A brute force to find lost DHL tracking numbers when the receipt has deteriorated and only a few digits are readable

find_tracking_number.rb

require "net/http"
require 'parallel'

start = "54608206666?"
start = "54608??????4"

def make_tracking_num(i, start)
  n = start.count("?")
  missing = sprintf("%0#{n}d" % i).split('')
  track = start.gsub '?', '%d'
  track = sprintf(track % missing)
  return(track)
end

def is_valid_tracking_num?(track)
  resp = Net::HTTP.get(URI("https://nolp.dhl.de/nextt-online-public/en/search?piececode=#{track}")).index('09.12.17 09:38')
  return(!resp.nil?)
end

valid = []

n = start.count("?")
to = ("9"*n).to_i

# Shuffle as going in order is less beneficial for end cases, so we rather make everything equally likely
posibilities = (0..to).map{|i| make_tracking_num(i, start) }.shuffle

Parallel.map(posibilities, progress: "Doing stuff",in_processes: 4) do |tn|
  def test(track)
    resp = Net::HTTP.get(URI("https://nolp.dhl.de/nextt-online-public/en/search?piececode=#{track}"))
    if resp.index('shipment').nil?
      puts "Something is wrong!!!!"
      return(nil)
    end
    return(resp)
  end

  resp = test(tn)
  if resp.nil?
    sleep(1)
    resp = test(tn)
  end

  match = resp.index('09.12.17 09')
  puts "Found: #{tn}" if !match.nil?
  sleep 0.1
end