Add ability to delete Maybe account (#698)

* Build out user deactivation and purging workflows

* Add i18n translations for user deletion

* Add tests for user deletion

* Fix lint issue

app/models/user.rb

@@ -38,4 +38,40 @@ class User < ApplicationRecord
   def has_seen_upgrade_alert?(upgrade)
     last_alerted_upgrade_commit_sha == upgrade.commit_sha
   end
+
+  # Deactivation
+  validate :can_deactivate, if: -> { active_changed? && !active }
+  after_update_commit :purge_later, if: -> { saved_change_to_active?(from: true, to: false) }
+
+  def deactivate
+    update active: false, email: deactivated_email
+  end
+
+  def can_deactivate
+    if admin? && family.users.count > 1
+      errors.add(:base, I18n.t("activerecord.errors.user.cannot_deactivate_admin_with_other_users"))
+    end
+  end
+
+  def purge_later
+    UserPurgeJob.perform_later(self)
+  end
+
+  def purge
+    if last_user_in_family?
+      family.destroy
+    else
+      destroy
+    end
+  end
+
+  private
+
+  def last_user_in_family?
+    family.users.count == 1
+  end
+
+  def deactivated_email
+    email.gsub(/@/, "-deactivated-#{SecureRandom.uuid}@")
+  end
 end