# encoding: utf-8
# This file is distributed under New Relic's license terms.
# See https://github.com/newrelic/rpm/blob/master/LICENSE for complete details.

require 'new_relic/agent/inbound_request_monitor'

module NewRelic
  module Agent
    class SyntheticsMonitor < InboundRequestMonitor
      SYNTHETICS_HEADER_KEY  = 'HTTP_X_NEWRELIC_SYNTHETICS'.freeze

      SUPPORTED_VERSION = 1
      EXPECTED_PAYLOAD_LENGTH = 5

      def on_finished_configuring(events)
        events.subscribe(:before_call, &method(:on_before_call))
      end

      def on_before_call(request) #THREAD_LOCAL_ACCESS
        encoded_header = request[SYNTHETICS_HEADER_KEY]
        return unless encoded_header

        incoming_payload = deserialize_header(encoded_header, SYNTHETICS_HEADER_KEY)

        return unless incoming_payload &&
          SyntheticsMonitor.is_valid_payload?(incoming_payload) &&
          SyntheticsMonitor.is_supported_version?(incoming_payload) &&
          SyntheticsMonitor.is_trusted?(incoming_payload)

        txn = Tracer.current_transaction
        txn.raw_synthetics_header = encoded_header
        txn.synthetics_payload    = incoming_payload
      end

      class << self

        def is_supported_version?(incoming_payload)
          incoming_payload.first == SUPPORTED_VERSION
        end

        def is_trusted?(incoming_payload)
          account_id = incoming_payload[1]
          NewRelic::Agent.config[:trusted_account_ids].include?(account_id)
        end

        def is_valid_payload?(incoming_payload)
          incoming_payload.length == EXPECTED_PAYLOAD_LENGTH
        end

        def reject_messaging_synthetics_header headers
          headers.reject {|k,_| k == NewRelic::Agent::CrossAppTracing::NR_MESSAGE_BROKER_SYNTHETICS_HEADER}
        end

      end

    end
  end
end
