# streamlit_chatbot.py
# A minimal self-contained Streamlit chatbot example.
# Run with: streamlit run streamlit_chatbot.py

import random
import streamlit as st

# --- Configure the page ---
st.set_page_config(
    page_title="Minimal Chatbot",
    page_icon="🤖",
    layout="centered",
)

# --- Session-state helpers ---
SESSION_KEY = "messages"

def init_session():
    """Initialize the chat history in session state."""
    if SESSION_KEY not in st.session_state:
        st.session_state[SESSION_KEY] = []

def append_message(role: str, content: str):
    """Add a message to the session state."""
    st.session_state[SESSION_KEY].append({"role": role, "content": content})

# --- Bot logic (stub) ---
def bot_response(user_input: str) -> str:
    """Mock LLM: echo the user or give a canned answer."""
    user_input = user_input.strip().lower()
    if not user_input:
        return "I didn't catch that. Please say something!"
    if "hello" in user_input or "hi" in user_input:
        return "Hello! How can I help you today?"
    if "bye" in user_input or "goodbye" in user_input:
        return "Goodbye! Have a great day."
    if "how are you" in user_input:
        return "I'm just code, but thanks for asking!"
    # Random fallback
    return random.choice(
        [
            "Interesting point.",
            "Tell me more.",
            "Could you clarify that?",
            "I'm listening.",
        ]
    )

# --- Main app ---
init_session()

st.title("🤖 Minimal Chatbot")
st.markdown("Ask me anything. Type `bye` to exit.")

# Display chat history
for msg in st.session_state[SESSION_KEY]:
    with st.chat_message(msg["role"]):
        st.write(msg["content"])

# Chat input
if prompt := st.chat_input("Type your message..."):
    # Show user message
    with st.chat_message("user"):
        st.write(prompt)
    append_message("user", prompt)

    # Generate & show bot response
    response = bot_response(prompt)
    with st.chat_message("assistant"):
        st.write(response)
    append_message("assistant", response)