module Semantic
  module Subscribers
    # LogSubscriber for event_group :action_view
    class ActionView < LogSubscriber
      include AnsiColors

      REGEX_BASEDIR = %r{^#{Rails.root}/(.*)}

      def initialize(*)
        super(:view)
        @partials = {}
      end

      def render_partial(event)
        identifier = pathname(event.payload[:identifier])
        partial_savings = @partials[event.transaction_id] ||= {}
        partial_saving = partial_savings[identifier] ||= {
          # TODO: might be smarter: origins=[{caller:, count:}]
          count: 0,
          first_origin: Rails.backtrace_cleaner.clean(caller)[1]
        }
        partial_saving[:count] += 1
      end

      def render_template(event)
        layout = event.payload[:layout]
        return unless layout

        identifier = pathname(event.payload[:identifier])
        return unless identifier

        logger.debug do
          pop_partial_savings(event.transaction_id)
          "Rendered template #{identifier}"
        end
      end

      def render_collection(event)
        identifier = pathname(event.payload[:identifier])
        return unless identifier

        count = event.payload[:count]
        cache_hits = event.payload[:cache_hits] || 0
        logger.debug do
          pop_partial_savings(event.transaction_id)
          "Rendered collection #{identifier} (#{count} times, #{cache_hits} cached)"
        end
      end

      def render_layout(event)
        identifier = pathname(event.payload[:identifier])
        return unless identifier

        logger.debug do
          pop_partial_savings(event.transaction_id)
          "Rendered layout #{identifier}"
        end
      end

      private

      def pop_partial_savings(transaction_id)
        partial_savings = @partials.delete(transaction_id)
        partial_savings.each do |partial, saving|
          count_info = " (#{saving[:count]} times)" if saving[:count] > 1
          logger.debug("Rendered partial #{partial}#{count_info}")
          logger.debug(Semantic::Helper.stackisize(saving[:first_origin], symbol: '⇤'))
        end
      end

      def pathname(location)
        m = REGEX_BASEDIR.match(location)
        m[1] if m
      end
    end
  end
end