module RequireResourceHelper
  # Adds resources such as stylesheet or javascript files to the corresponding array of
  # resources that will be 'required' by the layout. The +resource_type+ is either
  # :javascript or :stylesheet. The +extension+ is optional, and should normally correspond
  # with the resource type, e.g. 'css' for :stylesheet and 'js' for :javascript.
  def autorequire(resource_type, extension = nil)
    extensions = {:stylesheet => 'css', :javascript => 'js'}
    path = "#{RAILS_ROOT}/public/#{resource_type.to_s.pluralize}/" 
    candidates = [ "#{controller.controller_name}",
                   "#{controller.controller_name}_#{controller.action_name}" ]

    for candidate in candidates
      if FileTest.exist?("#{path}/#{candidate}.#{extension || extensions[resource_type]}")
        require_resource(resource_type, candidate)
      end
    end
  end

  def stylesheet_auto_link_tags
    autorequire(:stylesheet)
    @stylesheets.uniq.inject("") do |buffer, css|
      buffer << stylesheet_link_tag(css) + "\n    "
    end
  end

  def javascript_auto_include_tags
    autorequire(:javascript)
    @javascripts.uniq.inject("") do |buffer, js|
      buffer << javascript_include_tag(js) + "\n    "
    end
  end

  def require_resource(type, name)
    variable = type.to_s.pluralize
    array = instance_variable_get("@#{variable}")
    instance_variable_set("@#{variable}", (array || []) | [name])
  end

  def require_javascript(script)
    require_resource(:javascript, script)
  end

  def require_stylesheet(sheet)
    require_resource(:stylesheet, sheet)
  end
end