from typing import List, Tuple
import numpy as np
from llm_router import cohere_embed

class RAGIndex:
    def __init__(self):
        self.texts: List[str] = []
        self.vecs: np.ndarray | None = None

    def add(self, chunks: List[str]):
        if not chunks: return
        new_vecs_list = cohere_embed(chunks)
        if not new_vecs_list:
            # fallback: random to avoid crash (not ideal for accuracy)
            new_vecs = np.random.normal(size=(len(chunks), 384)).astype("float32")
        else:
            new_vecs = np.array(new_vecs_list, dtype="float32")
        if self.vecs is None:
            self.vecs = new_vecs
            self.texts = list(chunks)
        else:
            self.vecs = np.vstack([self.vecs, new_vecs])
            self.texts.extend(chunks)

    def retrieve(self, query: str, k: int = 6) -> List[Tuple[str, float]]:
        if not self.texts: return []
        qv_list = cohere_embed([query])
        if not qv_list: return []
        qv = np.array(qv_list[0], dtype="float32")
        sims = (self.vecs @ qv) / (np.linalg.norm(self.vecs, axis=1) * (np.linalg.norm(qv) + 1e-9))
        idx = np.argsort(-sims)[:k]
        return [(self.texts[i], float(sims[i])) for i in idx]