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

import polars as pl

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 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)