#!/usr/bin/env python
#
# Directly set a given ref to a commit, erroring if it doesn't
# exist and --create is not specified.  You might use this
# to implement something like immutable tags.
#
# Copyright 2016 Colin Walters <walters@verbum.org>
#
#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU Lesser General Public
#  License as published by the Free Software Foundation; either
#  version 2 of the License, or (at your option) any later version.
# 
#  This library 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
#  Lesser General Public License for more details.
# 
#  You should have received a copy of the GNU Lesser General Public
#  License along with this library. If not, see <http://www.gnu.org/licenses/>.

import gi
gi.require_version('OSTree', '1.0')
from gi.repository import GLib, Gio, OSTree
import argparse
import sys

staging_key = 'redhat.staging'

def fatal(msg):
    print >>sys.stderr, msg
    sys.exit(1)

parser = argparse.ArgumentParser(prog="ostree-edit-detached")
parser.add_argument("--repo", help="Repo path",
                    action='store', required=True)
parser.add_argument("--create", help="Branch",
                    action='store_true')
parser.add_argument("--ref", help="Branch",
                    action='store', required=True)
parser.add_argument("--commit", help="commit",
                    action='store', required=True)

args = parser.parse_args()

r = OSTree.Repo.new(Gio.File.new_for_path(args.repo))
r.open(None)

[_, current] = r.resolve_rev(args.ref, True)
if current is None:
    print("Ref {} does not currently exist".format(args.ref))
    if not args.create:
        print("--create not specified, exiting")
        sys.exit(1)
else:
    print("Previously, {} = {}".format(args.ref, current))
    if args.create:
        print("--create specified but ref already exists!")
        sys.exit(1)

[_,commit,commitstate] = r.load_commit(args.commit)
if commitstate != 0:
    print("Invalid commit state for {}: {}".format(args.commit, commitstate))

r.set_ref_immediate(None, args.ref, args.commit)
print("Set {} => {}".format(args.ref, args.commit))