# 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.

module NewRelic
  module Agent
    class Transaction
      class AbstractSegment
        attr_reader :start_time, :end_time, :duration, :exclusive_duration
        attr_accessor :name, :children_time, :transaction

        def initialize name
          @name = name
          @children_time = 0.0
          @record_metrics = true
          @transaction = nil
        end

        def start
          @start_time = Time.now
        end

        def finish
          @end_time = Time.now
          @duration = end_time.to_f - start_time.to_f
          @exclusive_duration = duration - children_time
          record_metrics if record_metrics?
          segment_complete
          @transaction.segment_complete self if transaction
        rescue => e
          # This rescue block was added for the benefit of this test:
          # test/multiverse/suites/bare/standalone_instrumentation_test.rb
          # See the top of the test for details.
          NewRelic::Agent.logger.error "Exception finishing segment: #{name}", e
        end

        def record_metrics?
          @record_metrics
        end

        def record_metrics= value
          @record_metrics = value
        end

        def record_metrics
          raise NotImplementedError, "Subclasses must implement record_metrics"
        end

        INSPECT_IGNORE = [:@transaction, :@transaction_state].freeze

        def inspect
          ivars = (instance_variables - INSPECT_IGNORE).inject([]) do |memo, var_name|
            memo << "#{var_name}=#{instance_variable_get(var_name).inspect}"
          end
          sprintf('#<%s:0x%x %s>', self.class.name, object_id, ivars.join(', '))
        end

        private

        # callback for subclasses to override
        def segment_complete
        end

        def metric_cache
          if transaction
            transaction.metrics
          else
            NewRelic::Agent.instance.stats_engine
          end
        end

        def transaction_state
          @transaction_state ||= if @transaction
            transaction.state
          else
            TransactionState.tl_get
          end
        end
      end
    end
  end
end