18dc689a4df4836fc6967bf0f74dc252964bd175-PR-1180

Committed 08 Sep 2024 06:14PM UTC coverage: 79.088% (-15.3%) from 94.372%

Build # 18dc689a4df4836fc6967bf0f74dc252964bd175-PR-1180

Build Type

Pull #1180

github

Committed by

josh1248

Commit Message

Change appropriate routes into admin scope

Pull Request Pull Request #1180: Transfer groundControl (and admin panel) from staff to admin route

Run Details

7 of 12 new or added lines in 1 file covered. (58.33%)

499 existing lines in 25 files now uncovered.

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Source File
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82.57

/lib/cadet/assessments/assessments.ex

defmodule Cadet.Assessments do
  @moduledoc """
  Assessments context contains domain logic for assessments management such as
  missions, sidequests, paths, etc.
  """
  use Cadet, [:context, :display]
  import Ecto.Query

  require Logger

  alias Cadet.Accounts.{
    Notification,
    Notifications,
    User,
    Team,
    TeamMember,
    CourseRegistration,
    CourseRegistrations
  }

  alias Cadet.Assessments.{Answer, Assessment, Query, Question, Submission, SubmissionVotes}
  alias Cadet.Autograder.GradingJob
  alias Cadet.Courses.{Group, AssessmentConfig}
  alias Cadet.Jobs.Log
  alias Cadet.ProgramAnalysis.Lexer
  alias Ecto.Multi
  alias Cadet.Incentives.Achievements
  alias Timex.Duration

  require Decimal

  @open_all_assessment_roles ~w(staff admin)a

  # These roles can save and finalise answers for closed assessments and
  # submitted answers
  @bypass_closed_roles ~w(staff admin)a

  def delete_assessment(id) do
    assessment = Repo.get(Assessment, id)

    is_voted_on =
      Question
      |> where(type: :voting)
      |> join(:inner, [q], asst in assoc(q, :assessment))
      |> where(
        [q, asst],
        q.question["contest_number"] == ^assessment.number and
          asst.course_id == ^assessment.course_id
      )
      |> Repo.exists?()

    if is_voted_on do
      {:error, {:bad_request, "Contest voting for this contest is still up"}}
    else
      Submission
      |> where(assessment_id: ^id)
      |> delete_submission_association(id)

      Question
      |> where(assessment_id: ^id)
      |> Repo.all()
      |> Enum.each(fn q ->
        delete_submission_votes_association(q)
      end)

      Repo.delete(assessment)
    end
  end

  defp delete_submission_votes_association(question) do
    SubmissionVotes
    |> where(question_id: ^question.id)
    |> Repo.delete_all()
  end

  defp delete_submission_association(submissions, assessment_id) do
    submissions
    |> Repo.all()
    |> Enum.each(fn submission ->
      Answer
      |> where(submission_id: ^submission.id)
      |> Repo.delete_all()
    end)

    Notification
    |> where(assessment_id: ^assessment_id)
    |> Repo.delete_all()

    Repo.delete_all(submissions)
  end

  @spec user_max_xp(CourseRegistration.t()) :: integer()
  def user_max_xp(%CourseRegistration{id: cr_id}) do
    Submission
    |> where(status: ^:submitted)
    |> where(student_id: ^cr_id)
    |> join(
      :inner,
      [s],
      a in subquery(Query.all_assessments_with_max_xp()),
      on: s.assessment_id == a.id
    )
    |> select([_, a], sum(a.max_xp))
    |> Repo.one()
    |> decimal_to_integer()
  end

  def assessments_total_xp(%CourseRegistration{id: cr_id}) do
    teams = find_teams(cr_id)
    submission_ids = get_submission_ids(cr_id, teams)

    submission_xp =
      Submission
      |> where(
        [s],
        s.id in ^submission_ids
      )
      |> where(is_grading_published: true)
      |> join(:inner, [s], a in Answer, on: s.id == a.submission_id)
      |> group_by([s], s.id)
      |> select([s, 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) + max(s.xp_bonus)
      })

    total =
      submission_xp
      |> subquery
      |> select([s], %{
        total_xp: sum(s.total_xp)
      })
      |> Repo.one()

    # for {key, val} <- total, into: %{}, do: {key, decimal_to_integer(val)}
    decimal_to_integer(total.total_xp)
  end

  def user_total_xp(course_id, user_id, course_reg_id) do
    user_course = CourseRegistrations.get_user_course(user_id, course_id)

    total_achievement_xp = Achievements.achievements_total_xp(course_id, course_reg_id)
    total_assessment_xp = assessments_total_xp(user_course)

    total_achievement_xp + total_assessment_xp
  end

  defp decimal_to_integer(decimal) do
    if Decimal.is_decimal(decimal) do
      Decimal.to_integer(decimal)
    else
      0
    end
  end

  def user_current_story(cr = %CourseRegistration{}) do
    {:ok, %{result: story}} =
      Multi.new()
      |> Multi.run(:unattempted, fn _repo, _ ->
        {:ok, get_user_story_by_type(cr, :unattempted)}
      end)
      |> Multi.run(:result, fn _repo, %{unattempted: unattempted_story} ->
        if unattempted_story do
          {:ok, %{play_story?: true, story: unattempted_story}}
        else
          {:ok, %{play_story?: false, story: get_user_story_by_type(cr, :attempted)}}
        end
      end)
      |> Repo.transaction()

    story
  end

  @spec get_user_story_by_type(CourseRegistration.t(), :unattempted | :attempted) ::
          String.t() | nil
  def get_user_story_by_type(%CourseRegistration{id: cr_id}, type)
      when is_atom(type) do
    filter_and_sort = fn query ->
      case type do
        :unattempted ->
          query
          |> where([_, s], is_nil(s.id))
          |> order_by([a], asc: a.open_at)

        :attempted ->
          query |> order_by([a], desc: a.close_at)
      end
    end

    Assessment
    |> where(is_published: true)
    |> where([a], not is_nil(a.story))
    |> where([a], a.open_at <= from_now(0, "second") and a.close_at >= from_now(0, "second"))
    |> join(:left, [a], s in Submission, on: s.assessment_id == a.id and s.student_id == ^cr_id)
    |> filter_and_sort.()
    |> order_by([a], a.config_id)
    |> select([a], a.story)
    |> first()
    |> Repo.one()
  end

  def assessment_with_questions_and_answers(
        assessment = %Assessment{password: nil},
        cr = %CourseRegistration{},
        nil
      ) do
    assessment_with_questions_and_answers(assessment, cr)
  end

  def assessment_with_questions_and_answers(
        assessment = %Assessment{password: nil},
        cr = %CourseRegistration{},
        _
      ) do
    assessment_with_questions_and_answers(assessment, cr)
  end

  def assessment_with_questions_and_answers(
        assessment = %Assessment{password: password},
        cr = %CourseRegistration{},
        given_password
      ) do
    cond do
      Timex.compare(Timex.now(), assessment.close_at) >= 0 ->
        assessment_with_questions_and_answers(assessment, cr)

      match?({:ok, _}, find_submission(cr, assessment)) ->
        assessment_with_questions_and_answers(assessment, cr)

      given_password == nil ->
        {:error, {:forbidden, "Missing Password."}}

      password == given_password ->
        find_or_create_submission(cr, assessment)
        assessment_with_questions_and_answers(assessment, cr)

      true ->
        {:error, {:forbidden, "Invalid Password."}}
    end
  end

  def assessment_with_questions_and_answers(id, cr = %CourseRegistration{}, password)
      when is_ecto_id(id) do
    role = cr.role

    assessment =
      if role in @open_all_assessment_roles do
        Assessment
        |> where(id: ^id)
        |> preload(:config)
        |> Repo.one()
      else
        Assessment
        |> where(id: ^id)
        |> where(is_published: true)
        |> preload(:config)
        |> Repo.one()
      end

    if assessment do
      assessment_with_questions_and_answers(assessment, cr, password)
    else
      {:error, {:bad_request, "Assessment not found"}}
    end
  end

  def assessment_with_questions_and_answers(
        assessment = %Assessment{id: id},
        course_reg = %CourseRegistration{role: role}
      ) do
    team_id =
      case find_team(id, course_reg.id) do
        {:ok, nil} ->
          -1

        {:ok, team} ->
          team.id

        {:error, :team_not_found} ->
          -1
      end

    if Timex.compare(Timex.now(), assessment.open_at) >= 0 or role in @open_all_assessment_roles do
      answer_query =
        Answer
        |> join(:inner, [a], s in assoc(a, :submission))
        |> where([_, s], s.student_id == ^course_reg.id or s.team_id == ^team_id)

      questions =
        Question
        |> where(assessment_id: ^id)
        |> join(:left, [q], a in subquery(answer_query), on: q.id == a.question_id)
        |> join(:left, [_, a], g in assoc(a, :grader))
        |> join(:left, [_, _, g], u in assoc(g, :user))
        |> select([q, a, g, u], {q, a, g, u})
        |> order_by(:display_order)
        |> Repo.all()
        |> Enum.map(fn
          {q, nil, _, _} -> %{q | answer: %Answer{grader: nil}}
          {q, a, nil, _} -> %{q | answer: %Answer{a | grader: nil}}
          {q, a, g, u} -> %{q | answer: %Answer{a | grader: %CourseRegistration{g | user: u}}}
        end)
        |> load_contest_voting_entries(course_reg, assessment)

      is_grading_published =
        Submission
        |> where(assessment_id: ^id)
        |> where(student_id: ^course_reg.id)
        |> select([s], s.is_grading_published)
        |> Repo.one()

      assessment =
        assessment
        |> Map.put(:questions, questions)
        |> Map.put(:is_grading_published, is_grading_published)

      {:ok, assessment}
    else
      {:error, {:forbidden, "Assessment not open"}}
    end
  end

  def assessment_with_questions_and_answers(id, cr = %CourseRegistration{}) do
    assessment_with_questions_and_answers(id, cr, nil)
  end

