"""Open-Meteo wrapper. Free, no key needed. Resolves to (lat, lon) — block,
district, or state centroid — depending on what the caller has.
"""
from __future__ import annotations
import logging
from functools import lru_cache
from typing import Optional

import httpx

from kcc_core import config

logger = logging.getLogger(__name__)


@lru_cache(maxsize=4096)
def forecast(lat: float, lon: float, days: int = 7) -> dict:
    """7-day forecast cached per (lat, lon) at ~3 decimal resolution."""
    url = (f"{config.OPEN_METEO_BASE}"
           f"?latitude={lat:.3f}&longitude={lon:.3f}"
           f"&daily=temperature_2m_max,temperature_2m_min,relative_humidity_2m_mean,"
           f"precipitation_sum,wind_speed_10m_max,weathercode"
           f"&current_weather=true&timezone=Asia%2FKolkata"
           f"&forecast_days={min(max(days,1),16)}")
    try:
        r = httpx.get(url, timeout=12.0)
        r.raise_for_status()
        return r.json()
    except Exception as e:
        logger.warning(f"[weather] failed for ({lat},{lon}): {e}")
        return {}


def summary(lat: float, lon: float) -> dict:
    """Compact summary: temp_mean, humidity_mean, rain_mm_7d, hot_days,
    rain_days, dominant_weathercode."""
    fc = forecast(lat, lon, days=7)
    daily = fc.get("daily", {})
    if not daily:
        return {}
    tmax = daily.get("temperature_2m_max", [])
    tmin = daily.get("temperature_2m_min", [])
    hum  = daily.get("relative_humidity_2m_mean", [])
    rain = daily.get("precipitation_sum", [])
    if not tmax:
        return {}
    n = len(tmax)
    tmean = [(a + b) / 2 for a, b in zip(tmax, tmin) if a is not None and b is not None]
    return {
        "temp_mean":      round(sum(tmean) / max(len(tmean), 1), 1),
        "temp_max":       max(tmax) if tmax else None,
        "temp_min":       min(tmin) if tmin else None,
        "humidity_mean":  round(sum(hum) / max(len(hum), 1), 1) if hum else None,
        "rain_mm_7d":     round(sum(rain), 1) if rain else 0.0,
        "rain_days":      sum(1 for r in (rain or []) if (r or 0) > 1.0),
        "hot_days":       sum(1 for t in tmax if t and t >= 35),
        "days":           n,
    }