"""Deterministic candidate generation from the ACTIVE official datasets.

The AI never receives an open question: for every task type the Hub first builds
the official candidate list (NCM top-K by description, CEST links for the NCM,
TIPI EX rows for the NCM). Providers may only pick from this list.
"""
from sqlalchemy import select
from sqlalchemy.orm import Session

from ..models import CestEntry, CestNcmEntry, Dataset, NcmEntry, TipiEntry
from .fingerprint import token_stems


def _active_dataset(session: Session, kind: str):
    return session.scalar(select(Dataset).where(Dataset.kind == kind, Dataset.status == "ACTIVE"))


def ncm_top_k(session: Session, description, k: int = 10):
    """Top-K official NCM codes by (stemmed) token overlap with the product description."""
    dataset = _active_dataset(session, "NCM")
    if dataset is None:
        return []
    stems = token_stems(description)
    if not stems:
        return []
    scored = []
    for entry in session.scalars(select(NcmEntry).where(NcmEntry.dataset_id == dataset.id)).all():
        score = len(stems & token_stems(entry.description)) / len(stems)
        if score > 0:
            scored.append((entry.code, entry.description, round(score, 4)))
    scored.sort(key=lambda row: (-row[2], row[0]))
    return scored[:k]


def cest_candidates_for_ncm(session: Session, ncm: str):
    dataset = _active_dataset(session, "CEST")
    if dataset is None:
        return []
    rows = session.execute(
        select(CestEntry, CestNcmEntry.ncm_code)
        .join(CestNcmEntry, CestNcmEntry.cest_entry_id == CestEntry.id)
        .where(CestEntry.dataset_id == dataset.id)
    ).all()
    return list(dict.fromkeys(entry for entry, ncm_code in rows if ncm.startswith(ncm_code)))


def ex_tipi_candidates_for_ncm(session: Session, ncm: str):
    dataset = _active_dataset(session, "TIPI_IPI")
    if dataset is None:
        return []
    return list(dict.fromkeys(
        entry for entry in session.scalars(select(TipiEntry).where(TipiEntry.dataset_id == dataset.id, TipiEntry.ncm == ncm, TipiEntry.ex.is_not(None))).all()
    ))