"""The lighting Recommendation Generator (LED upgrade).

Detects a dwelling's non-LED fixed-lighting bulbs and emits one "Lighting"
Recommendation whose single Option converts **every** bulb to LED (ADR-0023).
SAP 10.2 RdSAP §12-1 rates lamp efficacy LED > low-energy-unknown > CFL >
incandescent, so converting every non-LED type — incandescent, CFL, and the
"low energy, type unknown" (LEL) bulbs alike — strictly improves the Appendix L
lighting energy (worksheet line (232)).

Unlike the fabric generators this is a **whole-dwelling** Measure: its overlay
writes the four top-level bulb counts directly (`led = total`, the rest 0). It
is a free Optimiser candidate — an LED upgrade improves SAP at low cost, so the
Optimiser keeps or leaves it for least-cost-to-target (contrast ventilation's
forced dependency). Detection + pricing only; impact is produced later by
scoring (ADR-0016).
"""

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, LightingOverlay
from repositories.product.product_repository import ProductRepository

_LIGHTING_MEASURE_TYPE: Final[MeasureType] = MeasureType.LOW_ENERGY_LIGHTING


def recommend_lighting(
    epc: EpcPropertyData, products: ProductRepository
) -> Optional[Recommendation]:
    """Return a lighting Recommendation upgrading every non-LED bulb to LED — its
    single Option — else None when the dwelling has no non-LED bulbs (already
    all-LED, or no bulb counts lodged)."""
    led: int = epc.led_fixed_lighting_bulbs_count or 0
    cfl: int = epc.cfl_fixed_lighting_bulbs_count or 0
    incandescent: int = epc.incandescent_fixed_lighting_bulbs_count or 0
    low_energy: int = epc.low_energy_fixed_lighting_bulbs_count or 0

    non_led: int = cfl + incandescent + low_energy
    if non_led == 0:
        return None

    product = products.get(_LIGHTING_MEASURE_TYPE)
    overlay = EpcSimulation(
        lighting=LightingOverlay(
            led_fixed_lighting_bulbs_count=led + non_led,
            cfl_fixed_lighting_bulbs_count=0,
            incandescent_fixed_lighting_bulbs_count=0,
            low_energy_fixed_lighting_bulbs_count=0,
        )
    )
    cost = Cost(
        total=non_led * product.unit_cost_per_m2,
        contingency_rate=product.contingency_rate,
    )
    option = MeasureOption(
        measure_type=_LIGHTING_MEASURE_TYPE,
        description="Replace all non-LED bulbs with LED",
        overlay=overlay,
        cost=cost,
        material_id=product.id,
    )
    return Recommendation(surface="Lighting", options=(option,))