module ActiveModel::Serializable

def self.included(base)
  base.extend Utils
end

def as_json(options={})
  instrument('!serialize') do
    if root = options.fetch(:root, json_key)
      hash = { root => serializable_object(options) }
      hash.merge!(serializable_data)
      hash
    else
      serializable_object(options)
    end
  end
end

def embedded_in_root_associations
  {}
end

def get_namespace
  modules = self.class.name.split('::')
  modules[0..-2].join('::') if modules.size > 1
end

def instrument(action, &block)
  payload = instrumentation_keys.inject({ serializer: self.class.name }) do |payload, key|
    payload[:payload] = self.instance_variable_get(:"@#{key}")
    payload
  end
  ActiveSupport::Notifications.instrument("#{action}.active_model_serializers", payload, &block)
end

def instrumentation_keys
  [:object, :scope, :root, :meta_key, :meta, :wrap_in_array, :only, :except, :key_format]
end

def namespace
  get_namespace && Utils._const_get(get_namespace)
end

def serializable_data
  embedded_in_root_associations.tap do |hash|
    if respond_to?(:meta) && meta
      hash[meta_key] = meta
    end
  end
end

def serializable_object_with_notification(options={})
  instrument('!serialize') do
    serializable_object(options)
  end
end