app.py

import streamlit as st
from langchain import LLMChain
from langchain.chat_models import ChatOpenAI
from langchain.prompts import ChatPromptTemplate
from dotenv import load_dotenv
import os

# Load environment variables
load_dotenv()

# Set LangChain tracing (optional)
os.environ["LANGCHAIN_TRACING_V2"] = "true"
os.environ["LANGCHAIN_API_KEY"] = os.getenv("LANGCHAIN_API_KEY")

# Initialize the Hugging Face LLaMA 2 model via LangChain
llm = ChatOpenAI(
    model_name="meta-llama/Llama-2-7b-chat-hf",
    temperature=0.7,
    max_tokens=512,
    openai_api_key=os.getenv("OPENAI_API_KEY")  # If using OpenAI; otherwise, remove
)

# Define the prompt template
prompt = ChatPromptTemplate.from_messages(
    [
        ("system", "You are a helpful assistant."),
        ("user", "Question: {question}")
    ]
)

# Create the LLM Chain
chain = LLMChain(llm=llm, prompt=prompt, output_key="response")

# Streamlit App Interface
st.title('LangChain Demo with LLaMA 2 on Hugging Face')

# User input
input_text = st.text_input("Enter your question:")

# Display the response
if input_text:
    try:
        response = chain.run({"question": input_text})
        st.write(response)
    except Exception as e:
        st.error(f"Error: {e}")