app.py

import streamlit as st
from langchain_groq import ChatGroq
from langchain_community.utilities import ArxivAPIWrapper, WikipediaAPIWrapper
from langchain_community.tools import ArxivQueryRun, WikipediaQueryRun
from langchain.agents import initialize_agent, AgentType
from langchain_community.callbacks import StreamlitCallbackHandler
from langchain.tools import Tool
from duckduckgo_search import DDGS
import os
from dotenv import load_dotenv

# Custom DuckDuckGo Search with error handling
def duckduckgo_search(query):
    try:
        with DDGS() as ddgs:
            results = [r for r in ddgs.text(query, max_results=3)]
            return "\n".join([f"{r['title']}: {r['body']}" for r in results]) if results else "No results found"
    except Exception as e:
        return f"Search error: {str(e)}"

# Create custom search tool
search_tool = Tool(
    name="DuckDuckGo Search",
    func=duckduckgo_search,
    description="Useful for searching the internet"
)

# Arxiv and Wikipedia Tools
arxiv_wrapper = ArxivAPIWrapper(top_k_results=1, doc_content_chars_max=200)
arxiv = ArxivQueryRun(api_wrapper=arxiv_wrapper)

wiki_wrapper = WikipediaAPIWrapper(top_k_results=1, doc_content_chars_max=200)
wiki = WikipediaQueryRun(api_wrapper=wiki_wrapper)

st.title("🔎 LangChain - Chat with search")

# Sidebar for settings
st.sidebar.title("Settings")
api_key = st.sidebar.text_input("Enter your Groq API Key:", type="password")

if "messages" not in st.session_state:
    st.session_state["messages"] = [
        {"role": "assistant", "content": "Hi, I'm a chatbot who can search the web. How can I help you?"}
    ]

for msg in st.session_state.messages:
    st.chat_message(msg["role"]).write(msg['content'])

if prompt := st.chat_input(placeholder="What is machine learning?"):
    st.session_state.messages.append({"role": "user", "content": prompt})
    st.chat_message("user").write(prompt)

    llm = ChatGroq(groq_api_key=api_key, model_name="Llama3-8b-8192", streaming=True)
    tools = [search_tool, arxiv, wiki]

    search_agent = initialize_agent(
        tools,
        llm,
        agent=AgentType.ZERO_SHOT_REACT_DESCRIPTION,
        handle_parsing_errors=True,
        verbose=True
    )

    with st.chat_message("assistant"):
        st_cb = StreamlitCallbackHandler(st.container(), expand_new_thoughts=False)
        try:
            response = search_agent.invoke(
                {"input": prompt},
                {"callbacks": [st_cb]}
            )["output"]
            st.session_state.messages.append({'role': 'assistant', "content": response})
            st.write(response)
        except Exception as e:
            st.error(f"An error occurred: {str(e)}")
            st.session_state.messages.append({'role': 'assistant', "content": f"Error: {str(e)}"})