Script to delete merged branches in git

del_merged_branches.py

#!/usr/bin/env python3

# SPDX-License-Identifier: ISC
# Copyright © 2024 VideoLabs, VLC authors and VideoLAN
#
# Authors: Steve Lhomme <[email protected]>

import argparse
import subprocess
import sys

branches = []

# test branch (uncomment to test a particular branch)
# branches = ['ndk26']


def exit_err(errcode:int, err:str, line:int):
    print(str(line) + ': ' + err)
    exit(errcode)

# Argument parsing
parser = argparse.ArgumentParser(
    description="Delete local branches merged upstream")
parser.add_argument('--dry-run', '-d', action='store_true',
    help='do not delete branches, just shows what would be deleted')
parser.add_argument('--quiet', '-q', action='store_true',
    help='only log branches that will be deleted')
parser.add_argument('--verbose', '-v', action='store_true',
    help='show the commands that are run')
parser.add_argument('upstream', nargs='?', type=str,
    help='upstream branch to compare to (guessed if not provided)')
args = parser.parse_args()

def CURRENT_LINE():
    return sys._getframe(1).f_lineno

def call_git(cmd):
    if args.verbose:
        print('git ' + ' '.join(cmd))
    call = subprocess.Popen(['git'] + cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    stdout_bin, stderr_bin = call.communicate()
    errcode = call.wait()
    return stdout_bin.decode('utf-8'), stderr_bin, errcode

if branches:
    print('!! testing only branch(es) {} !!'.format(' '.join(branches)))
else:
    # delete branches that have been fully merged upstream
    branch_list, err, errcode = call_git(['branch', '--list', '--sort=-committerdate', '--format="%(refname:short)"'])
    if errcode != 0:
        exit_err(errcode, err.decode('utf-8'), CURRENT_LINE())

    branches = branch_list.replace('\n',' ').replace('"','').split()


if args.upstream and args.upstream != '':
    remote_split = args.upstream.split('/')
    test_remote_bin, err, errcode = call_git(['remote', 'show', '-n', remote_split[0]])
    if errcode != 0:
        exit_err(errcode, err.decode('utf-8'), CURRENT_LINE())
    upstream_default_branch = args.upstream
    default_branch = upstream_default_branch[len(remote_split[0]) + 1:]
else:
    # get the first remote branch
    all_remote_names_bin, err, errcode = call_git(['config', '--get-regexp', 'remote.*.fetch'])
    if errcode != 0:
        exit_err(errcode, err.decode('utf-8'), CURRENT_LINE())
    all_remotes_split = all_remote_names_bin.split('\n')
    remote_0 = all_remotes_split[0][len('remote.'):]
    origin_cut = remote_0.find('.fetch +refs')
    remote_split = [ remote_0[:origin_cut] ]
    all_remote_info_bin, err, errcode = call_git(['symbolic-ref', '--short', 'refs/remotes/' + remote_split[0] + '/HEAD'])
    if errcode != 0:
        exit_err(errcode, err.decode('utf-8'), CURRENT_LINE())
    all_remote_info = all_remote_info_bin.split('\n')
    upstream_default_branch = all_remote_info[0]

    if upstream_default_branch.startswith(remote_split[0] + '/'):
        default_branch = upstream_default_branch[len(remote_split[0]) + 1:]
        print('Using default upstream {}/{}'.format(remote_split[0], default_branch))
    else:
        exit_err(1, 'Could not guess the default branch')

for branch in branches:
    if branch == default_branch:
        continue
    if not args.quiet:
        print('* {}'.format(branch))

    # empty if no upstream
    # upstream_branch_bin, err, errcode = call_git(['branch', '--list', '--format="%(upstream)"', branch])
    upstream_branch_bin, err, errcode = call_git(['branch', '--list', '--format="%(upstream:short)"', branch])
    upstream_branch = upstream_branch_bin.replace('\n','').replace('"','')

    matches_remote = ''
    if upstream_branch:
        upstream_exists_bin, err, errcode = call_git(['rev-parse', '--quiet', '--verify', upstream_branch])
        upstream_exists = upstream_exists_bin.replace('\n','').replace('"','')

        if upstream_exists:
            matches_remote_bin, err, errcode = call_git(['merge-base', '--is-ancestor', upstream_branch, branch])
            matches_remote = matches_remote_bin

            upstream_branch_full_bin, err, errcode = call_git(['branch', '--list', '--format="%(upstream)"', branch])
            upstream_branch_full = upstream_branch_full_bin.replace('\n','').replace('"','')

            merged_upstream_bin, err, errcode = call_git(['branch', '--merged', upstream_branch, '--remotes'])
            # merged_upstream_bin, err, errcode = call_git(['branch', '--no-merged', upstream_branch])
            merged_upstream = merged_upstream_bin
            merged_remote = merged_upstream.find(upstream_branch_full) == -1
            if merged_remote:
                print('matches remote {}'.format(upstream_branch_full))
        else:
            print('upstream {} was deleted, unset-upstream'.format(upstream_branch))
            if not args.dry_run:
                merged_remote_bin, err, errcode = call_git(['branch', '--unset-upstream', branch])
                if errcode != 0:
                    exit_err(errcode, err.decode('utf-8'), CURRENT_LINE())

    # remove remote first (verify it merges cleanly first)
    all_merged_bin, err, errcode = call_git(['cherry', upstream_default_branch, branch])
    all_merged_list = all_merged_bin.split('\n')
    merged_added = 0
    merged_deleted = 0
    for merged in all_merged_list:
        if merged == '':
            continue
        if merged.startswith('+ '):
            merged_added = merged_added +1
        elif merged.startswith('- '):
            merged_deleted = merged_deleted +1

    # if merged_added == 0 and merged_deleted == 0:
    if merged_added == 0:
        print('Branch {} can be removed'.format(branch))

        if upstream_branch and not args.quiet:
            if merged_remote:
                print('Remote {} can be removed (merged)"'.format(upstream_branch))
            if matches_remote != '':
                print('Remote {} can be removed (local merged)"'.format(upstream_branch))

        if not args.dry_run:
            delete_branch_bin, err, errcode = call_git(['branch', '-D', branch])
            if errcode != 0:
                exit_err(errcode, err.decode('utf-8'), CURRENT_LINE())

    elif not args.quiet:
        print('Branch {} has not been merged (+{}-{} commits differ)'.format(branch, merged_added, merged_deleted))

    if not args.quiet:
        print('')