import streamlit as st
import random
import time

# Page config
st.set_page_config(page_title="StreamChat", page_icon="🤖")

# Initialize session state
if "messages" not in st.session_state:
    st.session_state.messages = []
if "thinking" not in st.session_state:
    st.session_state.thinking = False

# Helper: mock LLM response
def mock_llm(prompt: str) -> str:
    time.sleep(1.2)  # Simulate latency
    replies = [
        f"Interesting point! Re: '{prompt}' — I'd say let's explore this further.",
        f"Thanks for sharing '{prompt}'. From my perspective, that seems spot on.",
        f"Ah, '{prompt}' — reminds me of something I read in the docs.",
        f"'{prompt}'... 🤔 Let me ponder that for a moment.",
    ]
    return random.choice(replies)

# Sidebar
with st.sidebar:
    st.title("🤖 StreamChat")
    st.markdown("A lightweight Streamlit chatbot demo.")
    if st.button("Clear History"):
        st.session_state.messages.clear()
        st.rerun()

# Display chat messages
for msg in st.session_state.messages:
    with st.chat_message(msg["role"]):
        st.markdown(msg["content"])

# User input
if prompt := st.chat_input("Ask me anything...", disabled=st.session_state.thinking):
    # Add user message
    st.session_state.messages.append({"role": "user", "content": prompt})
    st.session_state.thinking = True
    st.rerun()

# If thinking, generate response
if st.session_state.thinking:
    last_user = st.session_state.messages[-1]["content"]
    with st.chat_message("assistant"):
        with st.spinner("Thinking..."):
            response = mock_llm(last_user)
        st.markdown(response)
    st.session_state.messages.append({"role": "assistant", "content": response})
    st.session_state.thinking = False
    st.rerun()