from pathlib import Path
import sys

from sqlalchemy import text

ROOT = Path(__file__).resolve().parents[1]
sys.path.insert(0, str(ROOT))

from app.database import engine  # noqa: E402


FIELDS = [
    ("product_net_weight_kg", "DECIMAL(12,4) NULL", "material_name"),
    ("product_gross_weight_kg", "DECIMAL(12,4) NULL", "product_net_weight_kg"),
    ("scrap_loss_rate", "DECIMAL(10,6) NULL", "product_gross_weight_kg"),
    ("waste_price_yuan_per_kg", "DECIMAL(12,4) NULL", "scrap_loss_rate"),
]


def column_exists(conn, column_name: str) -> bool:
    return bool(conn.execute(text("""
        SELECT COUNT(1)
        FROM information_schema.columns
        WHERE table_schema = DATABASE()
          AND table_name = 'products'
          AND column_name = :column_name
    """), {"column_name": column_name}).scalar())


def main() -> None:
    with engine.begin() as conn:
        for column_name, column_type, after_column in FIELDS:
            if not column_exists(conn, column_name):
                conn.execute(text(
                    f"ALTER TABLE products ADD COLUMN {column_name} {column_type} AFTER {after_column}"
                ))
    print("product ERP auxiliary fields migrated")


if __name__ == "__main__":
    main()