#
# Copyright Michael Orlitzky
#
# http://michael.orlitzky.com/
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# http://www.fsf.org/licensing/licenses/gpl.html
#
# 
# NOTE:
#
# All credit belongs to whomever reverse-engineered the Redtube
# Flash applet in the first place. I took the algorithm from this
# script:
#
# http://userscripts.org/scripts/review/8691
#
# and merely cleaned it up a bit while porting it to Ruby.
#

# The Redtube class needs the extra string methods..
require 'src/string'
require 'src/website'

# This class handles the algorithm magic needed to get
# the URL from a Redtube video id.
class Redtube < Website

  VALID_REDTUBE_URL_REGEX = /^(http:\/\/)?(www\.)?redtube\.com\/(\d+)$/
  
  def self.owns_url?(url)
    return url =~ VALID_REDTUBE_URL_REGEX
  end


  # The only public method. This calls the other parts
  # of the algorithm and, with any luck, we wind up with
  # the URL to the video.
  def get_video_url()
    # First, parse the video ID out of the URL.
    video_id = parse_video_id()
    
    padded_id = video_id.to_s.pad_left('0', 7)

    video_dir = self.get_video_dir(video_id)
    file_name = self.get_file_name(padded_id)

    # This mess is actually the only directory out of
    # which they serve videos.
    return 'http://dl.redtube.com/_videos_t4vn23s9jc5498tgj49icfj4678/' +
           "#{video_dir}/#{file_name}"
  end

  
  protected

  VIDEO_FILE_EXTENSION = '.flv'

  def parse_video_id()
    return /\d+/.match(@url)[0]
  end

  
  # Not sure what they're thinking with this one.
  def get_video_dir(video_id)
    return (video_id.to_f / 1000.0).floor.to_s.pad_left('0', 7)
  end


  # The first part of the algorithmic magic. Multiply each 
  # digit of the padded video id by the index of the
  # following digit, and sum them up.
  def int_magic(padded_video_id)
    ret = 0

    0.upto(6) do |a|
      ret += padded_video_id[a,1].to_i * (a+1)
    end
  
    return ret
  end


  # Part 2 of the magic. Sum the digits of the result
  # of the first magic.
  def more_magic(file_string)
    magic = self.int_magic(file_string).to_s
    
    ret = 0
    
    0.upto(magic.length - 1) do |a|
      ret += magic[a,1].to_i
    end

    return ret
  end


  # Complete fricking mystery
  def get_file_name(file_string)
    map = ['R', '1', '5', '3', '4', '2', 'O', '7', 'K', '9', 'H', 'B', 'C', 'D', 'X', 'F', 'G', 'A', 'I', 'J', '8', 'L', 'M', 'Z', '6', 'P', 'Q', '0', 'S', 'T', 'U', 'V', 'W', 'E', 'Y', 'N']

    # The stupid variable names I copied from the
    # source script. Considering myself disclaimed.
    my_int = self.more_magic(file_string)
    new_char = '0' + my_int.to_s
    
    if my_int >= 10 then
      new_char = my_int.to_s
    end
    
    file_name =  map[file_string[3] - 48 + my_int + 3]
    file_name += new_char[1,1]
    file_name += map[file_string[0] - 48 + my_int + 2]
    file_name += map[file_string[2] - 48 + my_int + 1]
    file_name += map[file_string[5] - 48 + my_int + 6]
    file_name += map[file_string[1] - 48 + my_int + 5]
    file_name += new_char[0,1]
    file_name += map[file_string[4] - 48 + my_int + 7]
    file_name += map[file_string[6] - 48 + my_int + 4]
    file_name += VIDEO_FILE_EXTENSION
    
    return file_name
  end 

  
end