"""
SmartTrip AI — Agentic Travel Planner
Streamlit chatbot interface with login, multi-turn chat, admin history view,
per-user chat persistence (SQLite), and daily rotating logs.
"""

import os
import uuid

import streamlit as st
from dotenv import load_dotenv
from langchain_core.messages import HumanMessage

from agent.agentic_workflow import GraphBuilder
from utils.auth import authenticate, get_all_users, get_demo_credentials_md
from utils.chat_store import (
    init_db,
    save_chat,
    get_user_chats,
    get_all_chats,
    get_users_with_chats,
    get_chat_stats,
)
from logger.logging import get_logger

load_dotenv()

logger = get_logger("smarttrip_ui")

# Initialise DB tables on startup (idempotent)
init_db()

# ─────────────────────────────────────────────────────────────────────────────
# Page config  (must be the very first Streamlit call)
# ─────────────────────────────────────────────────────────────────────────────
st.set_page_config(
    page_title="🌍 SmartTrip AI",
    page_icon="🌍",
    layout="wide",
    initial_sidebar_state="expanded",
)


# ─────────────────────────────────────────────────────────────────────────────
# Environment check — called once per session to warn about missing keys
# ─────────────────────────────────────────────────────────────────────────────
REQUIRED_ENV_VARS = [
    "MODEL_PROVIDER",
    "MODEL_NAME",
    "MODEL_BASE_URL",
    "OLLAMA_API_KEY",
    "OPENWEATHERMAP_API_KEY",
    "TAVILY_API_KEY",
]


def get_missing_keys() -> list:
    return [k for k in REQUIRED_ENV_VARS if not os.getenv(k)]


# ─────────────────────────────────────────────────────────────────────────────
# Agent graph — cached but ONLY when successfully built (never cache None)
# ─────────────────────────────────────────────────────────────────────────────
@st.cache_resource(show_spinner=False)
def get_agent_graph():
    """Build and compile the LangGraph agent once; reuse for all users."""
    missing = get_missing_keys()
    if missing:
        logger.error(f"Cannot build agent — missing env vars: {missing}")
        raise RuntimeError(
            f"Missing required environment variables: {', '.join(missing)}\n\n"
            "On Hugging Face Spaces: go to **Settings → Variables and secrets** "
            "and add each key listed above."
        )
    provider = os.getenv("MODEL_PROVIDER", "ollama")
    logger.info(f"Building LangGraph agent with provider='{provider}'")
    gb = GraphBuilder(model_provider=provider)
    return gb()


# ─────────────────────────────────────────────────────────────────────────────
# Session state helpers
# ─────────────────────────────────────────────────────────────────────────────
def init_session() -> None:
    defaults = {
        "authenticated": False,
        "username": None,
        "role": None,
        "display_name": None,
        "messages": [],
        "session_id": str(uuid.uuid4()),
        "admin_view": False,
    }
    for key, value in defaults.items():
        if key not in st.session_state:
            st.session_state[key] = value


def logout() -> None:
    for key in list(st.session_state.keys()):
        del st.session_state[key]
    st.rerun()


# ─────────────────────────────────────────────────────────────────────────────
# Sidebar
# ─────────────────────────────────────────────────────────────────────────────
def render_sidebar() -> None:
    with st.sidebar:
        st.markdown("## 🌍 SmartTrip AI")
        st.markdown("---")
        st.markdown(f"**👤 {st.session_state.display_name}**")
        st.markdown(f"Role: `{st.session_state.role}`")
        st.markdown("---")

        if st.button("🗑️ New Chat", use_container_width=True):
            st.session_state.messages = []
            st.session_state.session_id = str(uuid.uuid4())
            st.session_state.admin_view = False
            st.rerun()

        if st.button("🚪 Logout", use_container_width=True):
            logout()

        st.markdown("---")
        st.markdown("**🛠️ Available Tools**")
        st.markdown(
            "- 🌤️ Weather & Forecast\n"
            "- 📍 Attractions & Places\n"
            "- 🍽️ Restaurants\n"
            "- 🏄 Activities\n"
            "- 🚌 Transportation\n"
            "- 💰 Expense Calculator\n"
            "- 💱 Currency Converter"
        )

        if st.session_state.role == "admin":
            st.markdown("---")
            st.markdown("**🛡️ Admin Panel**")
            if not st.session_state.admin_view:
                if st.button("📊 View User Chat History", use_container_width=True):
                    st.session_state.admin_view = True
                    st.rerun()
            else:
                if st.button("💬 Back to Chat", use_container_width=True):
                    st.session_state.admin_view = False
                    st.rerun()

        st.markdown("---")
        st.caption("SmartTrip AI © 2025 | Demo Mode")


