#!/usr/bin/python
# -*- coding: utf-8 -*-
# ##################################################################
#
# 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; version 2.
#
# 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-2 for more details.
#
# ##################################################################

import logging
import optparse
import os
import shutil
import subprocess
import sys
import tempfile

from debian.deb822 import Dsc
import launchpadlib.launchpad

devnull = open('/dev/null', 'r+')
lp = None

def error(msg, *args, **kwargs):
    logging.error(msg, *args, **kwargs)
    sys.exit(1)

def check_call(cmd, *args, **kwargs):
    ret = subprocess.call(cmd, *args, **kwargs)
    if ret != 0:
        error('%s returned %d' % (cmd, ret))

def parse(args):
    usage = 'Usage: %prog [options] <source package>'
    p = optparse.OptionParser(usage)
    p.add_option('-t', '--to',
                 dest='dest_releases',
                 default=[],
                 action='append',
                 help='Backport to DEST release (required)',
                 metavar='DEST')
    p.add_option('-f', '--from',
                 dest='source_release',
                 default=None,
                 help='Backport from SOURCE release (default: devel release)',
                 metavar='SOURCE')
    p.add_option('-v', '--version',
                 dest='version',
                 default=None,
                 help='Package version to backport (or verify)',
                 metavar='VERSION')
    p.add_option('-u', '--upload',
                 dest='upload',
                 help='Specify an upload destination (required)',
                 metavar='UPLOAD')
    p.add_option('-l', '--launchpad',
                 dest='launchpad',
                 default='production',
                 help='Launchpad instance to connect to (default: %default)',
                 metavar='INSTANCE')

    opts, args = p.parse_args(args)
    if len(args) != 1:
        p.error('You must specify a source package')
    if not opts.dest_releases:
        p.error('You must specify at least one destination release')
    if not opts.upload:
        p.error('You must specify an upload destination')

    return opts, args

def find_release_package(workdir, package, opts):
    ubuntu = lp.distributions['ubuntu']
    archive = ubuntu.main_archive
    series = ubuntu.getSeries(name_or_version=opts.source_release)
    status = 'Published'
    for pocket in ('Updates', 'Security', 'Release'):
        try:
            srcpkg = archive.getPublishedSources(source_name=package,
                                                 distro_series=series,
                                                 pocket=pocket,
                                                 status=status,
                                                 exact_match=True)[0]
            break
        except IndexError:
            continue
    else:
        error('Unable to find package %s in release %s' %
              (package, opts.source_release))

    if opts.version and opts.version != srcpkg.source_package_version:
        error('Requested backport of version %s but %s is at version %s' %
              (opts.version, package, srcpkg.source_package_version))

    return srcpkg

def find_version_package(workdir, package, opts):
    ubuntu = lp.distributions['ubuntu']
    archive = ubuntu.main_archive
    try:
        # Might get more than one (i.e. same version in multiple
        # releases), but they should all be identical
        return archive.getPublishedSources(source_name=package,
                                           version=opts.version)[0]
    except IndexError:
        error('Package %s was never published with version %s in Ubuntu' %
              (package, opts.version))

def fetch_package(workdir, package, opts):
    # Returns the path to the .dsc file that was fetched
    ubuntu = lp.distributions['ubuntu']

    if not opts.source_release and not opts.version:
        opts.source_release = lp.distributions['ubuntu'].current_series.name

    # If source_release is specified, then version is just for
    # verification
    if opts.source_release:
        srcpkg = find_release_package(workdir, package, opts)
    else:
        srcpkg = find_version_package(workdir, package, opts)

    for f in srcpkg.sourceFileUrls():
        if f.endswith('.dsc'):
            check_call(['dget',
                        '--download-only',
                        '--allow-unauthenticated',
                        f],
                       cwd=workdir)
            return os.path.join(workdir, os.path.basename(f))
    else:
        error('Package %s contains no .dsc file' % package)

def get_backport_version(version, upload, release):
    v = version + ('~%s1' % release)
    if upload.startswith('ppa:'):
        v += '~ppa1'
    return v

def get_backport_dist(upload, release):
    if upload == 'ubuntu':
        return '%s-backports' % release
    else:
        return release

def do_backport(workdir, package, dscfile, release, opts):
    dsc = Dsc(open(os.path.join(workdir, dscfile)))
    v = dsc['Version']

    check_call(['dpkg-source',
                '-x',
                dscfile,
                package],
               cwd=workdir)
    srcdir = os.path.join(workdir, package)

    bp_version = get_backport_version(v, opts.upload, release)
    bp_dist = get_backport_dist(opts.upload, release)

    check_call(['dch',
                '--force-bad-version',
                '--preserve',
                '--newversion', bp_version,
                '--distribution', release,
                'No-change backport to %s' % release],
               cwd=srcdir)
    check_call(['debuild', '-S', '-sa'],
               cwd=srcdir)

    if ':' in bp_version:
        bp_version = bp_version[bp_version.find(':')+1:]

    print 'Please check the package in file://%s carefully' % workdir
    prompt = 'Do you want to upload this to %s? [Y/n]' % opts.upload
    while True:
        answer = raw_input(prompt).strip().lower()
        if answer in ('', 'y', 'yes'):
            check_call(['dput',
                        opts.upload,
                        '%s_%s_source.changes' %
                        (package, bp_version)],
                       cwd=workdir)

            break
        elif answer in ('n', 'no'):
            break
        shutil.rmtree(srcdir)

def main(args):
    global lp

    logging.basicConfig(level=logging.INFO)
    os.environ['DEB_VENDOR'] = 'Ubuntu'

    opts, (package,) = parse(args[1:])

    script_name = os.path.basename(sys.argv[0])
    lp = launchpadlib.launchpad.Launchpad.login_anonymously(script_name,
                                                            opts.launchpad)

    workdir = tempfile.mkdtemp(prefix='backportpackage-')
    try:
        dscfile = fetch_package(workdir, package, opts)

        for release in opts.dest_releases:
            do_backport(workdir, package, dscfile, release, opts)
    finally:
        shutil.rmtree(workdir)

if __name__ == '__main__':
    sys.exit(main(sys.argv))