skill-assessment-app/app/workers/quiz_status.rb

class QuizStatus
  attr_reader :candidate

  def initialize candidate
    @candidate = Candidate.find(candidate.to_i)
  end

  def started
    candidate.answers.count > 0
  end

  def on_summary
    candidate.submitted_answers.count == candidate.questions.count
  end

  def completed
    candidate.completed
  end

  def can_submit
    on_summary && candidate.answered_questions.count == candidate.questions.count
  end

  def progress
    answs = candidate.answered_questions.count.to_f
    total = candidate.quiz.questions.count.to_f

    (answs / total * 100).round.to_i
  end

  def current_question_id
    sql = "select q.id question_id
           from candidates c
             inner join questions q on q.quiz_id = c.quiz_id
             left join answers a on a.candidate_id = c.id AND a.question_id = q.id
           where q.active = true and c.id = #{candidate.to_i}
             and (a.id is null OR a.submitted is false)
           order by q.sort limit 1;"
    result = ActiveRecord::Base.connection.exec_query(sql).to_hash.first
    result['question_id'] unless result.nil?
  end
end