Model/tests/domain/epc/test_main_heating_system_overlay.py

"""The Landlord-Override main-heating-system → heating Simulation Overlay mapping.

A main-heating-system value resolves to the SAP `sap_main_heating_code` the
calculator reads from the primary system; the overlay is whole-dwelling.
"""

from __future__ import annotations

import pytest

from domain.epc.property_overrides.main_heating_system_type import MainHeatingSystemType
from domain.epc.property_overlays.main_fuel_overlay import fuel_overlay_for
from domain.epc.property_overlays.main_heating_system_overlay import (
    main_heating_overlay_for,
)
from domain.epc.property_overlays.water_heating_overlay import (
    water_heating_overlay_for,
)
from domain.modelling.scoring.overlay_applicator import apply_simulations
from tests.domain.sap10_calculator.worksheet._elmhurst_worksheet_000490 import (
    build_epc,
)


def test_gas_combi_overlays_the_primary_heating_code() -> None:
    # Act
    simulation = main_heating_overlay_for("Gas boiler, combi", 0)

    # Assert — condensing combi is SAP Table 4b code 104.
    assert simulation is not None
    assert simulation.heating is not None
    assert simulation.heating.sap_main_heating_code == 104


@pytest.mark.parametrize(
    ("main_heating_value", "code"),
    [
        ("Gas boiler, regular", 102),
        ("Gas CPSU", 120),
        ("Electric storage heaters, fan", 404),
        ("Direct-acting electric", 191),
    ],
)
def test_heating_archetypes_decode_to_their_sap_codes(
    main_heating_value: str, code: int
) -> None:
    # Act
    simulation = main_heating_overlay_for(main_heating_value, 0)

    # Assert
    assert simulation is not None
    assert simulation.heating is not None
    assert simulation.heating.sap_main_heating_code == code


@pytest.mark.parametrize(
    ("main_heating_value", "code"),
    [
        ("Electric storage heaters, old", 401),
        ("Electric storage heaters, slimline", 402),
        ("Electric storage heaters, convector", 403),
    ],
)
def test_storage_heater_subtypes_decode_to_their_codes(
    main_heating_value: str, code: int
) -> None:
    # Act
    simulation = main_heating_overlay_for(main_heating_value, 0)

    # Assert
    assert simulation is not None
    assert simulation.heating is not None
    assert simulation.heating.sap_main_heating_code == code


@pytest.mark.parametrize(
    "main_heating_value",
    ["Unknown", "", "Air source heat pump", "Community heating"],
)
def test_unresolvable_or_unmodelled_heating_produces_no_overlay(
    main_heating_value: str,
) -> None:
    # Heat pumps (main_heating_index_number) and community heating (community
    # codes) don't map to a Table 4b sap_main_heating_code yet — no overlay.

    # Act
    simulation = main_heating_overlay_for(main_heating_value, 0)

    # Assert
    assert simulation is None


def test_main_heating_override_remaps_the_primary_system_code() -> None:
    # Arrange
    baseline = build_epc()
    overlay = main_heating_overlay_for("Gas boiler, regular", 0)
    assert overlay is not None

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

    # Assert — the calculator reads the code off main_heating_details[0].
    assert result.sap_heating.main_heating_details[0].sap_main_heating_code == 102


def test_the_three_heating_overrides_compose_without_conflict() -> None:
    # Arrange — main_fuel, water_heating and main_heating_system all fold onto one
    # HeatingOverlay surface but set DISJOINT fields, so they compose (the
    # field-disjoint design that makes precedence moot for these three).
    baseline = build_epc()
    overlays = [
        fuel_overlay_for("electricity", 0),
        water_heating_overlay_for("Electric immersion, electricity", 0),
        main_heating_overlay_for("Electric storage heaters, fan", 0),
    ]
    assert all(o is not None for o in overlays)

    # Act
    result = apply_simulations(baseline, [o for o in overlays if o is not None])

    # Assert — each override landed on its own field.
    main = result.sap_heating.main_heating_details[0]
    assert main.main_fuel_type == 29
    assert main.sap_main_heating_code == 404
    assert result.sap_heating.water_heating_code == 903
    assert result.sap_heating.water_heating_fuel == 29


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

    # Assert
    assert simulation is not None