"""The source→frame mappings and cache-write path (pure parts of climate.py —
no network)."""
import datetime

import polars as pl
import pytest

import climate


def _om_daily(n=3):
    """A minimal Open-Meteo daily response."""
    return {
        "time": [f"2026-06-{d:02d}" for d in range(1, n + 1)],
        "temperature_2m_max": [80.0, 90.0, None],
        "temperature_2m_min": [60.0, 70.0, 55.0],
        "precipitation_sum": [0.0, 0.25, 0.1],
        "wind_speed_10m_max": [10.0, 20.0, 5.0],
        "wind_gusts_10m_max": [15.0, 30.0, 8.0],
        "apparent_temperature_max": [82.0, 95.0, 70.0],
        "apparent_temperature_min": [58.0, 68.0, 50.0],
        "relative_humidity_2m_mean": [50.0, 60.0, 70.0],
    }


def test_to_frame_schema_and_day_filter():
    df = climate._to_frame(_om_daily())
    # The None tmax day is dropped: a usable climate day needs a real high/low.
    assert len(df) == 2
    assert df["doy"].dtype == pl.Int16
    assert set(df.columns) == {"date", "tmax", "tmin", "precip", "wind", "gust",
                               "humid", "fmax", "fmin", "feels", "doy"}


def test_to_frame_tolerates_missing_series():
    daily = _om_daily()
    del daily["wind_gusts_10m_max"], daily["relative_humidity_2m_mean"]
    df = climate._to_frame(daily)
    assert df["gust"].is_null().all() and df["humid"].is_null().all()
    assert df["tmax"].is_not_null().all()   # required series unaffected


def test_combined_feels_picks_the_extreme_side():
    df = climate._to_frame(_om_daily())
    # Day 2: fmax 95 is 30 past the 65°F comfort point vs fmin 68 only 3 below —
    # the hot side wins; both days here are hot-side days.
    assert df.filter(pl.col("date") == datetime.date(2026, 6, 2))["feels"].item() == 95.0


def test_combined_feels_falls_back_to_the_present_side():
    """When one apparent-temperature side is missing, `feels` uses whichever side
    is present (the null-vs-value coalesce must reproduce the old NaN fallback)."""
    daily = _om_daily()
    daily["apparent_temperature_max"] = [None, None, None]   # hot side absent
    df = climate._to_frame(daily)
    row = df.filter(pl.col("date") == datetime.date(2026, 6, 1)).row(0, named=True)
    assert row["feels"] == 58.0                              # falls back to apparent low


def test_nasa_to_frame_converts_units_and_fills():
    param = {
        "T2M_MAX": {"20260601": 30.0, "20260602": -999.0},   # °C; -999 = missing
        "T2M_MIN": {"20260601": 20.0, "20260602": 15.0},
        "PRECTOTCORR": {"20260601": 25.4, "20260602": 0.0},  # mm
        "WS10M_MAX": {"20260601": 10.0, "20260602": 5.0},    # m/s
        "RH2M": {"20260601": 50.0, "20260602": 60.0},
    }
    df = climate._nasa_to_frame(param)
    assert len(df) == 1                                   # the missing-tmax day dropped
    row = df.row(0, named=True)
    assert row["tmax"] == 86.0                            # 30°C
    assert row["precip"] == 1.0                           # 25.4mm = 1in
    assert round(row["wind"], 1) == 22.4                  # 10 m/s in mph
    assert row["gust"] is None                            # POWER has no gusts (missing -> null)
    assert row["fmax"] > row["tmax"]                      # ≥80°F: the NWS heat index applies


def _metno_step(time, t, rh, wind, p1=None, p6=None):
    """One MET Norway timeseries step (instant details + optional precip blocks)."""
    data = {"instant": {"details": {
        "air_temperature": t, "relative_humidity": rh, "wind_speed": wind}}}
    if p1 is not None:
        data["next_1_hours"] = {"details": {"precipitation_amount": p1}}
    if p6 is not None:
        data["next_6_hours"] = {"details": {"precipitation_amount": p6}}
    return {"time": time, "data": data}


def test_metno_to_frame_aggregates_daily_and_converts_units():
    props = {"timeseries": [
        # Day 1: two hourly steps. The first also carries a next_6_hours block, which
        # must be IGNORED (next_1_hours wins) so precip isn't double-counted.
        _metno_step("2026-07-16T00:00:00Z", 20.0, 50.0, 2.0, p1=0.5, p6=3.0),
        _metno_step("2026-07-16T01:00:00Z", 25.0, 60.0, 4.0, p1=0.5),
        # Day 2: a 6-hourly step (only next_6_hours) + an instant-only tail step.
        _metno_step("2026-07-17T00:00:00Z", 10.0, 80.0, 10.0, p6=6.0),
        _metno_step("2026-07-17T06:00:00Z", 12.0, 70.0, 8.0),
    ]}
    df = climate._metno_to_frame(props)
    assert len(df) == 2
    d1 = df.filter(pl.col("date") == datetime.date(2026, 7, 16)).row(0, named=True)
    assert d1["tmax"] == 77.0 and d1["tmin"] == 68.0          # 25°C / 20°C -> °F
    assert round(d1["precip"], 4) == round(1.0 / 25.4, 4)     # 0.5+0.5 mm (not +3.0) -> in
    assert round(d1["wind"], 1) == 8.9                        # max 4 m/s -> mph
    assert d1["gust"] is None                                 # MET Norway has no gusts
    assert d1["feels"] is not None
    d2 = df.filter(pl.col("date") == datetime.date(2026, 7, 17)).row(0, named=True)
    assert round(d2["precip"], 4) == round(6.0 / 25.4, 4)     # only the 6-hour block


