Add organizer summary emails

app/mailers/hackathons/digest_mailer.rb

@@ -32,4 +32,25 @@ def admin_summary(sent_digests)
 
  mail to: Hackathons::SUPPORT_EMAIL, cc: User.admins.collect(&:email_address), subject:
  end
+
+ def organizer_summary(sent_digests)
+ # This reloads the (possible) sent_digests array as an
+ # ActiveRecord::Relation so that we can use includes to prevent an N+1.
+ @sent_digests = Hackathon::Digest.where(id: sent_digests.map(&:id)) ||
+ Hackathon::Digest.where(created_at: 6.days.ago...Time.now)
+
+ @sent_digests_by_hackathons = @sent_digests
+ .includes(listings: {hackathon: {logo_attachment: :blob}})
+ .flat_map(&:listings).group_by(&:hackathon)
+ .transform_values { |listings| listings.map(&:digest).uniq }
+
+ @listed_hackathons = @sent_digests_by_hackathons.keys
+ .sort_by { |hackathon| @sent_digests_by_hackathons[hackathon].count }.reverse!
+
+ @listed_hackathons.each do |hackathon|
+ @hackathon = hackathon
+ @count = @digests_by_hackathons[hackathon].count
+ mail to: hackathon.applicant_email, subject: "We've just sent your hackathon to #{@count} hackers."
+ end
+ end
 end

app/views/hackathons/digest_mailer/organizer_summary.html.erb

@@ -0,0 +1,13 @@
+<% content_for :greeting do %>
+ <p>G'day!</p>
+<% end %>
+
+<p>
+ We've just sent an email about <%= @hackathon.name %> to <%= @count %> hackers. Let us know how things go!
+</p>
+
+<% content_for :signature do %>
+ <p>
+ Best of luck with everything! 🦕 💸
+ </p>
+<% end %>