app.py

# import os 
# import streamlit as st
# from langchain.chains import ConversationChain
# from langchain_openai import ChatOpenAI
# from langchain.memory import ConversationBufferMemory

# os.environ["OPENAI_API_KEY"] = ""

# # Intialize the chatbot
# @st.cache_resource
# def init_chatbot():
#     memory = ConversationBufferMemory()
#     chatbot = ConversationChain(
#         llm =ChatOpenAI(model = "gpt-4o-mini"),
#         memory = memory,
#         verbose = False
#     )

#     return chatbot

# # Streamlit Application
# st.title("Langchain Chatbot")
# st.write("Hi, I'm a chatbot built with Langchain powered by GPT. How can I assist you today?")

# user_input = st.text_input("You:", placeholder = "Ask me anything....")

# if user_input:
#     with st.spinner("Thinking......"):
#         resp = chatbot.run(user_input)
#         st.write(f"Chatbot: {resp}")


import os
import streamlit as st
from langchain.chains import ConversationChain
from langchain_openai import ChatOpenAI
from langchain.memory import ConversationBufferMemory
from streamlit_extras.add_vertical_space import add_vertical_space

# Set up OpenAI API Key securely
if "openai_api_key" in st.secrets:
    os.environ["OPENAI_API_KEY"] = st.secrets["openai_api_key"]
else:
    st.error("🔑 OpenAI API Key is missing! Please add it to Streamlit secrets.")
    st.stop()

# Initialize chatbot with memory
def init_chatbot(model="gpt-4o-mini"):
    try:
        memory = ConversationBufferMemory()
        chatbot = ConversationChain(llm=ChatOpenAI(model=model), memory=memory, verbose=False)
        return chatbot
    except Exception as e:
        st.error(f"⚠️ Error initializing chatbot: {e}")
        return None

if "chatbot" not in st.session_state:
    st.session_state.chatbot = init_chatbot()

# Custom Styling
st.markdown("""
    <style>
        body {
            background-color: #f5f5f5;
        }
        .stChatMessage {
            padding: 10px;
            border-radius: 10px;
            margin: 5px 0;
        }
        .user-message {
            background-color: #dcf8c6;
            text-align: right;
        }
        .bot-message {
            background-color: #ffffff;
        }
    </style>
""", unsafe_allow_html=True)

# Sidebar - Model Selection
st.sidebar.title("⚙️ Settings")
model_choice = st.sidebar.radio("Select Model", ("gpt-4o-mini", "gpt-4", "gpt-3.5-turbo"))

# Update chatbot model if changed
if model_choice != st.session_state.chatbot.llm.model_name:
    st.session_state.chatbot = init_chatbot(model_choice)

# Title and Description
st.title("💬 LangChain AI Chatbot")
st.write("### Hi, I'm a chatbot powered by GPT. How can I assist you today?")

# Chat history storage
if "chat_history" not in st.session_state:
    st.session_state.chat_history = []

# User Input via Chat Input (better UX)
user_input = st.chat_input("Type your message here...")

# Process input
if user_input:
    with st.spinner("Thinking..."):
        try:
            response = st.session_state.chatbot.run(user_input)
            if response:
                st.session_state.chat_history.append(("user", user_input))
                st.session_state.chat_history.append(("bot", response))
        except Exception as e:
            st.error(f"⚠️ Error generating response: {e}")

# Display chat history
st.write("### 🗨️ Conversation")
for role, text in st.session_state.chat_history:
    with st.chat_message(role):
        st.markdown(f"**{role.capitalize()}**: {text}")

# Collapsible Chat History
with st.expander("📜 View Full Chat History"):
    for role, text in st.session_state.chat_history:
        st.write(f"**{role.capitalize()}**: {text}")

# Add spacing
add_vertical_space(2)

# Footer
st.markdown("---")
st.markdown("Developed with ❤️ using Streamlit & LangChain")