Model/tests/domain/epc/test_water_heating_overlay.py

"""The Landlord-Override water-heating → heating Simulation Overlay mapping.

A water-heating value resolves to the SAP `water_heating_code` (system) and
`water_heating_fuel` the calculator reads; the overlay is whole-dwelling.
"""

from __future__ import annotations

import pytest

from domain.epc.property_overlays.water_heating_overlay import (
    water_heating_overlay_for,
)
from domain.epc.property_overrides.water_heating_type import WaterHeatingType
from domain.modelling.scoring.overlay_applicator import apply_simulations
from tests.domain.sap10_calculator.worksheet._elmhurst_worksheet_000490 import (
    build_epc,
)


def test_from_main_system_mains_gas_overlays_water_heating() -> None:
    # Act
    simulation = water_heating_overlay_for("From main system, mains gas", 0)

    # Assert — "from main system" is water_heating_code 901, mains gas fuel 26.
    assert simulation is not None
    assert simulation.heating is not None
    assert simulation.heating.water_heating_code == 901
    assert simulation.heating.water_heating_fuel == 26


@pytest.mark.parametrize(
    ("water_heating_value", "code", "fuel"),
    [
        ("From main system, electricity", 901, 29),
        ("Electric immersion, electricity", 903, 29),
    ],
)
def test_water_heating_systems_decode_to_their_codes(
    water_heating_value: str, code: int, fuel: int
) -> None:
    # Act
    simulation = water_heating_overlay_for(water_heating_value, 0)

    # Assert
    assert simulation is not None
    assert simulation.heating is not None
    assert simulation.heating.water_heating_code == code
    assert simulation.heating.water_heating_fuel == fuel


@pytest.mark.parametrize(
    ("water_heating_value", "code", "fuel"),
    [
        ("From main system, oil", 901, 28),
        ("From main system, LPG (bulk)", 901, 27),
        ("From main system, bottled LPG", 901, 3),
        ("From main system, house coal", 901, 33),
        # "boiler/circulator for water heating only" is SAP Table 4a code 911.
        ("Gas boiler/circulator, mains gas", 911, 26),
    ],
)
def test_more_water_heating_combos_decode_to_their_codes(
    water_heating_value: str, code: int, fuel: int
) -> None:
    # Act
    simulation = water_heating_overlay_for(water_heating_value, 0)

    # Assert
    assert simulation is not None
    assert simulation.heating is not None
    assert simulation.heating.water_heating_code == code
    assert simulation.heating.water_heating_fuel == fuel


def test_from_main_wood_logs_decodes_to_the_wood_fuel_not_house_coal() -> None:
    # Act
    simulation = water_heating_overlay_for("From main system, wood logs", 0)

    # Assert — wood logs is RdSAP water_heating_fuel 6, from main system (901).
    # A wood-fired dwelling's DHW must not fall to house coal (33), which scores
    # ~14x the carbon (ADR-0043).
    assert simulation is not None
    assert simulation.heating is not None
    assert simulation.heating.water_heating_code == 901
    assert simulation.heating.water_heating_fuel == 6


@pytest.mark.parametrize(
    ("water_heating_value", "fuel"),
    [
        # Biomass (community) — RdSAP fuel 31. Under a coherent community main
        # the calculator scores DHW from the main, so this is a faithful,
        # score-neutral relabel off house coal; the fuel is still emitted so an
        # individual-main dwelling would score biomass, not coal (ADR-0043).
        ("From main system, biomass (community)", 31),
        # Dual fuel (mineral + wood) — RdSAP fuel 9.
        ("From main system, dual fuel (mineral and wood)", 9),
        # Biodiesel (community) — RdSAP fuel 34.
        ("From main system, biodiesel (community)", 34),
    ],
)
def test_biomass_family_water_heating_decodes_off_house_coal(
    water_heating_value: str, fuel: int
) -> None:
    # Act
    simulation = water_heating_overlay_for(water_heating_value, 0)

    # Assert — from main system (901), each to its own RdSAP fuel, not coal 33.
    assert simulation is not None
    assert simulation.heating is not None
    assert simulation.heating.water_heating_code == 901
    assert simulation.heating.water_heating_fuel == fuel


@pytest.mark.parametrize("water_heating_value", ["Unknown", ""])
def test_unresolvable_water_heating_produces_no_overlay(
    water_heating_value: str,
) -> None:
    # Act
    simulation = water_heating_overlay_for(water_heating_value, 0)

    # Assert
    assert simulation is None


def test_water_heating_override_remaps_the_hot_water_arrangement() -> None:
    # Arrange — landlord correction: HW is a separate electric immersion.
    baseline = build_epc()
    overlay = water_heating_overlay_for("Electric immersion, electricity", 0)
    assert overlay is not None

    # Act
    result = apply_simulations(baseline, [overlay])

    # Assert — the calculator reads these off sap_heating.
    assert result.sap_heating.water_heating_code == 903
    assert result.sap_heating.water_heating_fuel == 29


@pytest.mark.parametrize(
    "member", [m for m in WaterHeatingType if m is not WaterHeatingType.UNKNOWN]
)
def test_every_resolvable_water_heating_value_decodes(
    member: WaterHeatingType,
) -> None:
    # Act
    simulation = water_heating_overlay_for(member.value, 0)

    # Assert
    assert simulation is not None