feat(mailers): thank coaches when they reach an attendance milestone

app/jobs/send_coach_milestone_email_job.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class SendCoachMilestoneEmailJob < ApplicationJob
+  queue_as :default
+
+  def perform
+    CoachMilestoneEmailService.send_milestone_emails
+  end
+end

app/mailers/concerns/email_delivery.rb

@@ -11,12 +11,16 @@ def log_sent_email
     return unless member
     return unless @_mail_was_called
 
-    MemberEmailDelivery.find_or_create_by!(member:, email_type: action_name) do |delivery|
+    MemberEmailDelivery.find_or_create_by!(member:, email_type: email_type_for_log) do |delivery|
       delivery.subject = mail.subject
       delivery.body = mail.html_part ? mail.html_part.body.to_s : mail.body.to_s
       delivery.to = Array(mail.to)
       delivery.cc = Array(mail.cc)
       delivery.bcc = Array(mail.bcc)
     end
   end
+
+  def email_type_for_log
+    action_name
+  end
 end

app/mailers/member_mailer.rb

@@ -2,7 +2,7 @@ class MemberMailer < ApplicationMailer
   include EmailHeaderHelper
   include EmailDelivery
 
-  after_deliver :log_sent_email, only: %i[chaser signup_nudge signup_nudge_followup]
+  after_deliver :log_sent_email, only: %i[chaser signup_nudge signup_nudge_followup coach_milestone]
 
   def signup_nudge
     @member = params[:member]
@@ -31,6 +31,15 @@ def chaser
     end
   end
 
+  def coach_milestone
+    @member = params[:member]
+    @milestone = params[:milestone]
+    subject = "You’ve attended #{@milestone} codebar workshops — amazing 🎉"
+    mail_to_member(@member, subject, 'hello@codebar.io', 'hello@codebar.io') do |format|
+      format.html { render 'coach_milestone' }
+    end
+  end
+
   def welcome(member)
     if member.student?
       welcome_student(member)
@@ -99,4 +108,14 @@ def ban(member, ban)
       format.html { render 'ban' }
     end.deliver
   end
+
+  private
+
+  # One action serves every milestone, so the delivery log is keyed per
+  # milestone rather than per action (see EmailDelivery#email_type_for_log).
+  def email_type_for_log
+    return super unless action_name == 'coach_milestone'
+
+    "coach_milestone_#{params[:milestone]}"
+  end
 end

app/services/coach_milestone_email_service.rb

@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+# Thanks coaches once per attendance milestone (issue #2386). Run daily by
+# chaser:coach_milestones. Only the highest milestone reached is sent, so a
+# coach already past several milestones at launch gets one email rather than
+# one per milestone; the delivery log then keeps every milestone send-once.
+class CoachMilestoneEmailService
+  MILESTONES = [5].freeze
+  EMAIL_TYPE_PREFIX = 'coach_milestone_'
+
+  def self.send_milestone_emails
+    due = milestones_due
+    return if due.empty?
+
+    Member.not_banned.accepted_toc.where(id: due.keys).find_each do |member|
+      MemberMailer.with(member:, milestone: due[member.id]).coach_milestone.deliver_later
+    end
+  end
+
+  # { member_id => milestone } for coaches owed an email: the highest milestone
+  # at or below their count, unless that milestone or a higher one was already sent.
+  def self.milestones_due
+    sent = sent_milestones
+    attended_counts.each_with_object({}) do |(member_id, count), due|
+      milestone = milestone_for(count)
+      next unless milestone
+      next if sent.fetch(member_id, []).any? { |previous| previous >= milestone }
+
+      due[member_id] = milestone
+    end
+  end
+
+  # Attended past workshops per coach. The WHERE matches the partial index
+  # index_workshop_invitations_coach_attended_on_member_id.
+  def self.attended_counts
+    WorkshopInvitation.to_coaches.attended
+                      .joins(:workshop)
+                      .where('workshops.date_and_time < ?', Time.zone.now)
+                      .group(:member_id)
+                      .having('COUNT(*) >= ?', MILESTONES.min)
+                      .count
+  end
+
+  def self.milestone_for(count)
+    MILESTONES.select { |milestone| milestone <= count }.max
+  end
+
+  # { member_id => [milestones already emailed] }
+  def self.sent_milestones
+    MemberEmailDelivery.where('email_type LIKE ?', "#{EMAIL_TYPE_PREFIX}%")
+                       .where.not(member_id: nil)
+                       .pluck(:member_id, :email_type)
+                       .group_by(&:first)
+                       .transform_values { |rows| rows.map { |(_, type)| type.delete_prefix(EMAIL_TYPE_PREFIX).to_i } }
+  end
+
+  private_class_method :milestones_due, :attended_counts, :milestone_for, :sent_milestones
+end

