shenanigans.rb

require 'net/http'

# two_deep points to the bitly url underneath here
two_deep = 'http://tinyurl.com/679cto'

# one_deep points to google
one_deep = 'http://bit.ly/2V6CFi'

def follow_url(url, max_depth = 10)
  url = URI.parse(url)
  depth = 0
  res = nil
  
  # Starts an HTTP connection, no data requested yet
  Net::HTTP.start(url.host, url.port) do |http|
    # request only the header information of the path of the url
    res = http.head(url.path)
    
    # run until the response code is a 200, not a 307
    until res.code_type == Net::HTTPOK
      raise "Max depth of #{max_depth} was reached, give up!" if depth == max_depth
      
      # if response is 307, follow the url, reassign variables and do it again
      if res.code_type == Net::HTTPMovedPermanently
        
        # the location header only exists on responses that are 307's
        # it contains the next location that the client should redirect to
        url = URI.parse(res['location'])
        
        Net::HTTP.start(url.host, url.port) do |http|
          depth += 1
          res = http.head(url.path)
        end
      else
        # no normal response code was returned, bail out
        raise "Shenanigans! #{res.code_type}"
      end
    end
    
    return url, depth
    
  end
end

puts follow_url(two_deep)
puts follow_url(one_deep)