googl.rb

require 'mechanize'
require 'singleton'

BASE = 'http://goo.gl/'.freeze
REDIR = "#{BASE}?authen=1".freeze
NOISE = "#{BASE}?url=".freeze

class GooAPI
  include Singleton

   def self.shorten(long_url, debug = false)
    begin 
      @agent = Mechanize.new
      @agent.user_agent_alias = 'Linux Mozilla'

      @agent.get(BASE)
      page = @agent.get(REDIR)
      puts page.inspect if debug
      form = page.forms[0]
      form.url = long_url
      page = @agent.submit(form)
      return page.uri.to_s.sub(NOISE,'')
    catch
      return long_url  
    end  
  end
end

if $0 == __FILE__
  unless ARGV[0]
    puts "Usage: googl {long_url}"
    exit(99)
  end  
  puts GooAPI.shorten(ARGV[0])
end