import enum
from datetime import datetime
from sqlalchemy import BigInteger, Boolean, Column, DateTime, Enum, Integer, String
from .device import Base


PRIMARY_KEY_TYPE = BigInteger().with_variant(Integer, "sqlite")


class AlertTypeEnum(str, enum.Enum):
    offline = "offline"           # 设备离线
    degraded = "degraded"         # 设备丢包故障
    recovered = "recovered"       # 设备恢复
    system = "system"             # 系统告警（如上游断网检测）


class AlertEvent(Base):
    """告警事件表"""
    __tablename__ = "alert_events"

    id = Column(PRIMARY_KEY_TYPE, primary_key=True, autoincrement=True)
    device_id = Column(Integer, nullable=False, index=True, comment="关联设备 ID")
    alert_type = Column(Enum(AlertTypeEnum), nullable=False, comment="告警类型")
    message = Column(String(1024), default="", comment="告警消息摘要")

    # 离线起止
    start_at = Column(DateTime, nullable=False, comment="离线开始时间")
    end_at = Column(DateTime, nullable=True, comment="恢复时间")
    duration_minutes = Column(Integer, nullable=True, comment="离线时长（分钟）")

    is_resolved = Column(Boolean, default=False, comment="是否已恢复")
    notification_sent = Column(Boolean, default=False, comment="是否已发送通知")
    notification_attempts = Column(Integer, default=0, comment="通知尝试次数")
    last_notification_error = Column(
        String(512),
        nullable=True,
        comment="最近一次通知失败原因",
    )
    related_event_id = Column(
        BigInteger,
        nullable=True,
        comment="关联的原始或升级告警事件 ID",
    )
    previous_status = Column(String(16), nullable=True, comment="状态变更前状态")
    current_status = Column(String(16), nullable=True, comment="状态变更后状态")
    acknowledged_at = Column(DateTime, nullable=True, comment="用户确认时间")

    created_at = Column(DateTime, default=datetime.now, comment="创建时间")

    def __repr__(self):
        return f"<AlertEvent(id={self.id}, device={self.device_id}, type={self.alert_type})>"