# models/database/cart.py
"""Cart item database model."""
from datetime import datetime
from sqlalchemy import Column, Float, ForeignKey, Index, Integer, String, UniqueConstraint
from sqlalchemy.orm import relationship

from app.core.database import Base
from models.database.base import TimestampMixin


class CartItem(Base, TimestampMixin):
    """
    Shopping cart items.

    Stores cart items per session, vendor, and product.
    Sessions are identified by a session_id string (from browser cookies).
    """
    __tablename__ = "cart_items"

    id = Column(Integer, primary_key=True, index=True)
    vendor_id = Column(Integer, ForeignKey("vendors.id"), nullable=False)
    product_id = Column(Integer, ForeignKey("products.id"), nullable=False)
    session_id = Column(String(255), nullable=False, index=True)

    # Cart details
    quantity = Column(Integer, nullable=False, default=1)
    price_at_add = Column(Float, nullable=False)  # Store price when added to cart

    # Relationships
    vendor = relationship("Vendor")
    product = relationship("Product")

    # Constraints
    __table_args__ = (
        UniqueConstraint("vendor_id", "session_id", "product_id", name="uq_cart_item"),
        Index("idx_cart_session", "vendor_id", "session_id"),
        Index("idx_cart_created", "created_at"),  # For cleanup of old carts
    )

    def __repr__(self):
        return f"<CartItem(id={self.id}, session='{self.session_id}', product_id={self.product_id}, qty={self.quantity})>"

    @property
    def line_total(self) -> float:
        """Calculate line total."""
        return self.price_at_add * self.quantity