"""DocumentCategory 文档分类模型（支持树形目录结构）。"""

from sqlalchemy import Boolean, ForeignKey, Integer, String, Text
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.models.base import Base, TimestampMixin, UUIDPrimaryKeyMixin


class DocumentCategory(UUIDPrimaryKeyMixin, TimestampMixin, Base):
    """文档分类模型（树形结构）。

    通过 parent_id 实现层级关系，path 用于高效查询子树。
    is_folder=True 表示文件夹（可包含子项），False 表示叶子分类。
    """

    __tablename__ = "document_categories"

    knowledge_base_id: Mapped[str] = mapped_column(
        String(32),
        ForeignKey("knowledge_bases.id"),
        nullable=False,
        index=True,
        comment="所属知识库 ID",
    )
    parent_id: Mapped[str | None] = mapped_column(
        String(32),
        ForeignKey("document_categories.id"),
        nullable=True,
        index=True,
        comment="父分类 ID（NULL = 顶层）",
    )
    name: Mapped[str] = mapped_column(
        String(255),
        nullable=False,
        comment="分类名称",
    )
    path: Mapped[str] = mapped_column(
        String(500),
        default="/",
        nullable=False,
        comment="物化路径，如 /01_公司层/04_岗位AI角色/",
    )
    is_folder: Mapped[bool] = mapped_column(
        Boolean,
        default=True,
        nullable=False,
        comment="True=文件夹（可含子项），False=叶子分类",
    )
    sort_order: Mapped[int] = mapped_column(
        Integer,
        default=0,
        nullable=False,
        comment="排序序号",
    )
    deleted_at: Mapped[str | None] = mapped_column(
        String(32),
        nullable=True,
        index=True,
        comment="进入回收站时间（NULL=未删除），3 天后自动清理",
    )

    # 关系
    knowledge_base = relationship("KnowledgeBase", back_populates="categories", lazy="selectin")
    parent = relationship("DocumentCategory", remote_side="DocumentCategory.id", lazy="selectin")
    children = relationship("DocumentCategory", back_populates="parent", lazy="selectin")
    documents = relationship("Document", back_populates="category", lazy="selectin")

    def __repr__(self) -> str:
        return f"<DocumentCategory {self.name!r} path={self.path!r}>"