yay for services.

new_answer_controller.rb

module Api
  module V1
    class AnswerController < ApplicationController
      respond_to :json

      def create
        lesson_session.process_attempts(params[:attempts].values)
        API::ProcessAnswer.new(lesson_session, current_student).call if lesson_session.completed?

        render json: {}
      end

      private
      def lesson_session
        unless session = LessonSession.find_for(current_student, lesson_id)
          session = LessonSession.create(current_student, lesson_id)
        end

        session
      end

      def lesson_id
        params[:lesson_id]
      end
    end
  end
end

old_answer_controller.rb

module Api
  module V1
    class AnswerController < ApplicationController
      respond_to :json

      def create
        lesson_session.process_attempts(params[:attempts].values)

        # [g] make a service
        if lesson_session.completed?
          score = Score::LessonSession.build(lesson_session).to_i
          lessons_users = LessonsUser.find_by(student_id: current_student.id, lesson_id: lesson_id)
          if lessons_users
            count = lessons_users.count
            if score > lessons_users.score
              lessons_users.update(score: score, count: count + 1)
            else
              lessons_users.update(count: count + 1)
            end
          else
            LessonsUser.create(student_id: current_student.id, lesson_id: lesson_id, score: score, count: 1)
          end
        end

        render json: {}
      end

      private
      def lesson_session
        unless session = LessonSession.find_for(current_student, lesson_id)
          session = LessonSession.create(current_student, lesson_id)
        end

        session
      end

      def lesson_id
        params[:lesson_id]
      end
    end
  end
end

process_answer.rb

module API
  class ProcessAnswer

    def initialize(lesson_session, student)
      @session, @student = lesson_session, student
    end

    def call
      if lessons_user
        update_score_and_count
      else
        LessonsUser.create(student_id: student.id, lesson_id: lesson_id, score: score, count: 1)
      end
    end

    private
    attr_reader :session, :student

    def update_score_and_count
      update_hash = { count: increment_count }
      update_hash[:score] = score if higher_score?

      lessons_user.update(update_hash)
    end

    def higher_score?
      score > lessons_user.score
    end

    def increment_count
      count + 1
    end

    def score
      Score::LessonSession.build(session).to_i
    end

    def lessons_user
      @lessons_user ||= LessonsUser.find_by(student_id: student.id, lesson_id: lesson_id)
    end

    def count
      lessons_user.count
    end

    def lesson_id
      session.lesson.id
    end
  end
end