UX: Replace heuristic solution for extracting root domain.

Gemfile

@@ -28,6 +28,7 @@ end
 gem 'mail'
 gem 'mime-types', require: 'mime/types/columnar'
 gem 'mini_mime'
+gem 'mini_suffix'
 
 gem 'hiredis'
 gem 'redis', require:  ["redis", "redis/connection/hiredis"]

Gemfile.lock

@@ -177,6 +177,8 @@ GEM
     mini_portile2 (2.3.0)
     mini_racer (0.1.11)
       libv8 (~> 5.7)
+    mini_suffix (0.1.0)
+      ffi (~> 1.9)
     minitest (5.10.3)
     mocha (1.2.1)
       metaclass (~> 0.0.1)
@@ -451,6 +453,7 @@ DEPENDENCIES
   mime-types
   mini_mime
   mini_racer
+  mini_suffix
   minitest
   mocha
   mock_redis

app/assets/javascripts/discourse/widgets/topic-map.js.es6

@@ -168,17 +168,16 @@ createWidget('topic-map-expanded', {
 
     const result = [avatars];
     if (attrs.topicLinks) {
-
       const toShow = state.allLinksShown ? attrs.topicLinks : attrs.topicLinks.slice(0, LINKS_SHOWN);
-      const links = toShow.map(l => {
 
+      const links = toShow.map(l => {
         let host = '';
+
         if (l.title && l.title.length) {
-          const domain = l.domain;
-          if (domain && domain.length) {
-            const s = domain.split('.');
-            if (s[0] === 'www') s.shift();
-            host = h('span.domain', s.join('.'));
+          const rootDomain = l.root_domain;
+
+          if (rootDomain && rootDomain.length) {
+            host = h('span.domain', rootDomain);
           }
         }
 

app/serializers/topic_link_serializer.rb

@@ -8,7 +8,8 @@ class TopicLinkSerializer < ApplicationSerializer
              :reflection,
              :clicks,
              :user_id,
-             :domain
+             :domain,
+             :root_domain,
 
   def url
     object['url']
@@ -50,4 +51,8 @@ class TopicLinkSerializer < ApplicationSerializer
     object['domain']
   end
 
+  def root_domain
+    MiniSuffix.domain(domain)
+  end
+
 end

spec/serializers/topic_link_serializer_spec.rb

@@ -0,0 +1,13 @@
+require 'rails_helper'
+
+describe TopicLinkSerializer do
+
+  it "correctly serializes the topic link" do
+    post = Fabricate(:post, raw: 'https://meta.discourse.org/')
+    TopicLink.extract_from(post)
+    serialized = described_class.new(post.topic_links.first, root: false).as_json
+
+    expect(serialized[:domain]).to eq("meta.discourse.org")
+    expect(serialized[:root_domain]).to eq("discourse.org")
+  end
+end