How can I resend a Devise confirmation email automatically, but only once, for users who have not confirmed?

I am using Rails with Devise confirmable. When users sign up Devise automatically sends them a confirmation email. If they haven't confirmed after three days, I would like to send them another confirmation email with a new token. If they still do not confirm after this second email, we should send them no more. Mapped out on a timeline:

Day 1: User signs up & receives confirmation email; does not confirm
Day 2: User does not confirm
Day 3: Send another email prompting them to confirm; does not confirm
Day 4: User does not confirm; no more emails sent
Day 5: User does not confirm; no more emails sent
Day 6: etc.

I'd rather not add a new column to my Users model that keeps track of how many times they've been sent a confirmation email since I think I can do it in a Worker that runs every day using the information we already have. However I'm struggling a bit with getting the logic right.

Here's what I have so far:

# workers/resend_confirmation_worker.rb

class ResendConfirmationWorker
  include Sidekiq::Worker
  sidekiq_options queue: :resend_confirmation, retry: false

  def perform
    users = User.where('confirmation_sent_at IS NOT NULL and
                        confirmed_at IS NULL')
    users.each do |user|
      return if user.created_at < Time.zone.now - 4.days || user.created_at > Time.zone.now - 3.days
      user.resend_confirmation!
  end
end

# config/clock.rb

module Clockwork
  every(1.day, 'Resend confirmation') { ResendConfirmationWorker.perform_async }
end

Appreciate any help or suggestions for improvement.

Solution

d = 2.days.ago
users = User.where.not(confirmation_sent_at: nil)
            .where(confirmed_at: nil)
            .where(created_at: d.beginning_of_day..d.end_of_day)

users.find_each do |user|
  user.resend_confirmation!
end