# frozen_string_literal: true

require 'aws/rails/action_mailbox/sns_notification'

module ActionMailbox
  module Ingresses
    module Ses
      # Ingests inbound emails from Amazon SES/SNS and confirms subscriptions.
      #
      # Subscription requests must provide the following parameters in a JSON body:
      # - +Message+: Notification content
      # - +MessagId+: Notification unique identifier
      # - +Timestamp+: iso8601 timestamp
      # - +TopicArn+: Topic identifier
      # - +Type+: Type of event ("Subscription")
      #
      # Inbound email events must provide the following parameters in a JSON body:
      # - +Message+: Notification content
      # - +MessagId+: Notification unique identifier
      # - +Timestamp+: iso8601 timestamp
      # - +SubscribeURL+: Topic identifier
      # - +TopicArn+: Topic identifier
      # - +Type+: Type of event ("SubscriptionConfirmation")
      #
      # All requests are authenticated by validating the provided AWS signature.
      #
      # Returns:
      #
      # - <tt>204 No Content</tt> if a request is successfully processed
      # - <tt>401 Unauthorized</tt> if a request does not contain a valid signature
      # - <tt>404 Not Found</tt> if the Amazon ingress has not been configured
      # - <tt>422 Unprocessable Entity</tt> if a request provides invalid parameters
      class InboundEmailsController < ActionMailbox::BaseController
        before_action :verify_authenticity, :validate_topic, :confirm_subscription

        def create
          head :bad_request unless notification.message_content.present?

          ActionMailbox::InboundEmail.create_and_extract_message_id!(notification.message_content)
          head :no_content
        end

        private

        def verify_authenticity
          head :bad_request unless notification.present?
          head :unauthorized unless notification.verified?
        end

        def confirm_subscription
          return unless notification.type == 'SubscriptionConfirmation'
          return head :ok if notification.subscription_confirmed?

          Rails.logger.error('SNS subscription confirmation request rejected.')
          head :unprocessable_entity
        end

        def validate_topic
          return if valid_topic == notification.topic

          Rails.logger.warn("Ignoring unknown topic: #{topic}")
          head :unauthorized
        end

        def notification
          @notification ||= Aws::Rails::ActionMailbox::SnsNotification.new(request.raw_post)
        end

        def topic
          @topic ||= notification.topic
        end

        def valid_topic
          ::Rails.configuration.action_mailbox.ses.subscribed_topic
        end
      end
    end
  end
end