added a reverse index of user uploads + rake task

lib/tasks/images.rake

@@ -10,3 +10,39 @@ task "images:compress" => :environment do
   end
 end
 
+desc "updates reverse index of image uploads"
+task "images:reindex" => :environment do
+	RailsMultisite::ConnectionManagement.each_connection do |db|
+		puts "Reindexing #{db}"
+    Post.select([:id, :cooked]).find_each do |p|
+			doc = Nokogiri::HTML::fragment(p.cooked)
+			doc.search("img").each do |img|
+				src = img['src']
+				if src.present? && has_been_uploaded?(src) && m = uploaded_regex.match(src)
+          begin
+  					Post.exec_sql("INSERT INTO posts_uploads (post_id, upload_id) VALUES (?, ?)", p.id, m[:upload_id])
+          rescue ActiveRecord::RecordNotUnique
+          end
+				end
+			end
+			putc "."
+		end
+  end
+  puts "\ndone."
+end
+
+def uploaded_regex
+  /\/uploads\/#{RailsMultisite::ConnectionManagement.current_db}\/(?<upload_id>\d+)\/[0-9a-f]{16}\.(png|jpg|jpeg|gif|tif|tiff|bmp)/
+end
+
+def has_been_uploaded?(url)
+  url =~ /^\/[^\/]/ || url.start_with?(base_url) || (asset_host.present? && url.start_with?(asset_host))
+end
+
+def base_url
+  asset_host.present? ? asset_host : Discourse.base_url_no_prefix
+end
+
+def asset_host
+  ActionController::Base.asset_host
+end