Merge pull request #112 from happy-software/backpop_playlist_deltas

Backpop PlaylistDelta

lib/tasks/backpop_playlist_deltas.rake

@@ -0,0 +1,29 @@
+namespace :backpop_playlist_deltas do
+  desc 'Run a one-time job to back pop PlaylistSnapshot diffs into PlaylistDelta records'
+  task :run => :environment do
+    start_time = Time.now
+    puts "Started at #{start_time}"
+    PlaylistSnapshot.all.each do |snapshot|
+      next if snapshot.playlist_delta.present?
+
+      previous_snapshot = PlaylistSnapshot.where(playlist_id: snapshot.tracked_playlist.playlist_id).where("created_at < ?", snapshot.created_at).newest
+      next unless previous_snapshot.present?
+
+      current_playlist_items  = snapshot.playlist_items
+      previous_playlist_items = PlaylistSnapshot.get_working_songs(previous_snapshot.playlist_items)
+      diff                    = PlaylistDifferenceCalculator.calculate_diffs(current_playlist_items, previous_playlist_items)
+      next unless diff.any_changes?
+
+      PlaylistDelta.create!(
+        added:             diff.added_songs,
+        removed:           diff.removed_songs,
+        playlist_snapshot: snapshot,
+        tracked_playlist:  snapshot.tracked_playlist,
+      )
+    end
+
+    finish_time = Time.now
+    puts "Finished at: #{finish_time}"
+    puts "Total Runtime: #{finish_time - start_time}s"
+  end
+end