Track associated toggl entry id for uniqueness, show stats for time spent in different parts of the lecture flow.

app/models/lecture.rb

@@ -10,6 +10,30 @@ class Lecture < ApplicationRecord
     :problems_class,
   ], default: :lecture
 
+  def prepared?
+    tracked_time_entries.where(kind: [:preparation]).any?
+  end
+
+  def attended?
+    tracked_time_entries.where(kind: [:concurrent, :catchup]).any?
+  end
+
+  def reviewed?
+    tracked_time_entries.where(kind: [:review]).any?
+  end
+
+  def total_preparation_time
+    tracked_time_entries.preparation.sum(&:duration).seconds
+  end
+
+  def total_attendance_time
+    tracked_time_entries.where(kind: [:concurrent, :catchup]).sum(&:duration).seconds
+  end
+
+  def total_review_time
+    tracked_time_entries.review.sum(&:duration).seconds
+  end
+
   def week_number
     ((start_time.beginning_of_week - course.semester_start_date.to_time) / 1.week).floor + 1
   end