delegate removal from favorites and updating of user fav counts to delayed job

app/models/favorite.rb

@@ -14,10 +14,17 @@ class Favorite < ApplicationRecord
       post.append_user_to_fav_string(user.id)
       User.where(:id => user.id).update_all("favorite_count = favorite_count + 1")
       user.favorite_count += 1
-      # post.fav_count += 1 # this is handled in Post#clean_fav_string!
     end
   end
 
+  def self.purge_post(post_id, user_ids)
+    0.upto(99) do |uid|
+      Favorite.where("user_id % 100 = ?", uid).delete_all(post_id: post_id)
+    end
+
+    User.where(:id => user_ids).update_all("favorite_count = favorite_count - 1")
+  end
+
   def self.remove(user:, post: nil, post_id: nil)
     Favorite.transaction do
       if post && post_id.nil?