find_upstream_branch

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
############################################################################
#
# Name: find_upstream_branch
# Author: Dan Berindei (http://github.com/danberindei)
# Description: This script finds the integration branch for a task branch.
#              Task branches start with "t_", integration branches exist 
#              in the upstream repo as well.
#
############################################################################


import os
from os import path
import sys
import subprocess
import getopt


# Configuration: The following variables need to be set.
TOPIC_BRANCH_PREFIX="t_" # All branches whose name starts with this will be rebased against their updated branch point
GIT="git" # Path to the git binary executable

# The following variables need to be set in the git config:
# * sync.upstreamRepo - The upstream repo, usually upstream (if you have your own fork) or origin.
# * sync.releaseBranches - The release branches you want to sync with, must exist in the upstream repo.

upstream_repo = None
rel_branches = None
branch = None

def run_git(opts):
  #print("### git %s" % opts, file=sys.stderr);
  call = [GIT]
  for o in opts.split(' '):
    if o != '':
      call.append(o)
  return subprocess.run(call, capture_output=True, text=True).stdout

def find_upstream_repo():
  try:
    upstream = run_git("config sync.upstreamRepo").strip()
    return upstream
  except Exception:
    print("Can't find the upstream repo! Make sure you have configured sync.upstreamRepo in this repository.", file=sys.stderr)
    exit(1)

def find_rel_branches():
  try:
    release_branches = run_git("config sync.releaseBranches").split()
    #print "Release branches are %s" % release_branches
    return release_branches
  except Exception:
    print("Can't find any release branches! Make sure you have configured sync.releaseBranches in this repository.", file=sys.stderr)
    exit(1)

def parse_args():
  global upstream_repo
  global rel_branches
  global branch

  try:
    opts, args = getopt.getopt(sys.argv[1:], "hu:b:", ["help", "upstream_repo=", "rel_branches="])
  except getopt.GetoptError as err:
    # print help information and exit:
    print(str(err), file=sys.stderr) # will print something like "option -a not recognized"
    sys.exit(2)

  upstream_repo = None
  rel_branches = None
  for o, a in opts:
    if o in ("-u", "--upstream_repo"):
      upstream_repo = a
    elif o in ("-b", "--rel_branches"):
      rel_branches = a.split(',')
    elif o in ("-h", "--help"):
      usage()
      sys.exit()
    else:
      assert False, "unhandled option"

  if upstream_repo == None: upstream_repo = find_upstream_repo()
  if rel_branches == None: rel_branches = find_rel_branches()

  if (len(args) > 0): branch = args[0]

def usage():
  print("usage: ", sys.argv[0],"[-u <upstream repo>] [-b <comma separated branches>]", file=sys.stderr)

def find_upstream_branch():
  global branch

  if branch == None:
    branch = run_git("symbolic-ref --short HEAD").split('\n')[0]
  #print("Analysing topic branch %s" % branch, file=sys.stderr)

  #base_branch = subprocess.check_output("git rev-list --topo-order %s %s | git symbolic-ref --short --stdin | egrep -m1 '%s'" %
  #    (branch, " ".join(rel_branches), "|".join(rel_branches)), shell=True).strip()
  min_commits = 1000
  base_branch = "no_such_base_branch"
  for relbranch in rel_branches:
    if not relbranch.startswith(TOPIC_BRANCH_PREFIX):
      commits = len(run_git("--no-pager log --pretty=oneline -n %d %s..%s" % (min_commits + 1, relbranch, branch)).split("\n"))
      if commits < min_commits:
        min_commits = commits
        base_branch = relbranch

  print(base_branch)

def main():
  parse_args()
  find_upstream_branch()

if __name__ == "__main__":
  main()