"""Small shared helpers: slugs and [[wiki link]] parsing."""

from __future__ import annotations

import re

_WIKILINK_RE = re.compile(r"\[\[([^\]]+)\]\]")
_SLUG_STRIP = re.compile(r"[^a-z0-9]+")


def slugify(text: str) -> str:
    """Lowercase, collapse non-alphanumerics to single hyphens, trim.

    Mirrors the JS slugify() in editor.html — keep the two in sync.
    """
    s = _SLUG_STRIP.sub("-", text.strip().lower()).strip("-")
    return s or "untitled"


def parse_links(body_md: str) -> list[str]:
    """Return the distinct target slugs referenced by [[...]] in a note body."""
    seen: dict[str, None] = {}
    for m in _WIKILINK_RE.finditer(body_md or ""):
        seen.setdefault(slugify(m.group(1)), None)
    return list(seen)