import os
import json
import requests
import pandas as pd
import streamlit as st

# Configuration
def get_env_variable(name: str) -> str:
    try:
        return os.environ[name]
    except KeyError:
        st.error(f"Environment variable '{name}' not set.")
        st.stop()

CHAT_URL = get_env_variable("CHAT_URL")

# API interaction
def fetch_results(query: str) -> list[dict]:
    """
    Send a query to the chat API and return the parsed JSON response.
    """
    payload = {"query": query}
    response = requests.post(
        CHAT_URL,
        headers={"Content-Type": "application/json"},
        data=json.dumps(payload),
    )
    return response.json()

# UI components
def display_results_table(results: dict) -> None:
    """Normalize and display API results as a Streamlit table."""
    if "results" not in results:
        st.info(results.get('detail', 'No results found.'))
        return
    df = pd.json_normalize(results['results'])
    st.dataframe(df)

def display_messages(history: list[dict]) -> None:
    """Render chat messages from history including tables."""
    for msg in history:
        with st.chat_message(msg["role"]):
            st.markdown(msg["content"])
            if "data" in msg:
                display_results_table(msg["data"])

def main() -> None:
    st.title("BookDB 📚 🤖")

    # Initialize chat history
    if "messages" not in st.session_state:
        st.session_state.messages = []

    # Get user input
    query = st.chat_input("Ask about books...")
    
    if query:
        # Add user message to history
        st.session_state.messages.append({
            "role": "user",
            "content": query.strip()
        })
        
        # Fetch results and add assistant response
        results = fetch_results(query)
        st.session_state.messages.append({
            "role": "assistant",
            "content": "Here are the results:",
            "data": results
        })

    # Display all messages
    display_messages(st.session_state.messages)

if __name__ == "__main__":
    main()