"""
MQTT 服务 - 已废弃

告警上报已改为 HTTP + COS 方案（边缘端直传）。
此文件保留为空壳，避免其他模块 import 报错。
后续版本将彻底删除此文件。
"""

from typing import Dict, Any, Optional


class MQTTService:
    """MQTT 服务 (已废弃，保留空壳兼容旧代码)"""

    def __init__(self):
        pass

    @property
    def is_connected(self) -> bool:
        return False

    def register_alert_handler(self, handler):
        pass

    def register_heartbeat_handler(self, handler):
        pass

    def start(self):
        pass

    def stop(self):
        pass

    def get_statistics(self) -> Dict[str, Any]:
        return {
            "messages_received": 0,
            "alerts_received": 0,
            "heartbeats_received": 0,
            "errors": 0,
            "connected": False,
            "running": False,
            "deprecated": True,
        }


_mqtt_service: Optional[MQTTService] = None


def get_mqtt_service() -> MQTTService:
    """获取 MQTT 服务单例 (已废弃)"""
    global _mqtt_service
    if _mqtt_service is None:
        _mqtt_service = MQTTService()
    return _mqtt_service