recommendation also now returns easiest exercise as recommendation if no tag matched could be found

findMatchingExercises only searched for assessed submissions to get processed exercises, fixed this to look at all submissions

app/models/proxy_exercise.rb

@@ -41,7 +41,8 @@ class ProxyExercise < ActiveRecord::Base
 
     def findMatchingExercise(user)
       #exercises.shuffle.first
-      exercisesUserHasAccessed = user.submissions.where(cause: :assess).map{|s| s.exercise}.uniq
+      # hier vielleicht nur betrachten wenn der user die aufgabe assessed oder submitted hat
+      exercisesUserHasAccessed = user.submissions.map{|s| s.exercise}.uniq
       tagsUserHasSeen = exercisesUserHasAccessed.map{|ex| ex.tags}.uniq.flatten
       puts "exercisesUserHasAccessed #{exercisesUserHasAccessed}"
 
@@ -54,15 +55,19 @@ class ProxyExercise < ActiveRecord::Base
           potentialRecommendedExercises << ex
         end
       end
-      puts "potentialRecommendedExercises: #{potentialRecommendedExercises}"
-      recommendedExercise = selectBestMatchingExercise(user, exercisesUserHasAccessed, potentialRecommendedExercises)
-      recommendedExercise
+      if potentialRecommendedExercises.empty?
+        getEasiestExercise(exercises)
+      else
+        puts "potentialRecommendedExercises: #{potentialRecommendedExercises}"
+        recommendedExercise = selectBestMatchingExercise(user, exercisesUserHasAccessed, potentialRecommendedExercises)
+        recommendedExercise
+      end
     end
 
     def selectBestMatchingExercise(user, exercisesUserHasAccessed, potentialRecommendedExercises)
       topic_knowledge_user_and_max = getUserKnowledgeAndMaxKnowledge(user, exercisesUserHasAccessed)
       puts "topic_knowledge_user_and_max: #{topic_knowledge_user_and_max}"
-      puts "potentialRecommendedExercises: #{potentialRecommendedExercises.size}"
+      puts "potentialRecommendedExercises: #{potentialRecommendedExercises.size}: #{potentialRecommendedExercises.map{|p| p.title}}"
       topic_knowledge_user = topic_knowledge_user_and_max[:user_topic_knowledge]
       topic_knowledge_max = topic_knowledge_user_and_max[:max_topic_knowledge]
       relative_knowledge_improvement = {}
@@ -80,8 +85,8 @@ class ProxyExercise < ActiveRecord::Base
         end
       end
       puts "relative improvements #{relative_knowledge_improvement}"
-      exercise_with_greatest_improvements = relative_knowledge_improvement.max_by{|k,v| v}
-      exercise_with_greatest_improvements.first
+      exercise_with_greatest_improvements = relative_knowledge_improvement.max_by{|k,v| v}.first
+      exercise_with_greatest_improvements
     end
 
     # [score][quantile]
@@ -166,4 +171,8 @@ class ProxyExercise < ActiveRecord::Base
       {user_topic_knowledge: topic_knowledge_loss_user, max_topic_knowledge: topic_knowledge_max}
     end
 
+    def getEasiestExercise(exercises)
+      exercises.order(:expected_difficulty).first
+    end
+
 end