import streamlit as st
from rag_youtube_bot import get_transcript, build_rag_chain, ask_question


st.set_page_config(
    page_title="🎥 YouTube RAG Chatbot",
    page_icon="🤖",
    layout="wide"
)


st.markdown("""
    <style>
        .main {
            background-color: #0e1117;
            color: white;
        }
        .stTextInput>div>div>input {
            background-color: #1c1f26;
            color: white;
        }
        .stButton>button {
            background-color: #ff4b4b;
            color: white;
            border-radius: 10px;
        }
        .stTextArea textarea {
            background-color: #1c1f26;
            color: white;
        }
    </style>
""", unsafe_allow_html=True)


st.title("🎥 YouTube RAG Chatbot")
st.markdown("##### 🤖 Ask anything about a YouTube video — powered by LangChain + DeepSeek")


if "rag_chain" not in st.session_state:
    st.session_state.rag_chain = None
if "transcript" not in st.session_state:
    st.session_state.transcript = None
if "chat_history" not in st.session_state:
    st.session_state.chat_history = []  # stores (question, answer) pairs


st.sidebar.header("🧠 About This App")
st.sidebar.write("""
This app uses:
- **LangChain + DeepSeek (HuggingFace)**
- **RAG (Retrieval-Augmented Generation)**
- **YouTube transcripts as knowledge base**
""")

if st.sidebar.button("🔁 Clear Session"):
    st.session_state.clear()
    st.rerun()

yt_link = st.text_input("🎬 Enter a YouTube video link:")

col1, col2 = st.columns([1, 3])

with col1:
    fetch_btn = st.button("📜 Fetch Transcript")

with col2:
    st.markdown("")

if fetch_btn and yt_link:
    with st.spinner("Fetching transcript..."):
        transcript = get_transcript(yt_link)
        if transcript:
            st.session_state.transcript = transcript
            st.success("✅ Transcript fetched successfully!")
            with st.spinner("Building RAG model..."):
                st.session_state.rag_chain = build_rag_chain(transcript)
                st.success("RAG model ready! Ask your questions below 👇")
        else:
            st.error("❌ Transcript not available for this video.")

if st.session_state.rag_chain:
    st.subheader("💬 Chat with the Video")

    for q, a in st.session_state.chat_history:
        with st.chat_message("user"):
            st.markdown(f"**You:** {q}")
        with st.chat_message("assistant"):
            st.markdown(f"**Bot:** {a}")

    user_input = st.chat_input("Ask your question here...")
    if user_input:
        with st.chat_message("user"):
            st.markdown(f"**You:** {user_input}")

        with st.spinner("Thinking... 🤔"):
            answer = ask_question(st.session_state.rag_chain, user_input)

        with st.chat_message("assistant"):
            st.markdown(f"**Bot:** {answer}")

        st.session_state.chat_history.append((user_input, answer))