  @doc """
  Returns a list of assessments with all fields and an indicator showing whether it has been attempted
  by the supplied user
  """
  def all_assessments(cr = %CourseRegistration{}) do
    teams = find_teams(cr.id)
    submission_ids = get_submission_ids(cr.id, teams)

    submission_aggregates =
      Submission
      |> join(:left, [s], ans in Answer, on: ans.submission_id == s.id)
      |> where(
        [s],
        s.id in ^submission_ids
      )
      |> group_by([s], s.assessment_id)
      |> select([s, ans], %{
        assessment_id: s.assessment_id,
        # s.xp_bonus should be the same across the group, but we need an aggregate function here
        xp: fragment("? + ? + ?", sum(ans.xp), sum(ans.xp_adjustment), max(s.xp_bonus)),
        graded_count: ans.id |> count() |> filter(not is_nil(ans.grader_id))
      })

    submission_status =
      Submission
      |> where(
        [s],
        s.id in ^submission_ids
      )
      |> select([s], [:assessment_id, :status, :is_grading_published])

    assessments =
      cr.course_id
      |> Query.all_assessments_with_aggregates()
      |> subquery()
      |> join(
        :left,
        [a],
        sa in subquery(submission_aggregates),
        on: a.id == sa.assessment_id
      )
      |> join(:left, [a, _], s in subquery(submission_status), on: a.id == s.assessment_id)
      |> select([a, sa, s], %{
        a
        | xp: sa.xp,
          graded_count: sa.graded_count,
          user_status: s.status,
          is_grading_published: s.is_grading_published
      })
      |> filter_published_assessments(cr)
      |> order_by(:open_at)
      |> preload(:config)
      |> Repo.all()

    {:ok, assessments}
  end

  defp get_submission_ids(cr_id, teams) do
    query =
      from(s in Submission,
        where: s.student_id == ^cr_id or s.team_id in ^Enum.map(teams, & &1.id),
        select: s.id
      )

    Repo.all(query)
  end

  @doc """
  A helper function which removes grading information from all assessments
  if it's grading is not published.
  """
  def format_all_assessments(assessments) do
    Enum.map(assessments, fn a ->
      if a.is_grading_published do
        a
      else
        a
        |> Map.put(:xp, 0)
        |> Map.put(:graded_count, 0)
      end
    end)
  end

  @doc """
  A helper function which removes grading information from the assessment
  if it's grading is not published.
  """
  def format_assessment_with_questions_and_answers(assessment) do
    if assessment.is_grading_published do
      assessment
    else
      %{
        assessment
        | questions:
            Enum.map(assessment.questions, fn q ->
              %{
                q
                | answer: %{
                    q.answer
                    | xp: 0,
                      xp_adjustment: 0,
                      autograding_status: :none,
                      autograding_results: [],
                      grader: nil,
                      grader_id: nil,
                      comments: nil
                  }
              }
            end)
      }
    end
  end

  def filter_published_assessments(assessments, cr) do
    role = cr.role

    case role do
      :student -> where(assessments, is_published: true)
      _ -> assessments
    end
  end

  def create_assessment(params) do
    %Assessment{}
    |> Assessment.changeset(params)
    |> Repo.insert()
  end

  @doc """
  The main function that inserts or updates assessments from the XML Parser
  """
  @spec insert_or_update_assessments_and_questions(map(), [map()], boolean()) ::
          {:ok, any()}
          | {:error, Ecto.Multi.name(), any(), %{optional(Ecto.Multi.name()) => any()}}
  def insert_or_update_assessments_and_questions(
        assessment_params,
        questions_params,
        force_update
      ) do
    assessment_multi =
      Multi.insert_or_update(
        Multi.new(),
        :assessment,
        insert_or_update_assessment_changeset(assessment_params, force_update)
      )

    if force_update and invalid_force_update(assessment_multi, questions_params) do
      {:error, "Question count is different"}
    else
      questions_params
      |> Enum.with_index(1)
      |> Enum.reduce(assessment_multi, fn {question_params, index}, multi ->
        Multi.run(multi, "question#{index}", fn _repo, %{assessment: %Assessment{id: id}} ->
          question =
            Question
            |> where([q], q.display_order == ^index and q.assessment_id == ^id)
            |> Repo.one()

          # the is_nil(question) check allows for force updating of brand new assessments
          if !force_update or is_nil(question) do
            {status, new_question} =
              question_params
              |> Map.put(:display_order, index)
              |> build_question_changeset_for_assessment_id(id)
              |> Repo.insert()

            if status == :ok and new_question.type == :voting do
              insert_voting(
                assessment_params.course_id,
                question_params.question.contest_number,
                new_question.id
              )
            else
              {status, new_question}
            end
          else
            params =
              question_params
              |> Map.put_new(:max_xp, 0)
              |> Map.put(:display_order, index)

            if question_params.type != Atom.to_string(question.type) do
              {:error,
               create_invalid_changeset_with_error(
                 :question,
                 "Question types should remain the same"
               )}
            else
              question
              |> Question.changeset(params)
              |> Repo.update()
            end
          end
        end)
      end)
      |> Repo.transaction()
    end
  end

  # Function that checks if the force update is invalid. The force update is only invalid
  # if the new question count is different from the old question count.
  defp invalid_force_update(assessment_multi, questions_params) do
    assessment_id =
      (assessment_multi.operations
       |> List.first()
       |> elem(1)
       |> elem(1)).data.id

    if assessment_id do
      open_date = Repo.get(Assessment, assessment_id).open_at
      # check if assessment is already opened
      if Timex.compare(open_date, Timex.now()) >= 0 do
        false
      else
        existing_questions_count =
          Question
          |> where([q], q.assessment_id == ^assessment_id)
          |> Repo.all()
          |> Enum.count()

        new_questions_count = Enum.count(questions_params)
        existing_questions_count != new_questions_count
      end
    else
      false
    end
  end

  @spec insert_or_update_assessment_changeset(map(), boolean()) :: Ecto.Changeset.t()
  defp insert_or_update_assessment_changeset(
         params = %{number: number, course_id: course_id},
         force_update
       ) do
    Assessment
    |> where(number: ^number)
    |> where(course_id: ^course_id)
    |> Repo.one()
    |> case do
      nil ->
        Assessment.changeset(%Assessment{}, params)

      %{id: assessment_id} = assessment ->
        answers_exist =
          Answer
          |> join(:inner, [a], q in assoc(a, :question))
          |> join(:inner, [a, q], asst in assoc(q, :assessment))
          |> where([a, q, asst], asst.id == ^assessment_id)
          |> Repo.exists?()

        # Maintain the same open/close date when updating an assessment
        params =
          params
          |> Map.delete(:open_at)
          |> Map.delete(:close_at)
          |> Map.delete(:is_published)

        cond do
          not answers_exist ->
            # Delete all realted submission_votes
            SubmissionVotes
            |> join(:inner, [sv, q], q in assoc(sv, :question))
            |> where([sv, q], q.assessment_id == ^assessment_id)
            |> Repo.delete_all()

            # Delete all existing questions
            Question
            |> where(assessment_id: ^assessment_id)
            |> Repo.delete_all()

            Assessment.changeset(assessment, params)

          force_update ->
            Assessment.changeset(assessment, params)

          true ->
            # if the assessment has submissions, don't edit
            create_invalid_changeset_with_error(:assessment, "has submissions")
        end
    end
  end

  @spec build_question_changeset_for_assessment_id(map(), number() | String.t()) ::
          Ecto.Changeset.t()
  defp build_question_changeset_for_assessment_id(params, assessment_id)
       when is_ecto_id(assessment_id) do
    params_with_assessment_id = Map.put_new(params, :assessment_id, assessment_id)

    Question.changeset(%Question{}, params_with_assessment_id)
  end

  def reassign_voting(assessment_id, is_reassigning_voting) do
    if is_reassigning_voting do
      if is_voting_published(assessment_id) do
        Submission
        |> where(assessment_id: ^assessment_id)
        |> delete_submission_association(assessment_id)

        Question
        |> where(assessment_id: ^assessment_id)
        |> Repo.all()
        |> Enum.each(fn q ->
          delete_submission_votes_association(q)
        end)
      end

      voting_assigned_question_ids =
        SubmissionVotes
        |> select([v], v.question_id)
        |> Repo.all()

      unpublished_voting_questions =
        Question
        |> where(type: :voting)
        |> where([q], q.id not in ^voting_assigned_question_ids)
        |> where(assessment_id: ^assessment_id)
        |> join(:inner, [q], asst in assoc(q, :assessment))
        |> select([q, asst], %{course_id: asst.course_id, question: q.question, id: q.id})
        |> Repo.all()

      for q <- unpublished_voting_questions do
        insert_voting(q.course_id, q.question["contest_number"], q.id)
      end

      {:ok, "voting assigned"}
    else
      {:ok, "no change to voting"}
    end
  end

  def is_voting_published(assessment_id) do
    voting_assigned_question_ids =
      SubmissionVotes
      |> select([v], v.question_id)
      |> Repo.all()

    Question
    |> where(type: :voting)
    |> where(assessment_id: ^assessment_id)
    |> where([q], q.id in ^voting_assigned_question_ids)
    |> Repo.exists?()
  end

  def update_final_contest_entries do
    # 1435 = 1 day - 5 minutes
    if Log.log_execution("update_final_contest_entries", Duration.from_minutes(1435)) do
      Logger.info("Started update of contest entry pools")
      questions = fetch_unassigned_voting_questions()

      for q <- questions do
        insert_voting(q.course_id, q.question["contest_number"], q.question_id)
      end

      Logger.info("Successfully update contest entry pools")
    end
  end

  # fetch voting questions where entries have not been assigned
  def fetch_unassigned_voting_questions do
    voting_assigned_question_ids =
      SubmissionVotes
      |> select([v], v.question_id)
      |> Repo.all()

    valid_assessments =
      Assessment
      |> select([a], %{number: a.number, course_id: a.course_id})
      |> Repo.all()

    valid_questions =
      Question
      |> where(type: :voting)
      |> where([q], q.id not in ^voting_assigned_question_ids)
      |> join(:inner, [q], asst in assoc(q, :assessment))
      |> select([q, asst], %{course_id: asst.course_id, question: q.question, question_id: q.id})
      |> Repo.all()

    # fetch only voting where there is a corresponding contest
    Enum.filter(valid_questions, fn q ->
      Enum.any?(
        valid_assessments,
        fn a -> a.number == q.question["contest_number"] and a.course_id == q.course_id end
      )
    end)
  end

  @doc """
  Generates and assigns contest entries for users with given usernames.
  """
  def insert_voting(
        course_id,
        contest_number,
        question_id
      ) do
    contest_assessment = Repo.get_by(Assessment, number: contest_number, course_id: course_id)

    if is_nil(contest_assessment) do
      changeset = change(%Assessment{}, %{number: ""})

      error_changeset =
        Ecto.Changeset.add_error(
          changeset,
          :number,
          "invalid contest number"
        )

