Add finishing rate to exercise statistics

app/models/exercise.rb

@@ -352,7 +352,11 @@ class Exercise < ActiveRecord::Base
   end
 
   def has_user_solved(user)
-    return maximum_score(user).to_i == maximum_score.to_i
+    maximum_score(user).to_i == maximum_score.to_i
+  end
+
+  def finishers
+    ExternalUser.joins(:submissions).where(submissions: {exercise_id: id, score: maximum_score, cause: %w(submit assess)}).distinct
   end
 
   def set_default_values

app/views/exercises/statistics.html.slim

@@ -2,9 +2,15 @@ script src="http://labratrevenge.com/d3-tip/javascripts/d3.tip.v0.6.3.js"
 h1 = @exercise
 
 = row(label: '.participants', value: @exercise.users.distinct.count)
+
 - [:intermediate, :final].each do |scope|
   = row(label: ".#{scope}_submissions") do
     = "#{@exercise.submissions.send(scope).count} (#{t('.users', count: @exercise.submissions.send(scope).distinct.count(:user_id))})"
+
+= row(label: '.finishing_rate') do
+  p == @exercise.finishers.count ? "#{t('shared.out_of', maximum_value: @exercise.users.distinct.count, value: @exercise.finishers.count)} #{t('exercises.statistics.external_users')}" : empty
+  p = progress_bar((100.0 / @exercise.users.distinct.count * @exercise.finishers.count).round(2))
+
 = row(label: '.average_score') do
   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)

config/locales/de.yml

@@ -350,7 +350,8 @@ de:
       worktime: Arbeitszeit
       average_worktime: Durchschnittliche Arbeitszeit
       internal_users: Interne Nutzer
-      external_user: Externe Nutzer
+      external_users: Externe Nutzer
+      finishing_rate: Abschlussrate
     submit:
       failure: Beim Übermitteln Ihrer Punktzahl ist ein Fehler aufgetreten. Bitte versuchen Sie es später erneut.
       full_score_redirect_to_rfc: Herzlichen Glückwunsch! Sie haben die maximale Punktzahl für diese Aufgabe an den Kurs übertragen. Ein anderer Teilnehmer hat eine Frage zu der von Ihnen gelösten Aufgabe. Er würde sich sicherlich sehr über ihre Hilfe und Kommentare freuen.

config/locales/en.yml

@@ -351,6 +351,7 @@ en:
       average_worktime: Average Working Time
       internal_users: Internal Users
       external_users: External Users
+      finishing_rate: Finishing Rate
     submit:
       failure: An error occured while transmitting your score. Please try again later.
       full_score_redirect_to_rfc: Congratulations! You achieved and submitted the highest possible score for this exercise. Another participant has a question concerning the exercise you just solved. Your help and comments will be greatly appreciated!