"""The Simulation Overlay (`EpcSimulation`) — the change a single Measure
Option makes to a Property's EpcPropertyData.

An all-optional partial mirror of EpcPropertyData / SapBuildingPart, covering
the retrofit-relevant surface only (wall fields first). It is *not* an
EpcPropertyData — composition, not inheritance — and carries no scores.
Building parts are targeted by `BuildingPartIdentifier` so a measure addresses
the exact `SapBuildingPart` (the main wall vs an extension). See CONTEXT.md.
"""

from dataclasses import dataclass, field
from typing import Mapping, Optional

from datatypes.epc.domain.epc_property_data import BuildingPartIdentifier


@dataclass(frozen=True)
class BuildingPartOverlay:
    """All-optional partial of `SapBuildingPart` (wall surface first).

    A `None` field means "leave the baseline value unchanged".
    """

    wall_insulation_type: Optional[int] = None
    # Added solid-wall insulation depth (mm) — drives the calculator's Table 6
    # bucket / §5.8 documentary U-value for EWI (`wall_insulation_type=1`) and
    # IWI (`wall_insulation_type=3`); λ defaults to 0.04 W/m·K in the calculator.
    wall_insulation_thickness: Optional[int] = None
    roof_insulation_thickness: Optional[int] = None
    floor_insulation_thickness: Optional[int] = None
    floor_insulation_type_str: Optional[str] = None


@dataclass(frozen=True)
class VentilationOverlay:
    """All-optional partial of `SapVentilation` — the whole-dwelling ventilation
    change a Measure Option makes (e.g. retrofit MEV). Unlike a
    `BuildingPartOverlay` this targets no building part; it folds onto the
    dwelling's single `sap_ventilation`.

    `mechanical_ventilation_kind` names the SAP10.2 §2 mechanical-ventilation
    kind (the `MechanicalVentilationKind` enum name, e.g.
    ``"EXTRACT_OR_PIV_OUTSIDE"`` for decentralised MEV). A `None` field means
    "leave the baseline value unchanged".
    """

    mechanical_ventilation_kind: Optional[str] = None


@dataclass(frozen=True)
class WindowOverlay:
    """All-optional partial of one `SapWindow` — the change a glazing Measure
    makes to a single window (ADR-0022).

    `glazing_type` is the SAP10.2 Table U2 code (drives only the §5 daylight
    factor when a per-window U is lodged). `u_value` and `solar_transmittance`
    are written into the window's `WindowTransmissionDetails` — where the
    calculator reads heat loss and solar gain from — because our calculator
    consumes the lodged values directly rather than deriving them from
    `glazing_type`. A `None` field means "leave the baseline value unchanged".
    """

    glazing_type: Optional[int] = None
    u_value: Optional[float] = None
    solar_transmittance: Optional[float] = None


@dataclass(frozen=True)
class LightingOverlay:
    """All-optional partial of the dwelling's fixed-lighting bulb counts — the
    whole-dwelling lighting change a Measure Option makes (e.g. an all-LED
    upgrade — ADR-0023). Unlike a `BuildingPartOverlay` or `WindowOverlay` this
    targets no building part or window; its fields are the four **top-level**
    `EpcPropertyData` bulb counts, folded directly by name.

    The counts are absolute target states, not deltas (an all-LED upgrade sets
    ``led = total``, the rest 0). A `None` field means "leave the baseline value
    unchanged".
    """

    led_fixed_lighting_bulbs_count: Optional[int] = None
    cfl_fixed_lighting_bulbs_count: Optional[int] = None
    incandescent_fixed_lighting_bulbs_count: Optional[int] = None
    low_energy_fixed_lighting_bulbs_count: Optional[int] = None


def _no_building_parts() -> dict[BuildingPartIdentifier, BuildingPartOverlay]:
    return {}


def _no_windows() -> dict[int, WindowOverlay]:
    return {}


@dataclass(frozen=True)
class EpcSimulation:
    """A Simulation Overlay: the per-building-part changes a Measure Option
    makes, keyed by `BuildingPartIdentifier`; per-window changes keyed by the
    `sap_windows` index; plus an optional whole-dwelling `ventilation` change
    (the Measure Dependency surface — ADR-0016)."""

    building_parts: Mapping[BuildingPartIdentifier, BuildingPartOverlay] = field(
        default_factory=_no_building_parts
    )
    windows: Mapping[int, WindowOverlay] = field(default_factory=_no_windows)
    ventilation: Optional[VentilationOverlay] = None
    lighting: Optional[LightingOverlay] = None