api to get total and active posts for a course

allow course with slashes

api/comment_threads.rb

@@ -97,3 +97,15 @@ delete "#{APIPREFIX}/threads/:thread_id" do |thread_id|
   thread.destroy
   thread.to_hash.to_json
 end
+
+get "#{APIPREFIX}/courses/*/stats"  do |course_id| # retrieve stats by course
+  begin
+    threads = Content.where(_type: "CommentThread", course_id: course_id)
+    active_threads = threads.where(:last_activity_at.gte => 1.day.ago)
+    course_stats = {
+      "num_threads" => threads.count,
+      "num_active_threads" => active_threads.count
+    }
+    course_stats.to_json
+  end
+end

spec/api/comment_thread_spec.rb

@@ -539,6 +539,31 @@ describe "app" do
         end
       end
 
+      # Test active and non active thread count for a course
+      it "test the number of active and non active threads for a course" do
+        User.all.delete
+        Content.all.delete
+        @user = create_test_user(999)
+        @threads = {}
+        5.times do |n|
+          thread_key = "t#{n}"
+          thread = make_thread(@user, thread_key, DFLT_COURSE_ID, "pdq")
+          @threads[n] = thread
+        end
+        time_threshold = 2.day.ago
+        @threads[0].last_activity_at = time_threshold
+        @threads[0].save!
+        @threads[1].last_activity_at = time_threshold
+        @threads[1].save!
+
+        get "/api/v1/courses/#{DFLT_COURSE_ID}/stats"
+        last_response.should be_ok
+        response = parse last_response.body
+        response["num_threads"].should == 5
+        response["num_active_threads"].should == 3
+      end
+
+
       def test_unicode_data(text)
         thread = create(:comment_thread, body: text)
         create(:comment, comment_thread: thread, body: text)