Pushing: ActionMailer for Push Notifications

gem 'pushing'
gem 'jbuilder' # if you don't have it in your Gemfile

gem 'apnotic' # APNs
gem 'andpush' # FCM

# app/notifiers/tweet_notifier.rb
class TweetNotifier < ApplicationNotifier
  def new_direct_message(message_id, token_id)
    @message = DirectMessage.find(message_id)
    @token   = DeviceToken.find(token_id)

    push apn: @token.apn? && @token.device_token, fcm: @token.fcm?
  end
end

# app/views/tweet_notifier/new_direct_message.json+apn.jbuilder
json.aps do
  json.alert do
    json.title "#{@tweet.user.display_name} tweeted:"
    json.body truncate(@tweet.body, length: 235)
  end

  json.badge 1
  json.sound 'bingbong.aiff'
end

# app/views/tweet_notifier/new_direct_message.json+fcm.jbuilder
json.to @token.registration_id

json.notification do
  json.title "#{@tweet.user.display_name} tweeted:"
  json.body truncate(@tweet.body, length: 1024)

  json.icon 1
  json.sound 'default'
end

TweetNotifier.new_direct_message(message_id, device_token.id).deliver_now!
# => sends a push notification immediately

TweetNotifier.new_direct_message(message_id, device_token.id).deliver_later!
# => enqueues a job that sends a push notification later

push apn: @token.device_token, fcm: false
# => only sends a push notification to APNs

push apn: @token.device_token
# => same as above but without the `:fcm` key, only sends a push notification to APNs

push apn: { device_token: @token.device_token, environment: @token.apn_environment }

push apn: { device_token: @token.device_token, headers: { apns_topic: 'your.otherapp.ios' } }

push fcm: @token.fcm?,
     apn: {
       device_token: @token.apn? && @token.device_token,
       environment: @token.apn_environment,
       headers: {
         apns_id:          uuid,
         apns_expiration:  7.days.from_now,
         apns_priority:    5,
         apns_topic:       'your.otherapp.ios',
         apns_collapse_id: 'not-so-important-notification'
       }
     }

class ApplicationNotifier < Pushing::Base
  rescue_from Pushing::ApnDeliveryError do |error|
    response = error.response

    if response.status == 410 || (response.status == 400 && response.json[:reason] == 'BadDeviceToken')
      token = error.notification.device_token
      Rails.logger.info("APN device token #{token} has been expired and will be removed.")

      # delete or expire device token accordingly
    else
      raise # Make sure to raise any other types of error to re-enqueue the job
    end
  end
end

class ApplicationNotifier < Pushing::Base
  rescue_from Pushing::FcmDeliveryError do |error|
    if error.response&.headers['Retry-After']
      # re-enqueue the job honoring the 'Retry-After' header
    else
      raise # Make sure to raise any other types of error to re-enqueue the job
    end
  end
end

# app/observers/fcm_token_handler.rb
class FcmTokenHandler
  def delivered_notification(payload, response)
    return if response.json[:canonical_ids].to_i.zero?

    response.json[:results].select {|result| result[:registration_id] }.each do |result|
      result[:registration_id] # => returns a canonical id

      # Update registration ids accordingly
    end
  end
end

# app/notifiers/application_notifier.rb
class ApplicationNotifier < Pushing::Base
  register_observer FcmTokenHandler.new

  ...
end

Pushing.configure do |config|
  # Adapter that is used to send push notifications through FCM
  config.fcm.adapter = Rails.env.test? ? :test : :andpush

  # Your FCM servery key that can be found here: https://console.firebase.google.com/project/_/settings/cloudmessaging
  config.fcm.server_key = 'YOUR_FCM_SERVER_KEY'

  # Adapter that is used to send push notifications through APNs
  config.apn.adapter = Rails.env.test? ? :test : :apnotic

  # The environment that is used by default to send push notifications through APNs
  config.apn.environment = Rails.env.production? ? :production : :development

  # The scheme that is used for negotiating connection trust between your provider
  # servers and Apple Push Notification service. As documented in the offitial doc,
  # there are two schemes available:
  #
  #   :token       - Token-based provider connection trust (default)
  #   :certificate - Certificate-based provider connection trust
  #
  # This option is only applied when using an adapter that uses the HTTP/2-based
  # API.
  config.apn.connection_scheme = :token

  # Path to the certificate or auth key for establishing a connection to APNs.
  #
  # This config is always required.
  config.apn.certificate_path = 'path/to/your/certificate'

  # Password for the certificate specified above if there's any.
  # config.apn.certificate_password = 'passphrase'

  # A 10-character key identifier (kid) key, obtained from your developer account.
  # If you haven't created an Auth Key for your app, create a new one at:
  #   https://developer.apple.com/account/ios/authkey/
  #
  # Required if the +connection_scheme+ is set to +:token+.
  config.apn.key_id = 'DEF123GHIJ'

  # The issuer (iss) registered claim key, whose value is your 10-character Team ID,
  # obtained from your developer account. Your team id could be found at:
  #   https://developer.apple.com/account/#/membership
  #
  # Required if the +connection_scheme+ is set to +:token+.
  config.apn.team_id = 'ABC123DEFG'

  # Header values that are added to every request to APNs. documentation for the
  # headers available can be found here:
  #   https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/CommunicatingwithAPNs.html#//apple_ref/doc/uid/TP40008194-CH11-SW13
  config.apn.default_headers = {
    apns_priority:    10,
    apns_topic:       'your.awesomeapp.ios',
    apns_collapse_id: 'wrong.topicname.com'
  }
end

# config/initializers/pushing.rb
Pushing.configure do |config|
  config.apn.adapter = Rails.env.test? ? :test : :apnotic
  config.fcm.adapter = Rails.env.test? ? :test : :andpush
end

TweetNotifier.deliveries.clear # => clears the test inbox

assert_changes -> { TweetNotifier.deliveries.apn.size }, from: 0, to: 1 do
  TweetNotifier.new_direct_message(message.id, apn_device_token.id).deliver_now!
end

apn_message = TweetNotifier.deliveries.apn.first
assert_equal 'apn-device-token',  apn_message.device_token
assert_equal "Hey coffee break?", apn_message.payload[:aps][:alert][:body]

assert_changes -> { TweetNotifier.deliveries.fcm.size }, from: 0, to: 1 do
  TweetNotifier.new_direct_message(message.id, fcm_registration_id.id).deliver_now!
end

fcm_payload = TweetNotifier.deliveries.fcm.first.payload
assert_equal 'fcm-registration-id', fcm_payload[:to]
assert_equal "Hey coffee break?",   fcm_payload[:notification][:body]