#!/usr/bin/python
# pull-lp-source -- pull a source package from Launchpad
# Basic usage: pull-lp-source <source package> [<distro>]
#
# Copyright (C) 2008 Iain Lane <iain@orangesquash.org.uk>
#
# BackportFromLP class taken from prevu tool, which has
# copyright (C) 2006 John Dong <jdong@ubuntu.com>.
# 
# 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 3
# 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, Fifth Floor, Boston, MA  02110-1301, USA.
#

# TODO: Determine before going to LP whether a source package and distro exist or not.
# TODO: Determine current development distro programatically

import sys
import os

class BackportFromLP:

	def __getitem__(self, name):
		return getattr(self, name)
	
	def __init__(self, package, target_distro):
		self.package = package
		self.target_distro = target_distro
		self.__prepare_sources()
	
	def __prepare_sources(self):
		# Scrape the source package from Launchpad :)
		import re		

		contents = os.popen('wget -q https://launchpad.net/ubuntu/%(target_distro)s/+source/%(package)s -O-' % self).read()
		links = re.findall('a href=\"(.*\.dsc)\"', contents)
		
		if len(links) == 1 and \
		(os.system('dget -x http://launchpad.net%s' % links[0])) == 0:
			print '\nSuccess!'
		else:
			raise ValueError, '\nFailed to fetch and extract the source. ' +\
				'Ensure that the package specified is a valid source ' +\
				'package name and that Launchpad is not down.'

default_distro = 'intrepid'

def usage():
	print 'Usage: %s <package> [distro]' % sys.argv[0]

if __name__ == '__main__':

	args = sys.argv[1:] or []

	if args == [] or args[0] in ('-h', '--help'):
		usage()
		sys.exit(0)

	if len(args) >= 1:
		package = args[0]

	if len(args) == 2:
		distro = args[1]
	elif len(args) == 1:
		distro = os.getenv('DIST') or default_distro
	else: # incorrect args
		usage()
		sys.exit(1)

	# Correct-ish args, can proceed
	try:
		print 'Attempting to get %s from distro %s...' % \
			(package, distro.capitalize())
		BackportFromLP(package, distro)
	except ValueError, e:
		print 'Error when downloading package %s from distro %s: %s' % \
			(package, distro, e)