      {:error, error_changeset}
    else
      if Timex.compare(contest_assessment.close_at, Timex.now()) < 0 do
        compile_entries(course_id, contest_assessment, question_id)
      else
        # contest has not closed, do nothing
        {:ok, nil}
      end
    end
  end

  def compile_entries(
        course_id,
        contest_assessment,
        question_id
      ) do
    # Returns contest submission ids with answers that contain "return"
    contest_submission_ids =
      Submission
      |> join(:inner, [s], ans in assoc(s, :answers))
      |> join(:inner, [s, ans], cr in assoc(s, :student))
      |> where([s, ans, cr], cr.role == "student")
      |> where([s, _], s.assessment_id == ^contest_assessment.id and s.status == "submitted")
      |> where(
        [_, ans, cr],
        fragment(
          "?->>'code' like ?",
          ans.answer,
          "%return%"
        )
      )
      |> select([s, _ans], {s.student_id, s.id})
      |> Repo.all()
      |> Enum.into(%{})

    contest_submission_ids_length = Enum.count(contest_submission_ids)

    voter_ids =
      CourseRegistration
      |> where(role: "student", course_id: ^course_id)
      |> select([cr], cr.id)
      |> Repo.all()

    votes_per_user = min(contest_submission_ids_length, 10)

    votes_per_submission =
      if Enum.empty?(contest_submission_ids) do
        0
      else
        trunc(Float.ceil(votes_per_user * length(voter_ids) / contest_submission_ids_length))
      end

    submission_id_list =
      contest_submission_ids
      |> Enum.map(fn {_, s_id} -> s_id end)
      |> Enum.shuffle()
      |> List.duplicate(votes_per_submission)
      |> List.flatten()

    {_submission_map, submission_votes_changesets} =
      voter_ids
      |> Enum.reduce({submission_id_list, []}, fn voter_id, acc ->
        {submission_list, submission_votes} = acc

        user_contest_submission_id = Map.get(contest_submission_ids, voter_id)

        {votes, rest} =
          submission_list
          |> Enum.reduce_while({MapSet.new(), submission_list}, fn s_id, acc ->
            {user_votes, submissions} = acc

            max_votes =
              if votes_per_user == contest_submission_ids_length and
                   not is_nil(user_contest_submission_id) do
                # no. of submssions is less than 10. Unable to find
                votes_per_user - 1
              else
                votes_per_user
              end

            if MapSet.size(user_votes) < max_votes do
              if s_id != user_contest_submission_id and not MapSet.member?(user_votes, s_id) do
                new_user_votes = MapSet.put(user_votes, s_id)
                new_submissions = List.delete(submissions, s_id)
                {:cont, {new_user_votes, new_submissions}}
              else
                {:cont, {user_votes, submissions}}
              end
            else
              {:halt, acc}
            end
          end)

        votes = MapSet.to_list(votes)

        new_submission_votes =
          votes
          |> Enum.map(fn s_id ->
            %SubmissionVotes{
              voter_id: voter_id,
              submission_id: s_id,
              question_id: question_id
            }
          end)
          |> Enum.concat(submission_votes)

        {rest, new_submission_votes}
      end)

    submission_votes_changesets
    |> Enum.with_index()
    |> Enum.reduce(Multi.new(), fn {changeset, index}, multi ->
      Multi.insert(multi, Integer.to_string(index), changeset)
    end)
    |> Repo.transaction()
  end

  def update_assessment(id, params) when is_ecto_id(id) do
    simple_update(
      Assessment,
      id,
      using: &Assessment.changeset/2,
      params: params
    )
  end

  def update_question(id, params) when is_ecto_id(id) do
    simple_update(
      Question,
      id,
      using: &Question.changeset/2,
      params: params
    )
  end

  def publish_assessment(id) when is_ecto_id(id) do
    update_assessment(id, %{is_published: true})
  end

  def create_question_for_assessment(params, assessment_id) when is_ecto_id(assessment_id) do
    assessment =
      Assessment
      |> where(id: ^assessment_id)
      |> join(:left, [a], q in assoc(a, :questions))
      |> preload([_, q], questions: q)
      |> Repo.one()

    if assessment do
      params_with_assessment_id = Map.put_new(params, :assessment_id, assessment.id)

      %Question{}
      |> Question.changeset(params_with_assessment_id)
      |> put_display_order(assessment.questions)
      |> Repo.insert()
    else
      {:error, "Assessment not found"}
    end
  end

  def get_question(id) when is_ecto_id(id) do
    Question
    |> where(id: ^id)
    |> join(:inner, [q], assessment in assoc(q, :assessment))
    |> preload([_, a], assessment: a)
    |> Repo.one()
  end

  def delete_question(id) when is_ecto_id(id) do
    question = Repo.get(Question, id)
    Repo.delete(question)
  end

  @doc """
  Public internal api to submit new answers for a question. Possible return values are:
  `{:ok, nil}` -> success
  `{:error, error}` -> failed. `error` is in the format of `{http_response_code, error message}`

  Note: In the event of `find_or_create_submission` failing due to a race condition, error will be:
   `{:bad_request, "Missing or invalid parameter(s)"}`

  """
  def answer_question(
        question = %Question{},
        cr = %CourseRegistration{id: cr_id},
        raw_answer,
        force_submit
      ) do
    with {:ok, team} <- find_team(question.assessment.id, cr_id),
         {:ok, submission} <- find_or_create_submission(cr, question.assessment),
         {:status, true} <- {:status, force_submit or submission.status != :submitted},
         {:ok, _answer} <- insert_or_update_answer(submission, question, raw_answer, cr_id) do
      update_submission_status_router(submission, question)

      {:ok, nil}
    else
      {:status, _} ->
        {:error, {:forbidden, "Assessment submission already finalised"}}

      {:error, :race_condition} ->
        {:error, {:internal_server_error, "Please try again later."}}

      {:error, :team_not_found} ->
        {:error, {:bad_request, "Your existing Team has been deleted!"}}

      {:error, :invalid_vote} ->
        {:error, {:bad_request, "Invalid vote! Vote is not saved."}}

      _ ->
        {:error, {:bad_request, "Missing or invalid parameter(s)"}}
    end
  end

  defp find_teams(cr_id) do
    query =
      from(t in Team,
        join: tm in assoc(t, :team_members),
        where: tm.student_id == ^cr_id
      )

    Repo.all(query)
  end

  defp find_team(assessment_id, cr_id)
       when is_ecto_id(assessment_id) and is_ecto_id(cr_id) do
    query =
      from(t in Team,
        where: t.assessment_id == ^assessment_id,
        join: tm in assoc(t, :team_members),
        where: tm.student_id == ^cr_id,
        limit: 1
      )

    assessment_team_size =
      Map.get(
        Repo.one(
          from(a in Assessment,
            where: a.id == ^assessment_id,
            select: %{max_team_size: a.max_team_size}
          )
        ),
        :max_team_size,
        0
      )

    case assessment_team_size > 1 do
      true ->
        case Repo.one(query) do
          nil -> {:error, :team_not_found}
          team -> {:ok, team}
        end

      # team is nil for individual assessments
      false ->
        {:ok, nil}
    end
  end

  def get_submission(assessment_id, %CourseRegistration{id: cr_id})
      when is_ecto_id(assessment_id) do
    {:ok, team} = find_team(assessment_id, cr_id)

    case team do
      %Team{} ->
        Submission
        |> where(assessment_id: ^assessment_id)
        |> where(team_id: ^team.id)
        |> join(:inner, [s], a in assoc(s, :assessment))
        |> preload([_, a], assessment: a)
        |> Repo.one()

      nil ->
        Submission
        |> where(assessment_id: ^assessment_id)
        |> where(student_id: ^cr_id)
        |> join(:inner, [s], a in assoc(s, :assessment))
        |> preload([_, a], assessment: a)
        |> Repo.one()
    end
  end

  def get_submission_by_id(submission_id) when is_ecto_id(submission_id) do
    Submission
    |> where(id: ^submission_id)
    |> join(:inner, [s], a in assoc(s, :assessment))
    |> preload([_, a], assessment: a)
    |> Repo.one()
  end

  def finalise_submission(submission = %Submission{}) do
    with {:status, :attempted} <- {:status, submission.status},
         {:ok, updated_submission} <- update_submission_status(submission) do
      # Couple with update_submission_status and update_xp_bonus to ensure notification is sent
      Notifications.write_notification_when_student_submits(submission)
      # Send email notification to avenger
      %{notification_type: "assessment_submission", submission_id: updated_submission.id}
      |> Cadet.Workers.NotificationWorker.new()
      |> Oban.insert()

      # Begin autograding job
      GradingJob.force_grade_individual_submission(updated_submission)
      update_xp_bonus(submission)

      {:ok, nil}
    else
      {:status, :attempting} ->
        {:error, {:bad_request, "Some questions have not been attempted"}}

      {:status, :submitted} ->
        {:error, {:forbidden, "Assessment has already been submitted"}}

      _ ->
        {:error, {:internal_server_error, "Please try again later."}}
    end
  end

  def unsubmit_submission(
        submission_id,
        cr = %CourseRegistration{id: course_reg_id, role: role}
      )
      when is_ecto_id(submission_id) do
    submission =
      Submission
      |> join(:inner, [s], a in assoc(s, :assessment))
      |> preload([_, a], assessment: a)
      |> Repo.get(submission_id)

    # allows staff to unsubmit own assessment
    bypass = role in @bypass_closed_roles and submission.student_id == course_reg_id

    with {:submission_found?, true} <- {:submission_found?, is_map(submission)},
         {:is_open?, true} <- {:is_open?, bypass or is_open?(submission.assessment)},
         {:status, :submitted} <- {:status, submission.status},
         {:allowed_to_unsubmit?, true} <-
           {:allowed_to_unsubmit?,
            role == :admin or bypass or is_nil(submission.student_id) or
              Cadet.Accounts.Query.avenger_of?(cr, submission.student_id)},
         {:is_grading_published?, false} <-
           {:is_grading_published?, submission.is_grading_published} do
      Multi.new()
      |> Multi.run(
        :rollback_submission,
        fn _repo, _ ->
          submission
          |> Submission.changeset(%{
            status: :attempted,
            xp_bonus: 0,
            unsubmitted_by_id: course_reg_id,
            unsubmitted_at: Timex.now()
          })
          |> Repo.update()
        end
      )
      |> Multi.run(:rollback_answers, fn _repo, _ ->
        Answer
        |> join(:inner, [a], q in assoc(a, :question))
        |> join(:inner, [a, _], s in assoc(a, :submission))
        |> preload([_, q, s], question: q, submission: s)
        |> where(submission_id: ^submission.id)
        |> Repo.all()
        |> Enum.reduce_while({:ok, nil}, fn answer, acc ->
          case acc do
            {:error, _} ->
              {:halt, acc}

