initialize the queue with previously unprocessed likes/posts

app/like_queue.rb

···
 class LikeQueue
   BATCH_SIZE = 25
 
-  def initialize
+  def initialize(likes = [])
     @mutex = Mutex.new
-    @queue = []
+    @queue = likes
   end
 
   def push(like)

lib/tasks/import.rake

···
     raise "Required USER parameter missing"
   end
 
-  queue = LikeQueue.new
+  queue = LikeQueue.new(Like.where(post: nil).to_a)
   report = ImportReport.new
 
   importer = Importer.new(ENV['USER'])