# ─────────────────────────────────────────────────────────────────────────────
# Login page
# ─────────────────────────────────────────────────────────────────────────────
def render_login_page() -> None:
    # Top-right demo credentials panel
    title_col, creds_col = st.columns([3, 1])
    with title_col:
        st.markdown("## 🌍 SmartTrip AI — Your Agentic Travel Planner")
        st.markdown(
            "Plan personalised trips with real-time weather, places, restaurants, "
            "activities, and smart expense breakdowns — all in one conversation."
        )
    with creds_col:
        with st.expander("🔑 Demo Credentials", expanded=True):
            st.markdown(get_demo_credentials_md())

    st.markdown("---")

    _, center, _ = st.columns([1, 2, 1])
    with center:
        st.subheader("🔐 Login to get started")

        with st.form("login_form", clear_on_submit=False):
            username = st.text_input("Username", placeholder="e.g. user1")
            password = st.text_input("Password", type="password", placeholder="Enter password")
            submitted = st.form_submit_button("Login →", use_container_width=True)

        if submitted:
            if not username.strip() or not password.strip():
                st.error("Please enter both username and password.")
            else:
                user_data = authenticate(username, password)
                if user_data:
                    st.session_state.authenticated = True
                    st.session_state.username = user_data["username"]
                    st.session_state.role = user_data["role"]
                    st.session_state.display_name = user_data["display_name"]
                    st.session_state.messages = []
                    st.session_state.session_id = str(uuid.uuid4())
                    st.session_state.admin_view = False
                    logger.info(
                        f"Login successful: '{username}' (role={user_data['role']})"
                    )
                    st.rerun()
                else:
                    st.error(
                        "❌ Invalid username or password. "
                        "Use the demo credentials shown at the top-right."
                    )
                    logger.warning(
                        f"Failed login attempt for username='{username}'"
                    )


# ─────────────────────────────────────────────────────────────────────────────
# Admin: chat history viewer
# ─────────────────────────────────────────────────────────────────────────────
def render_admin_page() -> None:
    st.title("🛡️ Admin Panel — User Chat History")

    stats = get_chat_stats()
    c1, c2, c3 = st.columns(3)
    c1.metric("💬 Total Messages", stats["total_messages"])
    c2.metric("👥 Unique Users", stats["unique_users"])
    c3.metric("🔗 Sessions", stats["unique_sessions"])

    st.markdown("---")

    all_usernames = get_all_users()
    filter_choice = st.selectbox(
        "👤 Filter by user",
        ["— All Users —"] + all_usernames,
        index=0,
    )

    if filter_choice == "— All Users —":
        chats = get_all_chats()
        header = "All Users"
    else:
        chats = get_user_chats(filter_choice)
        header = filter_choice

    if not chats:
        st.info(
            f"No chat history found for **{header}** yet."
            if header != "All Users"
            else "No chat history yet — users haven't started chatting."
        )
        return

    st.markdown(f"### 📋 {len(chats)} message(s) — **{header}**")

    for chat in chats:
        ts = chat["timestamp"][:19]
        session_short = chat["session_id"][:8]
        user = chat["username"]
        status_badge = "✅" if chat.get("status") == "success" else "❌"

        with st.expander(
            f"{status_badge}  `{ts}`  |  👤 **{user}**  |  session `{session_short}…`"
        ):
            st.markdown("**🧑 User asked:**")
            st.info(chat["user_message"])
            st.markdown("**🤖 SmartTrip AI replied:**")
            st.text_area(
                label="Response",
                value=chat["bot_response"],
                height=200,
                disabled=True,
                label_visibility="collapsed",
            )
            if chat.get("status") != "success":
                st.error(f"Status: {chat['status']}")