            {:ok, _} ->
              {:cont,
               answer
               |> Answer.grading_changeset(%{
                 xp: 0,
                 xp_adjustment: 0,
                 autograding_status: :none,
                 autograding_results: []
               })
               |> Repo.update()}
          end
        end)
      end)
      |> Repo.transaction()

      case submission.student_id do
        # Team submission, handle notifications for team members
        nil ->
          team = Repo.get(Team, submission.team_id)

          query =
            from(t in Team,
              join: tm in TeamMember,
              on: t.id == tm.team_id,
              join: cr in CourseRegistration,
              on: tm.student_id == cr.id,
              where: t.id == ^team.id,
              select: cr.id
            )

          team_members = Repo.all(query)

          Enum.each(team_members, fn tm_id ->
            Notifications.handle_unsubmit_notifications(
              submission.assessment.id,
              Repo.get(CourseRegistration, tm_id)
            )
          end)

        student_id ->
          Notifications.handle_unsubmit_notifications(
            submission.assessment.id,
            Repo.get(CourseRegistration, student_id)
          )
      end

      # Remove grading notifications for submissions
      Notification
      |> where(submission_id: ^submission_id, type: :submitted)
      |> select([n], n.id)
      |> Repo.all()
      |> Notifications.acknowledge(cr)

      {:ok, nil}
    else
      {:submission_found?, false} ->
        {:error, {:not_found, "Submission not found"}}

      {:is_open?, false} ->
        {:error, {:forbidden, "Assessment not open"}}

      {:status, :attempting} ->
        {:error, {:bad_request, "Some questions have not been attempted"}}

      {:status, :attempted} ->
        {:error, {:bad_request, "Assessment has not been submitted"}}

      {:allowed_to_unsubmit?, false} ->
        {:error, {:forbidden, "Only Avenger of student or Admin is permitted to unsubmit"}}

      {:is_grading_published?, true} ->
        {:error, {:forbidden, "Grading has not been unpublished"}}

      _ ->
        {:error, {:internal_server_error, "Please try again later."}}
    end
  end

  defp can_publish?(submission_id, cr = %CourseRegistration{id: course_reg_id, role: role}) do
    submission =
      Submission
      |> join(:inner, [s], a in assoc(s, :assessment))
      |> join(:inner, [_, a], c in assoc(a, :config))
      |> preload([_, a, c], assessment: {a, config: c})
      |> Repo.get(submission_id)

    # allows staff to unpublish own assessment
    bypass = role in @bypass_closed_roles and submission.student_id == course_reg_id

    with {:submission_found?, true} <- {:submission_found?, is_map(submission)},
         {:status, :submitted} <- {:status, submission.status},
         {:is_manually_graded?, true} <-
           {:is_manually_graded?, submission.assessment.config.is_manually_graded},
         {:fully_graded?, true} <- {:fully_graded?, is_fully_graded?(submission_id)},
         {:allowed_to_publish?, true} <-
           {:allowed_to_publish?,
            role == :admin or bypass or
              Cadet.Accounts.Query.avenger_of?(cr, submission.student_id)} do
      {:ok, submission}
    end
  end

  @doc """
    Unpublishes grading for a submission and send notification to student.
    Requires admin or staff who is group leader of student.

    Only manually graded assessments can be individually unpublished. We can only
    unpublish all submissions for auto-graded assessments.

    Returns `{:ok, nil}` on success, otherwise `{:error, {status, message}}`.
  """
  def unpublish_grading(submission_id, cr = %CourseRegistration{})
      when is_ecto_id(submission_id) do
    case can_publish?(submission_id, cr) do
      {:ok, submission} ->
        submission
        |> Submission.changeset(%{is_grading_published: false})
        |> Repo.update()

        Notifications.handle_unpublish_grades_notifications(
          submission.assessment.id,
          Repo.get(CourseRegistration, submission.student_id)
        )

        {:ok, nil}

      {:submission_found?, false} ->
        {:error, {:not_found, "Submission not found"}}

      {:allowed_to_publish?, false} ->
        {:error,
         {:forbidden, "Only Avenger of student or Admin is permitted to unpublish grading"}}

      {:is_manually_graded?, false} ->
        {:error,
         {:bad_request, "Only manually graded assessments can be individually unpublished"}}

      _ ->
        {:error, {:internal_server_error, "Please try again later."}}
    end
  end

  @doc """
    Publishes grading for a submission and send notification to student.
    Requires admin or staff who is group leader of student and all answers to be graded.

    Only manually graded assessments can be individually published. We can only
    publish all submissions for auto-graded assessments.

    Returns `{:ok, nil}` on success, otherwise `{:error, {status, message}}`.
  """
  def publish_grading(submission_id, cr = %CourseRegistration{})
      when is_ecto_id(submission_id) do
    case can_publish?(submission_id, cr) do
      {:ok, submission} ->
        submission
        |> Submission.changeset(%{is_grading_published: true})
        |> Repo.update()

        Notifications.write_notification_when_published(
          submission.id,
          :published_grading
        )

        Notification
        |> where(submission_id: ^submission.id, type: :submitted)
        |> select([n], n.id)
        |> Repo.all()
        |> Notifications.acknowledge(cr)

        {:ok, nil}

      {:submission_found?, false} ->
        {:error, {:not_found, "Submission not found"}}

      {:status, :attempting} ->
        {:error, {:bad_request, "Some questions have not been attempted"}}

      {:status, :attempted} ->
        {:error, {:bad_request, "Assessment has not been submitted"}}

      {:allowed_to_publish?, false} ->
        {:error, {:forbidden, "Only Avenger of student or Admin is permitted to publish grading"}}

      {:is_manually_graded?, false} ->
        {:error, {:bad_request, "Only manually graded assessments can be individually published"}}

      {:fully_graded?, false} ->
        {:error, {:bad_request, "Some answers are not graded"}}

      _ ->
        {:error, {:internal_server_error, "Please try again later."}}
    end
  end

  @doc """
    Publishes grading for a submission and send notification to student.
    This function is used by the auto-grading system to publish grading. Bypasses Course Reg checks.

    Returns `{:ok, nil}` on success, otherwise `{:error, {status, message}}`.
  """
  def publish_grading(submission_id)
      when is_ecto_id(submission_id) do
    submission =
      Submission
      |> join(:inner, [s], a in assoc(s, :assessment))
      |> preload([_, a], assessment: a)
      |> Repo.get(submission_id)

    with {:submission_found?, true} <- {:submission_found?, is_map(submission)},
         {:status, :submitted} <- {:status, submission.status} do
      submission
      |> Submission.changeset(%{is_grading_published: true})
      |> Repo.update()

      Notifications.write_notification_when_published(
        submission.id,
        :published_grading
      )

      {:ok, nil}
    else
      {:submission_found?, false} ->
        {:error, {:not_found, "Submission not found"}}

      {:status, :attempting} ->
        {:error, {:bad_request, "Some questions have not been attempted"}}

      {:status, :attempted} ->
        {:error, {:bad_request, "Assessment has not been submitted"}}

      _ ->
        {:error, {:internal_server_error, "Please try again later."}}
    end
  end

  @doc """
    Publishes grading for all graded submissions for an assessment and sends notifications to students.
    Requires admin.

    Returns `{:ok, nil}` on success, otherwise `{:error, {status, message}}`.
  """
  def publish_all_graded(publisher = %CourseRegistration{}, assessment_id) do
    if publisher.role == :admin do
      answers_query =
        Answer
        |> group_by([ans], ans.submission_id)
        |> select([ans], %{
          submission_id: ans.submission_id,
          graded_count: filter(count(ans.id), not is_nil(ans.grader_id)),
          autograded_count: filter(count(ans.id), ans.autograding_status == :success)
        })

      question_query =
        Question
        |> group_by([q], q.assessment_id)
        |> join(:inner, [q], a in Assessment, on: q.assessment_id == a.id)
        |> select([q, a], %{
          assessment_id: q.assessment_id,
          question_count: count(q.id)
        })

      submission_query =
        Submission
        |> join(:inner, [s], ans in subquery(answers_query), on: ans.submission_id == s.id)
        |> join(:inner, [s, ans], asst in subquery(question_query),
          on: s.assessment_id == asst.assessment_id
        )
        |> join(:inner, [s, ans, asst], cr in CourseRegistration, on: s.student_id == cr.id)
        |> where([s, ans, asst, cr], cr.course_id == ^publisher.course_id)
        |> where(
          [s, ans, asst, cr],
          asst.question_count == ans.graded_count or asst.question_count == ans.autograded_count
        )
        |> where([s, ans, asst, cr], s.is_grading_published == false)
        |> where([s, ans, asst, cr], s.assessment_id == ^assessment_id)
        |> select([s, ans, asst, cr], %{
          id: s.id
        })

      submissions = Repo.all(submission_query)

      Repo.update_all(submission_query, set: [is_grading_published: true])

      Enum.each(submissions, fn submission ->
        Notifications.write_notification_when_published(
          submission.id,
          :published_grading
        )
      end)

      {:ok, nil}
    else
      {:error, {:forbidden, "Only Admin is permitted to publish all grades"}}
    end
  end

  @doc """
     Unpublishes grading for all submissions with grades published for an assessment and sends notifications to students.
     Requires admin role.

     Returns `{:ok, nil}` on success, otherwise `{:error, {status, message}}`.
  """

  def unpublish_all(publisher = %CourseRegistration{}, assessment_id) do
    if publisher.role == :admin do
      submission_query =
        Submission
        |> join(:inner, [s], cr in CourseRegistration, on: s.student_id == cr.id)
        |> where([s, cr], cr.course_id == ^publisher.course_id)
        |> where([s, cr], s.is_grading_published == true)
        |> where([s, cr], s.assessment_id == ^assessment_id)
        |> select([s, cr], %{
          id: s.id,
          student_id: cr.id
        })

      submissions = Repo.all(submission_query)

      Repo.update_all(submission_query, set: [is_grading_published: false])

      Enum.each(submissions, fn submission ->
        Notifications.handle_unpublish_grades_notifications(
          assessment_id,
          Repo.get(CourseRegistration, submission.student_id)
        )
      end)

      {:ok, nil}
    else
      {:error, {:forbidden, "Only Admin is permitted to unpublish all grades"}}
    end
  end

  @spec update_submission_status(Submission.t()) ::
          {:ok, Submission.t()} | {:error, Ecto.Changeset.t()}
  defp update_submission_status(submission = %Submission{}) do
    submission
    |> Submission.changeset(%{status: :submitted, submitted_at: Timex.now()})
    |> Repo.update()
  end

