import asyncio
import threading
import logging
import time
from telegram import Bot
from telegram.constants import ParseMode
from decouple import config
import re

logger = logging.getLogger(__name__)
telegram_loop = None

BOT_TOKEN = config("TG_BOT_TOKEN", default="killme", cast=str)
CHAT_ID = config("TG_CHAT_ID", default="drake", cast=str)
# Optional forum topic to post into. If empty, messages go to the group's General topic.
TOPIC_ID = config("TG_TOPIC_ID", default="", cast=str)

if not BOT_TOKEN or not isinstance(BOT_TOKEN, str):
    raise ValueError(
        "TG_BOT_TOKEN environment variable must be set and must be a string."
    )
if not CHAT_ID:
    raise ValueError(
        "TG_CHAT_ID environment variable must be set and must be a string."
    )

bot = Bot(token=BOT_TOKEN)


def telegram_worker():
    """
    Run the event loop for Telegram in a separate daemon thread.
    """
    global telegram_loop
    telegram_loop = asyncio.new_event_loop()
    asyncio.set_event_loop(telegram_loop)
    try:
        logger.info("Telegram loop started.")
        telegram_loop.run_forever()
    except Exception as e:
        logger.exception(f"Telegram worker crashed! {e}", exc_info=True)
    finally:
        telegram_loop.close()


# Start the Telegram worker thread when the module is loaded
telegram_thread = threading.Thread(target=telegram_worker, daemon=True)
telegram_thread.start()

# Wait until telegram_loop is ready
timeout = 5
for _ in range(timeout * 10):  # up to 5 seconds
    if telegram_loop is not None:
        break
    time.sleep(0.1)
else:
    logger.error("Telegram loop failed to initialize in time.")


async def send_telegram_alert(markdown_message: str):
    logger.info("[TELEGRAM] Preparing to send alert...")
    kwargs = {}
    if TOPIC_ID:
        kwargs["message_thread_id"] = int(TOPIC_ID)
    await bot.send_message(
        chat_id=str(CHAT_ID),
        text=markdown_message,
        parse_mode=ParseMode.MARKDOWN_V2,
        **kwargs,
    )


async def send_telegram_photo(photo, markdown_caption: str):
    """Send a photo. `photo` may be raw bytes / a file-like object (uploaded
    directly to Telegram) or a public URL string."""
    logger.info("[TELEGRAM] Preparing to send photo...")
    kwargs = {}
    if TOPIC_ID:
        kwargs["message_thread_id"] = int(TOPIC_ID)
    await bot.send_photo(
        chat_id=str(CHAT_ID),
        photo=photo,
        caption=markdown_caption,
        parse_mode=ParseMode.MARKDOWN_V2,
        # Uploading media is slower than a text send; the defaults (5s) time out.
        connect_timeout=15,
        read_timeout=30,
        write_timeout=60,
        **kwargs,
    )


def escape_markdown_v2(text: str) -> str:
    escape_chars = r"_~`>#+-=|{}.!\\"
    return re.sub(f"([{re.escape(escape_chars)}])", r"\\\1", text)