"""End-to-end regression for the Off-Peak Meter day/night bill split (ADR-0014
2026-06-24 amendment).

Drives a real off-peak (Economy-7) storage-heating cert through the whole chain
— `cert_to_inputs` → `calculate_sap_from_inputs` → `EnergyBreakdown.from_sap_result`
→ `BillDerivation.derive` against the committed Fuel Rates snapshot. Before the
amendment this raised `UnpricedFuel` ("no rate for fuel ELECTRICITY_OFF_PEAK"),
which aborted the `modelling_e2e` batch (e.g. property 717572). It must now price
the dwelling day/night instead of crashing.
"""

from __future__ import annotations

from dataclasses import replace

from domain.sap10_ml.tests._fixtures import (
    make_building_part,
    make_minimal_sap10_epc,
    make_sap_heating,
)
from datatypes.epc.domain.epc_property_data import EpcPropertyData, MainHeatingDetail
from domain.sap10_calculator.calculator import calculate_sap_from_inputs
from domain.sap10_calculator.rdsap.cert_to_inputs import cert_to_inputs
from domain.fuel_rates.fuel import Fuel
from domain.billing.bill import BillSection, EnergyBreakdown
from domain.billing.bill_derivation import BillDerivation
from repositories.fuel_rates.fuel_rates_static_file_repository import (
    FuelRatesStaticFileRepository,
)

_TYPICAL_TFA_M2 = 60.0


def _off_peak_storage_epc() -> EpcPropertyData:
    # Integrated storage heaters (SAP code 408, Table 12a Grid 1 high-rate
    # fraction 0.20) on a Dual / Economy-7 (7-hour) meter.
    main = MainHeatingDetail(
        has_fghrs=False,
        main_fuel_type=29,  # electricity
        heat_emitter_type=1,
        emitter_temperature=1,
        main_heating_control=2401,
        main_heating_category=7,  # electric storage heaters
        sap_main_heating_code=408,
    )
    base = make_minimal_sap10_epc(
        total_floor_area_m2=_TYPICAL_TFA_M2,
        habitable_rooms_count=4,
        country_code="ENG",
        sap_building_parts=[make_building_part(construction_age_band="E")],
        sap_heating=make_sap_heating(main_heating_details=[main]),
    )
    return replace(
        base,
        sap_energy_source=replace(base.sap_energy_source, meter_type="1"),
    )


def test_off_peak_storage_dwelling_bills_heating_day_night_not_crashes() -> None:
    # Arrange — score the off-peak cert and price it at the committed snapshot.
    result = calculate_sap_from_inputs(cert_to_inputs(_off_peak_storage_epc()))
    rates = FuelRatesStaticFileRepository().get_current()

    # Act — the previously-crashing path: off-peak electricity reaches the bill.
    breakdown = EnergyBreakdown.from_sap_result(result)
    bill = BillDerivation(rates).derive(breakdown)

    # Assert — heating bills on the off-peak carrier at the 0.20-day/0.80-night
    # blend (0.20×29.73 + 0.80×13.89 = 17.058 p/kWh), not a crash and not the
    # flat standard rate (24.67 p) or pure night rate (13.89 p).
    heating = bill.sections[BillSection.HEATING]
    assert heating.kwh > 0.0
    implied_rate_p = heating.cost_gbp / heating.kwh * 100.0
    assert abs(implied_rate_p - 17.058) <= 1e-6
    # The off-peak meter contributes one standing charge (56.99 p/day).
    assert any(line.fuel is Fuel.ELECTRICITY_OFF_PEAK for line in breakdown.lines)
    assert bill.total_gbp > 0.0