# rag/modules/retriever.py
import numpy as np
from config import TOP_K

_index = None  # in-memory FAISS index

def set_index(index_obj):
    global _index
    _index = index_obj

def has_index() -> bool:
    return _index is not None

def retrieve_ids(query_embedding: list[float]) -> list[int]:
    if _index is None:
        raise RuntimeError("FAISS index is not loaded in memory.")
    q = np.array([query_embedding], dtype="float32")
    _, idx = _index.search(q, TOP_K)
    return [int(i) for i in idx[0]]