"""The Secondary Heating Removal Recommendation Generator (ADR-0028).

Offers to strip a dwelling's lodged secondary heating system so the main system
serves 100% of space heating. A **standalone, co-selectable** Recommendation —
not an Option in the Heating & Hot Water rec — because removing a secondary
heater is independent of (and combinable with) a tune-up or boiler upgrade.

Eligibility is purely physical: offered **iff a secondary is lodged**
(`sap_heating.secondary_heating_type` is set). RdSAP only records a secondary
when a *fixed* emitter is present (portable plug-in heaters are ignored), so a
lodged secondary is by definition a fixed unit worth removing. There is no
effectiveness gate — on an electric-storage main RdSAP §A.2.2 forces a default
secondary back, making removal a no-op, but that is the Optimiser's call (it
owns the economics), not eligibility's. Detection + pricing only; impact is
produced later by scoring (ADR-0016).

Priced at a flat per-dwelling decommission cost (one electrician visit to
disconnect a fixed/hard-wired heater + localised making-good), not scaled by
room count — the EPC lodges one secondary system with no heater count (ADR-0028).
"""

from typing import Final, Optional

from datatypes.epc.domain.epc_property_data import EpcPropertyData
from domain.modelling.measure_type import MeasureType
from domain.modelling.recommendation import Cost, MeasureOption, Recommendation
from domain.modelling.simulation import EpcSimulation, SecondaryHeatingOverlay
from repositories.product.product_repository import ProductRepository

_SECONDARY_HEATING_REMOVAL_MEASURE_TYPE: Final[MeasureType] = (
    MeasureType.SECONDARY_HEATING_REMOVAL
)


def recommend_secondary_heating_removal(
    epc: EpcPropertyData, products: ProductRepository
) -> Optional[Recommendation]:
    """Return a Secondary Heating Removal Recommendation — its single Option
    clears the lodged secondary system — else None when no secondary is lodged
    (nothing physical to remove)."""
    if epc.sap_heating.secondary_heating_type is None:
        return None

    product = products.get(_SECONDARY_HEATING_REMOVAL_MEASURE_TYPE)
    overlay = EpcSimulation(secondary_heating=SecondaryHeatingOverlay())
    cost = Cost(
        total=product.unit_cost_per_m2,
        contingency_rate=product.contingency_rate,
    )
    option = MeasureOption(
        measure_type=_SECONDARY_HEATING_REMOVAL_MEASURE_TYPE,
        description="Remove the secondary heating system",
        overlay=overlay,
        cost=cost,
        material_id=product.id,
    )
    return Recommendation(surface="Secondary Heating", options=(option,))