class Rage::Telemetry::Tracer

def setup_tracer(span, handler_refs)
  yield_call = <<~RUBY
      yield_called = true
      yield_result = yield
      span_result = DEFAULT_SPAN_RESULT
    rescue Exception => e
      yield_error = e
      span_result = Rage::Telemetry::SpanResult.new(e).freeze
  RUBY
  calls_chain = handler_refs.reverse.inject(yield_call) do |memo, handler_ref|
    handler_index = @all_handler_refs.index(handler_ref)
    handler_method = handler_ref.instance.method(handler_ref.method_name)
    handler_arguments = Rage::Internal.build_arguments(
      handler_method,
      { **span.handler_arguments, id: "\"#{span.id}\".freeze" }
    )
    <<~RUBY
      @all_handler_refs[#{handler_index}].instance.#{handler_ref.method_name}(#{handler_arguments}) do
        #{memo}
        span_result
      end
    RUBY
  end
  parameters = span.span_parameters.join(", ")
  self.class.class_eval <<~RUBY, __FILE__, __LINE__ + 1
    def #{tracer_name(span.id)}(#{parameters})
      span_result = yield_called = yield_result = yield_error = nil
      begin
        #{calls_chain}
      rescue Exception => e
        Rage.logger.error("Telemetry handler failed with error \#{e}:\\n\#{e.backtrace.join("\\n")}")
      end
      unless yield_called
        Rage.logger.warn("Telemetry handler didn't call `yield` when processing span '#{span.id}'\\n\#{caller.join("\\n")}")
        yield_result = yield
      end
      if yield_error
        raise yield_error
      else
        yield_result
      end
    end
  RUBY
end