import os
import pickle
import faiss
from config import FAISS_INDEX_PATH, DOCS_PATH, TOP_K


def load_index():
    if not os.path.exists(FAISS_INDEX_PATH):
        raise RuntimeError("❌ FAISS index not found. Click 'Build Index' first.")

    index = faiss.read_index(FAISS_INDEX_PATH)

    with open(DOCS_PATH, "rb") as f:
        documents = pickle.load(f)

    return index, documents


def retrieve(query_embedding):
    index, documents = load_index()
    distances, indices = index.search(query_embedding, TOP_K)
    return [documents[i] for i in indices[0]]