import os
import streamlit as st
from langchain.prompts import ChatPromptTemplate, SystemMessagePromptTemplate, HumanMessagePromptTemplate
from langchain_huggingface import HuggingFaceEndpoint, ChatHuggingFace
from youtube_transcript_api import YouTubeTranscriptApi
from langchain_community.document_loaders import YoutubeLoader
from langchain_google_genai import GoogleGenerativeAI,ChatGoogleGenerativeAI
from youtube_transcript_api._errors import TranscriptsDisabled


gemini_token = os.environ.get("gemini")
os.environ["GOOGLE_API_KEY"] = gemini_token

st.set_page_config(page_title="🎬 Tube2Insight", page_icon="🎥", layout="wide")

st.markdown("""
    <style>
        .stApp { background-color: #f7f9fc; }
        .video-card {
            background-color: #ffffff;
            border: 2px solid #e0e0e0;
            padding: 20px;
            border-radius: 15px;
            text-align: center;
            box-shadow: 2px 2px 10px #ddd;
        }
        .video-card:hover {
            border-color: #FF4B4B;
            box-shadow: 3px 3px 12px #bbb;
        }
    </style>
""", unsafe_allow_html=True)

st.markdown("<h1 style='text-align: center; color: #FF4B4B;'>🎬 Tube2Insight</h1>", unsafe_allow_html=True)
st.markdown("### Paste a YouTube link below to get an instant summary 👇")

video_url = st.text_input("📺 YouTube Video URL")

if st.button("🔍 Summarize"):
    if not video_url:
        st.warning("Please provide a video link.")
    else:
        with st.spinner("📄 Fetching transcript..."):
            try:
                docs = YoutubeLoader.from_youtube_url(video_url).load()
                transcript = docs[0].page_content
                st.success("✅ Transcript loaded!")
            except Exception as e:
                st.error(f"Error loading video: {e}")
                st.stop()

        with st.expander("📄 View Transcript"):
            st.write(transcript)

        llm = ChatGoogleGenerativeAI(
            model="gemini-2.0-flash",
            temperature=0.5,
            max_output_tokens=512
        )

        prompt = ChatPromptTemplate.from_messages([
            SystemMessagePromptTemplate.from_template("You are a helpful assistant summarizing YouTube transcripts."),
            HumanMessagePromptTemplate.from_template("{transcript}")
        ])
        messages = prompt.format_messages(transcript=transcript)

        with st.spinner("🧠 Summarizing with Gemini 2.0 Flash..."):
            response = llm.invoke(messages)

        st.markdown("### 📌 Summary")
        st.success(response.content)

st.markdown("---")
st.markdown(
    "<p style='text-align: center; color: gray;'>🚀 Built with LangChain + Gemini + Streamlit </p>",
    unsafe_allow_html=True
)