SASS support for Jammit in development mode (also with proper plugins support, for e.g. Compass)

jammit_sass_support.rb

# hack to auto compile sass when Jammit runs in development mode
# you can place this in an initializer

unless Rails.env.production?
  require 'sass/engine'

  module Jammit
    module Helper
      SASS_TIMESTAMPS = {}

      def include_stylesheets_with_sass(*packages)
        unless Rails.env.production?
          paths = Dir[Rails.root.join('app/stylesheets/*.scss')].select do |path|
            next if path =~ %r{/_[^/]+$} # skip partials
            t = File.mtime(path)
            if SASS_TIMESTAMPS[path] == t
              false
            else
              SASS_TIMESTAMPS[path] = t
            end
          end
          paths.each do |path|
            Rails.logger.info("Compiling #{path} with SASS.")
            engine = Sass::Engine.new(
              File.read(path),
              :load_paths => Sass::Plugin.engine_options[:load_paths],
              :cache      => false,
              :syntax     => :scss
            )
            css_file_path = Rails.root.join('public', 'stylesheets', File.basename(path).sub(/scss$/, 'css'))
            File.open(css_file_path, 'w') { |f| f.write(engine.render) }
          end
        end
        include_stylesheets_without_sass(*packages)
      end

      alias_method_chain :include_stylesheets, :sass
    end
  end
end