JManga downloader

#!/usr/bin/python
#
# Downloads all your JManga purchases.
# Obviously requires Python installed and I don't
# use windows so this should work but
# I have no way to test it.
#
# If you don't know how to run a python script
# ask someone who does.
#
# I really wanted JManga to succeed and was working
# on an iOS client. I should have seen this coming but
# I really wanted to believe. I assumed that with all the
# publishers behind it they would be in it for the long
# haul. Oh well. Here we are.
#
# Since I would really hate for people to lose all the
# cool obscure manga they bought I'm providing this
# downloader script. Just give it your username and
# password and it'll download all your manga. I don't
# have much manga to test with so I'm not entirely
# sure what will happen if you have a huge library but
# it should be fine.
#
# Shame they sent out the announcement email after they
# had turned off points purchasing. I would have bought
# a bunch of the stuff I was holding off on buying.
# Why did I wait? I wanted to read them on my iPad
# not my computer.
#
# Please don't put your manga on file sharing sites. :(
#

import sys
import urllib
import urllib2
import cookielib
import json
import os

def getCredentials():
    global username
    username = ""
    password = ""
    if len(sys.argv) != 3:
        username = raw_input('Username: ')
        password = raw_input('Password: ')
    else:
        username = sys.argv[1]
        password = sys.argv[2]
    if len(username) == 0:
        print 'error: did not enter a username'
        exit(1)
    if len(password) == 0:
        print 'error: did not enter a password'
        exit(1)
    return username, password

def getCookie(cookieJar, cookieName):
    for index, cookie in enumerate(cookieJar):
        if cookie.name == cookieName:
            return cookie.value
    return ''

def login(username, password):
    cookieJar = cookielib.CookieJar()
    opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cookieJar))
    loginString = {'formname' : 'RpcApiUser_Login', 'fail_url' : '/login', 'email' : username, 'password' : password, 'x' : '30', 'y' : '7'}
    loginCredentials = urllib.urlencode(loginString)
    result = opener.open('https://www.jmanga.com/formhandler', loginCredentials)
    result.read()
    if len(getCookie(cookieJar, 'manga_user')) == 0:
        print 'error: login failed'
        exit(1)
    print 'logged in'
    return opener
    #result = opener.open('http://jmanga.com/profile')
    #print result.read()

def extractSeriesIDs(html):
    seriesIDs = {}
    targetString = 'series_id='
    startOffset = 0
    while startOffset >= 0:
        startOffset = html.find(targetString, startOffset)
        if startOffset < 0:
            return seriesIDs.keys()
        startOffset += len(targetString)
        endIndex = html.find('&', startOffset)
        seriesIDs[html[startOffset:endIndex]] = True
    return seriesIDs.keys()

def decrypt(stringInput):
    b = bytearray(stringInput)
    key = b[0] ^ 0xff
    for i in range(len(b)):
        b[i] ^= key
    return b

def getBaseNameFromURL(url):
    filename = url.split('/')[-1]
    return filename.split('.')[0]

def downloadEncryptedImage(opener, url, name):
    imageBytes = decrypt(opener.open(url).read())
    with open(name, 'wb') as f:
        f.write(imageBytes)
        global username
        f.write(username)

def getChapterInfo(opener, chapterID):
    infoURL = 'http://api.jmanga.com/chapter?chapter%5Fid=' + chapterID
    return json.loads(opener.open(infoURL).read())

def downloadPage(opener, page, directory):
    locales = page['locale']
    preferredLocale = 'enUS'
    localeNames = locales.keys()
    # not all locales have an image
    # so we try our preferred locale and if that
    # fails then we try the others until we find
    # a valid one (assuming that, in this case,
    # they are all equivalent)
    try:
        i = localeNames.index(preferredLocale)
        localeNames.pop(i)
        localeNames.insert(0, preferredLocale)
    except ValueError:
        pass
    filename = os.path.join(directory, '{:04}.jpg'.format(int(page['number'])+1))
    imageKey = 'encrypted_composed_image_url'
    for localeName in localeNames:
        # Find the first image
        locale = locales[localeName]
        if imageKey in locale and not os.path.exists(filename):
            downloadEncryptedImage(opener, locale[imageKey], filename)
            break

def safeMakeDirs(path):
    if not os.path.exists(path):
        os.makedirs(path)

def downloadChapter(opener, chapter, directory):
    number = chapter['number']
    print 'chapter ' + number
    chapterDir = os.path.join(directory, '{:04}'.format(int(number)))
    safeMakeDirs(chapterDir)
    chapterInfo = getChapterInfo(opener, chapter['chapter_id'])
    pages = chapterInfo['pages']
    for index, page in enumerate(pages):
        sys.stdout.write('\t{0}/{1}\r'.format(int(index)+1, len(pages)))
        sys.stdout.flush()
        downloadPage(opener, page, chapterDir)
    sys.stdout.write('\n')

def downloadSeriesWithID(opener, seriesID):
    seriesInfoURL = 'http://api.jmanga.com/chapters?series%5Fid=' + seriesID
    result        = opener.open(seriesInfoURL)
    seriesInfo    = json.loads(result.read())
    series        = seriesInfo['series']
    localizedInfo = series['locale']['enUS']
    print localizedInfo['name']
    directory = os.path.join('jmanga', seriesID)
    safeMakeDirs(directory)
    downloadEncryptedImage(opener, localizedInfo['encrypted_image_url'], directory + '.jpg')
    chapters = seriesInfo['chapters']
    for chapter in chapters:
        if chapter['purchased']:
            downloadChapter(opener, chapter, directory)

def getMangaSeries(opener):
    listAddress = 'http://www.jmanga.com/ajax/'
    requestData = 'req=RpcApiUser_LoadMyManga&_='
    result = opener.open(listAddress, requestData)
    seriesIDs = extractSeriesIDs(result.read())
    for seriesID in seriesIDs:
        downloadSeriesWithID(opener, seriesID)

def main():
    username, password = getCredentials()
    opener = login(username, password)
    getMangaSeries(opener)

if __name__ == "__main__":
    main()