class AddVideoToCourseModule < ActiveRecord::Migration[5.2]
  def change
    Course.all.each do |course|
      unless course.course_modules.exists?(module_type: "video")
        atta_position = course.course_modules.find_by(module_type: 'attachment')&.position.to_i
        video_position = atta_position != 0 ? (atta_position + 1) : 11
        course.course_modules.where("position >= #{video_position}").update_all("position = position + 1")
        course.course_modules << CourseModule.new(module_type: "video", hidden: 1, module_name: "视频", position: video_position)
      end
    end
  end
end