require 'ddtrace/contrib/rails/utils'

module Datadog
  module Contrib
    module Rails
      # Code used to create and handle 'rails.render_template' and 'rails.render_partial' spans.
      module ActionView
        include Datadog::Patcher

        def self.instrument
          # patch Rails core components
          do_once(:instrument) do
            Datadog::RailsRendererPatcher.patch_renderer
          end
        end

        def self.start_render_template(payload)
          # retrieve the tracing context
          tracing_context = payload.fetch(:tracing_context)

          # create a new Span and add it to the tracing context
          tracer = Datadog.configuration[:rails][:tracer]
          span = tracer.trace('rails.render_template', span_type: Datadog::Ext::HTTP::TEMPLATE)
          tracing_context[:dd_rails_template_span] = span
        rescue StandardError => e
          Datadog::Tracer.log.debug(e.message)
        end

        def self.finish_render_template(payload)
          # retrieve the tracing context and the latest active span
          tracing_context = payload.fetch(:tracing_context)
          span = tracing_context[:dd_rails_template_span]
          return if !span || span.finished?

          # finish the tracing and update the execution time
          begin
            template_name = tracing_context[:template_name]
            layout = tracing_context[:layout]
            exception = tracing_context[:exception]

            span.set_tag('rails.template_name', template_name) if template_name
            span.set_tag('rails.layout', layout) if layout
            span.set_error(exception) if exception
          ensure
            span.finish()
          end
        rescue StandardError => e
          Datadog::Tracer.log.debug(e.message)
        end

        def self.start_render_partial(payload)
          # retrieve the tracing context
          tracing_context = payload.fetch(:tracing_context)

          tracer = Datadog.configuration[:rails][:tracer]
          span = tracer.trace('rails.render_partial', span_type: Datadog::Ext::HTTP::TEMPLATE)
          tracing_context[:dd_rails_partial_span] = span
        rescue StandardError => e
          Datadog::Tracer.log.debug(e.message)
        end

        def self.finish_render_partial(payload)
          # retrieve the tracing context and the latest active span
          tracing_context = payload.fetch(:tracing_context)
          span = tracing_context[:dd_rails_partial_span]
          return if !span || span.finished?

          # finish the tracing and update the execution time
          begin
            template_name = tracing_context[:template_name]
            exception = tracing_context[:exception]

            span.set_tag('rails.template_name', template_name) if template_name
            span.set_error(exception) if exception
          ensure
            span.finish()
          end
        rescue StandardError => e
          Datadog::Tracer.log.debug(e.message)
        end
      end
    end
  end
end