从豆瓣购书单中挑出有亚马逊促销的书籍

db2z.rb

# encoding:utf-8
require 'net/http'
require 'uri'

def fetch(uri_str, limit = 10) 
  # You should choose better exception.
  raise ArgumentError, 'HTTP redirect too deep' if limit == 0

  url = URI.parse(uri_str)
  req = Net::HTTP::Get.new(url.request_uri)
#  puts "fetch #{url.host}:#{url.port}#{url.request_uri}"
  response = Net::HTTP.start(url.host, url.port) { |http| http.request(req) }
  case response
  when Net::HTTPSuccess     then response
  when Net::HTTPRedirection then fetch(response['location'], limit - 1)
  when Net::HTTPServiceUnavailable then fetch(uri_str, limit - 1)
  else
    response.error!
  end 
end

cart_regexp = /( id:\')([\d]{8})(\')\
([\u0000-\uffff]*?)\
(title:\')([\u0000-\uffff]*?)(\')\
([\u0000-\uffff]*?)\
(sid:\')([\d]*?)(\')\
([\u0000-\uffff]*?)\
(path:\')([\u0000-\uffff]*?)(\')\
/

db2zlink_regexp = /\
(href=\"http:\/\/www\.douban\.com\/link2[^\s]*?vendor=joyo[^\s]*?\;)\
([^\s]*?)\
(url=)([^\s]*?)(\;)\
/

# promotion code of amazon.cn
prom_regexp = /\
(6HREB5FXXK)\
/

# save http://book.douban.com/cart into cart.html
carts = File.read("cart.html")

books = {}
# scan all books in cart
carts.scan(cart_regexp).each{ |m|
  title = m[5]
  sid = m[9]
  path = m[13]

  resp = fetch(path)
  puts "=== get #{title} Code = #{resp.code}"
  if resp.message == "OK"
    r = db2zlink_regexp.match(resp.body)
    unless r.nil? || r == 0
      # get the amazon.cn's link for the book.
      zurl = URI.unescape(r[4])
      resp2 = fetch(zurl)
      if resp2.message == "OK"
        puts "=== fetch ok"
        # test if the book is in promotion
        is_promed = prom_regexp.match(resp2.body)
        unless is_promed.nil? || is_promed == 0
          puts "#{title} is in promotion."
          books["#{title}"] = path
       else
          puts "#{title} is not in promotion."
        end
      end
    else
      puts "#{title} not match."
    end
  end
  sleep(3.0 / 1.0)
}

puts "=== books in promotion ==="
books.each { |k, v|
  puts "#{k}, #{v}"
}