huginn/app/models/agents/email_digest_agent.rb

module Agents
  class EmailDigestAgent < Agent
    include EmailConcern

    default_schedule "5am"

    cannot_create_events!

    description <<-MD
      The Email Digest Agent collects any Events sent to it and sends them all via email when scheduled.

      By default, the will have a `subject` and an optional `headline` before listing the Events.  If the Events'
      payloads contain a `message`, that will be highlighted, otherwise everything in
      their payloads will be shown.

      You can specify one or more `recipients` for the email, or skip the option in order to send the email to your
      account's default email address.

      You can provide a `from` address for the email, or leave it blank to default to the value of `EMAIL_FROM_ADDRESS` (`#{ENV['EMAIL_FROM_ADDRESS']}`).

      Set `expected_receive_period_in_days` to the maximum amount of time that you'd expect to pass between Events being received by this Agent.
    MD

    def default_options
      {
          'subject' => "You have some notifications!",
          'headline' => "Your notifications:",
          'expected_receive_period_in_days' => "2"
      }
    end

    def receive(incoming_events)
      incoming_events.each do |event|
        self.memory['queue'] ||= []
        self.memory['queue'] << event.payload
        self.memory['events'] ||= []
        self.memory['events'] << event.id
      end
    end

    def check
      if self.memory['queue'] && self.memory['queue'].length > 0
        ids = self.memory['events'].join(",")
        groups = self.memory['queue'].map { |payload| present(payload) }
        recipients.each do |recipient|
          log "Sending digest mail to #{recipient} with events [#{ids}]"
          SystemMailer.send_message(
            to: recipient,
            from: interpolated['from'],
            subject: interpolated['subject'],
            headline: interpolated['headline'],
            groups: groups
          ).deliver_later
        end
        self.memory['queue'] = []
        self.memory['events'] = []
      end
    end
  end
end