require 'elastic-apm'
module Ecoportal
  module API
    module Common
      module ElasticApmIntegration

        class UnexpectedServerError < StandardError
          def initialize(code, msg)
            super("Code: #{code} -- Error: #{msg}")
          end
        end

        APM_SERVICE_NAME = 'ecoportal-api-gem'

        # Log only errors that are only server's responsibility
        def log_unexpected_server_error(response)
          raise "Expecting Ecoportal::API::Common::Response. Given: #{response.class}" unless response.is_a?(Common::Response)
          return nil unless elastic_apm_service
          return nil unless unexpected_server_error?(response.status)
          if ElasticAPM.running?
            ElasticAPM.report(UnexpectedServerError.new(response.status, response.body))
          end
        end

        private

        def unexpected_server_error?(code)
          code && (code >= 500) && (code <= 599)
        end

        # finalizer to stop the agent
        close_elastic_apm = Proc.new do |id|
          begin
            if ElasticAPM.running?
              puts "Stopping ElasticAPM service"
              ElasticAPM.stop
            end
          rescue StandardError => e
            # Silent
          end
        end
        ObjectSpace.define_finalizer("ElasticAPM", close_elastic_apm)

        def elastic_apm_service
          return false if @disable_apm
          begin
            ElasticAPM.start(**elastic_apm_options) unless ElasticAPM.running?
          rescue StandardError => e
            @disable_apm = true
            puts "ElasticAPM services not available: #{e}"
          end
        end

        def elastic_apm_options
          {
            service_name: APM_SERVICE_NAME,
            server_url:   elastic_apm_url,
            secret_token: elastic_apm_key,
            environment:  environment,
            #http_compression: false,
            transaction_sample_rate:  0.1,
            transaction_max_spans:    100,
            span_frames_min_duration: "5ms"
          }.tap do |options|
            options.merge!({
              log_level: Logger::DEBUG,
              log_path:  File.join(__dir__, "elastic_apm.log")
            }) if false
          end
        end

        def elastic_apm_url
          @elastic_apm_url ||= "https://".tap do |url|
            url << "#{elastic_apm_account_id}"
            url << ".#{elastic_apm_base_url}"
            url << ":#{elastic_apm_port}"
          end
        end

        def elastic_apm_key
          @elastic_apm_key ||= ENV['ELASTIC_APM_KEY']
        end

        def elastic_apm_account_id
          @elastic_apm_account_id ||= ENV['ELASTIC_APM_ACCOUNT_ID']
        end

        def elastic_apm_base_url
          @elastic_apm_base_url ||= "apm.#{elastic_apm_region}.aws.cloud.es.io"
        end

        def elastic_apm_region
          @elastic_apm_region ||= ENV['ELASTIC_APM_REGION'] || "ap-southeast-2"
        end


        def elastic_apm_port
          @elastic_apm_port ||= ENV['ELASTIC_APM_PORT'] || "443"
        end

        def environment
          @environment ||= "unknown".tap do |value|
            if instance_variable_defined?(:@host) && env = @host.gsub(".ecoportal.com", '')
              value.clear << env
            end
          end
        end

      end
    end
  end
end