"""Add cart_items table for shopping cart"""

from alembic import op
import sqlalchemy as sa

# revision identifiers, used by Alembic.
revision = "0002_add_cart_items"
down_revision = "0001_initial_schema"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.create_table(
        "cart_items",
        sa.Column("id", sa.Integer(), primary_key=True, autoincrement=True),

        # Either a logged-in user *or* an anonymous session_id
        sa.Column(
            "user_id",
            sa.Integer(),
            sa.ForeignKey("users.id", ondelete="CASCADE"),
            nullable=True,
        ),
        sa.Column("session_id", sa.String(length=128), nullable=True),

        # IMPORTANT: reference products.id (PK), not slug
        sa.Column(
            "product_id",
            sa.Integer(),
            sa.ForeignKey("products.id", ondelete="CASCADE"),
            nullable=False,
        ),

        sa.Column(
            "quantity",
            sa.Integer(),
            nullable=False,
            server_default="1",
        ),
        sa.Column(
            "created_at",
            sa.DateTime(timezone=True),
            nullable=False,
            server_default=sa.text("now()"),
        ),
        sa.Column(
            "updated_at",
            sa.DateTime(timezone=True),
            nullable=False,
            server_default=sa.text("now()"),
        ),
        sa.Column(
            "deleted_at",
            sa.DateTime(timezone=True),
            nullable=True,
        ),
    )

    # Indexes to speed up cart lookups
    op.create_index(
        "ix_cart_items_user_product",
        "cart_items",
        ["user_id", "product_id"],
        unique=False,
    )
    op.create_index(
        "ix_cart_items_session_product",
        "cart_items",
        ["session_id", "product_id"],
        unique=False,
    )


def downgrade() -> None:
    op.drop_index("ix_cart_items_session_product", table_name="cart_items")
    op.drop_index("ix_cart_items_user_product", table_name="cart_items")
    op.drop_table("cart_items")
