#!/usr/bin/python

# google-reader-opml v1.3 - Back up Google Reader OPML
# Copyright (c) 2006-9, John Morrissey <jwm@horde.net>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, 5th Floor, Boston, MA 02110-1301
# USA.

# This script is a bit of a hack; we imitate a web browser and scrape
# the result. It would be nice if Google Reader OPML could be
# downloaded through some Google Reader API.

GOOGLE_USERNAME = ''
GOOGLE_PASSWORD = ''
OPML_OUTPUT = None
DEBUG = False

from getopt import gnu_getopt, GetoptError
import logging
import os
from stat import *
import sys
from time import gmtime, strftime
from urllib2 import HTTPError

import mechanize

def usage():
	print 'google-reader-opml v1.3'
	print 'Usage: %s [-h] [-u USER] [-p PASSWORD] OUTPUT-FILE' % os.path.basename(sys.argv[0])
	print ''
	print '    -h, --help                    display this help and exit'
	print '    -u USER, --user=USER          log in as USER'
	print '    -p PASSWORD, --user=PASSWORD  use password PASSWORD'

try:
	options = gnu_getopt(sys.argv[1:], 'hu:p:',
		['help=', 'user=', 'password='])
except GetoptError, e:
	print '%s: %s' % (os.path.basename(sys.argv[0]), str(e))
	usage()
	sys.exit(2)

if len(options[1]) != 1:
	usage()
	sys.exit(2)
OPML_OUTPUT = options[1][0]

for option in options[0]:
	if option[0] == '-h' or option[0] == '--help':
		usage()
		sys.exit(0)
	elif option[0] == '-u' or option[0] == '--user':
		GOOGLE_USERNAME = option[1]
	elif option[0] == '-p' or option[0] == '--password':
		GOOGLE_PASSWORD = option[1]

if not GOOGLE_USERNAME or not GOOGLE_PASSWORD or not OPML_OUTPUT:
	usage()
	sys.exit(2)

br = mechanize.Browser()
br.set_handle_robots(False)
br.set_handle_refresh(True, 10, True)
br.set_handle_redirect(True)
br.addheaders = [
	('User-agent', 'google-reader-opml 1.3'),
]

if DEBUG:
	br.set_debug_http(True)
	br.set_debug_responses(True)
	br.set_debug_redirects(True)
	logger = logging.getLogger('mechanize')
	logger.addHandler(logging.StreamHandler(sys.stdout))
	logger.setLevel(logging.DEBUG)

try:
	br.open('https://www.google.com/accounts/ServiceLogin')
except HTTPError, e:
	sys.exit('%d %s' % (e.code, e.msg))
if not br.viewing_html():
	sys.exit('Unable to retrieve HTML for login page, has %s changed?' % host)

def find_login_form(form):
	try:
		form.find_control('Email')
		form.find_control('Passwd')
	except:
		return False
	return True
try:
	br.select_form(predicate=find_login_form)
except mechanize.FormNotFoundError:
	sys.exit('Unable to locate login form, has google.com changed?')

br['Email'] = GOOGLE_USERNAME
br['Passwd'] = GOOGLE_PASSWORD

try:
	r = br.submit()
except HTTPError, e:
	sys.exit('%d %s' % (e.code, e.msg))

try:
	# Google Reader doesn't seem to support If-Modified-Since yet,
	# but we'll use it to be nice.
	lastmod = os.stat(OPML_OUTPUT)[ST_MTIME]
	br.addheaders = [
		('If-Modified-Since',
			strftime('%a, %d %b %Y %H:%M:%S GMT', gmtime(lastmod)))
	]
except OSError, e:
	pass

try:
	r = br.open('http://www.google.com/reader/subscriptions/export')
except HTTPError, e:
	if e.code == 304:
		sys.exit()
	else:
		sys.exit('Unable to fetch Google Reader OPML for %s: %s' % (GOOGLE_USERNAME, str(e)))

out = open(OPML_OUTPUT, 'w')
out.writelines(r.get_data())
out.close()