Adjust teacher permissions:

* Hide non-public exercises and proxy exercises
* Hide average working time value on statistic page
* Add hint about filter to submission page for teachers
* Hide display name from feedback page

app/policies/exercise_policy.rb

@@ -4,7 +4,7 @@ class ExercisePolicy < AdminOrAuthorPolicy
   end
 
   [:show?, :feedback?, :requests_for_comments?, :statistics?].each do |action|
-    define_method(action) { admin? || teacher? }
+    define_method(action) { admin? || teacher_in_study_group? || teacher? && @record.public? || author? }
   end
 
   def study_group_dashboard?

app/policies/proxy_exercise_policy.rb

@@ -4,7 +4,7 @@ class ProxyExercisePolicy < AdminOrAuthorPolicy
   end
 
   def show?
-    admin? || teacher?
+    admin? || teacher_in_study_group? || teacher? && @record.public? || author?
   end
 
   [:clone?, :destroy?, :edit?, :update?].each do |action|

app/views/exercises/external_users/statistics.html.slim

@@ -79,6 +79,8 @@ h1 = "#{@exercise} (external user #{link_to_if(policy(@external_user).show?, @ex
             = t('.within_grace_period')
           .col-sm-3.after_late_deadline.py-2
             = t('.after_late_deadline')
+      - unless current_user.try(:admin?)
+        p.mt-2 = t('.filter')
     - if current_user.try(:admin?)
       p = t('.addendum', delta: StatisticsHelper::WORKING_TIME_DELTA_IN_SECONDS / 60)
       .d-none#wtimes data-working_times=ActiveSupport::JSON.encode(@working_times_until);

app/views/exercises/feedback.html.slim

@@ -18,7 +18,8 @@ h1 = link_to_if(policy(@exercise).show?, @exercise, exercise_path(@exercise))
       li.card.mt-2
         .card-header role="tab" id="heading"
           div.clearfix.feedback-header
-            span.username = link_to(feedback.user.displayname, statistics_external_user_exercise_path(id: @exercise.id, external_user_id: feedback.user.id))
+            - if policy(@exercise).detailed_statistics?
+              span.username = link_to_if(policy(feedback.user).show?, feedback.user.displayname, statistics_external_user_exercise_path(id: @exercise.id, external_user_id: feedback.user.id))
             - if feedback.anomaly_notification
               i class="fa fa-envelope-o" data-placement="top" data-toggle="tooltip" data-container="body" title=feedback.anomaly_notification.reason
             span.date = feedback.created_at

app/views/exercises/statistics.html.slim

@@ -21,8 +21,9 @@ h1 = @exercise
   p == @exercise.average_score ? t('shared.out_of', maximum_value: @exercise.maximum_score, value: @exercise.average_score.round(2)) : empty
   p = progress_bar(@exercise.average_percentage)
 
-= row(label: '.average_worktime') do
-  p = @exercise.average_working_time
+- if policy(@exercise).detailed_statistics?
+  = row(label: '.average_worktime') do
+    p = @exercise.average_working_time
 
 - Hash[:internal_users => t('.internal_users'), :external_users => t('.external_users')].each_pair do |symbol, label|
   - if symbol==:internal_users && current_user.admin?

config/locales/de.yml

@@ -455,6 +455,7 @@ de:
         within_grace_period: Abgabe innerhalb der Gnadenfrist
         after_late_deadline: Verspätete Abgabe
         addendum: '* Differenzen von mehr als %{delta} Minuten werden ignoriert.'
+        filter: "Hinweis: Nur die letzte Abgabe vor einer Abgabefrist ist sichtbar."
   proxy_exercises:
       index:
         clone: Duplizieren

config/locales/en.yml

@@ -455,6 +455,7 @@ en:
         within_grace_period: Within Grace Period
         after_late_deadline: Too Late
         addendum: "* Deltas longer than %{delta} minutes are ignored."
+        filter: "Remember: Only the last submission per deadline is shown."
   proxy_exercises:
       index:
         clone: Duplicate

spec/policies/exercise_policy_spec.rb

@@ -3,7 +3,7 @@ require 'rails_helper'
 describe ExercisePolicy do
   subject { described_class }
 
-let(:exercise) { FactoryBot.build(:dummy) }
+let(:exercise) { FactoryBot.build(:dummy, public: true) }
 
   permissions :batch_update? do
     it 'grants access to admins only' do