#!/usr/bin/env python3

import argparse
import logging
import re
import subprocess
import sys
from pathlib import Path


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(
        description="Create a tag at HEAD by bumping the highest local X.Y.Z or vX.Y.Z tag. "
        "Preserves the latest tag's prefix; starts from v0.0.0 when no version tags exist.",
        formatter_class=argparse.ArgumentDefaultsHelpFormatter,
    )
    group = parser.add_mutually_exclusive_group(required=True)
    for part in ("major", "minor", "patch"):
        group.add_argument(f"--{part}", dest="part", action="store_const", const=part,
                           help=f"Bump the {part} version and reset lower components")
    parser.add_argument("--cwd", type=Path, default=Path.cwd(), help="Git repository directory")
    parser.add_argument("--push", action="store_true", help="Push only the new tag to origin")
    return parser.parse_args()


def git(cwd: Path, arguments: list[str]) -> str:
    result = subprocess.run(
        args=["git", *arguments], cwd=cwd, check=True, capture_output=True, text=True,
    )
    return result.stdout.strip()


def next_tag(tags: list[str], part: str) -> str:
    versions = []
    for tag in tags:
        match = re.fullmatch(r"(v?)(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)", tag)
        if match:
            versions.append((tuple(int(value) for value in match.groups()[1:]), match[1]))
    version, prefix = max(versions, default=((0, 0, 0), "v"))
    components = list(version)
    index = ("major", "minor", "patch").index(part)
    components[index] += 1
    components[index + 1:] = [0] * (2 - index)
    return f"{prefix}{'.'.join(str(value) for value in components)}"


def main() -> int:
    logging.basicConfig(level=logging.INFO, format="%(asctime)s %(levelname)s: %(message)s")
    arguments = parse_args()
    try:
        tags = git(cwd=arguments.cwd, arguments=["tag", "--list"]).splitlines()
        tag = next_tag(tags=tags, part=arguments.part)
        git(cwd=arguments.cwd, arguments=["tag", "--", tag, "HEAD"])
        logging.info(f"Created {tag} at HEAD")
        if arguments.push:
            git(cwd=arguments.cwd, arguments=["push", "origin", f"refs/tags/{tag}:refs/tags/{tag}"])
            logging.info(f"Pushed {tag} to origin")
    except subprocess.CalledProcessError as error:
        logging.error(f"Git failed: {(error.stderr or str(error)).strip()}")
        return 1
    except OSError as error:
        logging.error(f"{error}")
        return 1
    return 0


if __name__ == "__main__":
    sys.exit(main())