#!/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 current development distro programatically

import os
import subprocess
import sys
import urllib2
from optparse import OptionParser

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 \
	    subprocess.call(['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'

if __name__ == '__main__':
    usage = "Usage: %prog <package> [distribution]"
    optParser = OptionParser(usage)
    (options, args) = optParser.parse_args()
    
    if not args:
        print >> sys.stderr, "Need arguments."
        optParser.print_help()
        sys.exit(1)
    
    package = args[0]

    if len(args) == 2: # Custom distribution specified.
        distro = args[1]
    else:
        distro = os.getenv('DIST') or default_distro

	# Correct-ish args, can proceed.
    # Check distro by checking if Launchpad page exists
    try:
        urllib2.urlopen("https://launchpad.net/ubuntu/%s" % distro)
    except urllib2.HTTPError:
        print >> sys.stderr, "The distribution '%s' does not appear to exist on " \
            "Launchpad." % distro
        sys.exit(1)

    # Check package exists.
    """ TODO: Find a way to check that the package exists here.
    madison = subprocess.Popen(['rmadison', '-u', 'ubuntu', '-a', 'source', \
        '-s', distro, package], stdout = subprocess.PIPE)
    out = madison.communicate()[0]
    print madison.returncode
    assert (madison.returncode == 0)
    if madison == 0:
        print "The '%s' package doesn't appear to exist in %s." % (package, distro)
        sys.exit(1)
    """

    # All good - start downloading...
    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)