FEATURE: add opengraph and twitter meta tags on every page

app/helpers/application_helper.rb

@@ -148,6 +148,8 @@ module ApplicationHelper
       opts[:image] = "#{uri.scheme}:#{opts[:image]}"
     elsif opts[:image].present? && opts[:image].start_with?("/uploads/")
       opts[:image] = "#{Discourse.base_url}#{opts[:image]}"
+    elsif SiteSetting.default_opengraph_image_url.present?
+      opts[:image] = SiteSetting.default_opengraph_image_url
     end
 
     # Add opengraph tags

app/views/about/index.html.erb

@@ -104,3 +104,7 @@
 <br/>
 
 <% end %>
+
+<% content_for :head do %>
+  <%= raw crawlable_meta_data(title: SiteSetting.title, description: SiteSetting.site_description) %>
+<% end %>

app/views/categories/index.html.erb

@@ -12,3 +12,7 @@
 </div>
 
 <% content_for :title do %><%= @title %><% end %>
+
+<% content_for :head do %>
+  <%= raw crawlable_meta_data(title: SiteSetting.title, description: SiteSetting.site_description) %>
+<% end %>

app/views/list/list.erb

@@ -65,6 +65,10 @@
     <%= auto_discovery_link_tag(:rss, { action: :category_feed }, title: t('rss_topics_in_category', category: @category.name)) %>
     <%= raw crawlable_meta_data(title: @category.name, description: @category.description) %>
   <% end %>
+<% else %>
+  <% content_for :head do %>
+    <%= raw crawlable_meta_data(title: SiteSetting.title, description: SiteSetting.site_description) %>
+  <% end %>
 <% end %>
 
 <% if @title %>

app/views/static/show.html.erb

@@ -23,4 +23,11 @@
 
 <% if @title %>
   <% content_for :title do %><%= @title %><% end %>
+  <% content_for :head do %>
+    <%= raw crawlable_meta_data(title: @title, description: SiteSetting.site_description) %>
+  <% end %>
+<% else %>
+  <% content_for :head do %>
+    <%= raw crawlable_meta_data(title: SiteSetting.title, description: SiteSetting.site_description) %>
+  <% end %>
 <% end %>

lib/topic_view.rb

@@ -174,7 +174,7 @@ class TopicView
       # show poster avatar
       @desired_post.user.avatar_template_url.gsub("{size}", "100") if @desired_post.user
     else
-      @topic.image_url || SiteSetting.default_opengraph_image_url
+      @topic.image_url
     end
   end