src/streamlit_app.py

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

# Set OpenRouter API Key and Base URL
os.environ["OPENAI_API_KEY"] = st.secrets["OPENAI_API_KEY"]
os.environ['OPENAI_API_BASE'] = 'https://openrouter.ai/api/v1'

# Set up the model
llm = ChatOpenAI(
    temperature=0.7,
    model_name="deepseek/deepseek-chat-v3-0324:free"  # correct model path
)

# Set up memory
if "memory" not in st.session_state:
    st.session_state.memory = ConversationBufferMemory()

conversation = ConversationChain(
    llm=llm,
    memory=st.session_state.memory,
    verbose=False
)

# Streamlit UI
st.set_page_config(page_title="LLM Chatbot", page_icon="🤖")

st.title("Langchain Chatbot by Muhammad Izhan")

user_input = st.text_input("You:", key="input")

if user_input:
    response = conversation.predict(input=user_input)
    st.session_state.memory.chat_memory.add_user_message(user_input)
    st.session_state.memory.chat_memory.add_ai_message(response)
    st.write(f"**Bot:** {response}")

# Show chat history
if st.checkbox("Show Chat History"):
    for message in st.session_state.memory.chat_memory.messages:
        role = "You" if message.type == "human" else "Bot"
        st.markdown(f"**{role}:** {message.content}")