  @spec update_xp_bonus(Submission.t()) ::
          {:ok, Submission.t()} | {:error, Ecto.Changeset.t()}
  defp update_xp_bonus(submission = %Submission{id: submission_id}) do
    # to ensure backwards compatibility
    if submission.xp_bonus == 0 do
      assessment = submission.assessment
      assessment_conifg = Repo.get_by(AssessmentConfig, id: assessment.config_id)

      max_bonus_xp = assessment_conifg.early_submission_xp
      early_hours = assessment_conifg.hours_before_early_xp_decay

      ans_xp =
        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 =
        ans_xp
        |> subquery
        |> select([a], %{
          total_xp: sum(a.total_xp)
        })
        |> Repo.one()

      xp = decimal_to_integer(total.total_xp)

      cur_time =
        if submission.submitted_at == nil do
          Timex.now()
        else
          submission.submitted_at
        end

      xp_bonus =
        if xp <= 0 do
          0
        else
          if Timex.before?(cur_time, Timex.shift(assessment.open_at, hours: early_hours)) do
            max_bonus_xp
          else
            # This logic interpolates from max bonus at early hour to 0 bonus at close time
            decaying_hours =
              Timex.diff(assessment.close_at, assessment.open_at, :hours) - early_hours

            remaining_hours = Enum.max([0, Timex.diff(assessment.close_at, cur_time, :hours)])
            proportion = if(decaying_hours > 0, do: remaining_hours / decaying_hours, else: 1)
            bonus_xp = round(max_bonus_xp * proportion)
            Enum.max([0, bonus_xp])
          end
        end

      submission
      |> Submission.changeset(%{xp_bonus: xp_bonus})
      |> Repo.update()
    end
  end

  defp update_submission_status_router(submission = %Submission{}, question = %Question{}) do
    case question.type do
      :voting -> update_contest_voting_submission_status(submission, question)
      :mcq -> update_submission_status(submission, question.assessment)
      :programming -> update_submission_status(submission, question.assessment)
    end
  end

  defp update_submission_status(submission = %Submission{}, assessment = %Assessment{}) do
    model_assoc_count = fn model, assoc, id ->
      model
      |> where(id: ^id)
      |> join(:inner, [m], a in assoc(m, ^assoc))
      |> select([_, a], count(a.id))
      |> Repo.one()
    end

    Multi.new()
    |> Multi.run(:assessment, fn _repo, _ ->
      {:ok, model_assoc_count.(Assessment, :questions, assessment.id)}
    end)
    |> Multi.run(:submission, fn _repo, _ ->
      {:ok, model_assoc_count.(Submission, :answers, submission.id)}
    end)
    |> Multi.run(:update, fn _repo, %{submission: s_count, assessment: a_count} ->
      if s_count == a_count do
        submission |> Submission.changeset(%{status: :attempted}) |> Repo.update()
      else
        {:ok, nil}
      end
    end)
    |> Repo.transaction()
  end

  defp update_contest_voting_submission_status(submission = %Submission{}, question = %Question{}) do
    has_nil_entries =
      SubmissionVotes
      |> where(question_id: ^question.id)
      |> where(voter_id: ^submission.student_id)
      |> where([sv], is_nil(sv.score))
      |> Repo.exists?()

    unless has_nil_entries do
      submission |> Submission.changeset(%{status: :attempted}) |> Repo.update()
    end
  end

  defp load_contest_voting_entries(
         questions,
         %CourseRegistration{role: role, course_id: course_id, id: voter_id},
         assessment
       ) do
    Enum.map(
      questions,
      fn q ->
        if q.type == :voting do
          submission_votes = all_submission_votes_by_question_id_and_voter_id(q.id, voter_id)
          # fetch top 10 contest voting entries with the contest question id
          question_id = fetch_associated_contest_question_id(course_id, q)

          # fetch top 10 contest coting entries with contest question id based on popular score
          popular_results =
            if is_nil(question_id) do
              []
            else
              if leaderboard_open?(assessment, q) or role in @open_all_assessment_roles do
                fetch_top_popular_score_answers(question_id, 10)
              else
                []
              end
            end

          leaderboard_results =
            if is_nil(question_id) do
              []
            else
              if leaderboard_open?(assessment, q) or role in @open_all_assessment_roles do
                fetch_top_relative_score_answers(question_id, 10)
              else
                []
              end
            end

          # populate entries to vote for and leaderboard data into the question
          voting_question =
            q.question
            |> Map.put(:contest_entries, submission_votes)
            |> Map.put(
              :contest_leaderboard,
              leaderboard_results
            )
            |> Map.put(
              :popular_leaderboard,
              popular_results
            )

          Map.put(q, :question, voting_question)
        else
          q
        end
      end
    )
  end

  defp all_submission_votes_by_question_id_and_voter_id(question_id, voter_id) do
    SubmissionVotes
    |> where([v], v.voter_id == ^voter_id and v.question_id == ^question_id)
    |> join(:inner, [v], s in assoc(v, :submission))
    |> join(:inner, [v, s], a in assoc(s, :answers))
    |> select([v, s, a], %{submission_id: v.submission_id, answer: a.answer, score: v.score})
    |> Repo.all()
  end

  # Finds the contest_question_id associated with the given voting_question id
  def fetch_associated_contest_question_id(course_id, voting_question) do
    contest_number = voting_question.question["contest_number"]

    if is_nil(contest_number) do
      nil
    else
      Assessment
      |> where(number: ^contest_number, course_id: ^course_id)
      |> join(:inner, [a], q in assoc(a, :questions))
      |> order_by([a, q], q.display_order)
      |> select([a, q], q.id)
      |> Repo.one()
    end
  end

  defp leaderboard_open?(assessment, voting_question) do
    Timex.before?(
      Timex.shift(assessment.close_at, hours: voting_question.question["reveal_hours"]),
      Timex.now()
    )
  end

  @doc """
  Fetches top answers for the given question, based on the contest relative_score

  Used for contest leaderboard fetching
  """
  def fetch_top_relative_score_answers(question_id, number_of_answers) do
    Answer
    |> where(question_id: ^question_id)
    |> where(
      [a],
      fragment(
        "?->>'code' like ?",
        a.answer,
        "%return%"
      )
    )
    |> order_by(desc: :relative_score)
    |> join(:left, [a], s in assoc(a, :submission))
    |> join(:left, [a, s], student in assoc(s, :student))
    |> join(:inner, [a, s, student], student_user in assoc(student, :user))
    |> where([a, s, student], student.role == "student")
    |> select([a, s, student, student_user], %{
      submission_id: a.submission_id,
      answer: a.answer,
      relative_score: a.relative_score,
      student_name: student_user.name
    })
    |> limit(^number_of_answers)
    |> Repo.all()
  end

  @doc """
  Fetches top answers for the given question, based on the contest popular_score

  Used for contest leaderboard fetching
  """
  def fetch_top_popular_score_answers(question_id, number_of_answers) do
    Answer
    |> where(question_id: ^question_id)
    |> where(
      [a],
      fragment(
        "?->>'code' like ?",
        a.answer,
        "%return%"
      )
    )
    |> order_by(desc: :popular_score)
    |> join(:left, [a], s in assoc(a, :submission))
    |> join(:left, [a, s], student in assoc(s, :student))
    |> join(:inner, [a, s, student], student_user in assoc(student, :user))
    |> where([a, s, student], student.role == "student")
    |> select([a, s, student, student_user], %{
      submission_id: a.submission_id,
      answer: a.answer,
      popular_score: a.popular_score,
      student_name: student_user.name
    })
    |> limit(^number_of_answers)
    |> Repo.all()
  end

  @doc """
  Computes rolling leaderboard for contest votes that are still open.
  """
  def update_rolling_contest_leaderboards do
    # 115 = 2 hours - 5 minutes is default.
    if Log.log_execution("update_rolling_contest_leaderboards", Duration.from_minutes(115)) do
      Logger.info("Started update_rolling_contest_leaderboards")

      voting_questions_to_update = fetch_active_voting_questions()

      _ =
        voting_questions_to_update
        |> Enum.map(fn qn -> compute_relative_score(qn.id) end)

      Logger.info("Successfully update_rolling_contest_leaderboards")
    end
  end

  def fetch_active_voting_questions do
    Question
    |> join(:left, [q], a in assoc(q, :assessment))
    |> where([q, a], q.type == "voting")
    |> where([q, a], a.is_published)
    |> where([q, a], a.open_at <= ^Timex.now() and a.close_at >= ^Timex.now())
    |> Repo.all()
  end

  @doc """
  Computes final leaderboard for contest votes that have closed.
  """
  def update_final_contest_leaderboards do
    # 1435 = 24 hours - 5 minutes
    if Log.log_execution("update_final_contest_leaderboards", Duration.from_minutes(1435)) do
      Logger.info("Started update_final_contest_leaderboards")

      voting_questions_to_update = fetch_voting_questions_due_yesterday()

      _ =
        voting_questions_to_update
        |> Enum.map(fn qn -> compute_relative_score(qn.id) end)

      Logger.info("Successfully update_final_contest_leaderboards")
    end
  end

  def fetch_voting_questions_due_yesterday do
    Question
    |> join(:left, [q], a in assoc(q, :assessment))
    |> where([q, a], q.type == "voting")
    |> where([q, a], a.is_published)
    |> where([q, a], a.open_at <= ^Timex.now())
    |> where(
      [q, a],
      a.close_at < ^Timex.now() and a.close_at >= ^Timex.shift(Timex.now(), days: -1)
    )
    |> Repo.all()
  end

  @doc """
  Computes the current relative_score of each voting submission answer
  based on current submitted votes.
  """
  def compute_relative_score(contest_voting_question_id) do
    # query all records from submission votes tied to the question id ->
    # map score to user id ->
    # store as grade ->
    # query grade for contest question id.
    eligible_votes =
      SubmissionVotes
      |> where(question_id: ^contest_voting_question_id)
      |> where([sv], not is_nil(sv.score))
      |> join(:inner, [sv], ans in Answer, on: sv.submission_id == ans.submission_id)
      |> select(
        [sv, ans],
        %{ans_id: ans.id, score: sv.score, ans: ans.answer["code"]}
      )
      |> Repo.all()

    token_divider =
      Question
      |> select([q], q.question["token_divider"])
      |> Repo.get_by(id: contest_voting_question_id)

    entry_scores = map_eligible_votes_to_entry_score(eligible_votes, token_divider)
    normalized_scores = map_eligible_votes_to_popular_score(eligible_votes, token_divider)

    entry_scores
    |> Enum.map(fn {ans_id, relative_score} ->
      %Answer{id: ans_id}
      |> Answer.contest_score_update_changeset(%{
        relative_score: relative_score
      })
    end)
    |> Enum.map(fn changeset ->
      op_key = "answer_#{changeset.data.id}"
      Multi.update(Multi.new(), op_key, changeset)
    end)
    |> Enum.reduce(Multi.new(), &Multi.append/2)
    |> Repo.transaction()

    normalized_scores
    |> Enum.map(fn {ans_id, popular_score} ->
      %Answer{id: ans_id}
      |> Answer.popular_score_update_changeset(%{
        popular_score: popular_score
      })
    end)
    |> Enum.map(fn changeset ->
      op_key = "answer_#{changeset.data.id}"
      Multi.update(Multi.new(), op_key, changeset)
    end)
    |> Enum.reduce(Multi.new(), &Multi.append/2)
    |> Repo.transaction()
  end

  defp map_eligible_votes_to_entry_score(eligible_votes, token_divider) do
    # converts eligible votes to the {total cumulative score, number of votes, tokens}
    entry_vote_data =
      Enum.reduce(eligible_votes, %{}, fn %{ans_id: ans_id, score: score, ans: ans}, tracker ->
        {prev_score, prev_count, _ans_tokens} = Map.get(tracker, ans_id, {0, 0, 0})

