from pydantic import Field, computed_field
from sqlalchemy import ForeignKey, String, UniqueConstraint
from sqlalchemy.orm import Mapped, mapped_column, relationship

from src.models._common import BaseModelDb, ExportBaseModel, _hash


class Category(ExportBaseModel):
    name: str = Field(pattern=r"[^:\r\n]+")
    parent: Category | None = None

    @computed_field  # type: ignore[prop-decorator]
    @property
    def hash_id(self) -> str:
        return _hash(self.name, self.parent)

    @classmethod
    def from_str(cls, s: str) -> Category | None:
        if not s:
            return None
        components = s.split(":")
        name = components[-1]
        rest = ":".join(components[:-1])
        return cls(name=name, parent=cls.from_str(rest))

    def to_str(self) -> str | None:
        if not self.parent:
            return self.name
        else:
            return f"{self.parent.to_str()}:{self.name}"

    def __str__(self):
        return self.to_str()

    def __repr__(self):
        return f'Category.from_str("{self.__str__()}")'


class CategoryDb(BaseModelDb):
    __tablename__ = "category"
    __table_args__ = (
        UniqueConstraint("name", "parent_id", name="uq_category_name_parent"),
    )

    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
    name: Mapped[str] = mapped_column(String, nullable=False)
    parent_id: Mapped[int | None] = mapped_column(
        ForeignKey("category.id"), nullable=True
    )

    # Relationships
    parent = relationship(
        "CategoryDb", remote_side="CategoryDb.id", back_populates="children"
    )
    children = relationship("CategoryDb", back_populates="parent")
    budgets = relationship("CategoryBudgetDb", back_populates="category")