module Middleman::Features::AssetHost

def registered(app)
  app.compass_config do |config|
    if app.asset_host.is_a?(Proc)
      config.asset_host(&app.asset_host)
    end
  end
  app.register_asset_handler :asset_host do |path, prefix, request|
    original_output = app.before_asset_handler(:asset_host, path, prefix, request)
    valid_extensions = %w(.png .gif .jpg .jpeg .js .css)
    asset_prefix = app.asset_host.call(original_output)
    File.join(asset_prefix, original_output)
  end
end