from typing import List, Tuple
import numpy as np
import cohere
from settings import COHERE_API_KEY, COHERE_EMBED_MODEL

class RAGIndex:
    def __init__(self):
        self.client = cohere.Client(api_key=COHERE_API_KEY) if COHERE_API_KEY else None
        self.texts: List[str] = []
        self.vecs: np.ndarray | None = None

    def _embed(self, texts: List[str]) -> np.ndarray:
        if not texts: return np.zeros((0, 384), dtype="float32")
        if not self.client:
            # Fallback: random embeddings (avoid crash; not ideal)
            return np.random.normal(size=(len(texts), 384)).astype("float32")
        resp = self.client.embed(texts=texts, model=COHERE_EMBED_MODEL)
        vecs = np.array(getattr(resp, "embeddings", []) or getattr(resp, "data", []), dtype="float32")
        return vecs

    def add(self, chunks: List[str]):
        if not chunks: return
        new_vecs = self._embed(chunks)
        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 = self._embed([query])[0]
        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]