Add opengraph and twitter card support to topics

app/helpers/application_helper.rb

@@ -32,4 +32,25 @@ module ApplicationHelper
     current_user.try(:admin?)
   end
 
+  def crawlable_meta_data(url, title, description)
+    # Image to supply as meta data
+    image = "#{Discourse.base_url}#{SiteSetting.logo_url}"
+
+    # Add opengraph tags
+    result =  tag(:meta, property: 'og:site_name', content: SiteSetting.title) << "\n"
+    result << tag(:meta, property: 'og:image', content: image) << "\n"
+    result << tag(:meta, property: 'og:url', content: url) << "\n"
+    result << tag(:meta, property: 'og:title', content: title) << "\n"
+    result << tag(:meta, property: 'og:description', content: description) << "\n"
+
+    # Add twitter card
+    result << tag(:meta, property: 'twitter:card', content: "summary") << "\n"
+    result << tag(:meta, property: 'twitter:url', content: url) << "\n"
+    result << tag(:meta, property: 'twitter:title', content: title) << "\n"
+    result << tag(:meta, property: 'twitter:description', content: description) << "\n"
+    result << tag(:meta, property: 'twitter:image', content: image) << "\n"
+
+    result
+  end
+
 end

app/views/layouts/application.html.erb

@@ -12,12 +12,9 @@
     <link rel="icon" type="image/png" href=<%=SiteSetting.favicon_url%>>
     <%= javascript_include_tag "preload_store" %>
 
-
-
     <%= render :partial => "common/special_font_face" %>
     <%= render :partial => "common/discourse_stylesheet" %>
 
-
     <%= csrf_meta_tags %>
 
     <%= yield :head %>

app/views/topics/show.html.erb

@@ -24,4 +24,5 @@
 
 <% content_for :head do %>
   <%= auto_discovery_link_tag(@topic_view, {action: :feed, format: :rss}, title: t('rss_posts_in_topic', topic: @topic_view.title), type: 'application/rss+xml') %>
+  <%= crawlable_meta_data(@topic_view.absolute_url, @topic_view.title, @topic_view.summary) %>
 <% end %>

lib/topic_view.rb

@@ -2,6 +2,7 @@ require_dependency 'guardian'
 require_dependency 'topic_query'
 
 class TopicView
+  include ActionView::Helpers
 
   attr_accessor :topic, :min, :max, :draft, :draft_key, :draft_sequence, :posts
 
@@ -61,6 +62,10 @@ class TopicView
     "#{@topic.relative_url}?page=#{next_page}"
   end
 
+  def absolute_url
+    "#{Discourse.base_url}#{@topic.relative_url}"
+  end
+
   def relative_url
     @topic.relative_url
   end
@@ -69,6 +74,15 @@ class TopicView
     @topic.title
   end
 
+  def summary
+    return nil if posts.blank?
+    first_post_content = sanitize(posts.first.cooked, tags: [], attributes: [])
+    first_post_content.gsub!(/\n/, ' ')
+
+    return first_post_content if first_post_content.length <= 500
+    "#{first_post_content[0..500]}..."
+  end
+
   def filter_posts(opts = {})
     if opts[:post_number].present?
       # Get posts near a post

spec/components/topic_view_spec.rb

@@ -26,6 +26,14 @@ describe TopicView do
     lambda { TopicView.new(topic.id, nil) }.should raise_error(Discourse::NotLoggedIn)
   end
 
+  it "provides an absolute url" do
+    topic_view.absolute_url.should be_present
+  end
+
+  it "provides a summary of the first post" do
+    topic_view.summary.should be_present
+  end
+
   describe "#get_canonical_path" do
     let(:user) { Fabricate(:user) }
     let(:topic) { Fabricate(:topic) }