import git # pip3 install gitpython
import os
from functools import lru_cache

def get_repo(starting_directory: str = os.path.dirname(__file__)) -> git.Repo:
    """ Try finding the repository by traversing up the tree.

        By default, the repository containing this module is returned.
    """

    directory = starting_directory

    try:
        return git.Repo(directory)
    except git.InvalidGitRepositoryError:
        pass

    # We now have to traverse up the tree
    while directory != "/" and os.path.exists(directory):
        # Go to parent
        directory = os.path.abspath(directory + os.path.sep + "..")

        try:
            return git.Repo(directory)
        except git.InvalidGitRepositoryError:
            pass

    raise git.InvalidGitRepositoryError("Could not find git repository root in {}".format(starting_directory))


@lru_cache(maxsize=None)
def get_version(repo: git.Repo = None) -> str:
    """ Return a version string for the current commit.

    There is a practical issue: the repository changes over time, f.e. switching branches with 'git checkout'. We want
    to know the version that is running in memory, not the one that is on disk.

    As a work-around, we cache the version information, in that it is at least consistent. It is up to the caller
    to request the version early enough. """

    if repo is None:
        repo = get_repo()

    return "{} [{}]{}".format(repo.active_branch, repo.commit(), " (dirty)" if repo.is_dirty() else "")


# at least cache the current repo version immediately
try:
    _ = get_version()
except:
    pass


if __name__ == "__main__":
    print(get_version())