A selection of git commit message preparation scripts

git-prepare-commit-msg.py

#!/usr/bin/env python3
"""
A small Python script to produce commit messages.

.. rubric:: Prepare Commit Message

This hook is invoked by `git-commit[1] <https://git-scm.com/docs/git-commit>`_
right after preparing the default log message, and before the editor is started.

It takes one to three parameters. The first is the name of the file that
contains the commit log message. The second is the source of the commit message,
and can be: message (if a ``-m`` or ``-F`` option was given); template
(if a ``-t`` option
was given or the configuration option ``commit.template`` is set);
merge (if the commit is a merge or a :file:`.git/MERGE_MSG` file exists);
squash (if a :file:`.git/SQUASH_MSG` file exists); or commit, followed by a
commit object name (if a ``-c``, ``-C`` or ``--amend`` option was given).

If the exit status is non-zero, ``git commit`` will abort.

The purpose of the hook is to edit the message file in place, and it is not
suppressed by the ``--no-verify`` option. A non-zero exit means a failure of the
hook and aborts the commit. It should not be used as a replacement for the
pre-commit hook.

The sample :file:`prepare-commit-msg` hook that comes with Git removes the help
message found in the commented portion of the commit template.
"""
import re

from pathlib import Path

from git import Repo


def get_git_branch():
    """Return the currently checked out branch.

    :var str ret_value: Value to be returned, or the branch of the current
        commit decoded and stripped of whitespace.
    :return ret_value: The branch of the current commit.
    """
    git_r = Repo(Path('.'))
    return git_r.active_branch.name


def get_git_username():
    """Return the value of the git username from the configuration."""
    git_config = Repo(Path('.')).config_reader()
    return git_config.get_value('user', 'username')


def parse_branch_name(branch: str) -> dict:
    """Use regex to pull the issue number from the branch name."""
    ret_value = {}
    regex_match = re.match('^([0-9]*)(.*)', branch)
    try:
        issue_number = regex_match.groups()[0]
        issue_message = regex_match.groups()[1].replace('-', ' ').lstrip()
        ret_value.update({
            'issue_number': issue_number,
            'issue_message': issue_message
        })
    except IndexError as index_error:
        ret_value = {
            issue_number: '0',
            issue_message: index_error,
        }
    return ret_value


def prepare_message(branch_name: str, parsed_branch: dict, git_username: str):
    """Prepare a commit message."""
    if branch_name != 'main':
        issue_msg = parsed_branch.get('issue_message')
        issue_num = parsed_branch.get('issue_number')
        config_read = Repo(Path('.')).config_reader()
        user_email = config_read.get_value('user', 'email')
        user_name = config_read.get_value('user', 'name')
        ret_value = (f'{issue_msg}\n\nSee #{issue_num}\n\n'
                     f'@{git_username} - '
                     f'{user_email}\n\n'
                     f'{user_name}\n\n'
                     'Changelog: changed')
    else:
        ret_value = (f"Hey @{git_username}! - What do you think you're doing?"
                     '\n\nYou know better than to commit directly to main.'
                     '\n\nFix it or GitHub will murder 1 kitten for every commit'
                     'you attempt to make to main.'
                     'Changelog: kitten killer')
    return ret_value


def write_message():
    """Write the prepared commit message."""
    branch = get_git_branch()
    parsed_branch = parse_branch_name(branch)
    git_username = get_git_username()
    commit_msg = prepare_message(branch, parsed_branch, git_username)
    msg_file = Path('.git/COMMIT_EDITMSG')
    if msg_file.exists():
        with msg_file.open('a', encoding='utf-8') as msg_fh:
            msg_fh.write(commit_msg)
    return commit_msg


if __name__ == '__main__':
    write_message()

git-prepare-commit-msg.sh

#!/bin/bash
#
# git prepare-commit-msg hook for automatically prepending an issue key
# from the start of the current branch name to commit messages.

# check if commit is merge commit or a commit ammend
# if [ "$2" = "merge" ] || [ "$2" = "commit" ]; then
#     exit
# fi
ISSUE_KEY=$(git branch --show-current)
ISSUE_KEY="${ISSUE_KEY/[a-z]*\/}"
ISSUE_NUMBER=${ISSUE_KEY/-*[a-zA-Z]*}
TMP=$(mktemp /tmp/issuekey-XXXXX)
echo "$ISSUE_KEY" > "$TMP"
sed -E "s/[0-9]*-([A-Z]*-[0-9]*)-.*/\1/" < "$TMP"
ISSUE_KEY=$(sed -E "s/[0-9]*-([A-Z]*-[0-9]*)-.*/\1/" < "$TMP")

if [ $? -ne 0 ]; then
    # no issue key in branch, use the default message
    printf "exiting %s" "$ISSUE_KEY"
    exit
fi
# issue key matched from branch prefix, prepend to commit message
TEMP=$(mktemp /tmp/commitmsg-XXXXX)
(printf "\n\n%s\nCloses #%s\n\nChangelog: changed" "$ISSUE_KEY $(cat "$1")" "${ISSUE_NUMBER}") > "$TEMP"
# (printf "\n\n%s" "$ISSUE_KEY $(cat  $1)") > $TEMP
cat "$TEMP" > "$1"