"""
设备服务
管理边缘设备状态
"""
from datetime import datetime, timezone, timedelta
from typing import Dict, Any, List, Optional

from app.models import EdgeDevice, DeviceStatus, get_session
from app.utils.logger import logger


class DeviceService:
    """设备服务"""

    # 设备离线超时时间（秒）
    OFFLINE_TIMEOUT = 90

    def __init__(self):
        self._devices: Dict[str, Dict[str, Any]] = {}  # 内存缓存

    def handle_heartbeat(self, heartbeat_data: Dict[str, Any]) -> Optional[EdgeDevice]:
        """处理心跳消息"""
        device_id = heartbeat_data.get("device_id")
        if not device_id:
            logger.warning("心跳消息缺少 device_id")
            return None

        status_info = heartbeat_data.get("status", {})

        db = get_session()
        try:
            # 查找或创建设备
            device = db.query(EdgeDevice).filter(
                EdgeDevice.device_id == device_id
            ).first()

            now = datetime.now(timezone.utc)

            if device is None:
                # 新设备
                device = EdgeDevice(
                    device_id=device_id,
                    device_name=f"边缘设备_{device_id[:8]}",
                    status=DeviceStatus.ONLINE,
                    last_heartbeat=now,
                )
                db.add(device)
                logger.info(f"发现新设备: {device_id}")
            else:
                # 更新状态
                old_status = device.status
                device.status = DeviceStatus.ONLINE
                device.last_heartbeat = now

                if old_status != DeviceStatus.ONLINE:
                    logger.info(f"设备上线: {device_id}")

            # 更新运行信息
            if status_info:
                device.uptime_seconds = status_info.get("uptime_seconds")
                device.frames_processed = status_info.get("frames_processed")
                device.alerts_generated = status_info.get("alerts_generated")
                device.extra_info = status_info.get("stream_stats")

            device.updated_at = now

            db.commit()
            db.refresh(device)

            # 更新内存缓存
            self._devices[device_id] = device.to_dict()

            return device

        except Exception as e:
            db.rollback()
            logger.error(f"处理心跳失败: {e}")
            return None
        finally:
            db.close()

    def check_offline_devices(self) -> List[EdgeDevice]:
        """检查离线设备"""
        db = get_session()
        try:
            threshold = datetime.now(timezone.utc) - timedelta(seconds=self.OFFLINE_TIMEOUT)

            # 查找需要标记为离线的设备
            devices = db.query(EdgeDevice).filter(
                EdgeDevice.status == DeviceStatus.ONLINE,
                EdgeDevice.last_heartbeat < threshold
            ).all()

            offline_devices = []
            for device in devices:
                device.status = DeviceStatus.OFFLINE
                device.updated_at = datetime.now(timezone.utc)
                offline_devices.append(device)
                logger.info(f"设备离线: {device.device_id}")

            if offline_devices:
                db.commit()

            return offline_devices

        except Exception as e:
            db.rollback()
            logger.error(f"检查离线设备失败: {e}")
            return []
        finally:
            db.close()

    def get_device(self, device_id: str) -> Optional[EdgeDevice]:
        """获取设备信息"""
        db = get_session()
        try:
            return db.query(EdgeDevice).filter(
                EdgeDevice.device_id == device_id
            ).first()
        finally:
            db.close()

    def get_devices(
        self,
        status: Optional[str] = None,
        page: int = 1,
        page_size: int = 20
    ) -> tuple[List[EdgeDevice], int]:
        """获取设备列表"""
        db = get_session()
        try:
            query = db.query(EdgeDevice)

            if status:
                query = query.filter(EdgeDevice.status == status)

            total = query.count()
            devices = (
                query.order_by(EdgeDevice.last_heartbeat.desc())
                .offset((page - 1) * page_size)
                .limit(page_size)
                .all()
            )

            return devices, total
        finally:
            db.close()

    def get_statistics(self) -> Dict[str, Any]:
        """获取设备统计"""
        db = get_session()
        try:
            total = db.query(EdgeDevice).count()
            online = db.query(EdgeDevice).filter(
                EdgeDevice.status == DeviceStatus.ONLINE
            ).count()
            offline = db.query(EdgeDevice).filter(
                EdgeDevice.status == DeviceStatus.OFFLINE
            ).count()
            error = db.query(EdgeDevice).filter(
                EdgeDevice.status == DeviceStatus.ERROR
            ).count()

            return {
                "total": total,
                "online": online,
                "offline": offline,
                "error": error,
            }
        finally:
            db.close()


# 全局单例
_device_service = None


def get_device_service() -> DeviceService:
    """获取设备服务单例"""
    global _device_service
    if _device_service is None:
        _device_service = DeviceService()
    return _device_service