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

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

      once_and_reload do
        NotificationUtil.clear_subscribers(/\.action_controller$/)
        NotificationUtil.clear_subscribers(/\.action_view$/)

        append_ansi_formatter
        reset_subscribers
        register_log_subscriber
      end
    end

    private

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

    def force_preload_module
      self.class.module_parent.constants.each { |const| self.class.module_parent.const_get(const) }
    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_log_subscriber
      register_to_action_controller(:start_processing)
      register_to_action_controller(:process_action, :finish_processing)
      register_to_action_controller(: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_to_action_controller(hook, :any_hook)
      end
    end

    def register_to_action_controller(hook, method = hook)
      @subscribers << ActiveSupport::Notifications.subscribe("#{hook}.action_controller") do |event|
        @log_subscriber.send(method, event)
      end
    end

    def reset_subscribers
      if defined?(@subscribers)
        @subscribers.each { |sub| ActiveSupport::Notifications.unsubscribe(sub) }
        @subscribers.clear
      else
        @subscribers = []
      end

      @log_subscriber = Semantic::LogSubscriber.new(@session_key)
    end
  end
end