#!/usr/bin/python
# Copyright (C) 2014 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from __future__ import print_function

import argparse
import collections
import os
import subprocess
import sys


def get_config(name):
  args = ['git', 'config', '--get', name]
  p = subprocess.Popen(args, stdout=subprocess.PIPE)
  out, _ = p.communicate()
  ret = p.poll()
  if ret not in (0, 1):
    raise subprocess.CalledProcessError(ret, ' '.join(args), output=out)
  return out.strip()


def deref(name):
  p = subprocess.Popen(
      ['git', 'rev-parse', '--symbolic-full-name', name],
      stdout=subprocess.PIPE, stderr=subprocess.PIPE)
  out, _ = p.communicate()
  return out.strip()


def main(argv):
  p = argparse.ArgumentParser(description='Push changes to Gerrit for review')
  p.add_argument('-r', '--remote', default='', metavar='REMOTE',
                 help='remote name or URL to push to')
  p.add_argument('-b', '--branch', default='', metavar='BRANCH',
                 help='remote branch name, refs/for/BRANCH')
  p.add_argument('reviewers', nargs='*', metavar='REVIEWER',
                 help='reviewer names or aliases')
  p.add_argument('-t', '--topic', default='', metavar='TOPIC',
                 help='topic for new changes')
  p.add_argument('--dry-run', action='store_true',
                 help='dry run, print git command and exit')
  args = p.parse_args()

  if not args.remote or not args.branch:
    hp = 'refs/heads/'
    upstream = deref('HEAD')
    while upstream.startswith(hp):
      upstream = deref(upstream[len(hp):] + '@{u}')

    rp = 'refs/remotes/'
    if upstream.startswith(rp):
      def_remote, def_branch = upstream[len(rp):].split('/', 1)
    else:
      def_remote, def_branch = 'origin', 'master'
    args.remote = args.remote or def_remote
    args.branch = args.branch or def_branch

  opts = collections.defaultdict(list)
  opts['r'].extend((get_config('reviewer.' + r) or r) for r in args.reviewers)
  if args.topic:
    opts['topic'].append(args.topic)
  opts_str = ','.join('%s=%s' % (k, v) for k in opts for v in opts[k])
  if opts_str:
    opts_str = '%' + opts_str

  git_args = ['git', 'push', args.remote,
              'HEAD:refs/for/%s%s' % (args.branch, opts_str)]
  if args.dry_run:
    print(' '.join(git_args))
    return 0
  os.execvp('git', git_args)


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