from datetime import date
from decimal import Decimal

from app.engine.projection import project


def test_low_point_and_threshold():
    flows = [(date(2026, 8, 1), Decimal("-150")), (date(2026, 8, 10), Decimal("200"))]
    p = project(Decimal("100"), date(2026, 7, 31), flows, horizon_days=15,
                threshold=Decimal("60"))
    assert p.low_point == (date(2026, 8, 1), Decimal("-50"))
    assert p.first_below_zero == date(2026, 8, 1)
    assert p.first_below_threshold == date(2026, 8, 1)
    assert p.series[-1][1] == Decimal("150")


def test_no_crossing():
    p = project(Decimal("100"), date(2026, 7, 31), [], horizon_days=5)
    assert p.first_below_zero is None
    assert p.low_point[1] == Decimal("100")


def test_cashflow_on_start_date_excluded():
    """Cashflows dated exactly on start_date are excluded (part of starting balance)"""
    p = project(Decimal("100"), date(2026, 8, 1), [(date(2026, 8, 1), Decimal("-999"))],
                horizon_days=5)
    # All balances remain 100 because the -999 flow on start_date is ignored
    assert all(bal == Decimal("100") for _, bal in p.series)
    assert p.first_below_zero is None
    assert p.low_point[1] == Decimal("100")