Automate Semantic Versioning with Conventional Commits in Python

import re
from pathlib import Path


def get_next_version(current: str, commit_messages: list[str]) -> str:
    """Return the next semantic version based on conventional commit messages."""
    major, minor, patch = map(int, current.split("."))
    if any(msg.startswith("BREAKING CHANGE") for msg in commit_messages):
        return f"{major + 1}.0.0"
    if any(msg.startswith("feat") for msg in commit_messages):
        return f"{major}.{minor + 1}.0"
    if any(msg.startswith("fix") for msg in commit_messages):
        return f"{major}.{minor}.{patch + 1}"
    return current


def update_version_file(path: Path, new_version: str) -> None:
    """Update the version string in a simple VERSION file."""
    path.write_text(new_version + "\n")
    print(f"Updated {path} to version {new_version}")


if __name__ == "__main__":
    # Mock commit history as a list of conventional commit messages
    commits = [
        "feat: add user authentication",
        "fix: correct login redirect bug",
        "docs: update README",
        "feat: add profile page",
        "chore: bump dependencies",
    ]

    version_file = Path("VERSION")
    version_file.write_text("1.2.3\n")

    current = version_file.read_text().strip()
    new_version = get_next_version(current, commits)
    update_version_file(version_file, new_version)

    print(f"Current: {current}")
    print(f"Next: {new_version}")
    print(f"Final file content: {version_file.read_text().strip()!r}")