# apis/rest_countries.py
"""Country metadata from the REST Countries API with static fallback."""

from __future__ import annotations

from functools import lru_cache
from pathlib import Path
from typing import Any

import requests
import yaml

REST_COUNTRIES_URL = (
    "https://restcountries.com/v3.1/all"
    "?fields=name,cca2,cca3,region,subregion,capital,flags,latlng,area"
)
FALLBACK_PATH = Path(__file__).resolve().parents[1] / "data" / "countries_fallback.yaml"


@lru_cache(maxsize=1)
def _fallback_index() -> dict[str, dict[str, Any]]:
    with FALLBACK_PATH.open(encoding="utf-8") as handle:
        raw = yaml.safe_load(handle) or {}
    by_iso2: dict[str, dict[str, Any]] = {}
    by_iso3: dict[str, dict[str, Any]] = {}
    for iso2, entry in raw.items():
        normalized = {
            "name": entry["name"],
            "lat": float(entry["lat"]),
            "lng": float(entry["lng"]),
            "cca2": str(entry["cca2"]).upper(),
            "cca3": str(entry["cca3"]).upper(),
            "region": entry.get("region"),
            "subregion": entry.get("subregion"),
            "capital": entry.get("capital") or [],
            "area": entry.get("area"),
            "flag": entry.get("flag"),
            "flag_alt": entry.get("flag_alt"),
        }
        by_iso2[normalized["cca2"]] = normalized
        by_iso3[normalized["cca3"]] = normalized
    return {"iso2": by_iso2, "iso3": by_iso3}


def _entry_from_api_country(country: dict[str, Any]) -> dict[str, Any] | None:
    latlng = country.get("latlng")
    if not latlng or len(latlng) != 2:
        return None

    lat, lng = latlng
    if not isinstance(lat, (int, float)) or not isinstance(lng, (int, float)):
        return None

    return {
        "name": country["name"]["common"],
        "lat": float(lat),
        "lng": float(lng),
        "cca2": country.get("cca2", "").upper(),
        "cca3": country.get("cca3", "").upper(),
        "region": country.get("region"),
        "subregion": country.get("subregion"),
        "capital": country.get("capital") or [],
        "area": country.get("area"),
        "flag": (country.get("flags") or {}).get("png")
        or (country.get("flags") or {}).get("svg"),
        "flag_alt": (country.get("flags") or {}).get("alt"),
    }


@lru_cache(maxsize=1)
def _country_index() -> dict[str, dict[str, Any]]:
    by_iso2: dict[str, dict[str, Any]] = {}
    by_iso3: dict[str, dict[str, Any]] = {}

    try:
        resp = requests.get(REST_COUNTRIES_URL, timeout=20)
        resp.raise_for_status()
        payload = resp.json()
        if isinstance(payload, list):
            for country in payload:
                if not isinstance(country, dict):
                    continue
                entry = _entry_from_api_country(country)
                if not entry:
                    continue
                if entry["cca2"]:
                    by_iso2[entry["cca2"]] = entry
                if entry["cca3"]:
                    by_iso3[entry["cca3"]] = entry
    except Exception:
        pass

    if by_iso2:
        return {"iso2": by_iso2, "iso3": by_iso3}

    return _fallback_index()


def lookup_country(code: str) -> dict[str, Any] | None:
    normalized = (code or "").strip().upper()
    if not normalized:
        return None

    index = _country_index()
    if len(normalized) == 2:
        return index["iso2"].get(normalized)
    if len(normalized) == 3:
        return index["iso3"].get(normalized)
    return index["iso2"].get(normalized) or index["iso3"].get(normalized)