Adds altmetrics embed.

closes #718

app/assets/stylesheets/application.sass.scss

@@ -24,3 +24,7 @@
 .record-metadata {
   margin-bottom: 2em;
 }
+
+.altmetric-embed a {
+  border-bottom: none;
+}

app/views/purl/_stats.html.erb

@@ -0,0 +1,11 @@
+<% if document.doi.present? %>
+  <div class="section">
+    <div class="section-heading">
+      <h2>Usage metrics</h2>
+    </div>
+    <div class="section-body mt-3">
+      <p><a href="https://help.altmetric.com/support/solutions/articles/6000232837-what-is-altmetric-and-what-does-it-provide-" target='_blank' rel='noopener'>Altmetric</a> tracks online attention to this work. A badge is shown only when online mentions are found.</p>
+      <div class='altmetric-embed' data-badge-type='donut' data-doi="<%= document.doi_id %>" data-badge-popover='right' data-hide-no-mentions='true'></div>
+    </div>
+  </div>
+<% end %>

app/views/purl/show.html.erb

@@ -9,9 +9,13 @@
   <%= tag :link, rel: "alternate", title: "MODS XML", type: 'application/xml', href: purl_url(@purl, format: 'mods') if @purl.mods? %>
   <%= tag :link, rel: "alternate", title: "IIIF Manifest", type: 'application/json', href: iiif_manifest_url(@purl) if @purl.iiif_manifest? %>
   <%= tag :link, rel: "up", href: purl_url(@purl.containing_collections.first) if @purl.containing_collections.present? %>
-  <%= tag :meta, name: 'citation_doi', content: @purl.doi_id if @purl.doi.present? %>
   <%= tag :meta, name: 'citation_title', content: @purl.title %>
   <%= tag :meta, name: 'robots', content: 'noindex' unless @purl.rights.world_downloadable? %>
+
+  <% if @purl.doi %>
+    <script type='text/javascript' src='https://d1bxh8uas1mnw7.cloudfront.net/assets/embed.js'></script>  
+    <%= tag :meta, name: 'citation_doi', content: @purl.doi_id %>
+  <% end %>
 <% end %>
 
 <% keywords(@purl.mods.subject.compact.map(&:values).join(',')) if @purl.mods? && @purl.mods.subject %>
@@ -50,5 +54,7 @@ end
     <% if @purl.mods? %>
       <%= render 'mods_metadata_sections', document: @purl %>
     <% end %>
+
+    <%= render 'stats', document: @purl %>
   </div>
 </div>

spec/features/integration_spec.rb

@@ -172,10 +172,13 @@
   end
 
   context 'item with a DOI' do
-    it 'includes citation_doi meta tag' do
+    it 'includes altmetrics' do
       visit '/bb051dp0564'
+
       expect(page).to have_selector 'meta[name="citation_doi"][content="10.25740/bb051dp0564"]', visible: :hidden
       expect(page).to have_selector 'meta[name="citation_title"][content="The Distinct Impacts of Content Moderation"]', visible: :hidden
+      expect(page).to have_selector 'script[src="https://d1bxh8uas1mnw7.cloudfront.net/assets/embed.js"]', visible: :hidden
+      expect(page).to have_css '.altmetric-embed'
     end
   end