#!/usr/bin/python -u
# vim: set fileencoding=utf-8 :
#
# (C) 2009 Guido Guenther <agx@sigxcpu.org>
#    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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# heavily inspired by dom-safe-pull which is © 2009 Stéphane Glondu <steph@glondu.net>
#
"""fast forward debian, upstream and pristine-tar branch"""

import sys
import os, os.path
from gbp.command_wrappers import (GitFetch, GitMerge, Command,
                                  CommandExecFailed, PristineTar)
from gbp.config import (GbpOptionParser, GbpOptionGroup)
from gbp.errors import GbpError
from gbp.git import (GitRepositoryError, GitRepository)

def fast_forward_branch(branch, repo, options):
    """
    update branch to its remote branch, fail on non fast forward updates
    unless --force is given
    @return: branch updated or already up to date
    @rtype: boolean
    """
    update = False

    remote = repo.get_merge_branch(branch)
    if not remote:
        print >>sys.stderr, "Warning: no branch tracking '%s' found - skipping." % branch
        return False

    can_fast_forward, up_to_date = repo.is_fast_forward(branch, remote)

    if up_to_date: # Great, we're done
        print "Branch '%s' is already up to date." % branch
        return True

    if can_fast_forward:
        update = True
    else:
        if options.force:
            print "Non-fast forwarding '%s' due to --force" % branch
            update = True
        else:
            print >>sys.stderr, "Warning: Skipping non-fast forward of '%s' - use --force" % branch

    if update:
        print "Updating '%s'" % branch
        repo.set_branch(branch)
        GitMerge(remote)()
    return update

def main(argv):
    changelog = 'debian/changelog'
    retval = 0

    parser = GbpOptionParser(command=os.path.basename(argv[0]), prefix='',
                             usage='%prog [options] - safely update a repository from remote')
    branch_group = GbpOptionGroup(parser, "branch options", "branch layout options")
    parser.add_option_group(branch_group)
    branch_group.add_config_file_option(option_name="upstream-branch", dest="upstream_branch")
    branch_group.add_config_file_option(option_name="debian-branch", dest="debian_branch")
    branch_group.add_boolean_config_file_option(option_name="pristine-tar", dest="pristine_tar")
    parser.add_option("--force", action="store_true", dest="force", default=False,
                      help="force update even if not fast forward")
    parser.add_option("--redo-pq", action="store_true", dest="redo_pq", default=False,
                      help="Redo the patch queue branch after a pull. Warning: this drops the old patch-queue branch")
    parser.add_option("-v", "--verbose", action="store_true", dest="verbose", default=False,
                      help="verbose command execution")

    (options, args) = parser.parse_args(argv)

    if options.verbose:
        Command.verbose = True

    try:
        repo = GitRepository(os.path.curdir)
    except GitRepositoryError:
        print >>sys.stderr, "%s is not a git repository" % (os.path.abspath('.'))
        return 1

    try:
        branches = []
        current = repo.get_branch()

        for branch in [ options.debian_branch, options.upstream_branch ]:
            if repo.has_branch(branch):
                branches += [ branch ]

        if repo.has_branch(PristineTar.branch) and options.pristine_tar:
            branches += [ PristineTar.branch ]

        (ret, out) = repo.is_clean()
        if not ret:
            print >>sys.stderr, "You have uncommitted changes in your source tree:"
            print >>sys.stderr, out
            raise GbpError

        GitFetch()()
        for branch in branches:
            if not fast_forward_branch(branch, repo, options):
                retval = 2

        if options.redo_pq:
            repo.set_branch(options.debian_branch)
            Command("gbp-pq")(["drop"])
            Command("gbp-pq")(["import"])

        repo.set_branch(current)
    except CommandExecFailed:
        retval = 1
    except GbpError, err:
        if len(err.__str__()):
            print >>sys.stderr, err
        retval = 1

    return retval

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

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