"""add unique constraint on images(car_id, fullres_image)

Revision ID: 005
Revises: 004_widen_string_columns
Create Date: 2026-04-16
"""
from alembic import op

revision = "005_unique_images_constraint"
down_revision = "004_widen_string_columns"
branch_labels = None
depends_on = None


def upgrade() -> None:
    # Удаляем дубли через CTE + ROW_NUMBER (быстрее чем NOT IN subquery)
    op.execute("""
        WITH dupes AS (
            SELECT id,
                   ROW_NUMBER() OVER (PARTITION BY car_id, fullres_image ORDER BY id) AS rn
            FROM images
        )
        DELETE FROM images WHERE id IN (SELECT id FROM dupes WHERE rn > 1)
    """)
    op.create_unique_constraint(
        "uq_images_car_id_fullres",
        "images",
        ["car_id", "fullres_image"],
    )


def downgrade() -> None:
    op.drop_constraint("uq_images_car_id_fullres", "images", type_="unique")