"""Nexus — Python Self-Monitor Background Task
Every 30 seconds: check Redis, MySQL, WebSocket connections.
If critical service fails → send Telegram system alert.
If service recovers → send Telegram recovery notification.
"""

import asyncio
import logging
import time

from sqlalchemy import text

from server.infrastructure.database.session import AsyncSessionLocal
from server.infrastructure.redis.client import get_redis
from server.infrastructure.telegram import send_telegram_system_alert
from server.api.websocket import manager as ws_manager
from server.config import settings

logger = logging.getLogger("nexus.self_monitor")

MONITOR_INTERVAL = 30  # seconds
_TELEGRAM_COOLDOWN = 300  # 5 minutes — same alert won't re-push Telegram

# Track previous state for recovery detection
_prev_redis_ok = True
_prev_mysql_ok = True
# Track last Telegram push time per alert key (prevent spam)
_last_telegram_time: dict = {}


async def self_monitor_loop():
    """Background task: every 30s, self-check critical services.

    Checks:
    1. Redis connection — if lost, send Telegram warning; if recovered, send recovery
    2. MySQL connection — if lost, send Telegram warning; if recovered, send recovery
    3. WebSocket client count (via ConnectionManager)
    """
    global _prev_redis_ok, _prev_mysql_ok

    def _should_send(key: str) -> bool:
        """Rate-limit Telegram pushes to 1 per 5 minutes per alert key."""
        now = time.monotonic()
        last = _last_telegram_time.get(key, 0)
        if now - last < _TELEGRAM_COOLDOWN:
            return False
        _last_telegram_time[key] = now
        return True

    logger.info("Self-monitor loop started (interval: 30s)")
    while True:
        await asyncio.sleep(MONITOR_INTERVAL)

        # ── Redis check ──
        redis_ok = True
        try:
            redis = get_redis()
            await redis.ping()
        except Exception:
            redis_ok = False
            logger.warning("Redis health check failed", exc_info=True)
            try:
                if settings.REDIS_URL and _should_send("NOTIFY_SYSTEM_REDIS"):
                    await send_telegram_system_alert("⚠️ Redis连接丢失，心跳数据可能中断", notify_key="NOTIFY_SYSTEM_REDIS")
            except Exception:
                logger.error("Failed to send Redis alert via Telegram")

        # Redis recovery notification
        if redis_ok and not _prev_redis_ok:
            try:
                await send_telegram_system_alert("🟢 Redis连接已恢复正常", notify_key="NOTIFY_SYSTEM_REDIS")
                _last_telegram_time.pop("NOTIFY_SYSTEM_REDIS", None)  # clear cooldown
            except Exception:
                logger.error("Failed to send Redis recovery via Telegram")
            logger.info("Redis connection recovered")
        _prev_redis_ok = redis_ok

        # ── MySQL check ──
        mysql_ok = True
        try:
            async with AsyncSessionLocal() as session:
                await session.execute(text("SELECT 1"))
        except Exception:
            mysql_ok = False
            logger.warning("MySQL health check failed", exc_info=True)
            try:
                if _should_send("NOTIFY_SYSTEM_MYSQL"):
                    await send_telegram_system_alert("🔴 MySQL 连接异常，请检查数据库服务", notify_key="NOTIFY_SYSTEM_MYSQL")
            except Exception:
                logger.error("Failed to send MySQL alert via Telegram", exc_info=True)

        # MySQL recovery notification
        if mysql_ok and not _prev_mysql_ok:
            try:
                await send_telegram_system_alert("🟢 MySQL连接已恢复正常", notify_key="NOTIFY_SYSTEM_MYSQL")
                _last_telegram_time.pop("NOTIFY_SYSTEM_MYSQL", None)  # clear cooldown
            except Exception:
                logger.error("Failed to send MySQL recovery via Telegram")
            logger.info("MySQL connection recovered")
        _prev_mysql_ok = mysql_ok

        # ── Log status ──
        logger.debug(
            f"Self-monitor: redis={'ok' if redis_ok else 'error'}, "
            f"mysql={'ok' if mysql_ok else 'error'}, "
            f"ws_clients={ws_manager.client_count}"
        )