test

guesser.rb

require 'open-uri'

def decipher_function_name_pattern
  # Find "C" in this: var A = B.sig || C (B.s)
  /
  \.sig
  \s*
  \|\|
  (\w+)
  \(
  /x
end

def function_body_pattern
  # Match nested angle braces
  /
  (?<brace>
  {
  (
  [^{}]
  | \g<brace>
  )*
  }
  )
  /x
end

def function_pattern(function_name)
  # Match the function function_name (that has one argument)
  /
  #{function_name}
  \(
  \w+
  \)
  #{function_body_pattern}
  /x
end

js = open("http://s.ytimg.com/yts/jsbin/html5player-#{ARGV.first}.js").read

deciph_func_name    = js[decipher_function_name_pattern, 1]
deciph_func_pattern = function_pattern(deciph_func_name)
body_match          = deciph_func_pattern.match(js)

raise "could not extract body" unless body_match

body = body_match[:brace]

lines = body.split(";")

# The first line splits the string into an array and the last joins and returns
lines.delete_at(0)
lines.delete_at(lines.size - 1)

lines.map! do |line|
  if /\(\w+,(?<index>\d+)\)/      =~ line  # calling a two argument function (swap)
    "w#{index}"
  elsif /slice\((?<index>\d+)\)/  =~ line  # calling slice
    "s#{index}"
  elsif /reverse\(\)/             =~ line  # calling reverse
    "r"
  else
    raise "Cannot parse line: #{line}"
  end
end

cipher = lines.join(" ")
puts cipher