"""Spend model: per-Case real-GBP spend, COL-scaled by country.

London is the identity baseline (ratios = 1.0); cheaper countries scale the
COL-driven buckets (rent, non-rent essentials, kids) down while Holidays stay
fixed. The ×1.5 safety multiplier applies to the whole spend.
"""
from __future__ import annotations

import pytest

from fire_planner.spend_model import (
    ANCA,
    LONDON_RATIOS,
    VIKTOR,
    Case,
    ColRatios,
    case_base_spend,
    col_ratios_from_snapshot,
    kids_annual_spend,
    scaled_person_spend,
)


def test_london_identity_is_raw_sum() -> None:
    # Viktor's measured buckets sum to his nominal trailing-12mo spend.
    assert scaled_person_spend(VIKTOR, LONDON_RATIOS) == pytest.approx(40_492.0, abs=1.0)


def test_holidays_are_fixed_across_countries() -> None:
    cheap = ColRatios(rent_ratio=0.5, non_rent_ratio=0.5)
    scaled = scaled_person_spend(VIKTOR, cheap)
    # rent + non-rent halve; holidays unchanged.
    expected = VIKTOR.rent * 0.5 + VIKTOR.non_rent_usual * 0.5 + VIKTOR.holidays
    assert scaled == pytest.approx(expected)
    # Holidays floor: spend can never drop below the fixed holiday spend.
    assert scaled > VIKTOR.holidays


def test_safety_multiplier_applies_to_case() -> None:
    solo = case_base_spend(Case.SOLO, LONDON_RATIOS)
    assert solo == pytest.approx(scaled_person_spend(VIKTOR, LONDON_RATIOS) * 1.5)


def test_household_adds_anca() -> None:
    hh = case_base_spend(Case.HOUSEHOLD, LONDON_RATIOS)
    expected = (scaled_person_spend(VIKTOR, LONDON_RATIOS)
                + scaled_person_spend(ANCA, LONDON_RATIOS)) * 1.5
    assert hh == pytest.approx(expected)
    # Household ~£82k * 1.5 ≈ £121.6k at London prices.
    assert hh == pytest.approx(121_638.0, abs=50.0)


def test_family_base_equals_household_kids_are_separate() -> None:
    # Kids are modelled as a cashflow, not folded into the GK spend target.
    assert case_base_spend(Case.FAMILY, LONDON_RATIOS) == pytest.approx(
        case_base_spend(Case.HOUSEHOLD, LONDON_RATIOS))


def test_kids_are_col_driven_and_safety_scaled() -> None:
    assert kids_annual_spend(LONDON_RATIOS) == pytest.approx(15_000 * 1.5)
    cheap = ColRatios(rent_ratio=0.3, non_rent_ratio=0.5)
    # Kids scale by the non-rent (services) ratio.
    assert kids_annual_spend(cheap) == pytest.approx(15_000 * 0.5 * 1.5)


def test_col_ratios_from_snapshot_sofia() -> None:
    # Sofia vs London (Numbeo, May 2026): rent 679/2317, no-rent 713/1092.
    r = col_ratios_from_snapshot(
        city_no_rent=713.0, city_rent_1bed=679.0,
        london_no_rent=1092.0, london_rent_1bed=2317.0,
    )
    assert r.rent_ratio == pytest.approx(679.0 / 2317.0)
    assert r.non_rent_ratio == pytest.approx(713.0 / 1092.0)


def test_cheaper_country_lowers_case_spend() -> None:
    sofia = col_ratios_from_snapshot(713.0, 679.0, 1092.0, 2317.0)
    assert case_base_spend(Case.SOLO, sofia) < case_base_spend(Case.SOLO, LONDON_RATIOS)