class Sass::Tree::ImportNode

def _cssize(*args)
  super.children
rescue Sass::SyntaxError => e
  e.modify_backtrace(:filename => children.first.filename)
  e.add_backtrace(:filename => @filename, :line => @line)
  raise e
end

def _perform(environment)
  if path = css_import?
    return DirectiveNode.new("@import url(#{path})")
  end
  super
end

def css_import?
  if @imported_filename =~ /\.css$/
    @imported_filename
  elsif imported_file.is_a?(String) && imported_file =~ /\.css$/
    imported_file
  end
end

def cssize(*args)
  super.first
end

def import
  paths = @options[:load_paths]
  if @options[:importer]
    f = @options[:importer].find_relative(
      @imported_filename, @options[:filename], @options.dup)
    return f if f
  end
  paths.each do |p|
    if f = p.find(@imported_filename, @options.dup)
      return f
    end
  end
  message = "File to import not found or unreadable: #{@imported_filename}.\n"
  if paths.size == 1
    message << "Load path: #{paths.first}"
  else
    message << "Load paths:\n  " << paths.join("\n  ")
  end
  raise SyntaxError.new(message)
rescue SyntaxError => e
  raise SyntaxError.new(e.message, :line => self.line, :filename => @filename)
end

def imported_file
  @imported_file ||= import
end

def initialize(imported_filename)
  @imported_filename = imported_filename
  super(nil)
end

def invisible?; to_s.empty?; end

def perform!(environment)
  environment.push_frame(:filename => @filename, :line => @line)
  # TODO: re-enable caching
  root = imported_file.to_tree
  self.children = root.children
  self.children = perform_children(environment)
rescue Sass::SyntaxError => e
  e.modify_backtrace(:filename => imported_file.options[:filename])
  e.add_backtrace(:filename => @filename, :line => @line)
  raise e
ensure
  environment.pop_frame
end

def to_sass(tabs = 0, opts = {})
  "#{'  ' * tabs}@import #{@imported_filename}\n"
end

def to_scss(tabs = 0, opts = {})
  "#{'  ' * tabs}@import \"#{@imported_filename}\";\n"
end