"""站内通知模型（追加型，类似审计日志，不用业务表 mixin）。"""

from __future__ import annotations

from datetime import datetime, timezone

from sqlalchemy import BigInteger, CheckConstraint, Index, String, text
from sqlalchemy.dialects.mysql import DATETIME
from sqlalchemy.orm import Mapped, mapped_column

from dms.extensions import db


class Notification(db.Model):
    """用户站内通知：审批流等待处理等需用户关注的信息。

    通知只追加与状态流转（未读→已读、待处理→已同意/已拒绝），
    不做软删与乐观锁，故不使用 BusinessTableMixin。
    """

    __tablename__ = "sys_notification"
    __table_args__ = (
        CheckConstraint(
            "notify_type IN ('APPROVAL')",
            name="notification_notify_type",
        ),
        CheckConstraint(
            "action IN ('NONE', 'PENDING', 'AGREE', 'REJECT')",
            name="notification_action",
        ),
        CheckConstraint(
            "status IN ('UNREAD', 'READ')",
            name="notification_status",
        ),
        Index("ix_sys_notification_user_id", "user_id", "id"),
    )

    id: Mapped[int] = mapped_column(BigInteger, primary_key=True, autoincrement=True)
    user_id: Mapped[int] = mapped_column(BigInteger, nullable=False)
    title: Mapped[str] = mapped_column(String(200), nullable=False)
    content: Mapped[str | None] = mapped_column(String(1000), nullable=True)
    # 通知类别：APPROVAL 审批待办（后续审批流写入，预留扩展）
    notify_type: Mapped[str] = mapped_column(String(32), nullable=False)
    # 待办操作：NONE 无需操作 / PENDING 待处理 / AGREE 已同意 / REJECT 已拒绝
    action: Mapped[str] = mapped_column(String(16), nullable=False)
    status: Mapped[str] = mapped_column(String(16), nullable=False)
    created_at: Mapped[datetime] = mapped_column(
        DATETIME(fsp=3),
        nullable=False,
        # 应用侧 UTC 落库（与 sys_audit_log 同口径，序列化追加 Z）
        default=lambda: datetime.now(timezone.utc).replace(tzinfo=None),
        server_default=text("CURRENT_TIMESTAMP(3)"),
    )
    handled_at: Mapped[datetime | None] = mapped_column(DATETIME(fsp=3), nullable=True)