Add submission deadline to exercises and allow teachers to view their submissions

app/policies/application_policy.rb

@@ -33,9 +33,14 @@ class ApplicationPolicy
       users_in_same_study_group = study_group.users
     elsif @record.respond_to? :users # e.g. study_group
       users_in_same_study_group = @record.users
-    else # e.g. exercise
+    elsif @record.respond_to? :user # e.g. exercise
       study_groups = @record.user.study_groups
       users_in_same_study_group = study_groups.collect(&:users).flatten
+    elsif @record.respond_to? :study_groups # e.g. user
+      study_groups = @record.study_groups
+      users_in_same_study_group = study_groups.collect(&:users).flatten
+    else
+      return false
     end
 
     users_in_same_study_group.include? @user

app/policies/exercise_policy.rb

@@ -11,6 +11,14 @@ class ExercisePolicy < AdminOrAuthorPolicy
     admin? || teacher_in_study_group?
   end
 
+  def submission_statistics?
+    admin? || teacher_in_study_group?
+  end
+
+  def detailed_statistics?
+    admin?
+  end
+
   [:clone?, :destroy?, :edit?, :update?, :export_external_check?, :export_external_confirm?].each do |action|
     define_method(action) { admin? || teacher_in_study_group? || author? }
   end

app/policies/external_user_policy.rb

@@ -1,6 +1,14 @@
 class ExternalUserPolicy < AdminOnlyPolicy
+  def index?
+    admin? || teacher?
+  end
+
+  def show?
+    admin? || teacher_in_study_group?
+  end
+
   def statistics?
-    admin?
+    admin? || teacher_in_study_group?
   end
 
   def tag_statistics?