app/views/member_mailer/coach_milestone.html.haml

@@ -0,0 +1,16 @@
+%h1 Hi #{@member.name},
+
+%p
+  You’ve now attended #{@milestone} codebar workshops as a coach 🎉
+
+%p
+  This is just a very quick email to say a huge thank you. Without our wonderful coaches our workshops would not happen, so the difference you’re making is huge!
+
+%p
+  So the biggest thank you for being part of codebar and we’re excited to keep seeing you at our workshops 💜
+
+%p
+  #{'-- '}
+%br
+The biggest thank you,
+The codebar Team

lib/tasks/chaser.rake

@@ -8,4 +8,9 @@ namespace :chaser do
   task signup_nudges: :environment do
     SendSignupNudgeEmailJob.perform_later
   end
+
+  desc 'Send thank-you emails to coaches who reached an attendance milestone'
+  task coach_milestones: :environment do
+    SendCoachMilestoneEmailJob.perform_later
+  end
 end

spec/jobs/send_coach_milestone_email_job_spec.rb

@@ -0,0 +1,13 @@
+require 'rails_helper'
+
+RSpec.describe SendCoachMilestoneEmailJob do
+  describe '#perform' do
+    it 'delegates to the coach milestone email service' do
+      allow(CoachMilestoneEmailService).to receive(:send_milestone_emails)
+
+      described_class.new.perform
+
+      expect(CoachMilestoneEmailService).to have_received(:send_milestone_emails)
+    end
+  end
+end

spec/lib/tasks/chaser_coach_milestones_rake_spec.rb

@@ -0,0 +1,15 @@
+require 'rails_helper'
+
+RSpec.describe 'rake chaser:coach_milestones' do
+  it 'preloads the Rails environment' do
+    expect(task.prerequisites).to include 'environment'
+  end
+
+  it 'enqueues the coach milestone email job' do
+    allow(SendCoachMilestoneEmailJob).to receive(:perform_later)
+
+    task.invoke
+
+    expect(SendCoachMilestoneEmailJob).to have_received(:perform_later)
+  end
+end

spec/mailers/member_mailer_spec.rb

@@ -237,4 +237,38 @@
         .to change { MemberEmailDelivery.where(member:, email_type: 'signup_nudge_followup').count }.by(1)
     end
   end
+
+  describe '#coach_milestone' do
+    let(:mail) { described_class.with(member:, milestone: 5).coach_milestone.deliver_now }
+
+    it 'renders the headers' do
+      expect(mail.subject).to eq('You’ve attended 5 codebar workshops — amazing 🎉')
+      expect(mail.to).to eq([member.email])
+      expect(mail.from).to eq(['hello@codebar.io'])
+    end
+
+    it 'renders the body' do
+      expect(mail.body.encoded).to match("Hi #{member.name}")
+      expect(mail.body.encoded).to match('attended 5 codebar workshops as a coach')
+    end
+
+    it 'logs with the milestone in the email_type' do
+      expect { mail }
+        .to change { MemberEmailDelivery.where(member:, email_type: 'coach_milestone_5').count }.by(1)
+    end
+
+    it 'logs each milestone separately' do
+      described_class.with(member:, milestone: 5).coach_milestone.deliver_now
+      described_class.with(member:, milestone: 10).coach_milestone.deliver_now
+
+      expect(MemberEmailDelivery.where(member:).pluck(:email_type)).to contain_exactly('coach_milestone_5', 'coach_milestone_10')
+    end
+
+    it 'logs one row per milestone even if the delivery is performed twice' do
+      expect do
+        described_class.with(member:, milestone: 5).coach_milestone.deliver_now
+        described_class.with(member:, milestone: 5).coach_milestone.deliver_now
+      end.to change(MemberEmailDelivery, :count).by(1)
+    end
+  end
 end

