"""Label normalization shared by parsing + scoring."""

from __future__ import annotations

import json
import re

_ARTICLES = {"a", "an", "the"}


def normalize_label(text: str) -> str:
    """Lowercase, strip punctuation/articles, collapse whitespace."""
    text = text.strip().lower()
    text = re.sub(r"[^a-z0-9\s\-]", " ", text)
    tokens = [t for t in text.split() if t and t not in _ARTICLES]
    return " ".join(tokens)


def parse_label_json(raw: str) -> str | None:
    """Best-effort extraction of {"label": ...} from a model response."""
    raw = raw.strip()
    # Direct JSON.
    try:
        obj = json.loads(raw)
        if isinstance(obj, dict) and "label" in obj:
            return normalize_label(str(obj["label"]))
    except json.JSONDecodeError:
        pass
    # Embedded JSON object.
    m = re.search(r"\{.*?\"label\".*?\}", raw, re.DOTALL)
    if m:
        try:
            obj = json.loads(m.group(0))
            if "label" in obj:
                return normalize_label(str(obj["label"]))
        except json.JSONDecodeError:
            pass
    return None