#!/usr/bin/python
#
# pull-lp-source -- pull a source package from Launchpad
# Basic usage: pull-lp-source <source package> [<release>]
#
# Copyright (C) 2008 Iain Lane <iain@orangesquash.org.uk>
#
# BackportFromLP class taken from prevu tool, which is:
# 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.
# 
# See file /usr/share/common-licenses/GPL for more details.
#
# ##################################################################


import os
import re
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_release):
        self.package = package
        self.target_release = target_release
        self.__prepare_sources()
    
    def __prepare_sources(self):
        # Scrape the source package from Launchpad :)
        contents = urllib2.urlopen('https://launchpad.net/ubuntu/%(target_release)s/+source/%(package)s' % self).read()
        links = re.findall('a href=\"(.*\.dsc)\"', contents)
        
        if len(links) == 1 and \
        subprocess.call(['dget', '-xu', '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_release = 'intrepid'

if __name__ == '__main__':
    usage = "Usage: %prog <package> [release]"
    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.
        release = args[1]
    else:
        release = os.getenv('DIST') or default_release

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

    # Check package exists.
    try:

        sourcePage = urllib2.urlopen("https://launchpad.net/ubuntu/%s/+source/%s" % \
            (release, package)).read()
        m = re.search('"/ubuntu/%s/\+source/%s/(\d[^"]+)"' % (release, \
            package.replace('+', '\+')), sourcePage)
    
        if not m:
            print >> sys.stderr, "The '%s' package does not appear to exist in " \
                "the '%s' release." % (package, release)
            sys.exit(1)

    except urllib2.HTTPError, e: # Raised on 404
           
        if e.code == 404:

            print >> sys.stderr, "The '%s' package does not appear to exist in " \
                "the '%s' release." % (package, release)

        else: # Other code, probably LP malfunction
            
            print >> sys.stderr, "Error when checking Launchpad for package: %s " % e

        sys.exit(1)

    except urllib2.URLError, e: # Other error (NXDOMAIN, ...)

            (_, reason) = e.reason

            print >> sys.stderr, "Error when checking Launchpad for package: %s " % reason
            sys.exit(1)

    # All good - start downloading...
    try:
        print 'Attempting to get %s from release %s...' % \
            (package, release.capitalize())
        BackportFromLP(package, release)
    except ValueError, e:
        print 'Error when downloading package %s from release %s: %s.' % \
            (package, release, e)