add schema.org metatags

app/presenters/post_presenter.rb

@@ -21,7 +21,7 @@ class PostPresenter < Presenter
 
     path = options[:path_prefix] || "/posts"
 
-    html =  %{<article id="post_#{post.id}" class="#{preview_class(post, options[:pool])}" #{data_attributes(post)}>}
+    html =  %{<article itemscope itemtype="http://schema.org/ImageObject" id="post_#{post.id}" class="#{preview_class(post, options[:pool])}" #{data_attributes(post)}>}
     if options[:tags].present?
       tag_param = "?tags=#{CGI::escape(options[:tags])}"
     elsif options[:pool_id] || options[:pool]
@@ -32,7 +32,7 @@ class PostPresenter < Presenter
       tag_param = nil
     end
     html << %{<a href="#{path}/#{post.id}#{tag_param}">}
-    html << %{<img src="#{post.preview_file_url}" alt="#{h(post.tag_string)}">}
+    html << %{<img itemprop="thumbnailUrl" src="#{post.preview_file_url}" alt="#{h(post.tag_string)}">}
     html << %{</a>}
 
     if options[:pool]

app/presenters/tag_set_presenter.rb

@@ -12,7 +12,7 @@ class TagSetPresenter < Presenter
   def tag_list_html(template, options = {})
     html = ""
     if @tags.present?
-      html << "<ul>"
+      html << '<ul itemscope itemtype="http://schema.org/ImageObject">'
       @tags.each do |tag|
         html << build_list_item(tag, template, options)
       end
@@ -112,7 +112,12 @@ private
 
     humanized_tag = tag.tr("_", " ")
     path = options[:path_prefix] || "/posts"
-    html << %{<a class="search-tag" href="#{path}?tags=#{u(tag)}">#{h(humanized_tag)}</a> }
+    if categories[tag] == Tag.categories.artist
+      itemprop = 'itemprop="author"'
+    else
+      itemprop = nil
+    end
+    html << %{<a class="search-tag" #{itemprop} href="#{path}?tags=#{u(tag)}">#{h(humanized_tag)}</a> }
 
     unless options[:name_only]
       if counts[tag].to_i >= 10_000