"""Per-Measure-Type contingency rates.

The one cost component carried separately from a Product's fully-loaded total
(CONTEXT.md). Mirrors the legacy `recommendations/Costs.py::Costs.CONTINGENCIES`;
extended as each measure type lands.
"""

_CONTINGENCY_RATES: dict[str, float] = {
    "cavity_wall_insulation": 0.10,
    "loft_insulation": 0.10,
    "sloping_ceiling_insulation": 0.10,
    "flat_roof_insulation": 0.10,
    "suspended_floor_insulation": 0.20,
    "solid_floor_insulation": 0.26,
    "mechanical_ventilation": 0.26,
    "external_wall_insulation": 0.26,
    "internal_wall_insulation": 0.26,
    "double_glazing": 0.15,
    "secondary_glazing": 0.15,
    "low_energy_lighting": 0.26,
    "high_heat_retention_storage_heaters": 0.10,
    "air_source_heat_pump": 0.25,
    "gas_boiler_upgrade": 0.26,
    "system_tune_up": 0.10,
    "system_tune_up_zoned": 0.10,
    "solar_pv": 0.15,
    # Decommissioning a fixed secondary heater + localised making-good is small,
    # uncertain work: the rate covers the unknown heater count / hard-wired vs
    # plugged status / repaint extent (ADR-0028).
    "secondary_heating_removal": 0.25,
}


def contingency_rate(measure_type: str) -> float:
    """Return the contingency rate for a Measure Type, raising if unknown
    (strict — do not silently default, per the repo's strict-raise convention)."""
    try:
        return _CONTINGENCY_RATES[measure_type]
    except KeyError as exc:
        raise ValueError(
            f"no contingency rate configured for measure type {measure_type!r}"
        ) from exc