gtm_container_id:
+    client: true
+    default: ''
+    regex: "^GTM-"
+  gtm_ua_domain_name:
+    client: true
+    default: 'auto'
   top_menu:
     client: true
     refresh: true