from datetime import datetime
from sqlalchemy import String, ForeignKey, DateTime, func
from sqlalchemy.orm import Mapped, mapped_column, relationship
from app.database import Base


class Category(Base):
    __tablename__ = "categories"

    id: Mapped[int] = mapped_column(primary_key=True)
    user_id: Mapped[int | None] = mapped_column(ForeignKey("users.id"), nullable=True, index=True)
    name: Mapped[str] = mapped_column(String(200), nullable=False)
    type: Mapped[str] = mapped_column(String(20), nullable=False)   # income | expense | transfer
    parent_id: Mapped[int | None] = mapped_column(ForeignKey("categories.id"), nullable=True)
    icon: Mapped[str | None] = mapped_column(String(50))
    color: Mapped[str | None] = mapped_column(String(7))
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())

    user: Mapped["User | None"] = relationship("User", back_populates="categories")
    parent: Mapped["Category | None"] = relationship(
        "Category", remote_side="Category.id", back_populates="children"
    )
    children: Mapped[list["Category"]] = relationship("Category", back_populates="parent")
    operations: Mapped[list] = relationship("Operation", back_populates="category")
    budgets: Mapped[list] = relationship("Budget", back_populates="category")
    calendar_events: Mapped[list] = relationship("CalendarEvent", back_populates="category")