FIX: S3Cdn link clicks weren't working

app/models/topic_link_click.rb

@@ -30,7 +30,8 @@ class TopicLinkClick < ActiveRecord::Base
     urls << url.sub(/\?.*$/, '') if url.include?('?')
 
     # add a cdn link
-    if uri && Discourse.asset_host.present?
+    if uri
+      if Discourse.asset_host.present?
         cdn_uri = URI.parse(Discourse.asset_host) rescue nil
         if cdn_uri && cdn_uri.hostname == uri.hostname && uri.path.starts_with?(cdn_uri.path)
           is_cdn_link = true
@@ -38,6 +39,18 @@ class TopicLinkClick < ActiveRecord::Base
         end
       end
 
+      if SiteSetting.s3_cdn_url.present?
+        cdn_uri = URI.parse(SiteSetting.s3_cdn_url) rescue nil
+        if cdn_uri && cdn_uri.hostname == uri.hostname && uri.path.starts_with?(cdn_uri.path)
+          is_cdn_link = true
+
+          path = uri.path[(cdn_uri.path.length)..-1]
+          urls << path
+          urls << "#{Discourse.store.absolute_base_url}#{path}"
+        end
+      end
+    end
+
     link = TopicLink.select([:id, :user_id])
 
     # test for all possible URLs

spec/models/topic_link_click_spec.rb

@@ -144,6 +144,24 @@ describe TopicLinkClick do
 
         end
 
+        context "s3 cdns" do
+
+          it "works with s3 urls" do
+            SiteSetting.s3_cdn_url = "https://discourse-s3-cdn.global.ssl.fastly.net"
+
+            post = Fabricate(:post, topic: @topic, raw: "[test](//test.localhost/uploads/default/my-test-link)")
+            TopicLink.extract_from(post)
+
+            url = TopicLinkClick.create_from(
+              url: "https://discourse-s3-cdn.global.ssl.fastly.net/my-test-link",
+              topic_id: @topic.id,
+              ip: '127.0.0.3')
+
+            expect(url).to be_present
+          end
+
+        end
+
       end
 
       context 'with a HTTPS version of the same URL' do