Create TrackedTimeEntry as more general replacement of Attendance to include preparation and review

app/models/lecture.rb

@@ -3,6 +3,8 @@ class Lecture < ApplicationRecord
   has_one :attendance, dependent: :destroy
   has_one :recording, dependent: :nullify
 
+  has_many :tracked_time_entries, dependent: :destroy
+
   enum :kind, [
     :lecture,
     :problems_class,

app/models/tracked_time_entry.rb

@@ -0,0 +1,13 @@
+class TrackedTimeEntry < ApplicationRecord
+  belongs_to :lecture
+
+  enum :kind, [
+    :concurrent,
+    :catchup
+  ]
+
+  def duration
+    toggl_data['time_entries'].sum { |entry| entry['seconds'] }
+                              .seconds
+  end
+end