compare_branches.py

#!/usr/bin/env python3

# Copyright (c) 2021 Christian Mauderer <oss@c-mauderer.de>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

import git

import logging
import argparse
import sys

parser = argparse.ArgumentParser(
    description=(
        "Compare commits on two branches with a common parent\n"
    ))

parser.add_argument(
    "-l", "--loglevel",
    help = "Define log level.",
    type = str.upper,
    choices = ['DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL'],
    default = 'INFO'
)

parser.add_argument(
    "-1", "--one",
    help = "Name of the first branch",
    default = 'master',
)

parser.add_argument(
    "-2", "--two",
    help = "Name of the second branch",
    default = '6-freebsd-12',
)

parser.add_argument(
    "-r", "--repo",
    help = "Location of the repository.",
    default = '.',
)

args = parser.parse_args()

# set up logging
numeric_loglevel = getattr(logging, args.loglevel)
logging.basicConfig(level = numeric_loglevel, format="%(levelname)s: %(message)s")
logger = logging.getLogger(__name__)
logger.debug(f"Started with the following options: {str(args)}")

# Open repo
repo = git.Repo(args.repo)

def readable(commit):
    sha = commit.hexsha[:10]
    author = commit.author
    subject = commit.message.split("\n")[0]
    return f'{sha} ({author}: {subject})'

# find common ancestor of branches
one = repo.commit(args.one)
logger.info(f"Head of {args.one}: {readable(one)}")
two = repo.commit(args.two)
logger.info(f"Head of {args.two}: {readable(two)}")
merge_base = repo.merge_base(one, two)[0]
logger.info(f"Common ancestor: {readable(merge_base)}")

# Go through commits and index them by commit message
def get_commits(commit, merge_base):
    info = {}
    c = commit
    while c != merge_base:
        subject = c.message.split("\n")[0]
        author = c.author
        key = f"{author}: {subject}"
        info[key] = c
        c = c.parents[0]
    return info

one_commits = get_commits(one, merge_base)
two_commits = get_commits(two, merge_base)

for k in one_commits.keys():
    if k not in two_commits:
        logger.warning(f"Only on {args.one}: {readable(one_commits[k])}")

for k in two_commits.keys():
    if k not in one_commits:
        logger.warning(f"Only on {args.two}: {readable(two_commits[k])}")