"""Telegram notification client — sends messages via Bot API."""
from __future__ import annotations

import os
import time
from typing import Optional

from loguru import logger

TELEGRAM_API_URL = "https://api.telegram.org/bot{token}/sendMessage"
MAX_TEXT_LENGTH = 4096  # Telegram message limit
_RETRY_DELAYS = (5, 10)  # seconds between retries (2 retries = 3 total attempts)


class TelegramClient:
    def __init__(
        self,
        bot_token: Optional[str] = None,
        chat_id: Optional[str] = None,
    ):
        self.bot_token = bot_token or os.environ.get("TELEGRAM_BOT_TOKEN", "")
        raw_ids = chat_id or os.environ.get("TELEGRAM_CHAT_ID", "")
        # Support comma-separated multiple chat IDs: "123456789,987654321"
        self.chat_ids: list[str] = [cid.strip() for cid in raw_ids.split(",") if cid.strip()]

    def is_configured(self) -> bool:
        return bool(self.bot_token and self.chat_ids)

    def send_message(self, text: str) -> bool:
        """Send a message to all configured chats. Returns True if all succeeded."""
        if not self.is_configured():
            logger.warning("Telegram not configured (missing BOT_TOKEN or CHAT_ID)")
            return False

        if len(text) > MAX_TEXT_LENGTH:
            text = text[: MAX_TEXT_LENGTH - 20] + "\n\n[...truncated]"

        import httpx
        all_ok = True
        for chat_id in self.chat_ids:
            ok = self._send_to(httpx, chat_id, text)
            if not ok:
                all_ok = False
        return all_ok

    def _send_to(self, httpx, chat_id: str, text: str) -> bool:
        """Send to a single chat ID with retry. Returns True on success."""
        for attempt, delay in enumerate([0] + list(_RETRY_DELAYS), start=1):
            if delay:
                logger.debug(f"Telegram retry {attempt} for {chat_id} in {delay}s...")
                time.sleep(delay)
            try:
                response = httpx.post(
                    TELEGRAM_API_URL.format(token=self.bot_token),
                    json={
                        "chat_id": chat_id,
                        "text": text,
                        "parse_mode": "HTML",
                    },
                    timeout=30.0,
                )
                if response.status_code == 200 and response.json().get("ok"):
                    logger.info(f"Telegram message sent to {chat_id}")
                    return True
                else:
                    logger.error(f"Telegram API error for {chat_id}: {response.text[:200]}")
                    return False  # API errors won't be fixed by retrying
            except Exception as e:
                logger.warning(f"Telegram send attempt {attempt} to {chat_id} failed: {e}")

        logger.error(f"Telegram send to {chat_id} failed after all retries")
        return False