"""Compatibility wrapper for vector adapters.

Provides `InMemoryVectorIndex` to keep older imports working and attempts to
use FAISS adapter if present.
"""
from typing import List, Tuple
try:
    # try to import full adapter
    from .vector_adapter_full import FaissIndex, HostedVectorAdapter
    FAISS_AVAILABLE = True
except Exception:
    FAISS_AVAILABLE = False

import math


class InMemoryVectorIndex:
    def __init__(self):
        self.data: List[Tuple[str, List[float]]] = []

    def upsert(self, id: str, vector: List[float]):
        self.data.append((id, vector))

    def search(self, vector: List[float], top_k: int = 10):
        def score(a, b):
            dot = sum(x * y for x, y in zip(a, b))
            na = math.sqrt(sum(x * x for x in a))
            nb = math.sqrt(sum(x * x for x in b))
            return dot / (na * nb) if na and nb else 0.0

        scored = [(id, score(vec, vector)) for id, vec in self.data]
        scored.sort(key=lambda x: x[1], reverse=True)
        return scored[:top_k]