// Converts a Steam2 id ("STEAM_0:1:12345678", as stored by the plugin) into
// a Steam64 id, which is what profile URLs and avatar lookups need.
const STEAM64_BASE = 76561197960265728n;

export function steam2ToSteam64(steamId2: string): string | null {
  const match = /^STEAM_[0-5]:([01]):(\d+)$/.exec(steamId2.trim());
  if (!match) return null;
  const y = BigInt(match[1]);
  const z = BigInt(match[2]);
  return (STEAM64_BASE + y + z * 2n).toString();
}

export function steamProfileUrl(steamId2: string): string | null {
  const id64 = steam2ToSteam64(steamId2);
  return id64 ? `https://steamcommunity.com/profiles/${id64}` : null;
}

// Formats total minutes as "123h 45m" for display. Negative values (which
// shouldn't be possible, but have shown up from anomalous underlying data —
// e.g. a player_time counter that decreased between two session snapshots)
// are shown as "—" rather than a nonsensical negative duration.
export function formatMinutes(totalMinutes: number | null): string {
  if (totalMinutes == null || Number.isNaN(totalMinutes) || totalMinutes < 0) return '—';
  const h = Math.floor(totalMinutes / 60);
  const m = totalMinutes % 60;
  return `${h}h ${m}m`;
}

// ISO 3166-1 alpha-2 -> flag emoji, e.g. "DE" -> "🇩🇪". No external assets needed.
export function countryCodeToFlag(code: string | null): string {
  if (!code || code.length !== 2) return '🏳️';
  const codePoints = [...code.toUpperCase()].map((c) => 0x1f1a5 + c.charCodeAt(0));
  return String.fromCodePoint(...codePoints);
}

// ISO 3166-1 alpha-2 -> English display name, e.g. "DE" -> "Germany".
// Uses the built-in Intl.DisplayNames (Node 14+ / all modern browsers) —
// no extra dependency or lookup table needed.
const regionNames = new Intl.DisplayNames(['en'], { type: 'region' });
export function countryCodeToName(code: string | null): string {
  if (!code || code.length !== 2) return 'Unknown';
  try {
    return regionNames.of(code.toUpperCase()) ?? code;
  } catch {
    return code;
  }
}