YT_Sum_Frontend.py

import streamlit as st
from backend import build_index    # ← your backend file
import os

st.set_page_config(page_title="YouTube RAG QA", layout="wide")
st.title("🎥 YouTube Transcript RAG – Chat Interface")

# -----------------------------
# Sidebar for API Key
# -----------------------------
st.sidebar.header("Configuration")
api_key = st.sidebar.text_input("OpenAI API Key")

if api_key:
    os.environ["OPENAI_API_KEY"]=api_key
# -----------------------------
# Session State
# -----------------------------
if "main_chain" not in st.session_state:
    st.session_state.main_chain = None

# -----------------------------
# Input: YouTube Video ID
# -----------------------------
video_id = st.text_input("Enter YouTube Video URL or ID")

def extract_video_id(url):
    if "youtube.com" in url:
        return url.split("v=")[-1].split("&")[0]
    if "youtu.be" in url:
        return url.split("/")[-1]
    return url.strip()

# -----------------------------
# Build Index Button
# -----------------------------
if st.button("Build Index"):
    if not api_key:
        st.error("Please enter your OpenAI API key.")
    if not video_id:
        st.error("Please enter a YouTube link or ID.")
    else:
        vid = extract_video_id(video_id)
        with st.spinner("Fetching transcript & building vector index..."):
            vector_store, retriever, main_chain = build_index(vid)

            st.session_state.main_chain = main_chain

        st.success("Index successfully built! Now ask questions.")

st.divider()

# -----------------------------
# Ask Questions
# -----------------------------
if st.session_state.main_chain:
    st.subheader("Ask a question about the video")

    user_q = st.text_input("Your Question")

    if st.button("Ask"):
        if not user_q.strip():
            st.warning("Please enter a valid question.")
        else:
            with st.spinner("Thinking..."):
                answer = st.session_state.main_chain.invoke(user_q)
                st.write("### Answer:")
                st.write(answer)
else:
    st.info("Build the transcript index first.")