import urllib.request
import os


def url_open(url):
  req = urllib.request.Request(url)
  req.add_header('user-agent','Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36')
  response = urllib.request.urlopen(url)
  html = response.read()

  return html

def get_page(url):
  html = url_open(url).decode('utf-8')

  a = html.find('current-comment-page')+23
  b = html.find(']',a)

  return html[a:b]


def find_imgs(url):
  html = url_open(url).decode('utf-8')
  img_addrs = []

  a = html.find('img src=')

  while a != -1:
    b = html.find('.jpg',a ,a+255)
    if b != -1:
      img_addrs.append('https:'+html[a+9:b+4]) # 'img src='为9个偏移 '.jpg'为4个偏移
    else:
      b = a+9
    a = html.find('img src=', b)

  return img_addrs


def save_imgs(folder, img_addrs):
  for each in img_addrs:
    filename = each.split('/')[-1]
    with open(filename, 'wb') as f:
      img = url_open(each)
      f.write(img)
    print(img_addrs)

def download_mm(folder = 'xxoo', pages = 5):
  os.mkdir(folder)
  os.chdir(folder)

  url = 'http://jandan.net/ooxx/'
  page_num = int(get_page(url))

  for i in range(pages):
    page_num -= i
    page_url = url + 'page-'+ str(page_num) + '#comments'
    img_addrs = find_imgs(page_url)
    save_imgs(folder, img_addrs)

if __name__ == '__main__':
  download_mm()