spec/services/coach_milestone_email_service_spec.rb

@@ -0,0 +1,132 @@
+require 'rails_helper'
+
+RSpec.describe CoachMilestoneEmailService do
+  describe '.send_milestone_emails' do
+    subject(:call) { described_class.send_milestone_emails }
+
+    around do |example|
+      original_adapter = ActiveJob::Base.queue_adapter
+      ActiveJob::Base.queue_adapter = :test
+      example.run
+    ensure
+      ActiveJob::Base.queue_adapter = original_adapter
+    end
+
+    def attend(member, count, role: 'Coach', weeks_ago: 1)
+      count.times do |i|
+        workshop = Fabricate(:workshop, chapter:, date_and_time: (weeks_ago + i).weeks.ago)
+        Fabricate(:workshop_invitation, member:, workshop:, role:, attended: true)
+      end
+    end
+
+    let(:chapter) { Fabricate(:chapter) }
+
+    let!(:coach_at_five) { Fabricate(:member).tap { |m| attend(m, 5) } }
+    let!(:coach_at_seven) { Fabricate(:member).tap { |m| attend(m, 7) } }
+    let!(:coach_at_four) { Fabricate(:member).tap { |m| attend(m, 4) } }
+    let!(:coach_with_future_fifth) do
+      Fabricate(:member).tap do |m|
+        attend(m, 4)
+        Fabricate(:workshop_invitation, member: m, workshop: Fabricate(:workshop, chapter:), role: 'Coach',
+                                        attended: true)
+      end
+    end
+    let!(:coach_invited_not_attended) do
+      Fabricate(:member).tap do |m|
+        5.times do |i|
+          Fabricate(:workshop_invitation, member: m, role: 'Coach', attending: true, attended: nil,
+                                          workshop: Fabricate(:workshop, chapter:, date_and_time: (i + 1).weeks.ago))
+        end
+      end
+    end
+    let!(:student_at_five) { Fabricate(:member).tap { |m| attend(m, 5, role: 'Student') } }
+    let!(:coach_already_thanked) do
+      Fabricate(:member).tap do |m|
+        attend(m, 5)
+        Fabricate(:member_email_delivery, member: m, email_type: 'coach_milestone_5')
+      end
+    end
+    let!(:coach_with_other_email_logged) do
+      Fabricate(:member).tap do |m|
+        attend(m, 5)
+        Fabricate(:member_email_delivery, member: m, email_type: 'chaser')
+      end
+    end
+    let!(:coach_thanked_for_higher_milestone) do
+      Fabricate(:member).tap do |m|
+        attend(m, 6)
+        Fabricate(:member_email_delivery, member: m, email_type: 'coach_milestone_10')
+      end
+    end
+    let!(:banned_coach) { Fabricate(:banned_member).tap { |m| attend(m, 5) } }
+    let!(:coach_without_toc) { Fabricate(:member_without_toc).tap { |m| attend(m, 5) } }
+
+    it 'thanks coaches who attended at least five past workshops and were not thanked before' do
+      expect { perform_enqueued_jobs { call } }.to change(MemberEmailDelivery, :count).by(3)
+
+      expect(MemberEmailDelivery.where(member: coach_at_five, email_type: 'coach_milestone_5')).to exist
+      expect(MemberEmailDelivery.where(member: coach_at_seven, email_type: 'coach_milestone_5')).to exist
+      expect(MemberEmailDelivery.where(member: coach_with_other_email_logged, email_type: 'coach_milestone_5'))
+        .to exist
+    end
+
+    it 'does not thank a coach below the milestone' do
+      expect { perform_enqueued_jobs { call } }
+        .not_to(change { MemberEmailDelivery.where(member: coach_at_four).count })
+    end
+
+    it 'does not count workshops that have not taken place yet' do
+      expect { perform_enqueued_jobs { call } }
+        .not_to(change { MemberEmailDelivery.where(member: coach_with_future_fifth).count })
+    end
+
+    it 'does not count invitations that were accepted but not attended' do
+      expect { perform_enqueued_jobs { call } }
+        .not_to(change { MemberEmailDelivery.where(member: coach_invited_not_attended).count })
+    end
+
+    it 'does not count workshops attended as a student' do
+      expect { perform_enqueued_jobs { call } }
+        .not_to(change { MemberEmailDelivery.where(member: student_at_five).count })
+    end
+
+    it 'does not thank a coach twice for the same milestone' do
+      expect { perform_enqueued_jobs { call } }
+        .not_to(change { MemberEmailDelivery.where(member: coach_already_thanked).count })
+    end
+
+    it 'does not thank a coach already thanked for a higher milestone' do
+      expect { perform_enqueued_jobs { call } }
+        .not_to(change { MemberEmailDelivery.where(member: coach_thanked_for_higher_milestone).count })
+    end
+
+    it 'does not thank banned coaches' do
+      expect { perform_enqueued_jobs { call } }
+        .not_to(change { MemberEmailDelivery.where(member: banned_coach).count })
+    end
+
+    it 'does not thank coaches who have not accepted the terms of conduct' do
+      expect { perform_enqueued_jobs { call } }
+        .not_to(change { MemberEmailDelivery.where(member: coach_without_toc).count })
+    end
+
+    it 'is idempotent across runs' do
+      perform_enqueued_jobs { described_class.send_milestone_emails }
+
+      expect { perform_enqueued_jobs { described_class.send_milestone_emails } }
+        .not_to change(MemberEmailDelivery, :count)
+    end
+
+    context 'when a higher milestone is configured' do
+      before { stub_const("#{described_class}::MILESTONES", [5, 10]) }
+
+      let!(:coach_at_twelve) { Fabricate(:member).tap { |m| attend(m, 12) } }
+
+      it 'sends only the highest milestone reached' do
+        perform_enqueued_jobs { call }
+
+        expect(MemberEmailDelivery.where(member: coach_at_twelve).pluck(:email_type)).to eq(['coach_milestone_10'])
+      end
+    end
+  end
+end