module Middleman::Features::AssetHost

def registered(app)
  app.after_feature_init do
    if Middleman::Server.asset_host.is_a?(Proc)
      ::Compass.configuration.asset_host(&Middleman::Server.asset_host)
    end
  end
  Middleman::Assets.register :asset_host do |path, prefix, request|
    original_output = Middleman::Assets.before(:asset_host, path, prefix, request)
    valid_extensions = %w(.png .gif .jpg .jpeg .js .css)
    asset_prefix = Middleman::Server.asset_host.call(original_output)
    File.join(asset_prefix, original_output)
  end
end