import jieba
import re

def tokenize(text: str) -> str:
    return " ".join(jieba.cut(text))


def build_match_query(text: str, limit: int = 12) -> str:
    """Build a safe FTS5 MATCH query from user/model text."""
    terms: list[str] = []
    seen: set[str] = set()
    for token in tokenize(text or "").split():
        token = token.strip()
        if not token or not re.search(r"\w", token, flags=re.UNICODE):
            continue
        upper = token.upper()
        if upper in {"AND", "OR", "NOT", "NEAR"}:
            continue
        if token in seen:
            continue
        seen.add(token)
        terms.append('"' + token.replace('"', '""') + '"')
        if len(terms) >= limit:
            break
    return " OR ".join(terms)