        Map.put(
          tracker,
          ans_id,
          # assume each voter is assigned 10 entries which will make it fair.
          {prev_score + score, prev_count + 1, Lexer.count_tokens(ans)}
        )
      end)

    # calculate the score based on formula {ans_id, score}
    Enum.map(
      entry_vote_data,
      fn {ans_id, {sum_of_scores, number_of_voters, tokens}} ->
        {ans_id, calculate_formula_score(sum_of_scores, number_of_voters, tokens, token_divider)}
      end
    )
  end

  defp map_eligible_votes_to_popular_score(eligible_votes, token_divider) do
    # converts eligible votes to the {total cumulative score, number of votes, tokens}
    entry_vote_data =
      Enum.reduce(eligible_votes, %{}, fn %{ans_id: ans_id, score: score, ans: ans}, tracker ->
        {prev_score, prev_count, _ans_tokens} = Map.get(tracker, ans_id, {0, 0, 0})

        Map.put(
          tracker,
          ans_id,
          # assume each voter is assigned 10 entries which will make it fair.
          {prev_score + score, prev_count + 1, Lexer.count_tokens(ans)}
        )
      end)

    # calculate the score based on formula {ans_id, score}
    Enum.map(
      entry_vote_data,
      fn {ans_id, {sum_of_scores, number_of_voters, tokens}} ->
        {ans_id,
         calculate_normalized_score(sum_of_scores, number_of_voters, tokens, token_divider)}
      end
    )
  end

  # Calculate the score based on formula
  # score(v,t) = v - 2^(t/token_divider) where v is the normalized_voting_score
  # normalized_voting_score = sum_of_scores / number_of_voters / 10 * 100
  defp calculate_formula_score(sum_of_scores, number_of_voters, tokens, token_divider) do
    normalized_voting_score =
      calculate_normalized_score(sum_of_scores, number_of_voters, tokens, token_divider)

    normalized_voting_score - :math.pow(2, min(1023.5, tokens / token_divider))
  end

  # Calculate the normalized score based on formula
  # normalized_voting_score = sum_of_scores / number_of_voters / 10 * 100
  defp calculate_normalized_score(sum_of_scores, number_of_voters, _tokens, _token_divider) do
    sum_of_scores / number_of_voters / 10 * 100
  end

  @doc """
  Function returning submissions under a grader. This function returns only the
  fields that are exposed in the /grading endpoint.

  The input parameters are the user and query parameters. Query parameters are
  used to filter the submissions.

  The return value is `{:ok, %{"count": count, "data": submissions}}`

  # Parameters
  - `pageSize`: Integer. The number of submissions to return. Default is 10.
  - `offset`: Integer. The number of submissions to skip. Default is 0.
  - `title`: String. Assessment title.
  - `status`: String. Submission status.
  - `isFullyGraded`: Boolean. Whether the submission is fully graded.
  - `isGradingPublished`: Boolean. Whether the grading is published.
  - `group`: Boolean. Only the groups under the grader should be returned.
  - `groupName`: String. Group name.
  - `name`: String. User name.
  - `username`: String. User username.
  - `type`: String. Assessment Config type.
  - `isManuallyGraded`: Boolean. Whether the assessment is manually graded.

  # Implementation
  Uses helper functions to build the filter query. Helper functions are separated by tables in the database.
  """

  @spec submissions_by_grader_for_index(CourseRegistration.t()) ::
          {:ok,
           %{
             :count => integer,
             :data => %{
               :assessments => [any()],
               :submissions => [any()],
               :users => [any()],
               :teams => [any()],
               :team_members => [any()]
             }
           }}
  def submissions_by_grader_for_index(
        grader = %CourseRegistration{course_id: course_id},
        params \\ %{
          "group" => "false",
          "isFullyGraded" => "false",
          "pageSize" => "10",
          "offset" => "0",
          "sortBy" => "",
          "sortDirection" => ""
        }
      ) do
    submission_answers_query =
      from(ans in Answer,
        group_by: ans.submission_id,
        select: %{
          submission_id: ans.submission_id,
          xp: sum(ans.xp),
          xp_adjustment: sum(ans.xp_adjustment),
          graded_count: filter(count(ans.id), not is_nil(ans.grader_id))
        }
      )

    question_answers_query =
      from(q in Question,
        group_by: q.assessment_id,
        join: a in Assessment,
        on: q.assessment_id == a.id,
        select: %{
          assessment_id: q.assessment_id,
          question_count: count(q.id),
          title: max(a.title),
          config_id: max(a.config_id)
        }
      )

    query =
      from(s in Submission,
        left_join: ans in subquery(submission_answers_query),
        on: ans.submission_id == s.id,
        as: :ans,
        left_join: asst in subquery(question_answers_query),
        on: asst.assessment_id == s.assessment_id,
        as: :asst,
        left_join: cr in CourseRegistration,
        on: s.student_id == cr.id,
        as: :cr,
        left_join: user in User,
        on: user.id == cr.user_id,
        as: :user,
        left_join: group in Group,
        on: cr.group_id == group.id,
        as: :group,
        inner_join: config in AssessmentConfig,
        on: asst.config_id == config.id,
        as: :config,
        where: ^build_user_filter(params),
        where: s.assessment_id in subquery(build_assessment_filter(params, course_id)),
        where: s.assessment_id in subquery(build_assessment_config_filter(params)),
        where: ^build_submission_filter(params),
        where: ^build_course_registration_filter(params, grader),
        limit: ^elem(Integer.parse(Map.get(params, "pageSize", "10")), 0),
        offset: ^elem(Integer.parse(Map.get(params, "offset", "0")), 0),
        select: %{
          id: s.id,
          status: s.status,
          xp_bonus: s.xp_bonus,
          unsubmitted_at: s.unsubmitted_at,
          unsubmitted_by_id: s.unsubmitted_by_id,
          student_id: s.student_id,
          team_id: s.team_id,
          assessment_id: s.assessment_id,
          is_grading_published: s.is_grading_published,
          xp: ans.xp,
          xp_adjustment: ans.xp_adjustment,
          graded_count: ans.graded_count,
          question_count: asst.question_count
        }
      )

    query =
      sort_submission(query, Map.get(params, "sortBy", ""), Map.get(params, "sortDirection", ""))

    query =
      from([s, ans, asst, cr, user, group] in query, order_by: [desc: s.inserted_at, asc: s.id])

    submissions = Repo.all(query)

    count_query =
      from(s in Submission,
        left_join: ans in subquery(submission_answers_query),
        on: ans.submission_id == s.id,
        as: :ans,
        left_join: asst in subquery(question_answers_query),
        on: asst.assessment_id == s.assessment_id,
        as: :asst,
        where: s.assessment_id in subquery(build_assessment_filter(params, course_id)),
        where: s.assessment_id in subquery(build_assessment_config_filter(params)),
        where: ^build_user_filter(params),
        where: ^build_submission_filter(params),
        where: ^build_course_registration_filter(params, grader),
        select: count(s.id)
      )

    count = Repo.one(count_query)

    {:ok, %{count: count, data: generate_grading_summary_view_model(submissions, course_id)}}
  end

  # Given a query from submissions_by_grader_for_index,
  # sorts it by the relevant field and direction
  # sort_by is a string of either "", "assessmentName", "assessmentType", "studentName",
  # "studentUsername", "groupName", "progressStatus", "xp"
  # sort_direction is a string of either "", "sort-asc", "sort-desc"
  defp sort_submission(query, sort_by, sort_direction) do
    cond do
      sort_direction == "sort-asc" ->
        sort_submission_asc(query, sort_by)

      sort_direction == "sort-desc" ->
        sort_submission_desc(query, sort_by)

      true ->
        query
    end
  end

  defp sort_submission_asc(query, sort_by) do
    cond do
      sort_by == "assessmentName" ->
        from([s, ans, asst, cr, user, group, config] in query,
          order_by: fragment("upper(?)", asst.title)
        )

      sort_by == "assessmentType" ->
        from([s, ans, asst, cr, user, group, config] in query, order_by: asst.config_id)

      sort_by == "studentName" ->
        from([s, ans, asst, cr, user, group, config] in query,
          order_by: fragment("upper(?)", user.name)
        )

      sort_by == "studentUsername" ->
        from([s, ans, asst, cr, user, group, config] in query,
          order_by: fragment("upper(?)", user.username)
        )

      sort_by == "groupName" ->
        from([s, ans, asst, cr, user, group, config] in query,
          order_by: fragment("upper(?)", group.name)
        )

      sort_by == "progressStatus" ->
        from([s, ans, asst, cr, user, group, config] in query,
          order_by: [
            asc: config.is_manually_graded,
            asc: s.status,
            asc: ans.graded_count - asst.question_count,
            asc: s.is_grading_published
          ]
        )

      sort_by == "xp" ->
        from([s, ans, asst, cr, user, group, config] in query,
          order_by: ans.xp + ans.xp_adjustment
        )

      true ->
        query
    end
  end

  defp sort_submission_desc(query, sort_by) do
    cond do
      sort_by == "assessmentName" ->
        from([s, ans, asst, cr, user, group, config] in query,
          order_by: [desc: fragment("upper(?)", asst.title)]
        )

      sort_by == "assessmentType" ->
        from([s, ans, asst, cr, user, group, config] in query, order_by: [desc: asst.config_id])

      sort_by == "studentName" ->
        from([s, ans, asst, cr, user, group, config] in query,
          order_by: [desc: fragment("upper(?)", user.name)]
        )

      sort_by == "studentUsername" ->
        from([s, ans, asst, cr, user, group, config] in query,
          order_by: [desc: fragment("upper(?)", user.username)]
        )

      sort_by == "groupName" ->
        from([s, ans, asst, cr, user, group, config] in query,
          order_by: [desc: fragment("upper(?)", group.name)]
        )

      sort_by == "progressStatus" ->
        from([s, ans, asst, cr, user, group, config] in query,
          order_by: [
            desc: config.is_manually_graded,
            desc: s.status,
            desc: ans.graded_count - asst.question_count,
            desc: s.is_grading_published
          ]
        )

      sort_by == "xp" ->
        from([s, ans, asst, cr, user, group, config] in query,
          order_by: [desc: ans.xp + ans.xp_adjustment]
        )

      true ->
        query
    end
  end

  defp build_assessment_filter(params, course_id) do
    assessments_filters =
      Enum.reduce(params, dynamic(true), fn
        {"title", value}, dynamic ->
          dynamic([assessment], ^dynamic and ilike(assessment.title, ^"%#{value}%"))

