napiprojekt.rb

#!/usr/bin/env ruby
#-*- coding: utf-8 -*-
require 'open-uri'
require 'digest/md5'

class Napiprojekt
  DOWNLOAD_URL = 'http://www.napiprojekt.pl/unit_napisy/dl.php?l=%s&f=%s&t=%s&v=other&kolejka=false&nick=%s&pass=%s&napios=%s'
  ZIP_PASSWORD = 'iBlm8NTigvru0Jr0'

  def initialize(file)
    @file = file
    @md5 = checksum(file)
    @f = f_digest(@md5)
  end

  def download
    # puts "MD5: #{md5}, F: #{f}"

    url = DOWNLOAD_URL % [language, @md5, @f, nick, pass, 'Linux/UNIX']
    result = open(url, 'r') { |io| io.read }

    return nil if result.start_with? 'NPc'
    result
  end

  def extract
    dir = File.dirname(File.realpath(@file))
    input_subtitle_file = File.join(dir, @md5 + '.txt')
    output_subtitle_file = File.join(dir, File.basename(@file).rpartition('.').first + '.txt')
    path_7za = `which 7za`.strip

    `#{path_7za} x -p#{ZIP_PASSWORD} -o"#{dir}" "#{archive_name}" 2>&1`
    File.rename(input_subtitle_file, output_subtitle_file)
    output_subtitle_file
  end

  def get_subtitles
    data = download
    return nil if data.nil?

    File.write(archive_name, data, :mode => 'w')
    path = extract
    File.delete(archive_name)

    path
  end

  private

  def archive_name
    @file.sub(/\.\w{2,4}$/, '.7z')
  end

  def language
    'PL'
  end

  def nick
    ''
  end

  def pass
    ''
  end

  def checksum(file)
    content = open(file, 'r') { |io| io.read(10485760) }
    Digest::MD5.hexdigest(content)
  end

  # WTF
  def f_digest(md5sum)
    # raise 'Not a MD5 sum' unless md5sum =~ /^[0-9a-f]{32}$/

    idx = [0xe, 0x3, 0x6, 0x8, 0x2]
    mul = [2, 2, 5, 4, 3]
    add = [0x0, 0xd, 0x10, 0xb, 0x5]

    idx.map.with_index do |i, j|
      t = add[j] + md5sum[i].to_i(16)
      v = md5sum[t, 2].to_i(16)

      ((v * mul[j]) % 16).to_s(16)
    end.join ''
  end
end

########################################################

def do_it(filename)
  print File.basename(filename) + ": "

  np = Napiprojekt.new filename
  path = np.get_subtitles

  if path.nil?
    puts 'NOT FOUND'
  else
    puts 'OK'
  end
end

if ARGV.empty?
  ARGF.each { |line| do_it line.strip }
else
  ARGV.each { |file| do_it file }
end