"""Building geometry derived purely from an EpcPropertyData.

Reusable outside the SAP calculator (e.g. for Modelling cost quantities).
Today this re-derives the heat-loss wall area; the calculator computes the
same quantity inline (`heat_transmission._part_geometry`). A later, calculator-
branch-coordinated refactor should DRY the two onto this module so there is a
single source of truth. See the project memory on calculator geometry.
"""

from datatypes.epc.domain.epc_property_data import (
    BuildingPartIdentifier,
    EpcPropertyData,
)


def gross_heat_loss_wall_area(
    epc: EpcPropertyData, identifier: BuildingPartIdentifier
) -> float:
    """Gross external wall area of one building part, in m^2: the sum over its
    storeys of heat-loss perimeter x room height. This is the heat-loss area
    (party walls are excluded — they are not on the heat-loss perimeter); it is
    not netted of window/door openings.
    """
    part = next(
        candidate
        for candidate in epc.sap_building_parts
        if candidate.identifier is identifier
    )
    area = sum(
        fd.heat_loss_perimeter_m * fd.room_height_m
        for fd in part.sap_floor_dimensions
    )
    return round(area, 2)


def roof_area(epc: EpcPropertyData, identifier: BuildingPartIdentifier) -> float:
    """Roof area of one building part, in m^2. Per RdSAP10 §3.8 the roof area is
    the greatest of the part's per-storey floor areas (not the top-floor area,
    which can be smaller)."""
    part = next(
        candidate
        for candidate in epc.sap_building_parts
        if candidate.identifier is identifier
    )
    return round(
        max(fd.total_floor_area_m2 for fd in part.sap_floor_dimensions), 2
    )


def ground_floor_area(
    epc: EpcPropertyData, identifier: BuildingPartIdentifier
) -> float:
    """Ground-floor area of one building part, in m^2 — the area of its lowest
    floor (``floor == 0``), the surface a ground-floor insulation measure
    treats."""
    part = next(
        candidate
        for candidate in epc.sap_building_parts
        if candidate.identifier is identifier
    )
    ground = next(fd for fd in part.sap_floor_dimensions if fd.floor == 0)
    return round(ground.total_floor_area_m2, 2)