Import Action Mailbox

4 files changed, 106 insertions, 0 deletions

diff --git a/actionmailbox/app/models/action_mailbox/inbound_email/incineratable.rb b/actionmailbox/app/models/action_mailbox/inbound_email/incineratable.rb
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+++ b/actionmailbox/app/models/action_mailbox/inbound_email/incineratable.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+# Ensure that the `InboundEmail` is automatically scheduled for later incineration if the status has been
+# changed to `processed`. The later incineration will be invoked at the time specified by the
+# `ActionMailbox.incinerate_after` time using the `IncinerationJob`.
+module ActionMailbox::InboundEmail::Incineratable
+  extend ActiveSupport::Concern
+
+  included do
+    after_update_commit :incinerate_later, if: -> { status_previously_changed? && processed? }
+  end
+
+  def incinerate_later
+    ActionMailbox::IncinerationJob.schedule self
+  end
+
+  def incinerate
+    Incineration.new(self).run
+  end
+end
diff --git a/actionmailbox/app/models/action_mailbox/inbound_email/incineratable/incineration.rb b/actionmailbox/app/models/action_mailbox/inbound_email/incineratable/incineration.rb
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+++ b/actionmailbox/app/models/action_mailbox/inbound_email/incineratable/incineration.rb
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+# frozen_string_literal: true
+
+# Command class for carrying out the actual incineration of the `InboundMail` that's been scheduled
+# for removal. Before the incineration – which really is just a call to `#destroy!` – is run, we verify
+# that it's both eligible (by virtue of having already been processed) and time to do so (that is,
+# the `InboundEmail` was processed after the `incinerate_after` time).
+class ActionMailbox::InboundEmail::Incineratable::Incineration
+  def initialize(inbound_email)
+    @inbound_email = inbound_email
+  end
+
+  def run
+    @inbound_email.destroy! if due? && processed?
+  end
+
+  private
+    def due?
+      @inbound_email.updated_at < ActionMailbox.incinerate_after.ago.end_of_day
+    end
+
+    def processed?
+      @inbound_email.processed?
+    end
+end
diff --git a/actionmailbox/app/models/action_mailbox/inbound_email/message_id.rb b/actionmailbox/app/models/action_mailbox/inbound_email/message_id.rb
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+++ b/actionmailbox/app/models/action_mailbox/inbound_email/message_id.rb
@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+# The `Message-ID` as specified by rfc822 is supposed to be a unique identifier for that individual email.
+# That makes it an ideal tracking token for debugging and forensics, just like `X-Request-Id` does for
+# web request.
+#
+# If an inbound email does not, against the rfc822 mandate, specify a Message-ID, one will be generated
+# using the approach from `Mail::MessageIdField`.
+module ActionMailbox::InboundEmail::MessageId
+  extend ActiveSupport::Concern
+
+  included do
+    before_save :generate_missing_message_id
+  end
+
+  class_methods do
+    # Create a new `InboundEmail` from the raw `source` of the email, which be uploaded as a Active Storage
+    # attachment called `raw_email`. Before the upload, extract the Message-ID from the `source` and set
+    # it as an attribute on the new `InboundEmail`.
+    def create_and_extract_message_id!(source, **options)
+      create! message_id: extract_message_id(source), **options do |inbound_email|
+        inbound_email.raw_email.attach io: StringIO.new(source), filename: "message.eml", content_type: "message/rfc822"
+      end
+    end
+
+    private
+      def extract_message_id(source)
+        Mail.from_source(source).message_id rescue nil
+      end
+  end
+
+  private
+    def generate_missing_message_id
+      self.message_id ||= Mail::MessageIdField.new.message_id.tap do |message_id|
+        logger.warn "Message-ID couldn't be parsed or is missing. Generated a new Message-ID: #{message_id}"
+      end
+    end
+end
diff --git a/actionmailbox/app/models/action_mailbox/inbound_email/routable.rb b/actionmailbox/app/models/action_mailbox/inbound_email/routable.rb
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+++ b/actionmailbox/app/models/action_mailbox/inbound_email/routable.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+# A newly received `InboundEmail` will not be routed synchronously as part of ingress controller's receival.
+# Instead, the routing will be done asynchronously, using a `RoutingJob`, to ensure maximum parallel capacity.
+#
+# By default, all newly created `InboundEmail` records that have the status of `pending`, which is the default,
+# will be scheduled for automatic, deferred routing.
+module ActionMailbox::InboundEmail::Routable
+  extend ActiveSupport::Concern
+
+  included do
+    after_create_commit :route_later, if: :pending?
+  end
+
+  # Enqueue a `RoutingJob` for this `InboundEmail`.
+  def route_later
+    ActionMailbox::RoutingJob.perform_later self
+  end
+
+  # Route this `InboundEmail` using the routing rules declared on the `ApplicationMailbox`.
+  def route
+    ApplicationMailbox.route self
+  end
+end