"""utilities to assist in working with pygit2"""

from mercurial.node import bin, sha1nodeconstants

pygit2_module = None

def get_pygit2():

    global pygit2_module

    if pygit2_module is None:

        try:

            import pygit2 as pygit2_module

            pygit2_module.InvalidSpecError

        except (ImportError, AttributeError):

            pass

    return pygit2_module

def pygit2_version():

    mod = get_pygit2()

    v = "N/A"

    if mod:

        try:

            v = mod.__version__

        except AttributeError:

            pass

    return b"(pygit2 %s)" % v.encode("utf-8")

def togitnode(n):

    """Wrapper to convert a Mercurial binary node to a unicode hexlified node.

    pygit2 and sqlite both need nodes as strings, not bytes.

    """

    assert len(n) == 20

    return n.hex()

def fromgitnode(n):

    """Opposite of togitnode."""

    assert len(n) == 40

    return bin(n)

nullgit = togitnode(sha1nodeconstants.nullid)