import importlib.util
from pathlib import Path

spec = importlib.util.spec_from_file_location("buy", Path(__file__).resolve().parent.parent / "tools" / "buy.py")
buy = importlib.util.module_from_spec(spec)
spec.loader.exec_module(buy)

BUILDINGS = [
    {"building_ticker": "HWP", "costs": [{"material_ticker": "BBH", "material_amount": 4}, {"material_ticker": "LTA", "material_amount": 2}], "area_cost": 25},
    {"building_ticker": "HB2", "costs": [{"material_ticker": "BTA", "material_amount": 2}], "area_cost": 12},
]
PLAN = {"plan_data": {"buildings": [{"name": "HWP", "amount": 1}], "infrastructure": [{"building": "HB2", "amount": 1}]}}


def test_construction_items_include_mcg_and_full_amount_when_nothing_built():
    need = buy.construction_items(PLAN, BUILDINGS, built={})
    assert need == {"BBH": 4, "LTA": 2, "MCG": 100 + 48, "BTA": 2}


def test_construction_items_gap_only_counts_unbuilt_units():
    need = buy.construction_items(PLAN, BUILDINGS, built={"HWP": 1, "HB2": 1})
    assert need == {}                                  # already fully built: nothing to buy


def test_construction_items_partial_gap():
    plan = {"plan_data": {"buildings": [{"name": "HWP", "amount": 3}], "infrastructure": []}}
    need = buy.construction_items(plan, BUILDINGS, built={"HWP": 1})
    assert need == {"BBH": 8, "LTA": 4, "MCG": 200}     # 2 more HWP needed, not 3


def test_stock_items_only_keeps_net_consumption():
    flows = {"C": {"inp": 11.13, "out": 0}, "AL": {"inp": 42.78, "out": 44.57}, "BHP": {"inp": 0, "out": 14.26}}
    got = buy.stock_items(flows, days=2)
    assert got == {"C": 22.26}                          # AL nets to +1.78/day (own smelters cover the HWP): not bought


def test_net_of_on_hand_floors_at_zero():
    got = buy.net_of_on_hand({"C": 20, "O": 5}, {"C": 30, "O": 2})
    assert got == {"C": 0.0, "O": 3.0}