easy-going-rails/lib/semantic/dev_loader.rb

module Semantic
  # use the Zeitwerk autoloader to reattach_appender for development autoreloading feature
  class DevLoader
    def initialize(session_key)
      @session_key = session_key
      @subscribers = {}

      RailsSemanticLogger::ActionController::LogSubscriber.logger.level = :fatal # useful for remanent Rack::Log started

      launch
    end

    def launch
      once_and_reload do
        append_ansi_formatter

        Semantic::NotificationUtil.clear_subscribers(/\.action_controller$/)
        Semantic::NotificationUtil.clear_subscribers(/\.action_view$/)
        reset_subscribers

        register_action_controller
        register_action_view
      end
    end

    private

    def once_and_reload(&)
      yield
      Rails.autoloaders.main.on_load('ApplicationController', &)
    end

    def append_ansi_formatter
      SemanticLogger.clear_appenders!
      formatter = Semantic::AnsiFormatter.new
      SemanticLogger.add_appender(io: $stdout,
                                  formatter:,
                                  filter: ->(log) { !formatter.reject(log) })
    end

    def register_action_controller
      sub_instance = Semantic::Subscribers::ActionController.new(@session_key)
      register_hook(sub_instance, :start_processing)
      register_hook(sub_instance, :process_action, :finish_processing)
      register_hook(sub_instance, :redirect_to)
      %i[send_file send_data halted_callback unpermitted_parameters send_stream write_fragment
         read_fragment expire_fragment exist_fragment?].each do |hook|
        register_hook(sub_instance, hook, :any_hook)
      end
    end

    def register_action_view
      sub_instance = Semantic::Subscribers::ActionView.new
      %i[render_template render_partial render_collection render_layout].each do |hook|
        register_hook(sub_instance, hook)
      end
    end

    def register_hook(sub_instance, hook, method = hook)
      @subscribers[sub_instance.class] ||= []
      @subscribers[sub_instance.class] << ActiveSupport::Notifications.subscribe("#{hook}.#{sub_instance.event_group}") do |event|
        sub_instance.send(method, event)
      end
    end

    def reset_subscribers
      return if @subscribers.empty?

      @subscribers.each_pair do |clazz, subs|
        # puts "reset #{subs.size} subscribers for class <#{clazz}>"
        subs.each { |sub| ActiveSupport::Notifications.unsubscribe(sub) }
        subs.clear
      end
    end
  end
end