fix-git-branch-names.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import os
import pathlib
import sys
import argparse
import subprocess

"""
Finds all Git repositories under current directory and renames 'master' branch
to 'main', both remotely and locally.

Feel free to share/modify/whatever as long as you are not a racist.
Use at your own risk.
"""

def log_info(message):
    sys.stderr.write("- {}\n".format(message))

def execute(cmd, cwd, is_dry_run):
    log_info("::: Executing: '{}'".format(" ".join(cmd)))
    if not is_dry_run:
        p = subprocess.Popen(cmd, cwd=cwd)
        stdout, stderr = p.communicate()
        return p.returncode
    else:
        return 0

def fix_repo_branch_name(repo_dir, new_name, is_dry_run):
    old_name = "master"
    remote_name = "origin"
    returncode = execute(
            cmd=["git", "branch", "-m", old_name, new_name],
            cwd=repo_dir,
            is_dry_run=is_dry_run,
            )
    if returncode != 0:
        return False
    for cmd in (
            ["git", "push"],
            ["git", "push", remote_name, ":{}".format(old_name)],
            ["git", "push", "--set-upstream", "origin", new_name],
            ["git", "fetch", remote_name],
            ["git", "remote", "prune", remote_name],):
        returncode = execute(cmd=cmd,
                cwd=repo_dir,
                is_dry_run=is_dry_run)
        if returncode != 0:
            break
    return True

def git_repo_dirs(root_dir=None):
    if root_dir is None:
        root_dir = os.path.curdir
    root_dirpath = pathlib.Path(root_dir)
    for path in root_dirpath.rglob("*"):
        if path.is_dir() and path.stem == ".git":
            yield path.parent

def main():
    parser = argparse.ArgumentParser(description=None)
    parser.add_argument("--new-name",
            default="main",
            help="New name for branch [default='%(default)s'].")
    parser.add_argument("--dry-run",
            action="store_true",
            default=False,
            help="Do not execute changes -- just report procedures.")
    parser.add_argument("--ignore-errors",
            action="store_true",
            default=False,
            help="Do not stop on errors.")
    args = parser.parse_args()
    for git_repo_dir in git_repo_dirs():
        log_info("'{}'".format(os.path.abspath(git_repo_dir)))
        success = fix_repo_branch_name(git_repo_dir, args.new_name, args.dry_run)
        if not success and not args.ignore_errors:
            sys.exit(1)

if __name__ == '__main__':
    main()