"""Geolocation + sunrise/sunset lookup with a manual-refresh JSON cache."""

from __future__ import annotations

import json
import urllib.request
from datetime import datetime, tzinfo
from pathlib import Path
from typing import Optional


def to_local_hm(iso_utc: str, tz: Optional[tzinfo] = None) -> str:
    """Convert an ISO-8601 UTC timestamp to local HH:MM."""
    dt = datetime.fromisoformat(iso_utc)
    local = dt.astimezone(tz)  # tz=None -> system local zone
    return local.strftime("%H:%M")


def read_cache(path: Path) -> Optional[dict]:
    path = Path(path)
    if not path.exists():
        return None
    try:
        return json.loads(path.read_text())
    except (json.JSONDecodeError, OSError):
        return None


def write_cache(payload: dict, path: Path) -> None:
    path = Path(path)
    path.parent.mkdir(parents=True, exist_ok=True)
    path.write_text(json.dumps(payload, indent=2))


GEO_URL = "http://ip-api.com/json"
SUN_URL = "https://api.sunrise-sunset.org/json?lat={lat}&lng={lon}&formatted=0"


def _http_get(url: str, timeout: float = 10.0) -> str:
    with urllib.request.urlopen(url, timeout=timeout) as resp:
        return resp.read().decode()


def geolocate() -> tuple[str, str]:
    """Return (lat, lon) as strings from IP geolocation."""
    data = json.loads(_http_get(GEO_URL))
    return str(data["lat"]), str(data["lon"])


def fetch_sun(lat: str, lon: str) -> dict:
    """Fetch sunrise/sunset JSON for coords. Caller handles caching."""
    url = SUN_URL.format(lat=lat, lon=lon)
    return json.loads(_http_get(url))