def test_recent_forecast_falls_back_to_metno(monkeypatch, tmp_path):
    """When Open-Meteo's forecast API fails, the MET Norway backup serves the frame."""
    monkeypatch.setattr(climate, "CACHE_DIR", str(tmp_path))
    cell = {"id": "fallback_cell", "center_lat": 47.6062, "center_lon": -122.3321}
    met = {"timeseries": [
        _metno_step("2026-07-16T00:00:00Z", 18.0, 55.0, 3.0, p1=0.0),
        _metno_step("2026-07-17T00:00:00Z", 22.0, 45.0, 5.0, p6=1.0),
    ]}

    class Resp:
        def json(self): return {"properties": met}

    def fake_request(url, params, timeout, *, phase, headers=None, attempts=climate.MAX_ATTEMPTS):
        if url == climate.FORECAST_URL:
            raise RuntimeError("open-meteo forecast outage")
        assert url == climate.METNO_URL
        assert headers and headers.get("User-Agent"), "MET Norway needs a User-Agent"
        return Resp()

    monkeypatch.setattr(climate, "_request", fake_request)
    df = climate._load_recent_forecast(cell)
    assert len(df) == 2 and df["date"].max() == datetime.date(2026, 7, 17)


def test_recent_forecast_serves_stale_cache_when_all_sources_fail(monkeypatch, tmp_path):
    """With Open-Meteo AND MET Norway both down, an existing (stale) cache is served
    rather than failing — and it is NOT rewritten, so its mtime stays old and the
    next request still retries upstream first."""
    import os
    import time
    monkeypatch.setattr(climate, "CACHE_DIR", str(tmp_path))
    cell = {"id": "stale_cell", "center_lat": 47.6, "center_lon": -122.3}
    # Seed an rf cache, then age it well past the TTL so it counts as stale.
    stale = climate._to_frame(_om_daily())
    path = climate._rf_cache_path(cell["id"])
    climate._write_cache(stale, path)
    old = time.time() - (climate.FORECAST_TTL_HOURS + 5) * 3600
    os.utime(path, (old, old))

    def all_down(url, params, timeout, *, phase, headers=None, attempts=climate.MAX_ATTEMPTS):
        raise RuntimeError(f"{phase} down")
    monkeypatch.setattr(climate, "_request", all_down)

    df = climate._load_recent_forecast(cell)
    assert df.height == stale.height                    # served the stale cache
    assert abs(os.path.getmtime(path) - old) < 2        # not rewritten (mtime unchanged)


def test_om_daily_params_carries_the_window():
    cell = {"center_lat": 47.6, "center_lon": -122.3}
    p = climate._om_daily_params(cell, start_date="2026-01-01", end_date="2026-02-01")
    assert p["latitude"] == 47.6 and p["daily"] == climate.DAILY_VARS
    assert p["temperature_unit"] == "fahrenheit"
    assert p["start_date"] == "2026-01-01" and p["end_date"] == "2026-02-01"
    p2 = climate._om_daily_params(cell, past_days=25, forecast_days=8)
    assert p2["past_days"] == 25 and "start_date" not in p2


def test_write_cache_strips_the_derived_doy(tmp_path):
    df = climate._to_frame(_om_daily())
    path = str(tmp_path / "cell.parquet")
    climate._write_cache(df, path)
    stored = pl.read_parquet(path)
    assert "doy" not in stored.columns
    assert len(stored) == len(df)


def _wb_frame(tmax, humid, tmin=None):
    """Frame with raw RH (`humid`) for the wet-bulb / humidity derivations."""
    n = len(tmax)
    return pl.DataFrame({
        "date": [datetime.date(2026, 7, 1) + datetime.timedelta(days=i) for i in range(n)],
        "tmax": [float(x) for x in tmax],
        "tmin": [float(t) for t in (tmin or [x - 15 for x in tmax])],
        "humid": [float(h) for h in humid],
    })


def test_wetbulb_stull_spot_values():
    # Stull (2011): 20 °C / 50% -> ~13.7 °C; 30 °C / 80% -> ~27.2 °C. In °F here.
    df = climate._derive_wetbulb(_wb_frame([68.0, 86.0], [50.0, 80.0]))
    wb = df["wetbulb"].to_list()
    assert wb[0] == pytest.approx((13.7 * 9 / 5) + 32, abs=0.6)
    assert wb[1] == pytest.approx((27.2 * 9 / 5) + 32, abs=0.6)


def test_wetbulb_never_exceeds_dry_bulb():
    df = climate._derive_wetbulb(_wb_frame([40.0, 60.0, 85.0, 100.0], [20.0, 55.0, 70.0, 95.0]))
    for tmax, wb in zip(df["tmax"], df["wetbulb"]):
        assert wb is not None and wb <= tmax + 0.05


def test_wetbulb_null_outside_validity_range():
    # RH 3% (< 5) and a scorching 130 °F (> 50 °C) both fall outside Stull's fit.
    df = climate._derive_wetbulb(_wb_frame([70.0, 130.0], [3.0, 40.0]))
    assert df["wetbulb"].to_list() == [None, None]


def test_wetbulb_noop_without_humidity():
    df = pl.DataFrame({"tmax": [70.0], "tmin": [55.0]})
    assert "wetbulb" not in climate._derive_wetbulb(df).columns


def test_derive_metrics_adds_wetbulb_and_absolute_humidity():
    out = climate._derive_metrics(_wb_frame([68.0], [50.0]))
    assert "wetbulb" in out.columns
    # _derive_humidity replaces raw RH (50) with absolute humidity (g/m³, ~8-9).
    assert out["humid"][0] < 30 and out["humid"][0] != 50.0