        {_, _}, dynamic ->
          dynamic
      end)

    from(a in Assessment,
      where: a.course_id == ^course_id,
      where: ^assessments_filters,
      select: a.id
    )
  end

  defp build_submission_filter(params) do
    Enum.reduce(params, dynamic(true), fn
      {"status", value}, dynamic ->
        dynamic([submission], ^dynamic and submission.status == ^value)

      {"isFullyGraded", value}, dynamic ->
        dynamic(
          [ans: ans, asst: asst],
          ^dynamic and asst.question_count == ans.graded_count == ^value
        )

      {"isGradingPublished", value}, dynamic ->
        dynamic([submission], ^dynamic and submission.is_grading_published == ^value)

      {_, _}, dynamic ->
        dynamic
    end)
  end

  defp build_course_registration_filter(params, grader) do
    Enum.reduce(params, dynamic(true), fn
      {"group", "true"}, dynamic ->
        dynamic(
          [submission],
          (^dynamic and
             submission.student_id in subquery(
               from(cr in CourseRegistration,
                 join: g in Group,
                 on: cr.group_id == g.id,
                 where: g.leader_id == ^grader.id,
                 select: cr.id
               )
             )) or submission.student_id == ^grader.id
        )

      {"groupName", value}, dynamic ->
        dynamic(
          [submission],
          ^dynamic and
            submission.student_id in subquery(
              from(cr in CourseRegistration,
                join: g in Group,
                on: cr.group_id == g.id,
                where: g.name == ^value,
                select: cr.id
              )
            )
        )

      {_, _}, dynamic ->
        dynamic
    end)
  end

  defp build_user_filter(params) do
    Enum.reduce(params, dynamic(true), fn
      {"name", value}, dynamic ->
        dynamic(
          [submission],
          ^dynamic and
            submission.student_id in subquery(
              from(user in User,
                where: ilike(user.name, ^"%#{value}%"),
                inner_join: cr in CourseRegistration,
                on: user.id == cr.user_id,
                select: cr.id
              )
            )
        )

      {"username", value}, dynamic ->
        dynamic(
          [submission],
          ^dynamic and
            submission.student_id in subquery(
              from(user in User,
                where: ilike(user.username, ^"%#{value}%"),
                inner_join: cr in CourseRegistration,
                on: user.id == cr.user_id,
                select: cr.id
              )
            )
        )

      {_, _}, dynamic ->
        dynamic
    end)
  end

  defp build_assessment_config_filter(params) do
    assessment_config_filters =
      Enum.reduce(params, dynamic(true), fn
        {"type", value}, dynamic ->
          dynamic([assessment_config: config], ^dynamic and config.type == ^value)

        {"isManuallyGraded", value}, dynamic ->
          dynamic([assessment_config: config], ^dynamic and config.is_manually_graded == ^value)

        {_, _}, dynamic ->
          dynamic
      end)

    from(a in Assessment,
      inner_join: config in AssessmentConfig,
      on: a.config_id == config.id,
      as: :assessment_config,
      where: ^assessment_config_filters,
      select: a.id
    )
  end

  defp generate_grading_summary_view_model(submissions, course_id) do
    users =
      CourseRegistration
      |> where([cr], cr.course_id == ^course_id)
      |> join(:inner, [cr], u in assoc(cr, :user))
      |> join(:left, [cr, u], g in assoc(cr, :group))
      |> preload([cr, u, g], user: u, group: g)
      |> Repo.all()

    assessment_ids = submissions |> Enum.map(& &1.assessment_id) |> Enum.uniq()

    assessments =
      Assessment
      |> where([a], a.id in ^assessment_ids)
      |> join(:left, [a], q in assoc(a, :questions))
      |> join(:inner, [a], ac in assoc(a, :config))
      |> preload([a, q, ac], questions: q, config: ac)
      |> Repo.all()

    team_ids = submissions |> Enum.map(& &1.team_id) |> Enum.uniq()

    teams =
      Team
      |> where([t], t.id in ^team_ids)
      |> Repo.all()

    team_members =
      TeamMember
      |> where([tm], tm.team_id in ^team_ids)
      |> Repo.all()

    %{
      users: users,
      assessments: assessments,
      submissions: submissions,
      teams: teams,
      team_members: team_members
    }
  end

  @spec get_answers_in_submission(integer() | String.t()) ::
          {:ok, {[Answer.t()], Assessment.t()}}
          | {:error, {:bad_request, String.t()}}
  def get_answers_in_submission(id) when is_ecto_id(id) do
    answer_query =
      Answer
      |> where(submission_id: ^id)
      |> join(:inner, [a], q in assoc(a, :question))
      |> join(:inner, [_, q], ast in assoc(q, :assessment))
      |> join(:inner, [..., ast], ac in assoc(ast, :config))
      |> join(:left, [a, ...], g in assoc(a, :grader))
      |> join(:left, [_, ..., g], gu in assoc(g, :user))
      |> join(:inner, [a, ...], s in assoc(a, :submission))
      |> join(:left, [_, ..., s], st in assoc(s, :student))
      |> join(:left, [..., st], u in assoc(st, :user))
      |> join(:left, [..., s, _, _], t in assoc(s, :team))
      |> join(:left, [..., t], tm in assoc(t, :team_members))
      |> join(:left, [..., tm], tms in assoc(tm, :student))
      |> join(:left, [..., tms], tmu in assoc(tms, :user))
      |> preload([_, q, ast, ac, g, gu, s, st, u, t, tm, tms, tmu],
        question: {q, assessment: {ast, config: ac}},
        grader: {g, user: gu},
        submission:
          {s, student: {st, user: u}, team: {t, team_members: {tm, student: {tms, user: tmu}}}}
      )

    answers =
      answer_query
      |> Repo.all()
      |> Enum.sort_by(& &1.question.display_order)
      |> Enum.map(fn ans ->
        if ans.question.type == :voting do
          empty_contest_entries = Map.put(ans.question.question, :contest_entries, [])
          empty_popular_leaderboard = Map.put(empty_contest_entries, :popular_leaderboard, [])
          empty_contest_leaderboard = Map.put(empty_popular_leaderboard, :contest_leaderboard, [])
          question = Map.put(ans.question, :question, empty_contest_leaderboard)
          Map.put(ans, :question, question)
        else
          ans
        end
      end)

    if answers == [] do
      {:error, {:bad_request, "Submission is not found."}}
    else
      assessment_id = Submission |> where(id: ^id) |> select([s], s.assessment_id) |> Repo.one()
      assessment = Assessment |> where(id: ^assessment_id) |> Repo.one()
      {:ok, {answers, assessment}}
    end
  end

  defp is_fully_graded?(submission_id) do
    submission =
      Submission
      |> Repo.get_by(id: submission_id)

    question_count =
      Question
      |> where(assessment_id: ^submission.assessment_id)
      |> select([q], count(q.id))
      |> Repo.one()

    graded_count =
      Answer
      |> where([a], submission_id: ^submission_id)
      |> where([a], not is_nil(a.grader_id))
      |> select([a], count(a.id))
      |> Repo.one()

    question_count == graded_count
  end

  def is_fully_autograded?(submission_id) do
    submission =
      Submission
      |> Repo.get_by(id: submission_id)

    question_count =
      Question
      |> where(assessment_id: ^submission.assessment_id)
      |> select([q], count(q.id))
      |> Repo.one()

    graded_count =
      Answer
      |> where([a], submission_id: ^submission_id)
      |> where([a], a.autograding_status == :success)
      |> select([a], count(a.id))
      |> Repo.one()

    question_count == graded_count
  end

  @spec update_grading_info(
          %{submission_id: integer() | String.t(), question_id: integer() | String.t()},
          %{},
          CourseRegistration.t()
        ) ::
          {:ok, nil}
          | {:error, {:forbidden | :bad_request | :internal_server_error, String.t()}}
  def update_grading_info(
        %{submission_id: submission_id, question_id: question_id},
        attrs,
        cr = %CourseRegistration{id: grader_id}
      )
      when is_ecto_id(submission_id) and is_ecto_id(question_id) do
    attrs = Map.put(attrs, "grader_id", grader_id)

    answer_query =
      Answer
      |> where(submission_id: ^submission_id)
      |> where(question_id: ^question_id)

    answer_query =
      answer_query
      |> join(:inner, [a], s in assoc(a, :submission))
      |> preload([_, s], submission: s)

    answer = Repo.one(answer_query)

    is_own_submission = grader_id == answer.submission.student_id

    submission =
      Submission
      |> join(:inner, [s], a in assoc(s, :assessment))
      |> preload([_, a], assessment: {a, :config})
      |> Repo.get(submission_id)

    is_grading_auto_published = submission.assessment.config.is_grading_auto_published

    with {:answer_found?, true} <- {:answer_found?, is_map(answer)},
         {:status, true} <-
           {:status, answer.submission.status == :submitted or is_own_submission},
         {:valid, changeset = %Ecto.Changeset{valid?: true}} <-
           {:valid, Answer.grading_changeset(answer, attrs)},
         {:ok, _} <- Repo.update(changeset) do
      update_xp_bonus(submission)

      if is_grading_auto_published and is_fully_graded?(submission_id) do
        publish_grading(submission_id, cr)
      end

      {:ok, nil}
    else
      {:answer_found?, false} ->
        {:error, {:bad_request, "Answer not found or user not permitted to grade."}}

      {:valid, changeset} ->
        {:error, {:bad_request, full_error_messages(changeset)}}

      {:status, _} ->
        {:error, {:method_not_allowed, "Submission is not submitted yet."}}

      {:error, _} ->
        {:error, {:internal_server_error, "Please try again later."}}
    end
  end

  def update_grading_info(
        _,
        _,
        _
      ) do
    {:error, {:forbidden, "User is not permitted to grade."}}
  end

