Merge pull request #188 from openHPI/feature/ordered_exercise_collection

Ordered exercise collections

app/models/exercise.rb

@@ -14,7 +14,8 @@ class Exercise < ActiveRecord::Base
 
   has_and_belongs_to_many :proxy_exercises
   has_many :user_proxy_exercise_exercises
-  has_and_belongs_to_many :exercise_collections
+  has_many :exercise_collection_items
+  has_many :exercise_collections, through: :exercise_collection_items
   has_many :user_exercise_interventions
   has_many :interventions, through: :user_exercise_interventions
   has_many :exercise_tags

app/models/exercise_collection.rb

@@ -1,23 +1,26 @@
 class ExerciseCollection < ActiveRecord::Base
   include TimeHelper
 
-  has_and_belongs_to_many :exercises
+  has_many :exercise_collection_items
+  alias_method :items, :exercise_collection_items
+  has_many :exercises, through: :exercise_collection_items
   belongs_to :user, polymorphic: true
 
-  def exercise_working_times
-    working_times = {}
-    exercises.each do |exercise|
-      working_times[exercise.id] = time_to_f exercise.average_working_time
+  def collection_statistics
+    statistics = {}
+    exercise_collection_items.each do |item|
+      statistics[item.position] = {exercise_id: item.exercise.id, exercise_title: item.exercise.title, working_time: time_to_f(item.exercise.average_working_time)}
     end
-    working_times
+    statistics
   end
 
   def average_working_time
     if exercises.empty?
       0
     else
-      values = exercise_working_times.values.reject { |v| v.nil?}
-      values.reduce(:+) / exercises.size
+      values = collection_statistics.values.reject { |o| o[:working_time].nil?}
+      sum = values.reduce(0) {|sum, item| sum + item[:working_time]}
+      sum / values.size
     end
   end
 

app/models/exercise_collection_item.rb

@@ -0,0 +1,4 @@
+class ExerciseCollectionItem < ActiveRecord::Base
+  belongs_to :exercise_collection
+  belongs_to :exercise
+end