class Rufus::Scheduler

def do_schedule(job_type, t, callable, opts, return_job_instance, block)
  fail NotRunningError.new(
    'cannot schedule, scheduler is down or shutting down'
  ) if @started_at == nil
  callable, opts = nil, callable if callable.is_a?(Hash)
  return_job_instance ||= opts[:job]
  job_class =
    case job_type
      when :once
        opts[:_t] ||= Rufus::Scheduler.parse(t, opts)
        opts[:_t].is_a?(Time) ? AtJob : InJob
      when :every
        EveryJob
      when :interval
        IntervalJob
      when :cron
        CronJob
    end
  job = job_class.new(self, t, opts, block || callable)
  raise ArgumentError.new(
    "job frequency (#{job.frequency}) is higher than " +
    "scheduler frequency (#{@frequency})"
  ) if job.respond_to?(:frequency) && job.frequency < @frequency
  @jobs.push(job)
  return_job_instance ? job : job.job_id
end