  @spec force_regrade_submission(integer() | String.t(), CourseRegistration.t()) ::
          {:ok, nil} | {:error, {:forbidden | :not_found, String.t()}}
  def force_regrade_submission(
        submission_id,
        _requesting_user = %CourseRegistration{id: grader_id}
      )
      when is_ecto_id(submission_id) do
    with {:get, sub} when not is_nil(sub) <- {:get, Repo.get(Submission, submission_id)},
         {:status, true} <- {:status, sub.student_id == grader_id or sub.status == :submitted} do
      GradingJob.force_grade_individual_submission(sub, true)
      {:ok, nil}
    else
      {:get, nil} ->
        {:error, {:not_found, "Submission not found"}}

      {:status, false} ->
        {:error, {:bad_request, "Submission not submitted yet"}}
    end
  end

  def force_regrade_submission(_, _) do
    {:error, {:forbidden, "User is not permitted to grade."}}
  end

  @spec force_regrade_answer(
          integer() | String.t(),
          integer() | String.t(),
          CourseRegistration.t()
        ) ::
          {:ok, nil} | {:error, {:forbidden | :not_found, String.t()}}
  def force_regrade_answer(
        submission_id,
        question_id,
        _requesting_user = %CourseRegistration{id: grader_id}
      )
      when is_ecto_id(submission_id) and is_ecto_id(question_id) do
    answer =
      Answer
      |> where(submission_id: ^submission_id, question_id: ^question_id)
      |> preload([:question, :submission])
      |> Repo.one()

    with {:get, answer} when not is_nil(answer) <- {:get, answer},
         {:status, true} <-
           {:status,
            answer.submission.student_id == grader_id or answer.submission.status == :submitted} do
      GradingJob.grade_answer(answer, answer.question, true)
      {:ok, nil}
    else
      {:get, nil} ->
        {:error, {:not_found, "Answer not found"}}

      {:status, false} ->
        {:error, {:bad_request, "Submission not submitted yet"}}
    end
  end

  def force_regrade_answer(_, _, _) do
    {:error, {:forbidden, "User is not permitted to grade."}}
  end

  defp find_submission(cr = %CourseRegistration{}, assessment = %Assessment{}) do
    {:ok, team} = find_team(assessment.id, cr.id)

    submission =
      case team do
        %Team{} ->
          Submission
          |> where(team_id: ^team.id)
          |> where(assessment_id: ^assessment.id)
          |> Repo.one()

        nil ->
          Submission
          |> where(student_id: ^cr.id)
          |> where(assessment_id: ^assessment.id)
          |> Repo.one()
      end

    if submission do
      {:ok, submission}
    else
      {:error, nil}
    end
  end

  # Checks if an assessment is open and published.
  @spec is_open?(Assessment.t()) :: boolean()
  def is_open?(%Assessment{open_at: open_at, close_at: close_at, is_published: is_published}) do
    Timex.between?(Timex.now(), open_at, close_at, inclusive: :start) and is_published
  end

  @spec get_group_grading_summary(integer()) ::
          {:ok, [String.t(), ...], []}
  def get_group_grading_summary(course_id) do
    subs =
      Answer
      |> join(:left, [ans], s in Submission, on: s.id == ans.submission_id)
      |> join(:left, [ans, s], st in CourseRegistration, on: s.student_id == st.id)
      |> join(:left, [ans, s, st], a in Assessment, on: a.id == s.assessment_id)
      |> join(:inner, [ans, s, st, a], ac in AssessmentConfig, on: ac.id == a.config_id)
      |> where(
        [ans, s, st, a, ac],
        not is_nil(st.group_id) and s.status == ^:submitted and
          ac.show_grading_summary and a.course_id == ^course_id
      )
      |> group_by([ans, s, st, a, ac], s.id)
      |> select([ans, s, st, a, ac], %{
        group_id: max(st.group_id),
        config_id: max(ac.id),
        config_type: max(ac.type),
        num_submitted: count(),
        num_ungraded: filter(count(), is_nil(ans.grader_id))
      })

    raw_data =
      subs
      |> subquery()
      |> join(:left, [t], g in Group, on: t.group_id == g.id)
      |> join(:left, [t, g], l in CourseRegistration, on: l.id == g.leader_id)
      |> join(:left, [t, g, l], lu in User, on: lu.id == l.user_id)
      |> group_by([t, g, l, lu], [t.group_id, t.config_id, t.config_type, g.name, lu.name])
      |> select([t, g, l, lu], %{
        group_name: g.name,
        leader_name: lu.name,
        config_id: t.config_id,
        config_type: t.config_type,
        ungraded: filter(count(), t.num_ungraded > 0),
        submitted: count()
      })
      |> Repo.all()

    showing_configs =
      AssessmentConfig
      |> where([ac], ac.course_id == ^course_id and ac.show_grading_summary)
      |> order_by(:order)
      |> group_by([ac], ac.id)
      |> select([ac], %{
        id: ac.id,
        type: ac.type
      })
      |> Repo.all()

    data_by_groups =
      raw_data
      |> Enum.reduce(%{}, fn raw, acc ->
        if Map.has_key?(acc, raw.group_name) do
          acc
          |> put_in([raw.group_name, "ungraded" <> raw.config_type], raw.ungraded)
          |> put_in([raw.group_name, "submitted" <> raw.config_type], raw.submitted)
        else
          acc
          |> put_in([raw.group_name], %{})
          |> put_in([raw.group_name, "groupName"], raw.group_name)
          |> put_in([raw.group_name, "leaderName"], raw.leader_name)
          |> put_in([raw.group_name, "ungraded" <> raw.config_type], raw.ungraded)
          |> put_in([raw.group_name, "submitted" <> raw.config_type], raw.submitted)
        end
      end)

    headings =
      showing_configs
      |> Enum.reduce([], fn config, acc ->
        acc ++ ["submitted" <> config.type, "ungraded" <> config.type]
      end)

    default_row_data =
      headings
      |> Enum.reduce(%{}, fn heading, acc ->
        put_in(acc, [heading], 0)
      end)

    rows = data_by_groups |> Enum.map(fn {_k, row} -> Map.merge(default_row_data, row) end)
    cols = ["groupName", "leaderName"] ++ headings

    {:ok, cols, rows}
  end

  defp create_empty_submission(cr = %CourseRegistration{}, assessment = %Assessment{}) do
    {:ok, team} = find_team(assessment.id, cr.id)

    case team do
      %Team{} ->
        %Submission{}
        |> Submission.changeset(%{team: team, assessment: assessment})
        |> Repo.insert()
        |> case do
          {:ok, submission} -> {:ok, submission}
        end

      nil ->
        %Submission{}
        |> Submission.changeset(%{student: cr, assessment: assessment})
        |> Repo.insert()
        |> case do
          {:ok, submission} -> {:ok, submission}
        end
    end
  end

  defp find_or_create_submission(cr = %CourseRegistration{}, assessment = %Assessment{}) do
    case find_submission(cr, assessment) do
      {:ok, submission} -> {:ok, submission}
      {:error, _} -> create_empty_submission(cr, assessment)
    end
  end

  defp insert_or_update_answer(
         submission = %Submission{},
         question = %Question{},
         raw_answer,
         course_reg_id
       ) do
    answer_content = build_answer_content(raw_answer, question.type)

    if question.type == :voting do
      insert_or_update_voting_answer(submission.id, course_reg_id, question.id, answer_content)
    else
      answer_changeset =
        %Answer{}
        |> Answer.changeset(%{
          answer: answer_content,
          question_id: question.id,
          submission_id: submission.id,
          type: question.type,
          last_modified_at: Timex.now()
        })

      Repo.insert(
        answer_changeset,
        on_conflict: [
          set: [answer: get_change(answer_changeset, :answer), last_modified_at: Timex.now()]
        ],
        conflict_target: [:submission_id, :question_id]
      )
    end
  end

  def has_last_modified_answer?(
        question = %Question{},
        cr = %CourseRegistration{id: cr_id},
        last_modified_at,
        force_submit
      ) do
    with {:ok, submission} <- find_or_create_submission(cr, question.assessment),
         {:status, true} <- {:status, force_submit or submission.status != :submitted},
         {:ok, is_modified} <- answer_last_modified?(submission, question, last_modified_at) do
      {:ok, is_modified}
    else
      {:status, _} ->
        {:error, {:forbidden, "Assessment submission already finalised"}}

      {:error, :race_condition} ->
        {:error, {:internal_server_error, "Please try again later."}}

      {:error, :invalid_vote} ->
        {:error, {:bad_request, "Invalid vote! Vote is not saved."}}

      _ ->
        {:error, {:bad_request, "Missing or invalid parameter(s)"}}
    end
  end

  defp answer_last_modified?(
         submission = %Submission{},
         question = %Question{},
         last_modified_at
       ) do
    case Repo.get_by(Answer, submission_id: submission.id, question_id: question.id) do
      %Answer{last_modified_at: existing_last_modified_at} ->
        existing_iso8601 = DateTime.to_iso8601(existing_last_modified_at)

        if existing_iso8601 == last_modified_at do
          {:ok, false}
        else
          {:ok, true}
        end

      nil ->
        {:ok, false}
    end
  end

  def insert_or_update_voting_answer(submission_id, course_reg_id, question_id, answer_content) do
    set_score_to_nil =
      SubmissionVotes
      |> where(voter_id: ^course_reg_id, question_id: ^question_id)

    voting_multi =
      Multi.new()
      |> Multi.update_all(:set_score_to_nil, set_score_to_nil, set: [score: nil])

    answer_content
    |> Enum.with_index(1)
    |> Enum.reduce(voting_multi, fn {entry, index}, multi ->
      multi
      |> Multi.run("update#{index}", fn _repo, _ ->
        SubmissionVotes
        |> Repo.get_by(
          voter_id: course_reg_id,
          submission_id: entry.submission_id
        )
        |> SubmissionVotes.changeset(%{score: entry.score})
        |> Repo.insert_or_update()
      end)
    end)
    |> Multi.run("insert into answer table", fn _repo, _ ->
      Answer
      |> Repo.get_by(submission_id: submission_id, question_id: question_id)
      |> case do
        nil ->
          Repo.insert(%Answer{
            answer: %{completed: true},
            submission_id: submission_id,
            question_id: question_id,
            type: :voting
          })

        _ ->
          {:ok, nil}
      end
    end)
    |> Repo.transaction()
    |> case do
      {:ok, _result} -> {:ok, nil}
      {:error, _name, _changeset, _error} -> {:error, :invalid_vote}
    end
  end

  defp build_answer_content(raw_answer, question_type) do
    case question_type do
      :mcq ->
        %{choice_id: raw_answer}

      :programming ->
        %{code: raw_answer}

      :voting ->
        raw_answer
        |> Enum.map(fn ans ->
          for {key, value} <- ans, into: %{}, do: {String.to_existing_atom(key), value}
        end)
    end
  end
end

source-academy / backend / 18dc689a4df4836fc6967bf0f74dc252964bd175-PR-1180

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