import faiss
import numpy as np
import threading
from app.core.config import settings

class FaissIndexWrapper:
    def __init__(self):
        self.index_lock = threading.Lock()
        self.index = None
        self.load_index(settings.INDEX_FILE)

    def load_index(self, path):
        with self.index_lock:
            self.index = faiss.read_index(path)
            print(f"[FAISS] Index loaded from {path}")

    def update_index(self, path):
        """热更新替换当前索引"""
        with self.index_lock:
            new_index = faiss.read_index(path)
            self.index = new_index
            print(f"[FAISS] Index hot-swapped from {path}")

    def search(self, vector: np.ndarray, top_k: int = 5):
        with self.index_lock:
            D, I = self.index.search(vector.astype(np.float32), top_k)
            return D[0], I[0]

# 单例，供 API 层引用
faiss_index = FaissIndexWrapper()