Add live course statistics for teachers

app/controllers/courses_controller.rb

@@ -218,6 +218,15 @@ def statistics
     @answered = @course.answered_questions.count
   end
 
+  def live_statistics
+    time_range = 1.hour.ago..Time.zone.now
+
+    @online_users = @course.users.online.count
+    # number of submissions per minute for the last hour
+    @submissions_per_minute = @course.submissions.where(created_at: time_range).group('MINUTE(created_at)').count
+    @activities_being_worked_on = @course.activities_being_worked_on(3, time_range)
+  end
+
   def scoresheet
     @title = I18n.t('courses.scoresheet.scoresheet')
     @crumbs = [[@course.name, course_path(@course)], [I18n.t('courses.scoresheet.scoresheet'), '#']]

app/models/course.rb

@@ -223,6 +223,15 @@ def series_being_worked_on(limit = 3, exclude = [])
     result
   end
 
+  def activities_being_worked_on(limit = 3, time_range = 1.hour.ago..Time.zone.now)
+    exercises.joins('inner join submissions ON submissions.exercise_id = activities.id')
+             .where(submissions: { created_at: time_range, course_id: id })
+             .group('activities.id')
+             .select('activities.*, COUNT(*) as submission_count')
+             .reorder(Arel.sql('COUNT(*) DESC'))
+             .first(limit)
+  end
+
   def homepage_activities(user, limit = 3)
     result = []
     incomplete_activities = series.visible.joins(:activities) # all activities in visible series

app/models/user.rb

@@ -202,6 +202,8 @@ class User < ApplicationRecord
       .reorder 'correct.count': direction, 'attempted.count': direction
   }
 
+  scope :online, -> { where(seen_at: 5.minutes.ago..) }
+
   def provider_allows_blank_email
     return if institution&.uses_lti? || institution&.uses_oidc? || institution&.uses_smartschool?
 

app/policies/course_policy.rb

@@ -71,6 +71,10 @@ def statistics?
     course_admin?
   end
 
+  def live_statistics?
+    course_admin?
+  end
+
   def update_membership?
     course_admin?
   end

app/views/courses/live_statistics.json.jbuilder

@@ -0,0 +1,7 @@
+json.online_users @online_users
+json.submissions_per_minute @submissions_per_minute
+json.activities_being_worked_on @activities_being_worked_on&.each do |activity|
+  json.extract! activity, :id, :name
+  json.url course_activity_url(@course, activity)
+  json.submission_count activity.submission_count
+end

config/routes.rb

@@ -107,6 +107,7 @@
       end
       member do
         get 'statistics'
+        get 'live_statistics'
         get 'subscribe/:secret', to: 'courses#registration', as: 'registration'
         get 'manage_series'
         get 'scoresheet'

test/controllers/courses_controller_test.rb

@@ -854,4 +854,75 @@ def with_users_signed_in(users)
     event3 = cal.events.third
     assert_nil event3
   end
+
+  test 'live statistics should contain the number of online users' do
+    add_admins
+    sign_in @admins.first
+    # Visit the course page to register the user as online
+    get course_path(@course)
+
+    get live_statistics_course_path(@course, format: :json)
+
+    stats = response.parsed_body
+    assert_equal 1, stats['online_users']
+  end
+
+  test 'live submissions contain the number of submissions per minute for the last hour' do
+    add_admins
+    sign_in @admins.first
+
+    time1 = 1.minutes.ago
+    time2 = 27.minutes.ago
+    time3 = 45.minutes.ago
+    time4 = 3.hours.ago
+
+    # Create a submissions
+    create :submission, course: @course, created_at: time1
+    create :submission, course: @course, created_at: time2
+    create :submission, course: @course, created_at: time2
+    create :submission, course: @course, created_at: time3
+    create :submission, course: @course, created_at: time4
+
+    get live_statistics_course_path(@course, format: :json)
+
+    stats = response.parsed_body
+    assert_equal 1, stats['submissions_per_minute'][time1.min.to_s]
+    assert_equal 2, stats['submissions_per_minute'][time2.min.to_s]
+    assert_equal 1, stats['submissions_per_minute'][time3.min.to_s]
+  end
+
+  test 'live statistics should contain the three activities with most submissions in the past hour and their submission count' do
+    add_admins
+    sign_in @admins.first
+
+    exercise1 = create :exercise
+    exercise2 = create :exercise
+    exercise3 = create :exercise
+    exercise4 = create :exercise
+
+    create :series, course: @course, exercises: [exercise1, exercise2, exercise3, exercise4]
+
+    # Create a submissions
+    create :submission, course: @course, exercise: exercise1
+    3.times do
+      create :submission, course: @course, exercise: exercise2
+    end
+    2.times do
+      create :submission, course: @course, exercise: exercise3
+    end
+    4.times do
+      create :submission, course: @course, exercise: exercise4, created_at: 2.hours.ago
+    end
+
+    get live_statistics_course_path(@course, format: :json)
+
+    stats = response.parsed_body
+    assert_equal 3, stats['activities_being_worked_on'][0]['submission_count']
+    assert_equal 2, stats['activities_being_worked_on'][1]['submission_count']
+    assert_equal 1, stats['activities_being_worked_on'][2]['submission_count']
+
+    assert_equal exercise2.name, stats['activities_being_worked_on'][0]['name']
+    assert_equal exercise3.name, stats['activities_being_worked_on'][1]['name']
+    assert_equal exercise1.name, stats['activities_being_worked_on'][2]['name']
+  end
 end

