module Tekeya
  module Feed
    module Activity
      module Resque
        # A resque worker to copy activities when an entity tracks another
        class FeedCopy
          include Tekeya::Feed::Activity::Resque

          @queue = :activity_queue

          # @private
          def self.perform(tracked_feed_key, tracker_feed_key)
            # get the keys to the activities so we can increment the counters later
            activity_keys = ::Tekeya.redis.zrange(tracked_feed_key, 0, -1)

            ::Tekeya.redis.multi do
              # copy the latest activities from the tracked entity to the tracker feed
              ::Tekeya.redis.zunionstore(tracker_feed_key, [tracker_feed_key, tracked_feed_key])

              # increment the activity counter
              activity_keys.each do |activity_key|
                activity_counter_key = "#{activity_key}:counter"
                ::Tekeya.redis.incr(activity_counter_key)
              end
            end

            # trim the tracker feed and cleanup
            collect_garbage trim_feed(tracker_feed_key)
          end
        end
      end
    end
  end
end