import re

_NON_SLUG = re.compile(r"[^a-z0-9]+")
_DASHES = re.compile(r"-+")


def slugify(value: str, *, max_length: int = 100) -> str:
    slug = _NON_SLUG.sub("-", value.strip().lower())
    slug = _DASHES.sub("-", slug).strip("-")
    if not slug:
        raise ValueError("slug cannot be empty")
    if max_length < 1:
        raise ValueError("max_length must be >= 1")
    return slug[:max_length].strip("-")