from __future__ import annotations

from decimal import Decimal

from sqlalchemy import CheckConstraint, ForeignKey, Numeric
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.models.base import Base


class OrderItem(Base):
    __tablename__ = "order_items"
    __table_args__ = (
        CheckConstraint("quantity > 0", name="ck_order_items_quantity_positive"),
        CheckConstraint("unit_price > 0", name="ck_order_items_unit_price_positive"),
        CheckConstraint("subtotal >= 0", name="ck_order_items_subtotal_non_negative"),
    )

    id: Mapped[int] = mapped_column(primary_key=True)
    order_id: Mapped[int] = mapped_column(ForeignKey("orders.id"), nullable=False, index=True)
    product_id: Mapped[int] = mapped_column(ForeignKey("products.id"), nullable=False, index=True)
    quantity: Mapped[int] = mapped_column(nullable=False)
    unit_price: Mapped[Decimal] = mapped_column(Numeric(10, 2), nullable=False)
    subtotal: Mapped[Decimal] = mapped_column(Numeric(10, 2), nullable=False)

    order = relationship("Order", back_populates="items")
    product = relationship("Product", lazy="joined")

    @property
    def product_name(self) -> str:
        return self.product.name