Source code for ferrosoft.apps.emiflow.services.vehicle

#  Copyright (c) 2025 Ferrosoft GmbH. All rights reserved.
"""Heuristic mapping from freight weight to a likely :class:`VehicleType`.

Used during bulk import when the source data does not specify the
vehicle type explicitly. The thresholds are hard-coded approximations
and will likely become tenant-configurable.
"""
from decimal import Decimal

from ferrosoft.apps.emiflow.models import VehicleType
from ferrosoft.apps.ferrobase.models.decimal import DecimalWithUnit




def detect_vehicle_type(
    weight: DecimalWithUnit,
) -> VehicleType:
    """Guess the vehicle type that would typically carry ``weight``.

    Returns :class:`~VehicleType.ROAD` for less than 30 t,
    :class:`~VehicleType.RAIL` for 30..60 t, and
    :class:`~VehicleType.INLAND_SHIPPING` above. Kilogram input is
    converted to metric tons before comparison.
    """
    if weight.unit.symbol == "kg":
        weight = (weight / Decimal(1000)).with_unit("t")

    # These values are just assumptions and likely need to be made configurable.
    if weight < Decimal(30):
        return VehicleType.ROAD
    elif weight < Decimal(60):
        return VehicleType.RAIL
    else:
        return VehicleType.INLAND_SHIPPING