Fetch episodes from ASCIIcasts.com ; use existing PDF, or create one

fetch_asciicasts.rb

#!/usr/bin/env ruby -U

# fetch available Railscasts transcripts ( ASCIIcasts ); use existing PDF where available
#   original concept: https://github.com/korin/casts/blob/master/asciicasts/fetch.rb
#   get wkhtmltopdf from: http://code.google.com/p/wkhtmltopdf/downloads/list

require 'uri'
require 'open-uri'
require 'nokogiri'
require 'pdfkit'

BASE_URL = "http://asciicasts.com"
USER_CSS_FILE = "/tmp/_fetch_asciicasts_print.css"

def shorten (string, count = 30)
  return string if string.length <= count 

  ellipsis = '...'
  string[0,count-ellipsis.length] + ellipsis
end

def filename(url, title, episode_number)
  File.basename(url) + ".pdf"  # could also be: "##{episode_number} #{title}.pdf"
end

def save_pdf(url,dest)
  doc = Nokogiri::HTML(open(url))
  doc.xpath('//p[@id="otherFormats"]/a').each do |link|
    uri = URI.parse(link['href'])
    next unless File.extname(uri.path) =~ /\.pdf/
    
    file = open(dest, "wb")
    file.write(open(uri.to_s).read)
    file.close
    return true
  end
  
  user_css_fileURL = "file://#{USER_CSS_FILE}"
  kit = PDFKit.new(url, :margin_bottom => 0, :margin_left => 0, :margin_right => 0, :margin_top => 0, :orientation => "Landscape", :user_style_sheet => user_css_fileURL)
  file = kit.to_file(dest)
  return true
end

File.open(USER_CSS_FILE, "w") { |file| file.write(DATA.read) }

doc = Nokogiri::XML(open("#{BASE_URL}/episodes/all"))
doc.css('dl#episodeArchive > dt').each do |item|
  episode_number = item.xpath('text()').text   # first text node
  link = item.css('a').first
  url = BASE_URL + link['href']
  title = link.text
  next_element = item.next_element rescue nil
  description = if ( (not next_element.nil?) and next_element.name == 'dd' )
    next_element.text
  else
    nil
  end
  # TODO: scrape tags, to be set in resulting pdf

  file_name = filename(url, title, episode_number)
  # dest = File.join(File.dirname(__FILE__), "PDFs", file_name)
  dest = File.join(File.dirname(__FILE__), file_name)
  next if File.exists?(dest)

  puts(format("working on #%03d: %42s  =>  %s", episode_number, shorten(title, 40), dest))

  save_pdf(url, dest)
end

__END__
/*

img { page-break-before: avoid; page-break-inside: avoid; }
.dp-highlighter { page-break-before: avoid; page-break-inside: avoid; }
p { page-break-before: avoid; page-break-inside: avoid; }

*/