def METHOD_NAME(link, source_dir=None, link_is_in_wheel_cache=False):
    # type: (Link, Optional[str], bool) -> DirectUrl
    if link.is_vcs:
        vcs_backend = vcs.get_backend_for_scheme(link.scheme)
        assert vcs_backend
        url, requested_revision, _ = (
            vcs_backend.get_url_rev_and_auth(link.url_without_fragment)
        )
        # For VCS links, we need to find out and add commit_id.
        if link_is_in_wheel_cache:
            # If the requested VCS link corresponds to a cached
            # wheel, it means the requested revision was an
            # immutable commit hash, otherwise it would not have
            # been cached. In that case we don't have a source_dir
            # with the VCS checkout.
            assert requested_revision
            commit_id = requested_revision
        else:
            # If the wheel was not in cache, it means we have
            # had to checkout from VCS to build and we have a source_dir
            # which we can inspect to find out the commit id.
            assert source_dir
            commit_id = vcs_backend.get_revision(source_dir)
        return DirectUrl(
            url=url,
            info=VcsInfo(
                vcs=vcs_backend.name,
                commit_id=commit_id,
                requested_revision=requested_revision,
            ),
            subdirectory=link.subdirectory_fragment,
        )
    elif link.is_existing_dir():
        return DirectUrl(
            url=link.url_without_fragment,
            info=DirInfo(),
            subdirectory=link.subdirectory_fragment,
        )
    else:
        hash = None
        hash_name = link.hash_name
        if hash_name:
            hash = "{}={}".format(hash_name, link.hash)
        return DirectUrl(
            url=link.url_without_fragment,
            info=ArchiveInfo(hash=hash),
            subdirectory=link.subdirectory_fragment,
        )