gistfile1.rb

class LinkShortener
  def call(env)
    request = Rack::Request.new(env)

    case env['REQUEST_PATH']
    when '/shorten'
      [200, {'Content-Type' => 'text/plain'}, shorten_link(request.params['src'])]
    when /\/(.*)/
      [200, {'Content-Type' => 'text/plain'}, unshorten_link($1)]
    end
  end

  def unshorten_link(counter)
    Maglev::PERSISTENT_ROOT["shortened:#{counter}"]
  end

  def shorten_link(link)
    Maglev::PERSISTENT_ROOT[:last_counter] ||= 0
    Maglev::PERSISTENT_ROOT[:last_counter] += 1

    counter = Maglev::PERSISTENT_ROOT[:last_counter].to_s(36)
    Maglev::PERSISTENT_ROOT["shortened:#{counter}"] = link

    Maglev.commit_transaction

    counter
  end
end

run LinkShortener.new