from __future__ import annotations

from datetime import date
from decimal import Decimal
from pathlib import Path

import httpx
import pytest

from broker_sync.fx import FxCache
from broker_sync.fx_ecb import (
    fetch_ecb_rates,
    fetch_ecb_rates_historical,
    populate_fx_cache,
)
from broker_sync.models import FxRateSource

_FIXTURE = Path(__file__).parent / "fixtures" / "ecb_2026-04-01.xml"


def _transport_serving_fixture() -> httpx.MockTransport:
    xml = _FIXTURE.read_text()

    def handler(req: httpx.Request) -> httpx.Response:
        assert req.url.host == "www.ecb.europa.eu"
        assert req.url.path.endswith("/eurofxref-daily.xml")
        return httpx.Response(200, content=xml, headers={"content-type": "application/xml"})

    return httpx.MockTransport(handler)


async def test_fetch_returns_dict_of_decimals() -> None:
    rates = await fetch_ecb_rates(date(2026, 4, 1), transport=_transport_serving_fixture())
    # GBP is rebased to 1.0 (everything else is rate_to_GBP).
    assert rates["GBP"] == Decimal("1")
    # USD: ECB says EUR→USD = 1.0823, EUR→GBP = 0.8564.
    # Therefore USD→GBP = 0.8564 / 1.0823 ≈ 0.7913...
    assert rates["USD"] == Decimal("0.8564") / Decimal("1.0823")
    # EUR→GBP = 0.8564 directly.
    assert rates["EUR"] == Decimal("0.8564")
    # JPY is a tiny number: 0.8564 / 163.45 ≈ 0.00524
    assert rates["JPY"] == Decimal("0.8564") / Decimal("163.45")


async def test_fetch_rejects_non_2xx() -> None:

    def handler(req: httpx.Request) -> httpx.Response:
        return httpx.Response(503)

    with pytest.raises(RuntimeError, match="ECB"):
        await fetch_ecb_rates(date(2026, 4, 1), transport=httpx.MockTransport(handler))


async def test_populate_fx_cache_writes_non_gbp(tmp_path: Path) -> None:
    cache = FxCache(tmp_path / "fx.db")
    rates = {
        "GBP": Decimal("1"),
        "USD": Decimal("0.79"),
        "EUR": Decimal("0.86"),
    }
    await populate_fx_cache(cache, rates, date(2026, 4, 1))

    # GBP is not stored — convert_to_gbp handles it via the passthrough rule.
    assert cache.get("GBP", date(2026, 4, 1)) is None

    usd = cache.get("USD", date(2026, 4, 1))
    assert usd is not None
    assert usd[0] == Decimal("0.79")
    assert usd[1] is FxRateSource.ECB_LIVE

    eur = cache.get("EUR", date(2026, 4, 1))
    assert eur is not None
    assert eur[0] == Decimal("0.86")


async def test_fetch_historical_raises_not_implemented() -> None:
    with pytest.raises(NotImplementedError):
        await fetch_ecb_rates_historical(date(2020, 1, 1), date(2026, 1, 1))