overdrive-helper.py

import argparse, requests, urllib, os
from pyquery import PyQuery as pq

# CLI arguments
parser = argparse.ArgumentParser(description='OverDrive helper script')

parser.add_argument('--session',
                    help='manually set the session id (overrides \'OD_SESSION\' env)')

parser.add_argument('book',
                    help='URL of the book you want to get')

parser.add_argument('--noreturn', action='store_true',
                    help='don\'t return the book when we\'re done')

# Error code defs
def parseError(error):
    if error == 220:
        return 'not enough copies available'
    elif error == 640:
        return 'reached checkout limit'
    elif error == 710:
        return 'excessive checkout limit reached'
    elif error == 780:
        return 'not available in correct format'
    else:
        return error

# Internal function for CLI
def _handleError(url):
    try:
        error = int(dict(urllib.parse.parse_qs(urllib.parse.urlsplit(url).query))['ErrorType'][0])
    except KeyError:
        return url # for the sendToAmazon function
    parser.error(parseError(error))

# Checks out book
def checkoutBook(library, book, session):
    return requests.get(library + 'BANGPurchase.dll?Action=OneClickCheckout&ReserveID=' + book, cookies={'SecureSession': session})

# Internal function for getting the next transaction ID
def _getTransID(library, session):
    html = pq(requests.get(library + 'MyAccount.htm?PerPage=1', cookies={'SecureSession': session}).content)
    return html('.myaccount-early-return').attr('data-transaction')

# Returns a book
def returnBook(library, book, session):
    return requests.get(library+'BANGPurchase.dll?Action=EarlyReturn&URL=MyAccount.htm&TransactionID='+_getTransID(library, session)+'&ReserveID='+book, cookies={'SecureSession': session})

# Sends the book to Amazon
def sendToAmazon(library, book, session):
    return requests.get(library + 'BANGPurchase.dll?Action=Download&FormatID=420&ReserveID=' + book, cookies={'SecureSession': session}, allow_redirects=False)

# CLI main function
if __name__ == '__main__':
    args = parser.parse_args()

    # Gets session ID
    # TODO: Check session id validity
    if args.session:
        session = args.session
    elif os.getenv('OD_SESSION'):
        session = os.getenv('OD_SESSION')
    else:
        parser.error('no session specified')

    # Gets the book ID and library base from the book url
    try:
        book = dict(urllib.parse.parse_qs(urllib.parse.urlsplit(args.book).query))['id'][0]
        liburl = urllib.parse.urljoin(args.book, '/10/45/en/')
    except:
        parser.error("invalid book URL")
    
    _handleError(checkoutBook(liburl, book, session).url)
    print(_handleError(sendToAmazon(liburl, book, session).headers['Location']))

    if not args.noreturn:
        _handleError(returnBook(liburl, book, session).url)

You can also import it as a library and use it in another program.