module Assets::Base
  if Assets.production?
    def bundle
      include_links + tag_for_file('application_compressed')
    end
  else
    def bundle
      include_links + include_files
    end
  end

  def compress
    raise 'You need java to compress assets' if `which java`.empty?

    compressor = "#{File.dirname(__FILE__)}/compressor.jar"
    file = system_path('application_compressed')

    File.open file, 'w+' do |it|
      it.puts files.map {|it| File.read system_path(it) }.join("\n")
    end

    `java -jar #{compressor} --charset utf-8 -o #{file} #{file}`
  end

  protected

  def sources
    raise 'Abstract method'
  end

  def tag(url)
    raise 'Abstract method'
  end

  def url_path(asset_name)
    raise 'Abstract method'
  end

  def links
    sources.select {|it| it[/^http/] }
  end

  def include_links
    links.map {|it| tag it }.join
  end

  def files
    sources - links
  end

  def tag_for_file(asset_name)
    tag url_path(asset_name)
  end

  def include_files
    files.map {|it| tag_for_file it }.join
  end

  def system_path(asset_name)
    'public' + url_path(asset_name)
  end
end