app.py

import gradio as gr
import os, re

from langchain_google_genai import GoogleGenerativeAIEmbeddings, ChatGoogleGenerativeAI
from youtube_transcript_api import YouTubeTranscriptApi
from langchain.schema import Document
from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain_community.vectorstores import FAISS
from langchain.chains import LLMChain
from langchain.prompts.chat import (
    ChatPromptTemplate,
    SystemMessagePromptTemplate,
    HumanMessagePromptTemplate,
)


def get_transcript(video_url):
    try:
        # Use a regular expression to extract video ID from the YouTube URL
        video_id_match = re.search(r"(?:https?://)?(?:www\.)?(?:youtube\.com\/(?:[^\/\n\s]+\/\S+\/|(?:v|e(?:mbed)?)\/|\S*?[?&]v=)|youtu\.be\/)([a-zA-Z0-9_-]{11})", video_url)
        
        if not video_id_match:
            return "Invalid YouTube URL"
        
        video_id = video_id_match.group(1)
        
        # Fetch the transcript
        transcript = YouTubeTranscriptApi.get_transcript(video_id)

        # Join the transcript text into a single string
        text = "\n".join([t["text"] for t in transcript])
        return text  # Return the transcript as a string
        
    except Exception as e:
        return f"Error fetching transcript: Unable to fetch subtitles."


    
def create_db_from_video_url(video_url, api_key):
    """
    Creates an Embedding of the Video and performs 
    """
    embeddings = GoogleGenerativeAIEmbeddings(model="models/text-embedding-004", google_api_key=api_key)
    
    transcripts = get_transcript(video_url)
    
    # Convert transcript string into a Document
    doc_convert = Document(page_content=transcripts)

    # cannot provide this directly to the model so we are splitting the transcripts into small chunks
    text_splitter = RecursiveCharacterTextSplitter(chunk_size=1000, chunk_overlap=100)
    docs = text_splitter.split_documents([doc_convert])

    db = FAISS.from_documents(docs, embedding=embeddings)
    return db

    
def get_response(video, request):
    """
    Usind Gemini Pro to get the response. It can handle upto 32k tokens.
    """
    API_KEY = os.environ.get("API_Key")
    db = create_db_from_video_url(video, API_KEY)
    docs = db.similarity_search(query=request, k=5)
    docs_content = " ".join([doc.page_content for doc in docs])

    chat = ChatGoogleGenerativeAI(model="gemini-1.5-flash", google_api_key=API_KEY, convert_system_message_to_human=True)

    # creating a template for request
    template = """
    You are an assistant that can answer questions about youtube videos based on
    video transcripts: {docs}

    Only use factual information from the transcript to answer the question.

    If you don't have enough information to answer the question, say "I don't know".

    Your Answers should be detailed.
    """

    system_msg_prompt = SystemMessagePromptTemplate.from_template(template)

    # human prompt
    human_template = "Answer the following questions: {question}"
    human_msg_prompt = HumanMessagePromptTemplate.from_template(human_template)

    chat_prompt = ChatPromptTemplate.from_messages(
        [system_msg_prompt, human_msg_prompt]
    )

    chain = LLMChain(llm=chat, prompt=chat_prompt)

    response = chain.run(question=request, docs=docs_content)

    return response

# creating title, description for the web app
title = "YouTube Video Assistant 🧑‍💻"
description = "Answers to the Questions asked by the user on the specified YouTube video. (English Only).\n\n"\
"Click here to view [demo](https://huggingface.co/spaces/Kathir0011/YouTube_Video_Assistant/blob/main/README.md)."
article = "Other Projects:<br/>"\
"💰 [Health Insurance Predictor](http://health-insurance-cost-predictor-k19.streamlit.app/)<br/>"\
"📰 [Fake News Detector](https://fake-news-detector-k19.streamlit.app/)<br/>"\
"🪶 [Birds Classifier](https://huggingface.co/spaces/Kathir0011/Birds_Classification)"

# building the app
youtube_video_assistant = gr.Interface(
    fn=get_response,
    inputs=[gr.Text(label="Enter the Youtube Video URL:", placeholder="Example: https://www.youtube.com/watch?v=MnDudvCyWpc"),
            gr.Text(label="Enter your Question", placeholder="Example: What's the video is about?")],
    outputs=gr.TextArea(label="Answers using Gemini-1.5-flash:"),
    title=title,
    description=description,
    article=article
)

# launching the web app
youtube_video_assistant.launch()