# ─────────────────────────────────────────────────────────────────────────────
# Chat page
# ─────────────────────────────────────────────────────────────────────────────
def render_chat_page() -> None:
    # Header with top-right credentials reminder
    left_col, right_col = st.columns([3, 1])
    with left_col:
        st.markdown("## 🌍 SmartTrip AI — Your Agentic Travel Planner")
    with right_col:
        with st.expander("🔑 Demo Credentials", expanded=False):
            st.markdown(get_demo_credentials_md())

    st.markdown("---")

    # ── Warn immediately if any required env vars are missing ─────────────────
    missing = get_missing_keys()
    if missing:
        st.error(
            f"⚠️ **Missing environment variables:** `{'`, `'.join(missing)}`\n\n"
            "The AI cannot respond until these are set.\n\n"
            "**On Hugging Face Spaces:** go to **Settings → Variables and secrets** "
            "and add each key listed above, then restart the Space."
        )
        return  # Don't render the chat box if keys are missing

    # Welcome message when no conversation yet
    if not st.session_state.messages:
        with st.chat_message("assistant"):
            st.markdown(
                "👋 Hi! I'm **SmartTrip AI**, your intelligent travel planning companion!\n\n"
                "I can help you with:\n"
                "- 🗺️ Complete day-by-day itineraries (mainstream + off-beat)\n"
                "- 🌤️ Real-time weather & forecasts\n"
                "- 📍 Attractions, restaurants & activities\n"
                "- 🚌 Transportation options\n"
                "- 💰 Detailed cost breakdowns & daily budgets\n"
                "- 💱 Live currency conversion\n\n"
                "**Try:** *\"Plan a 5-day trip to Bali for 2 people with a budget of $1500\"*"
            )

    # Render conversation history
    for msg in st.session_state.messages:
        with st.chat_message(msg["role"]):
            st.markdown(msg["content"])

    # Chat input (Streamlit pins this to the bottom automatically)
    user_input = st.chat_input(
        "Ask me about your trip… e.g. Plan a 4-day trip to Rajasthan under ₹25,000"
    )

    if not user_input:
        return

    # Show user bubble
    st.session_state.messages.append({"role": "user", "content": user_input})
    with st.chat_message("user"):
        st.markdown(user_input)

    # Build multi-turn context: include last 6 messages (3 pairs)
    prior_msgs = st.session_state.messages[:-1]
    if prior_msgs:
        context_lines = []
        for m in prior_msgs[-6:]:
            prefix = "User" if m["role"] == "user" else "Assistant"
            context_lines.append(f"{prefix}: {m['content']}")
        full_query = (
            "Previous conversation:\n"
            + "\n".join(context_lines)
            + f"\n\nCurrent question: {user_input}"
        )
    else:
        full_query = user_input

    # Invoke agent and stream response
    with st.chat_message("assistant"):
        with st.spinner("SmartTrip AI is planning your trip… 🗺️"):
            try:
                graph = get_agent_graph()

                output = graph.invoke({"messages": [HumanMessage(content=full_query)]})

                if isinstance(output, dict) and "messages" in output:
                    response = output["messages"][-1].content
                else:
                    response = str(output)

                st.markdown(response)
                status = "success"
                logger.info(
                    f"Query answered | user='{st.session_state.username}' "
                    f"session='{st.session_state.session_id[:8]}'"
                )

            except Exception as exc:
                err_msg = str(exc)
                response = (
                    f"⚠️ **Agent error:** {err_msg}\n\n"
                    "Check that all API keys are set in **HF Space → Settings → Variables and secrets**."
                )
                st.markdown(response)
                status = "error"
                logger.error(
                    f"Agent error | user='{st.session_state.username}' | {exc}"
                )
                logger.error(
                    f"Agent error | user='{st.session_state.username}' | {exc}"
                )

    st.session_state.messages.append({"role": "assistant", "content": response})

    # Persist to SQLite
    save_chat(
        session_id=st.session_state.session_id,
        username=st.session_state.username,
        role=st.session_state.role,
        user_message=user_input,
        bot_response=response,
        status=status,
    )


# ─────────────────────────────────────────────────────────────────────────────
# Entry point...
# ─────────────────────────────────────────────────────────────────────────────
def main() -> None:
    init_session()

    if not st.session_state.authenticated:
        render_login_page()
        return

    render_sidebar()

    if st.session_state.role == "admin" and st.session_state.admin_view:
        render_admin_page()
    else:
        render_chat_page()


if __name__ == "__main__":
    main()