Busca la informacion de un libro segun su isbn

isbn_search.rb

#!/usr/bin/ruby1.9.1

# Script para traducir isbn a informacion del libro buscando en varias
# librerias online. Se probo por ultima vez el 2009-12-11.
# 
# Author:: Luis Parravicini
# Copyright:: Copyright (C) 2009 Luis Parravicini
# License:: GPL v2
#
# http://ktulu.com.ar/blog/2009/12/11/traduciendo-isbn/
#

require 'mechanize'
require 'activesupport'
require 'set' 
require 'fileutils'



# Fuente de datos que obtiene informacion de un libro a partir del isbn.
class Source
  def initialize(agent)
    @agent = agent
  end 

  def name
    self.class.name.downcase
  end 

  def search(isbn)
    data = custom_search(isbn)
    unless data.nil? || empty?(data)
      data.each do |k, v|
        unless data[k].nil?
          data[k].strip!
          data[k].gsub(/\s+/, ' ')
        end 
      end 
      data[:isbn] = isbn

      data
    end 
  end 

  def empty?(book)
    values = book.select { |k, v| k != :isbn }.values.compact
    values.empty?
  end
end

class CasaDelLibro < Source
  def custom_search(isbn)
    page = @agent.get("http://www.casadellibro.com/busquedas/quickResults?tbusq=i&buscar=#{isbn}")
    result = page.search("div.fBusqueda")
    return if result.nil?

    data = {}
    img = result.at('div.imagen img.fbus')
    img = img['src'] unless img.nil?
    data[:cover] = img
    book = result.at('div.datosLibro')
    unless book.nil?
      data[:title] = book.at('.tit').try(:inner_text)
      data[:authors] = book.at('.pAutores').try(:inner_text)
      data[:authors].gsub!(/^\s*de\s+/, '') unless data[:authors].nil?
      house = book.at('.pEditorial')
      unless house.nil?
        data[:editorial] = house.inner_text
        #TODO next_sibling no deberia skipear \n ?
        e = house
        while e = e.next_sibling
          break if e.name == 'p'
        end
        data[:edition] = e.try(:inner_text)
      end
    end

    data
  end
end

class Lsf < Source
  def custom_search(isbn)
    page = @agent.get("http://www.lsf.com.ar/m/ficha.aspx?codigo=#{isbn}")

    book = {}
    data = page

    img = data.at('img#ctl00_ContentPlaceHolder1_img_tapa')
    img = img['src'] unless img.nil?
    return if img == '#'
    book[:cover] = img unless img =~ /nodisponible\.gif$/
    data = data.search('div.vistaMaxInfo')
    unless data.nil?
      book[:title] = data.at('div.vistaMaxInfoTit').try(:inner_text)
      book[:authors] = data.at('div.autores').try(:inner_text)
      book[:house] = data.at('#ctl00_ContentPlaceHolder1_div_editorial').try(:inner_text)
      book[:house].gsub!(/^\s*Editorial\s*:\s*/i, '') unless book[:house].nil?
    end

    book
  end
end

class ALibris < Source
  def custom_search(isbn)
    page = @agent.get("http://www.alibris.com/search/books/isbn/#{isbn}")

    book = {}
    img = page.at('img.cvr')
    img = img['src'] unless img.nil?
    book[:cover] = img unless img =~ /no_image\.gif$/

    data = page.at('div#box-1col-merch-isbn')
    unless data.nil?
      book[:house] = data.at('div.publisher-details').try(:inner_text)
      data = data.at('div.author-title')
      unless data.nil?
        book[:authors] = data.at('a').try(:inner_text)
        book[:title] = data.at('h2').try(:inner_text)
        edition = data.at('p').try(:inner_text)

        book[:edition] = if edition =~ /^\(.+\)$/
          edition[1..-2]
        else
          edition
        end
      end
    end

    book
  end
end

class Amazon < Source
  def custom_search(isbn)
    page = @agent.get("http://www.amazon.com/s/ref=nb_ss?url=search-alias%3Dstripbooks&field-keywords=#{isbn}&x=0&y=0")

    book = {}
    data = page.at('div#result_0')
    return if data.nil?
    img = data.at('div.productImage img')
    img = img['src'] unless img.nil?
    book[:cover] = img unless img =~ /no-img-sm/

    data = data.at('div.productTitle')
    unless data.nil?
      author = data.at('span.ptBrand').try(:inner_text)
      unless author.nil?
        author.gsub!(/^\s*by\s+/, '')
        book[:authors] = author
      end
      book[:title] = data.at('a').try(:inner_text)
      book[:edition] = data.at('span.format').try(:inner_text)
    end

    book
  end
end

def unmarshal(fname)
  if File.exists?(fname)
    File.open(fname) { |f| Marshal::load(f) }
  else
    {}
  end
end

def marshal(fname, data)
  tmp = fname + ".tmp"
  File.open(tmp, 'w') { |f| Marshal::dump(data, f) }
  FileUtils.rm(fname) if File.exists?(fname)
  FileUtils.mv tmp, fname
end

# Genera un csv con informacion de un libro por cada isbn leido.
# no quotea nada de la info del libro, asume que esta no va a romper el
# csv.
def dump_csv(stream)
  while isbn = stream.gets
    break if isbn.nil?
    isbn.strip!
    book = $books[isbn]
    data = [isbn]
    unless book.nil?
      data += [book[:title], book[:authors], book[:house], book[:edition]]
    end

    puts data.map { |x| "\"#{x}\"" }.join(",")
  end
end

# Obtiene informacion del libro a partir del isbn. Cuando una fuente de
# datos no conoce cierto isbn, se lo guarda en un cache negativo con un
# ttl de NEGATIVE_TTL
def fetch_book(isbn)
  book = nil

  now = Time.now
  $strategies.sort_by { rand }.each do |s|
    print '.'

    neg = $negative[isbn]
    if neg.nil? || neg[s.name].nil? || neg[s.name]+NEGATIVE_TTL < now
      book = s.search(isbn)
      unless book.nil?
        book[:sources] ||= Set.new
        book[:sources].add(s.name)

        $books[isbn] = book
        break
      else
        $negative[isbn] ||= {}
        $negative[isbn][s.name] = Time.now
      end
    end
  end
  puts

  book
end


NEGATIVE_TTL = 20.day
NEGATIVE = 'negative.cache'
BOOKS = 'books'

$negative = unmarshal(NEGATIVE)
$books = unmarshal(BOOKS)

agent = WWW::Mechanize.new
agent.user_agent_alias = 'Windows IE 7'
$strategies = [
  Lsf.new(agent),
  CasaDelLibro.new(agent),
  ALibris.new(agent),
  Amazon.new(agent),
]

csv = ARGV.shift == '--csv'

if csv
  dump_csv($stdin)
  exit
end

while true do
  print '> '
  isbn = $stdin.gets
  break if isbn.nil?

  isbn.strip!
  next if isbn.empty?
  #TODO si size < 10 deberia completar con 0
  if isbn.size != 13 && isbn.size != 10
    puts "no tiene longitud de isbn"
    next
  end
  isbn.upcase! # algunos isbn terminan en 'x'

  if $books.has_key?(isbn)
    book = $books[isbn]
  else
    book = fetch_book(isbn)
  end
  puts book

  marshal(BOOKS, $books)
  marshal(NEGATIVE, $negative)
end