"""The dated price lookup: carry forward, never backward, and know when it is stale."""

from datetime import date, timedelta
from decimal import Decimal

from fintracker.pricing.prices import STALE_AFTER_DAYS, PriceTable, Quote

D = Decimal
GAZP, TBRU = 10, 11


def table() -> PriceTable:
    return PriceTable(
        {
            GAZP: [
                Quote(D(100), "RUB", date(2025, 3, 3)),
                Quote(D(110), "RUB", date(2025, 3, 6), accrued_interest=D(5)),
            ]
        },
        {GAZP: Quote(D(120), "RUB", date(2025, 3, 10))},
    )


def at(d: date, instrument_id: int = GAZP) -> Quote:
    quote = table().at(instrument_id, d)
    assert quote is not None
    return quote


def latest(d: date, instrument_id: int = GAZP) -> Quote:
    quote = table().latest(instrument_id, d)
    assert quote is not None
    return quote


def test_a_quiet_day_reuses_the_last_close():
    assert at(date(2025, 3, 5)).price == D(100)


def test_there_is_no_price_before_the_first_quote():
    assert table().at(GAZP, date(2025, 3, 2)) is None
    assert table().at(TBRU, date(2025, 3, 5)) is None


def test_staleness_is_measured_from_the_day_the_price_was_quoted():
    quoted = date(2025, 3, 6)
    quote = at(quoted + timedelta(days=30))
    assert quote.as_of == quoted
    assert not quote.is_stale_on(quoted + timedelta(days=STALE_AFTER_DAYS))
    assert quote.is_stale_on(quoted + timedelta(days=STALE_AFTER_DAYS + 1))


def test_total_adds_accrued_interest():
    assert at(date(2025, 3, 6)).total == D(115)
    assert at(date(2025, 3, 3)).total == D(100)


def test_the_intraday_price_wins_once_the_daily_bar_is_behind():
    assert latest(date(2025, 3, 11)).price == D(120)
    # …but never a price from the future of the day being valued
    assert latest(date(2025, 3, 7)).price == D(110)


def test_price_last_alone_is_enough_to_value_an_instrument():
    only_last = PriceTable({}, {TBRU: Quote(D(7), "RUB", date(2025, 3, 10))})
    assert only_last.at(TBRU, date(2025, 3, 10)) is None
    quote = only_last.latest(TBRU, date(2025, 3, 10))
    assert quote is not None and quote.price == D(7)