prepare-commit-msg

#!/usr/bin/env python3
# copy me into $repository_root/.git/hooks/
import os
import sys
import typing as T
from pathlib import Path
from subprocess import PIPE, run

BRANCHES_TO_SKIP: T.List[str] = os.environ.get(
    "BRANCHES_TO_SKIP", "master staging develop test production"
).split()


def main() -> None:
    branch_name = (
        run(["git", "symbolic-ref", "--short", "HEAD"], stdout=PIPE)
        .stdout.decode()
        .strip()
    )

    if not branch_name:
        try:
            branch_name = (
                Path(".git/rebase-merge/head-name")
                .read_text()
                .strip()
                .split("/")[-1]
            )
        except FileNotFoundError:
            branch_name = ""

    if branch_name in BRANCHES_TO_SKIP:
        return
    branch_name = branch_name.replace("_", "-")
    branch_name = branch_name.upper()
    if branch_name in BRANCHES_TO_SKIP:
        return

    path_to_commit_msg = Path(sys.argv[1])
    commit_msg = path_to_commit_msg.read_text()

    if commit_msg.startswith(branch_name):
        return

    if commit_msg.startswith("fixup! ") or commit_msg.startswith("squash! "):
        return

    path_to_commit_msg.write_text(f"{branch_name}: {commit_msg}")


if __name__ == "__main__":
    main()