from datasets import load_dataset
import pandas as pd
from sentence_transformers import SentenceTransformer
import faiss
from transformers import pipeline

class RAGPipeline:
    def __init__(self):
        self.embedder = SentenceTransformer("sentence-transformers/all-MiniLM-L6-v2")
        self.generator = pipeline("text2text-generation", model="google/flan-t5-base")

        # Load dataset directly
        ds = load_dataset("pubmed_qa", "pqa_labeled", split="train[:500]")
        self.documents = ds["context"]
        self.questions = ds["question"]

        self.index = self.build_faiss_index()

    def build_faiss_index(self):
        embeddings = self.embedder.encode(self.documents, convert_to_numpy=True)
        index = faiss.IndexFlatL2(embeddings.shape[1])
        index.add(embeddings)
        return index

    def retrieve(self, query, top_k=5):
        query_embedding = self.embedder.encode([query], convert_to_numpy=True)
        scores, indices = self.index.search(query_embedding, top_k)
        return [self.documents[i] for i in indices[0]]

    def generate_answer(self, query):
        docs = self.retrieve(query)
        context = " ".join(docs)
        prompt = f"Answer the following medical question using the context:\nContext: {context}\nQuestion: {query}"
        result = self.generator(prompt, max_length=200, do_sample=True)
        return result[0]['generated_text']