import os
import faiss
import numpy as np
import pickle
from typing import List, Tuple
from src.config import Settings

class VectorStore:
    def __init__(self, settings: Settings):
        self.settings = settings
        self.index = None
        self.docs: List[str] = []

    def build(self, texts: List[str], embedder) -> "VectorStore":
        self.docs = texts
        X = embedder(texts).astype("float32")
        self.index = faiss.IndexFlatIP(X.shape[1])
        self.index.add(X)
        return self

    def save(self):
        faiss.write_index(self.index, self.settings.index_path)
        with open(self.settings.docs_path, "wb") as f:
            pickle.dump(self.docs, f)

    def load(self) -> "VectorStore":
        if os.path.exists(self.settings.index_path) and os.path.exists(self.settings.docs_path):
            self.index = faiss.read_index(self.settings.index_path)
            with open(self.settings.docs_path, "rb") as f:
                self.docs = pickle.load(f)
        else:
            raise FileNotFoundError("Index or docs not found. Run ingestion first.")
        return self

    def search(self, query: str, embedder, k: int = 5) -> List[Tuple[str, float]]:
        q = embedder([query]).astype("float32")
        sims, ids = self.index.search(q, k)
        hits = []
        for idx, score in zip(ids[0], sims[0]):
            if idx == -1:
                continue
            hits.append((self.docs[idx], float(score)))
        return hits