Fix issues with bonus xp (#1172)

* removed unnecessary logic

* change the submission passed into update_xp_bonus

* Update bonus xp when grading is published

* Add extra logic to check if xp is an integer

* Remove outdated comment

* Use coalesce to check if total_xp = nil

---------

Co-authored-by: Richard Dominick <34370238+RichDom2185@users.noreply.github.com>

Author: thortol

lib/cadet/assessments/assessments.ex

@@ -1055,7 +1055,7 @@ defmodule Cadet.Assessments do
 
       # Begin autograding job
       GradingJob.force_grade_individual_submission(updated_submission)
-      update_xp_bonus(submission)
+      update_xp_bonus(updated_submission)
 
       {:ok, nil}
     else
@@ -1294,6 +1294,8 @@ defmodule Cadet.Assessments do
         |> Submission.changeset(%{is_grading_published: true})
         |> Repo.update()
 
+        update_xp_bonus(submission)
+
         Notifications.write_notification_when_published(
           submission.id,
           :published_grading
@@ -1493,23 +1495,18 @@ defmodule Cadet.Assessments do
         Answer
         |> where(submission_id: ^submission_id)
         |> order_by(:question_id)
-        |> group_by([a], a.id)
         |> select([a], %{
-          # grouping by submission, so s.xp_bonus will be the same, but we need an
-          # aggregate function
-          total_xp: sum(a.xp) + sum(a.xp_adjustment)
+          total_xp: a.xp + a.xp_adjustment
         })
 
       total =
         ans_xp
         |> subquery
         |> select([a], %{
-          total_xp: sum(a.total_xp)
+          total_xp: coalesce(sum(a.total_xp), 0)
         })
         |> Repo.one()
 
-      xp = decimal_to_integer(total.total_xp)
-
       cur_time =
         if submission.submitted_at == nil do
           Timex.now()
@@ -1518,7 +1515,7 @@ defmodule Cadet.Assessments do
         end
 
       xp_bonus =
-        if xp <= 0 do
+        if total.total_xp <= 0 do
           0
         else
           if Timex.before?(cur_time, Timex.shift(assessment.open_at, hours: early_hours)) do