# typed: true
require 'ddtrace/ext/http'
require 'ddtrace/contrib/analytics'
require 'ddtrace/contrib/active_support/notifications/event'
require 'ddtrace/contrib/active_model_serializers/ext'

module Datadog
  module Contrib
    module ActiveModelSerializers
      # Defines basic behaviors for an ActiveModelSerializers event.
      module Event
        def self.included(base)
          base.include(ActiveSupport::Notifications::Event)
          base.extend(ClassMethods)
        end

        # Class methods for ActiveModelSerializers events.
        # Note, they share the same process method and before_trace method.
        module ClassMethods
          def span_options
            { service: configuration[:service_name] }
          end

          def tracer
            -> { configuration[:tracer] }
          end

          def configuration
            Datadog.configuration[:active_model_serializers]
          end

          def process(span, event, _id, payload)
            span.service = configuration[:service_name]

            # Set analytics sample rate
            if Contrib::Analytics.enabled?(configuration[:analytics_enabled])
              Contrib::Analytics.set_sample_rate(span, configuration[:analytics_sample_rate])
            end

            # Measure service stats
            Contrib::Analytics.set_measured(span)

            # Set the resource name and serializer name
            res = resource(payload[:serializer])
            span.resource = res
            span.set_tag(Ext::TAG_SERIALIZER, res)

            span.span_type = Datadog::Ext::HTTP::TEMPLATE

            # Will be nil in 0.9
            span.set_tag(Ext::TAG_ADAPTER, payload[:adapter].class) unless payload[:adapter].nil?
          end

          private

          def resource(serializer)
            # Depending on the version of ActiveModelSerializers
            # serializer will be a string or an object.
            if serializer.respond_to?(:name)
              serializer.name
            else
              serializer
            end
          end
        end
      end
    end
  end
end