/**
 * Reverse geocoding for spot/shop location tags
 * ─────────────────────────────────────────────────────────────────────────────
 * Turns a pin into `city` / `country` / `country_code` tags via OpenStreetMap
 * **Nominatim**. Best-effort by design — it never throws, so a geocoder outage
 * can never block a publish.
 *
 * ⚠️ Nominatim sees the caller's IP. That is disclosed in `/privacy` →
 * "What leaves your device" → *Spot geocoding*. The coordinates are the
 * **spot/shop pin**, never the device's live GPS.
 *
 * Single source of truth for the request (spot create, shop create, shop edit),
 * so the `Accept-Language: en` + parse rules can't drift between callers.
 */

export interface GeocodedRegions {
  /** Best available human city/town/village/county name. */
  city: string;
  /** Nominatim's display country name (e.g. "United Kingdom"). */
  country: string;
  /** Region/state, used to build a readable location string. */
  state: string;
  /** ISO-3166-1 alpha-2, uppercased (e.g. "GB"). The stable stats grouping key. */
  countryCode: string;
}

const EMPTY: GeocodedRegions = { city: '', country: '', state: '', countryCode: '' };

/** Best-effort reverse geocode. Resolves to empty strings on any failure. */
export async function reverseGeocodeRegions(lat: number, lng: number): Promise<GeocodedRegions> {
  try {
    const res = await fetch(
      `https://nominatim.openstreetmap.org/reverse?lat=${lat}&lon=${lng}&format=json&zoom=10`,
      { headers: { 'Accept-Language': 'en', 'User-Agent': 'SkateSpots/1.0' } },
    );
    if (!res.ok) return EMPTY;
    const data = (await res.json()) as { address?: Record<string, string> };
    const addr = data.address ?? {};
    return {
      city: addr.city ?? addr.town ?? addr.village ?? addr.county ?? '',
      country: addr.country ?? '',
      state: addr.state ?? '',
      countryCode: String(addr.country_code ?? '').trim().toUpperCase(),
    };
  } catch {
    return EMPTY;
  }
}

/** Push the region tags onto an event tag list, skipping empty values. */
export function pushRegionTags(tags: string[][], geo: GeocodedRegions): void {
  if (geo.city) tags.push(['city', geo.city]);
  if (geo.country) tags.push(['country', geo.country]);
  if (geo.countryCode) tags.push(['country_code', geo.countryCode]);
}