test/models/course_test.rb

@@ -560,4 +560,46 @@ class CourseTest < ActiveSupport::TestCase
     CourseMembership.create(user: user, course: course, status: :course_admin)
     assert_equal 1, course.homepage_series(user).count
   end
+
+  test 'activities being worked on should return the activities with most recent submissions' do
+    course = create :course, series_count: 2, exercises_per_series: 2
+    user = create :student
+    CourseMembership.create(user: user, course: course, status: :student)
+
+    # no activity should return empty array
+    assert_equal [], course.activities_being_worked_on
+
+    # should return activities with most recent submissions
+    create :submission, user: user, exercise: course.series.first.exercises.first, course: course, created_at: DateTime.now - 30.minutes
+    # 2 submissions
+    create :submission, user: user, exercise: course.series.first.exercises.second, course: course
+    create :submission, user: user, exercise: course.series.first.exercises.second, course: course
+    # 3 submissions
+    create :submission, user: user, exercise: course.series.second.exercises.second, course: course
+    create :submission, user: user, exercise: course.series.second.exercises.second, course: course
+    create :submission, user: user, exercise: course.series.second.exercises.second, course: course
+    # should be ignored, more than 1 hour ago
+    create :submission, user: user, exercise: course.series.second.exercises.first, course: course, created_at: DateTime.now - 2.hours
+    create :submission, user: user, exercise: course.series.second.exercises.first, course: course, created_at: DateTime.now - 2.hours
+    create :submission, user: user, exercise: course.series.second.exercises.first, course: course, created_at: DateTime.now - 2.hours
+    create :submission, user: user, exercise: course.series.second.exercises.first, course: course, created_at: DateTime.now - 2.hours
+
+    assert_equal course.series.second.exercises.second, course.activities_being_worked_on.first
+    assert_equal course.series.first.exercises.second, course.activities_being_worked_on.second
+    assert_equal course.series.first.exercises.first, course.activities_being_worked_on.third
+
+    # should be able to limit number of activities
+    assert_equal 3, course.activities_being_worked_on.count
+    assert_equal 2, course.activities_being_worked_on(2).count
+    assert_equal 3, course.activities_being_worked_on(7).count
+
+    # should include submission_count
+    assert_equal 3, course.activities_being_worked_on.first[:submission_count]
+    assert_equal 2, course.activities_being_worked_on.second[:submission_count]
+    assert_equal 1, course.activities_being_worked_on.third[:submission_count]
+
+    # should be able to specify time range
+    assert_equal 4, course.activities_being_worked_on(7, 4.hours.ago..).count
+    assert_equal 2, course.activities_being_worked_on(7, 3.hours.ago..15.minutes.ago).count
+  end
 end

test/models/user_test.rb

@@ -1070,4 +1070,13 @@ def setup
     question.update(question_state: :answered)
     assert_equal false, user.reload.open_questions?
   end
+
+  test 'online scope should return users that have been active in the last 5 minutes' do
+    user = create :user
+    assert_equal 0, User.online.count
+    user.update(seen_at: Time.zone.now)
+    assert_equal 1, User.online.count
+    user.update(seen_at: 6.minutes.ago)
+    assert_equal 0, User.online.count
+  end
 end