Creating Toman anthology

#! python3
# -*- coding: utf-8 -*-

import requests, re, os
from hashlib import sha1
from datetime import datetime, timedelta

login = "Hellerick"
password = "не скажу"
user=1366

LF_folder = {
    r'C:\Users\OTK':r'd:\HCF\Data\LF',
    r'/home/hellerick':r'/home/hellerick/Documents/LF',
    }[os.environ['HOME']]

def main():
    downloadallmessages()

def downloadallmessages():
    code = getpage(0)
    username = re.search(r'<meta name="description" content="Show Posts - ([^"]+)" />',code).group(1)
    print('Username:', username)
    userfolder = os.path.join(LF_folder, username)
    if not os.path.exists(userfolder):
        os.makedirs(userfolder)
    pageq = re.search(r'\.\.\. </span><a class="navPages"[^>]+>(\d+)',code).group(1)
    print('Number of pages:', pageq)
    for pagen in range(int(pageq)):
        code = getpage(pagen)
        print('Page Nr', pagen)
        m = getmessages(code)
        for i in m:
            msgid = re.search(r'\AMSG:(\d+)\n',i).group(1)
            print('MSGID:', msgid)
            date = re.search(r'\nDATE:([0-9-]+)',i).group(1)
            datefolder = os.path.join(userfolder, date)
            if not os.path.exists(datefolder):
                os.makedirs(datefolder)
            with open(os.path.join(datefolder, msgid+'.txt'), mode='wt', encoding='utf-8') as f:
                f.write(i)

def getmessages(code):
    code = re.sub(r'\n','#LBR#',code)
    code = re.sub(r'\A.*?<div class="topic">','',code)
    code = re.sub(r'<div class="pagesection" style="margin-bottom: 0;">.*\Z','',code)
    code = re.sub(
        r'<strong>Today</strong> at',
        datetime.strftime(datetime.now()+timedelta(hours=-0),"%Y-%m-%d")+',',
        code)
    code = re.sub(
        r'<strong>Yesterday</strong> at',
        datetime.strftime(datetime.now()+timedelta(hours=-24),"%Y-%m-%d")+',',
        code)

    m = re.split('<div class="topic">', code)
    m = [re.sub('\A.*?#msg(\d+)">([^<]+)</a>.+?</strong> ([^<]+)&nbsp;.+<div class="list_posts">#LBR#\t*(.+)#LBR#\t\t\t\t\t</div>.*\Z',r'MSG:\1\nSUBJ:\2\nDATE:\3\nBODY:\4',i) for i in m]
    return m

def getpage(n):
    session = authorize(login, password)
    p = session.get('http://lingvoforum.net/index.php?action=profile;u={};area=showposts;start={}'.format(user,n*25)).text
    return p

def authorize(login, password):
    session = requests.Session()
    index = session.get("http://lingvoforum.net/")
    session_id = re.search("hashLoginPassword\(this, '(.+?)'\)", index.text).group(1)
    hash_password = hashLoginPassword(login, password, session_id)
    login_response = session.post("http://lingvoforum.net/index.php?action=login2", data = {
        "user": login, "passwrd": "", "coockielength": -1, "hash_passwrd": hash_password
    })
    return session

def hashLoginPassword(login, password, session_id):
    return sha1(sha1(php_to8bit(login).lower() + php_to8bit(password)).hexdigest().encode("ascii")
                + session_id.encode("ascii")).hexdigest()

def php_to8bit(string):
    res = b""
    byte = lambda i: bytes((i,))
    for n in (ord(c) for c in string):
        if n < 128:
            res += byte(n)
        elif n < 2048:
            res += byte(192 | n >> 6) + byte(128 | n & 63)
        elif n < 65536:
            res += byte(224 | n >> 12) + byte(128 | n >> 6 & 63) + byte(128 | n & 63)
        else:
            res += byte(240 | n >> 18) + byte(128 | n >> 12 & 63) + byte(128 | n >> 6 & 63) + byte(128 | n & 63)
    return res

if __name__ == "__main__":
    main()