osem-fcy/app/mailers/mailbot.rb

class Mailbot < ActionMailer::Base
  default from: "no-reply@example.com"

  def registration_mail(conference, person)
    build_email(conference,
                person.email,
                conference.email_settings.registration_subject,
                conference.email_settings.generate_registration_email(conference, person))
  end

  def acceptance_mail(event)
    conference = event.conference
    person = event.submitter
    build_email(conference,
                person.email,
                conference.email_settings.accepted_subject,
                conference.email_settings.generate_accepted_email(event))
  end

  def rejection_mail(event)
    conference = event.conference
    person = event.submitter
    build_email(conference,
                person.email,
                conference.email_settings.rejected_subject,
                conference.email_settings.generate_rejected_email(event))
  end

  def confirm_reminder_mail(event)
    conference = event.conference
    person = event.submitter

    build_email(conference,
                person.email,
                conference.email_settings.confirmed_without_registration_subject,
                conference.email_settings.confirmed_but_not_registered_email(event))
  end

  def conference_date_update_mail(conference)
    conference.registrations.each do |user|
      build_email(conference,
                  user.user.email,
                  conference.email_settings.updated_conference_dates_subject,
                  conference.email_settings.generate_conference_date_update_mail(conference, user))
    end
  end

  def conference_registration_date_update_mail(conference)
    conference.registrations.each do |user|
      build_email(conference,
                  user.user.email,
                  conference.email_settings.updated_conference_registration_dates_subject,
                  conference.email_settings.generate_conference_registration_date_update_mail(conference, user))
    end
  end

  def send_email_on_venue_update(conference)
    conference.registrations.each do |user|
      build_email(conference,
                  user.email,
                  conference.email_settings.venue_update_subject,
                  conference.email_settings.generate_send_email_on_venue_update(conference, user))
    end
  end

  def build_email(conference, to, subject, body)
    mail(to: to,
         from: conference.contact_email,
         reply_to: conference.contact_email,
         subject: subject,
         body: body)
  end
end