import asyncio
import logging
from contextlib import suppress

from aiogram import Bot, Dispatcher, Router, types
from aiogram.enums import ParseMode
from aiogram.filters import Command
from aiogram.webhook.aiohttp_server import SimpleRequestHandler
from django.conf import settings
from django.contrib.auth import get_user_model
from django.db.models import Q

from engine.vibes_auth.choices import SenderType
from engine.vibes_auth.models import ChatThread

logger = logging.getLogger(__name__)

USER_SUPPORT_GROUP_NAME = "User Support"


def is_telegram_enabled() -> bool:
    return bool(settings.TELEGRAM_TOKEN)


def _get_bot() -> Bot | None:
    if not is_telegram_enabled():
        logger.warning("Telegram forwarder disabled: missing aiogram or TELEGRAM_TOKEN")
        return None
    return Bot(token=settings.TELEGRAM_TOKEN, parse_mode=ParseMode.HTML)


def build_router() -> Router | None:
    if not is_telegram_enabled():
        return None

    User = get_user_model()
    router: Router = Router()

    @router.message(Command("start"))
    async def cmd_start(message: types.Message):
        parts = (message.text or "").split(maxsplit=1)
        if len(parts) < 2:
            await message.answer(
                "Welcome! To link your account, send: <code>/start ACTIVATION_TOKEN</code>\n"
                "You can find your activation token in your profile."
            )
            return
        token = parts[1].strip()

        def _link():
            try:
                retrieved_user = User.objects.get(activation_token=token)
            except User.DoesNotExist:
                return None
            attrs = dict(retrieved_user.attributes or {})
            attrs["telegram_id"] = message.from_user.id if message.from_user else None
            retrieved_user.attributes = attrs
            retrieved_user.save(update_fields=["attributes", "modified"])
            return retrieved_user

        user = await asyncio.to_thread(_link)
        if not user:
            await message.answer("Invalid activation token.")
            return
        await message.answer("Your Telegram account has been linked successfully.")

    @router.message(Command("unlink"))
    async def cmd_unlink(message: types.Message):
        tid = message.from_user.id if message.from_user else None
        if not tid:
            await message.answer("Cannot unlink: no Telegram user id.")
            return

        def _unlink():
            q = Q(attributes__telegram_id=tid)
            updated_query = User.objects.filter(q).update(attributes={})
            return updated_query

        updated = await asyncio.to_thread(_unlink)
        if updated:
            await message.answer("Unlinked successfully.")
        else:
            await message.answer("No linked account found.")

    @router.message(Command("help"))
    async def cmd_help(message: types.Message):
        await message.answer(
            "Commands:\n"
            "/start <token> — link your account\n"
            "/unlink — unlink your account\n"
            "As staff, you may use: <code>reply THREAD_UUID your message</code> to respond."
        )

    @router.message()
    async def any_message(message: types.Message):
        from engine.vibes_auth.messaging.services import (
            send_message as svc_send_message,
        )

        if not message.from_user or not message.text:
            return
        tid = message.from_user.id

        def _resolve_staff_and_command():
            try:
                staff_user = User.objects.get(
                    attributes__telegram_id=tid, is_staff=True, is_active=True
                )
            except User.DoesNotExist:
                return None, None, None
            # group check
            if not staff_user.groups.filter(name=USER_SUPPORT_GROUP_NAME).exists():
                return None, None, None
            text = message.text.strip() if message.text else ""
            if text.lower().startswith("reply "):
                parts = text.split(maxsplit=2)
                if len(parts) < 3:
                    return staff_user, None, "Usage: reply <THREAD_UUID> <message>"
                thread_id, message_body = parts[1], parts[2]
                try:
                    thread = ChatThread.objects.get(uuid=thread_id)
                except ChatThread.DoesNotExist:
                    return staff_user, None, "Thread not found."
                return staff_user, (thread, message_body), None
            return staff_user, None, "Unknown command. Send /help"

        staff, payload, error = await asyncio.to_thread(_resolve_staff_and_command)
        if not staff:
            return
        if error:
            await message.answer(error)
            return
        if payload:
            t, body = payload

            def _send():
                return svc_send_message(
                    t, sender_user=staff, sender_type=SenderType.STAFF, text=body
                )

            await asyncio.to_thread(_send)
            await message.answer("Sent.")

    return router


async def setup_webhook(webhook_base_url: str) -> None:
    bot = _get_bot()
    if not bot:
        return
    url = webhook_base_url.rstrip("/") + "/telegram/webhook/" + settings.TELEGRAM_TOKEN
    with suppress(Exception):
        await bot.delete_webhook(drop_pending_updates=True)
    await bot.set_webhook(url=url, drop_pending_updates=True)
    logger.info("Telegram webhook set to %s", url)


async def forward_thread_message_to_assigned_staff(thread_uuid: str, text: str) -> None:
    """Forward a thread message to assigned staff via Telegram if possible.

    This is a best-effort; failures are logged and never raised.
    """
    if not is_telegram_enabled():
        return

    def _resolve_chat_and_chat_id() -> tuple[int | None, str | None]:
        try:
            t = ChatThread.objects.select_related("assigned_to").get(uuid=thread_uuid)
        except ChatThread.DoesNotExist:
            return None, None
        staff = t.assigned_to
        if not staff:
            return None, None
        attrs = staff.attributes or {}
        chat_telegram_id = attrs.get("telegram_id") if isinstance(attrs, dict) else None
        return int(chat_telegram_id) if chat_telegram_id else None, str(t.uuid)

    chat_id, _tid = await asyncio.to_thread(_resolve_chat_and_chat_id)
    if not chat_id:
        return
    bot = _get_bot()
    if not bot:
        return
    try:
        await bot.send_message(chat_id=chat_id, text=text)
    except Exception as exc:  # noqa: BLE001
        logger.warning(
            "Failed to forward Telegram message for thread %s: %s", _tid, exc
        )


def install_aiohttp_webhook(app) -> None:
    if not is_telegram_enabled():
        logger.warning("Telegram forwarder not installed: disabled")
        return
    dp = Dispatcher()
    router = build_router()
    if router:
        dp.include_router(router)
    bot = _get_bot()
    if not bot:
        return
    SimpleRequestHandler(dispatcher=dp, bot=bot).register(
        app, path="/telegram/webhook/" + settings.TELEGRAM_TOKEN
    )
    logger.info("Telegram webhook handler installed on aiohttp app.")