Simple links shortening

helpers.rb

# It produces shorten version of given url.
#
#    p truncate_url("http://example.com/hello.html")
#    p truncate_url("http://example.com/yada-yada-yada/foobar/hello.html", :length => 40)
#
# will produce:
#
#    "http://example.com/hello.html"
#    "http://example.com/...foobar/hello.html"
def truncate_url(url, options={})
  options = { :length => 50, :ommision => "..." }.merge(options)
  if url && url.size > options[:length]
    proto, domain, *path = url.split(/\/+/)
    length = options[:length]-(proto.size+domain.size+4+options[:ommision].size)
    path = [options[:ommision], path.join("/")[-length, length]].join
    url = "#{proto}//#{domain}/#{path}"
  end
  return url
end