#!/usr/bin/env python3
"""Enforce Conventional Commits on the first line of the commit message.
https://www.conventionalcommits.org/en/v1.0.0/

Activate per clone with:
  git config core.hooksPath .githooks
"""

from __future__ import annotations

import re
import sys
from pathlib import Path

ALLOWED_PREFIXES = ("Merge ", "Revert ", "fixup! ", "squash! ", "amend! ")
PATTERN = re.compile(
    r"^(feat|fix|docs|style|refactor|perf|test|build|ci|chore|revert)"
    r"(\([a-z0-9._-]+\))?!?: .+"
)


def main(argv: list[str]) -> int:
    if len(argv) < 1:
        print("commit-msg: missing message file path", file=sys.stderr)
        return 1

    msg_file = Path(argv[0])
    text = msg_file.read_text(encoding="utf-8", errors="replace")
    first_line = text.splitlines()[0] if text else ""

    if any(first_line.startswith(p) for p in ALLOWED_PREFIXES):
        return 0

    if not PATTERN.match(first_line):
        sys.stderr.write("commit-msg: aborting — message does not follow Conventional Commits.\n")
        sys.stderr.write("  expected: <type>[(<scope>)][!]: <description>\n")
        sys.stderr.write("  types:    feat, fix, docs, style, refactor, perf, test, build, ci, chore, revert\n")
        sys.stderr.write(f"  got:      {first_line}\n")
        return 1

    return 0


if __name__ == "__main__":
    sys.exit(main(sys.argv[1:]))