"""Allocation rules on synthetic holdings — no database."""

from decimal import Decimal

from fintracker.analytics.allocation import CASH, UNKNOWN, Holding, bucket_of, split, weigh
from fintracker.models import AllocationDimension

D = Decimal
DIM = AllocationDimension


def holding(
    instrument_id: int,
    value: str,
    *,
    asset_class: str = "share",
    sector: str | None = "energy",
    country: str | None = "RU",
    currency: str = "RUB",
) -> Holding:
    return Holding(
        instrument_id=instrument_id,
        value_rub=D(value),
        asset_class=asset_class,
        sector=sector,
        country=country,
        currency=currency,
    )


def test_buckets_are_summed_per_dimension_and_sorted_by_value():
    rows = split(
        [
            holding(1, "100", asset_class="share"),
            holding(2, "300", asset_class="bond"),
            holding(3, "50", asset_class="share"),
        ],
        {},
        DIM.asset_class,
    )
    assert rows == [("bond", D(300), 1), ("share", D(150), 2)]


def test_cash_is_its_own_bucket_everywhere_but_the_currency_chart():
    holdings = [holding(1, "900", currency="RUB")]
    for dimension in (DIM.asset_class, DIM.sector, DIM.country):
        assert (CASH, D(100), 0) in split(holdings, {"RUB": D(100)}, dimension)
    # the currency question is "how exposed am I to this money", and cash is exposure too
    assert split(holdings, {"RUB": D(100)}, DIM.currency) == [("RUB", D(1000), 1)]


def test_an_unfilled_attribute_becomes_its_own_bucket_not_a_guess():
    rows = split([holding(1, "100", sector=None, country=None)], {}, DIM.sector)
    assert rows == [(UNKNOWN, D(100), 1)]
    assert bucket_of(holding(1, "1", country=None), DIM.country) == UNKNOWN


def test_every_dimension_covers_the_same_total():
    holdings = [
        holding(1, "600", asset_class="bond", sector="gov", country="RU", currency="RUB"),
        holding(2, "400", asset_class="etf", sector=None, country="US", currency="USD"),
    ]
    cash = {"RUB": D(200)}
    totals = {
        dimension: sum(value for _, value, _ in split(holdings, cash, dimension))
        for dimension in AllocationDimension
    }
    assert set(totals.values()) == {D(1200)}


def test_weights_add_up_to_one():
    weighted = weigh(
        split([holding(1, "300"), holding(2, "100")], {"RUB": D(100)}, DIM.asset_class)
    )
    assert sum(w for _, _, _, w in weighted) == D(1)


def test_a_short_keeps_its_value_but_does_not_inflate_the_longs():
    weighted = weigh([("share", D(100), 1), ("bond", D(-50), 1)])
    shares = next(row for row in weighted if row[0] == "share")
    shorts = next(row for row in weighted if row[0] == "bond")
    assert shares[3] == D(1)
    assert shorts[1] == D(-50)


def test_an_empty_portfolio_has_no_buckets():
    assert split([], {}, DIM.asset_class) == []
    assert weigh([]) == []