/**
 * Break-bulk (PER_ITEM) bulk bookings overload `cargoTotalWeightVgm` with the
 * ITEM COUNT; their real tonnage lives in `bulkTotalWeightTons`. Container
 * bookings never store a total at all — `cargoTotalWeightVgm` stays 0 and the
 * weight lives per line (`quantity × vgmPerUnitTons`). Every other booking
 * stores tons in `cargoTotalWeightVgm` directly. Rendering the raw VGM column
 * showed a 20-item / 100T booking as "20 tons" and every container booking as
 * "0 tons".
 */
export function cargoTonsAndItems(booking: {
  freightType?: string | null;
  cargoTotalWeightVgm?: number | string | null;
  bulkTotalWeightTons?: number | string | null;
  bookingContainers?: Array<{
    quantity?: number | string | null;
    vgmPerUnitTons?: number | string | null;
  }> | null;
}): { tons: number; items: number | null } {
  const bulkTons = Number(booking.bulkTotalWeightTons ?? 0);
  const vgm = Number(booking.cargoTotalWeightVgm ?? 0);
  if (booking.freightType === "BULK" && bulkTons > 0) {
    return { tons: bulkTons, items: vgm > 0 ? vgm : null };
  }
  if (vgm <= 0 && booking.bookingContainers?.length) {
    const lineTons = booking.bookingContainers.reduce(
      (sum, c) => sum + Number(c.quantity ?? 0) * Number(c.vgmPerUnitTons ?? 0),
      0,
    );
    return { tons: Math.round(lineTons * 1000) / 1000, items: null };
  }
  return { tons: vgm, items: null };
}